mirror of
https://github.com/edk2-porting/linux-next.git
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927cfb9788
We don't care about layout, so advertise that fact. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2073 lines
58 KiB
C
2073 lines
58 KiB
C
/*P:100
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* This is the Launcher code, a simple program which lays out the "physical"
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* memory for the new Guest by mapping the kernel image and the virtual
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* devices, then opens /dev/lguest to tell the kernel about the Guest and
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* control it.
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:*/
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#define _LARGEFILE64_SOURCE
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#define _GNU_SOURCE
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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <err.h>
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#include <stdint.h>
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#include <stdlib.h>
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#include <elf.h>
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#include <sys/mman.h>
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#include <sys/param.h>
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/eventfd.h>
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#include <fcntl.h>
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#include <stdbool.h>
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#include <errno.h>
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#include <ctype.h>
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#include <sys/socket.h>
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#include <sys/ioctl.h>
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#include <sys/time.h>
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#include <time.h>
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#include <netinet/in.h>
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#include <net/if.h>
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#include <linux/sockios.h>
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#include <linux/if_tun.h>
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#include <sys/uio.h>
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#include <termios.h>
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#include <getopt.h>
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#include <assert.h>
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#include <sched.h>
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#include <limits.h>
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#include <stddef.h>
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#include <signal.h>
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#include <pwd.h>
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#include <grp.h>
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#ifndef VIRTIO_F_ANY_LAYOUT
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#define VIRTIO_F_ANY_LAYOUT 27
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#endif
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/*L:110
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* We can ignore the 43 include files we need for this program, but I do want
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* to draw attention to the use of kernel-style types.
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*
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* As Linus said, "C is a Spartan language, and so should your naming be." I
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* like these abbreviations, so we define them here. Note that u64 is always
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* unsigned long long, which works on all Linux systems: this means that we can
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* use %llu in printf for any u64.
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*/
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typedef unsigned long long u64;
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typedef uint32_t u32;
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typedef uint16_t u16;
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typedef uint8_t u8;
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/*:*/
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#include <linux/virtio_config.h>
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#include <linux/virtio_net.h>
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#include <linux/virtio_blk.h>
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#include <linux/virtio_console.h>
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#include <linux/virtio_rng.h>
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#include <linux/virtio_ring.h>
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#include <asm/bootparam.h>
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#include "../../include/linux/lguest_launcher.h"
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#define BRIDGE_PFX "bridge:"
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#ifndef SIOCBRADDIF
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#define SIOCBRADDIF 0x89a2 /* add interface to bridge */
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#endif
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/* We can have up to 256 pages for devices. */
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#define DEVICE_PAGES 256
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/* This will occupy 3 pages: it must be a power of 2. */
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#define VIRTQUEUE_NUM 256
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/*L:120
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* verbose is both a global flag and a macro. The C preprocessor allows
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* this, and although I wouldn't recommend it, it works quite nicely here.
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*/
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static bool verbose;
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#define verbose(args...) \
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do { if (verbose) printf(args); } while(0)
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/*:*/
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/* The pointer to the start of guest memory. */
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static void *guest_base;
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/* The maximum guest physical address allowed, and maximum possible. */
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static unsigned long guest_limit, guest_max;
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/* The /dev/lguest file descriptor. */
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static int lguest_fd;
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/* a per-cpu variable indicating whose vcpu is currently running */
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static unsigned int __thread cpu_id;
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/* This is our list of devices. */
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struct device_list {
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/* Counter to assign interrupt numbers. */
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unsigned int next_irq;
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/* Counter to print out convenient device numbers. */
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unsigned int device_num;
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/* The descriptor page for the devices. */
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u8 *descpage;
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/* A single linked list of devices. */
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struct device *dev;
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/* And a pointer to the last device for easy append. */
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struct device *lastdev;
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};
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/* The list of Guest devices, based on command line arguments. */
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static struct device_list devices;
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/* The device structure describes a single device. */
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struct device {
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/* The linked-list pointer. */
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struct device *next;
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/* The device's descriptor, as mapped into the Guest. */
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struct lguest_device_desc *desc;
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/* We can't trust desc values once Guest has booted: we use these. */
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unsigned int feature_len;
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unsigned int num_vq;
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/* The name of this device, for --verbose. */
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const char *name;
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/* Any queues attached to this device */
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struct virtqueue *vq;
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/* Is it operational */
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bool running;
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/* Device-specific data. */
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void *priv;
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};
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/* The virtqueue structure describes a queue attached to a device. */
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struct virtqueue {
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struct virtqueue *next;
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/* Which device owns me. */
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struct device *dev;
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/* The configuration for this queue. */
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struct lguest_vqconfig config;
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/* The actual ring of buffers. */
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struct vring vring;
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/* Last available index we saw. */
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u16 last_avail_idx;
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/* How many are used since we sent last irq? */
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unsigned int pending_used;
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/* Eventfd where Guest notifications arrive. */
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int eventfd;
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/* Function for the thread which is servicing this virtqueue. */
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void (*service)(struct virtqueue *vq);
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pid_t thread;
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};
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/* Remember the arguments to the program so we can "reboot" */
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static char **main_args;
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/* The original tty settings to restore on exit. */
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static struct termios orig_term;
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/*
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* We have to be careful with barriers: our devices are all run in separate
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* threads and so we need to make sure that changes visible to the Guest happen
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* in precise order.
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*/
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#define wmb() __asm__ __volatile__("" : : : "memory")
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#define rmb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
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#define mb() __asm__ __volatile__("lock; addl $0,0(%%esp)" : : : "memory")
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/* Wrapper for the last available index. Makes it easier to change. */
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#define lg_last_avail(vq) ((vq)->last_avail_idx)
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/*
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* The virtio configuration space is defined to be little-endian. x86 is
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* little-endian too, but it's nice to be explicit so we have these helpers.
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*/
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#define cpu_to_le16(v16) (v16)
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#define cpu_to_le32(v32) (v32)
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#define cpu_to_le64(v64) (v64)
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#define le16_to_cpu(v16) (v16)
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#define le32_to_cpu(v32) (v32)
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#define le64_to_cpu(v64) (v64)
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/* Is this iovec empty? */
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static bool iov_empty(const struct iovec iov[], unsigned int num_iov)
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{
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unsigned int i;
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for (i = 0; i < num_iov; i++)
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if (iov[i].iov_len)
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return false;
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return true;
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}
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/* Take len bytes from the front of this iovec. */
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static void iov_consume(struct iovec iov[], unsigned num_iov,
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void *dest, unsigned len)
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{
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unsigned int i;
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for (i = 0; i < num_iov; i++) {
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unsigned int used;
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used = iov[i].iov_len < len ? iov[i].iov_len : len;
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if (dest) {
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memcpy(dest, iov[i].iov_base, used);
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dest += used;
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}
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iov[i].iov_base += used;
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iov[i].iov_len -= used;
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len -= used;
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}
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if (len != 0)
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errx(1, "iovec too short!");
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}
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/* The device virtqueue descriptors are followed by feature bitmasks. */
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static u8 *get_feature_bits(struct device *dev)
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{
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return (u8 *)(dev->desc + 1)
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+ dev->num_vq * sizeof(struct lguest_vqconfig);
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}
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/*L:100
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* The Launcher code itself takes us out into userspace, that scary place where
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* pointers run wild and free! Unfortunately, like most userspace programs,
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* it's quite boring (which is why everyone likes to hack on the kernel!).
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* Perhaps if you make up an Lguest Drinking Game at this point, it will get
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* you through this section. Or, maybe not.
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*
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* The Launcher sets up a big chunk of memory to be the Guest's "physical"
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* memory and stores it in "guest_base". In other words, Guest physical ==
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* Launcher virtual with an offset.
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*
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* This can be tough to get your head around, but usually it just means that we
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* use these trivial conversion functions when the Guest gives us its
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* "physical" addresses:
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*/
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static void *from_guest_phys(unsigned long addr)
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{
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return guest_base + addr;
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}
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static unsigned long to_guest_phys(const void *addr)
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{
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return (addr - guest_base);
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}
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/*L:130
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* Loading the Kernel.
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*
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* We start with couple of simple helper routines. open_or_die() avoids
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* error-checking code cluttering the callers:
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*/
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static int open_or_die(const char *name, int flags)
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{
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int fd = open(name, flags);
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if (fd < 0)
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err(1, "Failed to open %s", name);
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return fd;
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}
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/* map_zeroed_pages() takes a number of pages. */
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static void *map_zeroed_pages(unsigned int num)
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{
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int fd = open_or_die("/dev/zero", O_RDONLY);
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void *addr;
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/*
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* We use a private mapping (ie. if we write to the page, it will be
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* copied). We allocate an extra two pages PROT_NONE to act as guard
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* pages against read/write attempts that exceed allocated space.
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*/
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addr = mmap(NULL, getpagesize() * (num+2),
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PROT_NONE, MAP_PRIVATE, fd, 0);
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if (addr == MAP_FAILED)
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err(1, "Mmapping %u pages of /dev/zero", num);
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if (mprotect(addr + getpagesize(), getpagesize() * num,
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PROT_READ|PROT_WRITE) == -1)
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err(1, "mprotect rw %u pages failed", num);
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/*
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* One neat mmap feature is that you can close the fd, and it
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* stays mapped.
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*/
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close(fd);
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/* Return address after PROT_NONE page */
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return addr + getpagesize();
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}
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/* Get some more pages for a device. */
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static void *get_pages(unsigned int num)
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{
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void *addr = from_guest_phys(guest_limit);
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guest_limit += num * getpagesize();
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if (guest_limit > guest_max)
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errx(1, "Not enough memory for devices");
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return addr;
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}
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/*
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* This routine is used to load the kernel or initrd. It tries mmap, but if
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* that fails (Plan 9's kernel file isn't nicely aligned on page boundaries),
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* it falls back to reading the memory in.
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*/
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static void map_at(int fd, void *addr, unsigned long offset, unsigned long len)
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{
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ssize_t r;
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/*
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* We map writable even though for some segments are marked read-only.
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* The kernel really wants to be writable: it patches its own
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* instructions.
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*
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* MAP_PRIVATE means that the page won't be copied until a write is
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* done to it. This allows us to share untouched memory between
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* Guests.
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*/
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if (mmap(addr, len, PROT_READ|PROT_WRITE,
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MAP_FIXED|MAP_PRIVATE, fd, offset) != MAP_FAILED)
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return;
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/* pread does a seek and a read in one shot: saves a few lines. */
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r = pread(fd, addr, len, offset);
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if (r != len)
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err(1, "Reading offset %lu len %lu gave %zi", offset, len, r);
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}
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/*
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* This routine takes an open vmlinux image, which is in ELF, and maps it into
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* the Guest memory. ELF = Embedded Linking Format, which is the format used
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* by all modern binaries on Linux including the kernel.
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*
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* The ELF headers give *two* addresses: a physical address, and a virtual
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* address. We use the physical address; the Guest will map itself to the
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* virtual address.
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*
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* We return the starting address.
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*/
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static unsigned long map_elf(int elf_fd, const Elf32_Ehdr *ehdr)
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{
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Elf32_Phdr phdr[ehdr->e_phnum];
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unsigned int i;
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/*
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* Sanity checks on the main ELF header: an x86 executable with a
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* reasonable number of correctly-sized program headers.
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*/
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if (ehdr->e_type != ET_EXEC
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|| ehdr->e_machine != EM_386
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|| ehdr->e_phentsize != sizeof(Elf32_Phdr)
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|| ehdr->e_phnum < 1 || ehdr->e_phnum > 65536U/sizeof(Elf32_Phdr))
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errx(1, "Malformed elf header");
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/*
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* An ELF executable contains an ELF header and a number of "program"
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* headers which indicate which parts ("segments") of the program to
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* load where.
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*/
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/* We read in all the program headers at once: */
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if (lseek(elf_fd, ehdr->e_phoff, SEEK_SET) < 0)
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err(1, "Seeking to program headers");
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if (read(elf_fd, phdr, sizeof(phdr)) != sizeof(phdr))
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err(1, "Reading program headers");
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/*
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* Try all the headers: there are usually only three. A read-only one,
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* a read-write one, and a "note" section which we don't load.
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*/
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for (i = 0; i < ehdr->e_phnum; i++) {
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/* If this isn't a loadable segment, we ignore it */
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if (phdr[i].p_type != PT_LOAD)
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continue;
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verbose("Section %i: size %i addr %p\n",
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i, phdr[i].p_memsz, (void *)phdr[i].p_paddr);
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/* We map this section of the file at its physical address. */
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map_at(elf_fd, from_guest_phys(phdr[i].p_paddr),
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phdr[i].p_offset, phdr[i].p_filesz);
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}
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/* The entry point is given in the ELF header. */
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return ehdr->e_entry;
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}
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/*L:150
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* A bzImage, unlike an ELF file, is not meant to be loaded. You're supposed
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* to jump into it and it will unpack itself. We used to have to perform some
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* hairy magic because the unpacking code scared me.
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*
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* Fortunately, Jeremy Fitzhardinge convinced me it wasn't that hard and wrote
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* a small patch to jump over the tricky bits in the Guest, so now we just read
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* the funky header so we know where in the file to load, and away we go!
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*/
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static unsigned long load_bzimage(int fd)
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{
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struct boot_params boot;
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int r;
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/* Modern bzImages get loaded at 1M. */
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void *p = from_guest_phys(0x100000);
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/*
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* Go back to the start of the file and read the header. It should be
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* a Linux boot header (see Documentation/x86/boot.txt)
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*/
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lseek(fd, 0, SEEK_SET);
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read(fd, &boot, sizeof(boot));
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/* Inside the setup_hdr, we expect the magic "HdrS" */
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if (memcmp(&boot.hdr.header, "HdrS", 4) != 0)
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errx(1, "This doesn't look like a bzImage to me");
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/* Skip over the extra sectors of the header. */
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lseek(fd, (boot.hdr.setup_sects+1) * 512, SEEK_SET);
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/* Now read everything into memory. in nice big chunks. */
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while ((r = read(fd, p, 65536)) > 0)
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p += r;
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/* Finally, code32_start tells us where to enter the kernel. */
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return boot.hdr.code32_start;
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}
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/*L:140
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* Loading the kernel is easy when it's a "vmlinux", but most kernels
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* come wrapped up in the self-decompressing "bzImage" format. With a little
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* work, we can load those, too.
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*/
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static unsigned long load_kernel(int fd)
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{
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Elf32_Ehdr hdr;
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/* Read in the first few bytes. */
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if (read(fd, &hdr, sizeof(hdr)) != sizeof(hdr))
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err(1, "Reading kernel");
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/* If it's an ELF file, it starts with "\177ELF" */
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if (memcmp(hdr.e_ident, ELFMAG, SELFMAG) == 0)
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return map_elf(fd, &hdr);
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|
|
/* Otherwise we assume it's a bzImage, and try to load it. */
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return load_bzimage(fd);
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}
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|
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/*
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* This is a trivial little helper to align pages. Andi Kleen hated it because
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* it calls getpagesize() twice: "it's dumb code."
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*
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* Kernel guys get really het up about optimization, even when it's not
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* necessary. I leave this code as a reaction against that.
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*/
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static inline unsigned long page_align(unsigned long addr)
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{
|
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/* Add upwards and truncate downwards. */
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return ((addr + getpagesize()-1) & ~(getpagesize()-1));
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}
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|
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/*L:180
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* An "initial ram disk" is a disk image loaded into memory along with the
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* kernel which the kernel can use to boot from without needing any drivers.
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|
* Most distributions now use this as standard: the initrd contains the code to
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* load the appropriate driver modules for the current machine.
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*
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* Importantly, James Morris works for RedHat, and Fedora uses initrds for its
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* kernels. He sent me this (and tells me when I break it).
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*/
|
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static unsigned long load_initrd(const char *name, unsigned long mem)
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{
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int ifd;
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struct stat st;
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unsigned long len;
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|
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ifd = open_or_die(name, O_RDONLY);
|
|
/* fstat() is needed to get the file size. */
|
|
if (fstat(ifd, &st) < 0)
|
|
err(1, "fstat() on initrd '%s'", name);
|
|
|
|
/*
|
|
* We map the initrd at the top of memory, but mmap wants it to be
|
|
* page-aligned, so we round the size up for that.
|
|
*/
|
|
len = page_align(st.st_size);
|
|
map_at(ifd, from_guest_phys(mem - len), 0, st.st_size);
|
|
/*
|
|
* Once a file is mapped, you can close the file descriptor. It's a
|
|
* little odd, but quite useful.
|
|
*/
|
|
close(ifd);
|
|
verbose("mapped initrd %s size=%lu @ %p\n", name, len, (void*)mem-len);
|
|
|
|
/* We return the initrd size. */
|
|
return len;
|
|
}
|
|
/*:*/
|
|
|
|
/*
|
|
* Simple routine to roll all the commandline arguments together with spaces
|
|
* between them.
|
|
*/
|
|
static void concat(char *dst, char *args[])
|
|
{
|
|
unsigned int i, len = 0;
|
|
|
|
for (i = 0; args[i]; i++) {
|
|
if (i) {
|
|
strcat(dst+len, " ");
|
|
len++;
|
|
}
|
|
strcpy(dst+len, args[i]);
|
|
len += strlen(args[i]);
|
|
}
|
|
/* In case it's empty. */
|
|
dst[len] = '\0';
|
|
}
|
|
|
|
/*L:185
|
|
* This is where we actually tell the kernel to initialize the Guest. We
|
|
* saw the arguments it expects when we looked at initialize() in lguest_user.c:
|
|
* the base of Guest "physical" memory, the top physical page to allow and the
|
|
* entry point for the Guest.
|
|
*/
|
|
static void tell_kernel(unsigned long start)
|
|
{
|
|
unsigned long args[] = { LHREQ_INITIALIZE,
|
|
(unsigned long)guest_base,
|
|
guest_limit / getpagesize(), start };
|
|
verbose("Guest: %p - %p (%#lx)\n",
|
|
guest_base, guest_base + guest_limit, guest_limit);
|
|
lguest_fd = open_or_die("/dev/lguest", O_RDWR);
|
|
if (write(lguest_fd, args, sizeof(args)) < 0)
|
|
err(1, "Writing to /dev/lguest");
|
|
}
|
|
/*:*/
|
|
|
|
/*L:200
|
|
* Device Handling.
|
|
*
|
|
* When the Guest gives us a buffer, it sends an array of addresses and sizes.
|
|
* We need to make sure it's not trying to reach into the Launcher itself, so
|
|
* we have a convenient routine which checks it and exits with an error message
|
|
* if something funny is going on:
|
|
*/
|
|
static void *_check_pointer(unsigned long addr, unsigned int size,
|
|
unsigned int line)
|
|
{
|
|
/*
|
|
* Check if the requested address and size exceeds the allocated memory,
|
|
* or addr + size wraps around.
|
|
*/
|
|
if ((addr + size) > guest_limit || (addr + size) < addr)
|
|
errx(1, "%s:%i: Invalid address %#lx", __FILE__, line, addr);
|
|
/*
|
|
* We return a pointer for the caller's convenience, now we know it's
|
|
* safe to use.
|
|
*/
|
|
return from_guest_phys(addr);
|
|
}
|
|
/* A macro which transparently hands the line number to the real function. */
|
|
#define check_pointer(addr,size) _check_pointer(addr, size, __LINE__)
|
|
|
|
/*
|
|
* Each buffer in the virtqueues is actually a chain of descriptors. This
|
|
* function returns the next descriptor in the chain, or vq->vring.num if we're
|
|
* at the end.
|
|
*/
|
|
static unsigned next_desc(struct vring_desc *desc,
|
|
unsigned int i, unsigned int max)
|
|
{
|
|
unsigned int next;
|
|
|
|
/* If this descriptor says it doesn't chain, we're done. */
|
|
if (!(desc[i].flags & VRING_DESC_F_NEXT))
|
|
return max;
|
|
|
|
/* Check they're not leading us off end of descriptors. */
|
|
next = desc[i].next;
|
|
/* Make sure compiler knows to grab that: we don't want it changing! */
|
|
wmb();
|
|
|
|
if (next >= max)
|
|
errx(1, "Desc next is %u", next);
|
|
|
|
return next;
|
|
}
|
|
|
|
/*
|
|
* This actually sends the interrupt for this virtqueue, if we've used a
|
|
* buffer.
|
|
*/
|
|
static void trigger_irq(struct virtqueue *vq)
|
|
{
|
|
unsigned long buf[] = { LHREQ_IRQ, vq->config.irq };
|
|
|
|
/* Don't inform them if nothing used. */
|
|
if (!vq->pending_used)
|
|
return;
|
|
vq->pending_used = 0;
|
|
|
|
/* If they don't want an interrupt, don't send one... */
|
|
if (vq->vring.avail->flags & VRING_AVAIL_F_NO_INTERRUPT) {
|
|
return;
|
|
}
|
|
|
|
/* Send the Guest an interrupt tell them we used something up. */
|
|
if (write(lguest_fd, buf, sizeof(buf)) != 0)
|
|
err(1, "Triggering irq %i", vq->config.irq);
|
|
}
|
|
|
|
/*
|
|
* This looks in the virtqueue for the first available buffer, and converts
|
|
* it to an iovec for convenient access. Since descriptors consist of some
|
|
* number of output then some number of input descriptors, it's actually two
|
|
* iovecs, but we pack them into one and note how many of each there were.
|
|
*
|
|
* This function waits if necessary, and returns the descriptor number found.
|
|
*/
|
|
static unsigned wait_for_vq_desc(struct virtqueue *vq,
|
|
struct iovec iov[],
|
|
unsigned int *out_num, unsigned int *in_num)
|
|
{
|
|
unsigned int i, head, max;
|
|
struct vring_desc *desc;
|
|
u16 last_avail = lg_last_avail(vq);
|
|
|
|
/* There's nothing available? */
|
|
while (last_avail == vq->vring.avail->idx) {
|
|
u64 event;
|
|
|
|
/*
|
|
* Since we're about to sleep, now is a good time to tell the
|
|
* Guest about what we've used up to now.
|
|
*/
|
|
trigger_irq(vq);
|
|
|
|
/* OK, now we need to know about added descriptors. */
|
|
vq->vring.used->flags &= ~VRING_USED_F_NO_NOTIFY;
|
|
|
|
/*
|
|
* They could have slipped one in as we were doing that: make
|
|
* sure it's written, then check again.
|
|
*/
|
|
mb();
|
|
if (last_avail != vq->vring.avail->idx) {
|
|
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
|
|
break;
|
|
}
|
|
|
|
/* Nothing new? Wait for eventfd to tell us they refilled. */
|
|
if (read(vq->eventfd, &event, sizeof(event)) != sizeof(event))
|
|
errx(1, "Event read failed?");
|
|
|
|
/* We don't need to be notified again. */
|
|
vq->vring.used->flags |= VRING_USED_F_NO_NOTIFY;
|
|
}
|
|
|
|
/* Check it isn't doing very strange things with descriptor numbers. */
|
|
if ((u16)(vq->vring.avail->idx - last_avail) > vq->vring.num)
|
|
errx(1, "Guest moved used index from %u to %u",
|
|
last_avail, vq->vring.avail->idx);
|
|
|
|
/*
|
|
* Make sure we read the descriptor number *after* we read the ring
|
|
* update; don't let the cpu or compiler change the order.
|
|
*/
|
|
rmb();
|
|
|
|
/*
|
|
* Grab the next descriptor number they're advertising, and increment
|
|
* the index we've seen.
|
|
*/
|
|
head = vq->vring.avail->ring[last_avail % vq->vring.num];
|
|
lg_last_avail(vq)++;
|
|
|
|
/* If their number is silly, that's a fatal mistake. */
|
|
if (head >= vq->vring.num)
|
|
errx(1, "Guest says index %u is available", head);
|
|
|
|
/* When we start there are none of either input nor output. */
|
|
*out_num = *in_num = 0;
|
|
|
|
max = vq->vring.num;
|
|
desc = vq->vring.desc;
|
|
i = head;
|
|
|
|
/*
|
|
* We have to read the descriptor after we read the descriptor number,
|
|
* but there's a data dependency there so the CPU shouldn't reorder
|
|
* that: no rmb() required.
|
|
*/
|
|
|
|
/*
|
|
* If this is an indirect entry, then this buffer contains a descriptor
|
|
* table which we handle as if it's any normal descriptor chain.
|
|
*/
|
|
if (desc[i].flags & VRING_DESC_F_INDIRECT) {
|
|
if (desc[i].len % sizeof(struct vring_desc))
|
|
errx(1, "Invalid size for indirect buffer table");
|
|
|
|
max = desc[i].len / sizeof(struct vring_desc);
|
|
desc = check_pointer(desc[i].addr, desc[i].len);
|
|
i = 0;
|
|
}
|
|
|
|
do {
|
|
/* Grab the first descriptor, and check it's OK. */
|
|
iov[*out_num + *in_num].iov_len = desc[i].len;
|
|
iov[*out_num + *in_num].iov_base
|
|
= check_pointer(desc[i].addr, desc[i].len);
|
|
/* If this is an input descriptor, increment that count. */
|
|
if (desc[i].flags & VRING_DESC_F_WRITE)
|
|
(*in_num)++;
|
|
else {
|
|
/*
|
|
* If it's an output descriptor, they're all supposed
|
|
* to come before any input descriptors.
|
|
*/
|
|
if (*in_num)
|
|
errx(1, "Descriptor has out after in");
|
|
(*out_num)++;
|
|
}
|
|
|
|
/* If we've got too many, that implies a descriptor loop. */
|
|
if (*out_num + *in_num > max)
|
|
errx(1, "Looped descriptor");
|
|
} while ((i = next_desc(desc, i, max)) != max);
|
|
|
|
return head;
|
|
}
|
|
|
|
/*
|
|
* After we've used one of their buffers, we tell the Guest about it. Sometime
|
|
* later we'll want to send them an interrupt using trigger_irq(); note that
|
|
* wait_for_vq_desc() does that for us if it has to wait.
|
|
*/
|
|
static void add_used(struct virtqueue *vq, unsigned int head, int len)
|
|
{
|
|
struct vring_used_elem *used;
|
|
|
|
/*
|
|
* The virtqueue contains a ring of used buffers. Get a pointer to the
|
|
* next entry in that used ring.
|
|
*/
|
|
used = &vq->vring.used->ring[vq->vring.used->idx % vq->vring.num];
|
|
used->id = head;
|
|
used->len = len;
|
|
/* Make sure buffer is written before we update index. */
|
|
wmb();
|
|
vq->vring.used->idx++;
|
|
vq->pending_used++;
|
|
}
|
|
|
|
/* And here's the combo meal deal. Supersize me! */
|
|
static void add_used_and_trigger(struct virtqueue *vq, unsigned head, int len)
|
|
{
|
|
add_used(vq, head, len);
|
|
trigger_irq(vq);
|
|
}
|
|
|
|
/*
|
|
* The Console
|
|
*
|
|
* We associate some data with the console for our exit hack.
|
|
*/
|
|
struct console_abort {
|
|
/* How many times have they hit ^C? */
|
|
int count;
|
|
/* When did they start? */
|
|
struct timeval start;
|
|
};
|
|
|
|
/* This is the routine which handles console input (ie. stdin). */
|
|
static void console_input(struct virtqueue *vq)
|
|
{
|
|
int len;
|
|
unsigned int head, in_num, out_num;
|
|
struct console_abort *abort = vq->dev->priv;
|
|
struct iovec iov[vq->vring.num];
|
|
|
|
/* Make sure there's a descriptor available. */
|
|
head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
|
|
if (out_num)
|
|
errx(1, "Output buffers in console in queue?");
|
|
|
|
/* Read into it. This is where we usually wait. */
|
|
len = readv(STDIN_FILENO, iov, in_num);
|
|
if (len <= 0) {
|
|
/* Ran out of input? */
|
|
warnx("Failed to get console input, ignoring console.");
|
|
/*
|
|
* For simplicity, dying threads kill the whole Launcher. So
|
|
* just nap here.
|
|
*/
|
|
for (;;)
|
|
pause();
|
|
}
|
|
|
|
/* Tell the Guest we used a buffer. */
|
|
add_used_and_trigger(vq, head, len);
|
|
|
|
/*
|
|
* Three ^C within one second? Exit.
|
|
*
|
|
* This is such a hack, but works surprisingly well. Each ^C has to
|
|
* be in a buffer by itself, so they can't be too fast. But we check
|
|
* that we get three within about a second, so they can't be too
|
|
* slow.
|
|
*/
|
|
if (len != 1 || ((char *)iov[0].iov_base)[0] != 3) {
|
|
abort->count = 0;
|
|
return;
|
|
}
|
|
|
|
abort->count++;
|
|
if (abort->count == 1)
|
|
gettimeofday(&abort->start, NULL);
|
|
else if (abort->count == 3) {
|
|
struct timeval now;
|
|
gettimeofday(&now, NULL);
|
|
/* Kill all Launcher processes with SIGINT, like normal ^C */
|
|
if (now.tv_sec <= abort->start.tv_sec+1)
|
|
kill(0, SIGINT);
|
|
abort->count = 0;
|
|
}
|
|
}
|
|
|
|
/* This is the routine which handles console output (ie. stdout). */
|
|
static void console_output(struct virtqueue *vq)
|
|
{
|
|
unsigned int head, out, in;
|
|
struct iovec iov[vq->vring.num];
|
|
|
|
/* We usually wait in here, for the Guest to give us something. */
|
|
head = wait_for_vq_desc(vq, iov, &out, &in);
|
|
if (in)
|
|
errx(1, "Input buffers in console output queue?");
|
|
|
|
/* writev can return a partial write, so we loop here. */
|
|
while (!iov_empty(iov, out)) {
|
|
int len = writev(STDOUT_FILENO, iov, out);
|
|
if (len <= 0) {
|
|
warn("Write to stdout gave %i (%d)", len, errno);
|
|
break;
|
|
}
|
|
iov_consume(iov, out, NULL, len);
|
|
}
|
|
|
|
/*
|
|
* We're finished with that buffer: if we're going to sleep,
|
|
* wait_for_vq_desc() will prod the Guest with an interrupt.
|
|
*/
|
|
add_used(vq, head, 0);
|
|
}
|
|
|
|
/*
|
|
* The Network
|
|
*
|
|
* Handling output for network is also simple: we get all the output buffers
|
|
* and write them to /dev/net/tun.
|
|
*/
|
|
struct net_info {
|
|
int tunfd;
|
|
};
|
|
|
|
static void net_output(struct virtqueue *vq)
|
|
{
|
|
struct net_info *net_info = vq->dev->priv;
|
|
unsigned int head, out, in;
|
|
struct iovec iov[vq->vring.num];
|
|
|
|
/* We usually wait in here for the Guest to give us a packet. */
|
|
head = wait_for_vq_desc(vq, iov, &out, &in);
|
|
if (in)
|
|
errx(1, "Input buffers in net output queue?");
|
|
/*
|
|
* Send the whole thing through to /dev/net/tun. It expects the exact
|
|
* same format: what a coincidence!
|
|
*/
|
|
if (writev(net_info->tunfd, iov, out) < 0)
|
|
warnx("Write to tun failed (%d)?", errno);
|
|
|
|
/*
|
|
* Done with that one; wait_for_vq_desc() will send the interrupt if
|
|
* all packets are processed.
|
|
*/
|
|
add_used(vq, head, 0);
|
|
}
|
|
|
|
/*
|
|
* Handling network input is a bit trickier, because I've tried to optimize it.
|
|
*
|
|
* First we have a helper routine which tells is if from this file descriptor
|
|
* (ie. the /dev/net/tun device) will block:
|
|
*/
|
|
static bool will_block(int fd)
|
|
{
|
|
fd_set fdset;
|
|
struct timeval zero = { 0, 0 };
|
|
FD_ZERO(&fdset);
|
|
FD_SET(fd, &fdset);
|
|
return select(fd+1, &fdset, NULL, NULL, &zero) != 1;
|
|
}
|
|
|
|
/*
|
|
* This handles packets coming in from the tun device to our Guest. Like all
|
|
* service routines, it gets called again as soon as it returns, so you don't
|
|
* see a while(1) loop here.
|
|
*/
|
|
static void net_input(struct virtqueue *vq)
|
|
{
|
|
int len;
|
|
unsigned int head, out, in;
|
|
struct iovec iov[vq->vring.num];
|
|
struct net_info *net_info = vq->dev->priv;
|
|
|
|
/*
|
|
* Get a descriptor to write an incoming packet into. This will also
|
|
* send an interrupt if they're out of descriptors.
|
|
*/
|
|
head = wait_for_vq_desc(vq, iov, &out, &in);
|
|
if (out)
|
|
errx(1, "Output buffers in net input queue?");
|
|
|
|
/*
|
|
* If it looks like we'll block reading from the tun device, send them
|
|
* an interrupt.
|
|
*/
|
|
if (vq->pending_used && will_block(net_info->tunfd))
|
|
trigger_irq(vq);
|
|
|
|
/*
|
|
* Read in the packet. This is where we normally wait (when there's no
|
|
* incoming network traffic).
|
|
*/
|
|
len = readv(net_info->tunfd, iov, in);
|
|
if (len <= 0)
|
|
warn("Failed to read from tun (%d).", errno);
|
|
|
|
/*
|
|
* Mark that packet buffer as used, but don't interrupt here. We want
|
|
* to wait until we've done as much work as we can.
|
|
*/
|
|
add_used(vq, head, len);
|
|
}
|
|
/*:*/
|
|
|
|
/* This is the helper to create threads: run the service routine in a loop. */
|
|
static int do_thread(void *_vq)
|
|
{
|
|
struct virtqueue *vq = _vq;
|
|
|
|
for (;;)
|
|
vq->service(vq);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* When a child dies, we kill our entire process group with SIGTERM. This
|
|
* also has the side effect that the shell restores the console for us!
|
|
*/
|
|
static void kill_launcher(int signal)
|
|
{
|
|
kill(0, SIGTERM);
|
|
}
|
|
|
|
static void reset_device(struct device *dev)
|
|
{
|
|
struct virtqueue *vq;
|
|
|
|
verbose("Resetting device %s\n", dev->name);
|
|
|
|
/* Clear any features they've acked. */
|
|
memset(get_feature_bits(dev) + dev->feature_len, 0, dev->feature_len);
|
|
|
|
/* We're going to be explicitly killing threads, so ignore them. */
|
|
signal(SIGCHLD, SIG_IGN);
|
|
|
|
/* Zero out the virtqueues, get rid of their threads */
|
|
for (vq = dev->vq; vq; vq = vq->next) {
|
|
if (vq->thread != (pid_t)-1) {
|
|
kill(vq->thread, SIGTERM);
|
|
waitpid(vq->thread, NULL, 0);
|
|
vq->thread = (pid_t)-1;
|
|
}
|
|
memset(vq->vring.desc, 0,
|
|
vring_size(vq->config.num, LGUEST_VRING_ALIGN));
|
|
lg_last_avail(vq) = 0;
|
|
}
|
|
dev->running = false;
|
|
|
|
/* Now we care if threads die. */
|
|
signal(SIGCHLD, (void *)kill_launcher);
|
|
}
|
|
|
|
/*L:216
|
|
* This actually creates the thread which services the virtqueue for a device.
|
|
*/
|
|
static void create_thread(struct virtqueue *vq)
|
|
{
|
|
/*
|
|
* Create stack for thread. Since the stack grows upwards, we point
|
|
* the stack pointer to the end of this region.
|
|
*/
|
|
char *stack = malloc(32768);
|
|
unsigned long args[] = { LHREQ_EVENTFD,
|
|
vq->config.pfn*getpagesize(), 0 };
|
|
|
|
/* Create a zero-initialized eventfd. */
|
|
vq->eventfd = eventfd(0, 0);
|
|
if (vq->eventfd < 0)
|
|
err(1, "Creating eventfd");
|
|
args[2] = vq->eventfd;
|
|
|
|
/*
|
|
* Attach an eventfd to this virtqueue: it will go off when the Guest
|
|
* does an LHCALL_NOTIFY for this vq.
|
|
*/
|
|
if (write(lguest_fd, &args, sizeof(args)) != 0)
|
|
err(1, "Attaching eventfd");
|
|
|
|
/*
|
|
* CLONE_VM: because it has to access the Guest memory, and SIGCHLD so
|
|
* we get a signal if it dies.
|
|
*/
|
|
vq->thread = clone(do_thread, stack + 32768, CLONE_VM | SIGCHLD, vq);
|
|
if (vq->thread == (pid_t)-1)
|
|
err(1, "Creating clone");
|
|
|
|
/* We close our local copy now the child has it. */
|
|
close(vq->eventfd);
|
|
}
|
|
|
|
static void start_device(struct device *dev)
|
|
{
|
|
unsigned int i;
|
|
struct virtqueue *vq;
|
|
|
|
verbose("Device %s OK: offered", dev->name);
|
|
for (i = 0; i < dev->feature_len; i++)
|
|
verbose(" %02x", get_feature_bits(dev)[i]);
|
|
verbose(", accepted");
|
|
for (i = 0; i < dev->feature_len; i++)
|
|
verbose(" %02x", get_feature_bits(dev)
|
|
[dev->feature_len+i]);
|
|
|
|
for (vq = dev->vq; vq; vq = vq->next) {
|
|
if (vq->service)
|
|
create_thread(vq);
|
|
}
|
|
dev->running = true;
|
|
}
|
|
|
|
static void cleanup_devices(void)
|
|
{
|
|
struct device *dev;
|
|
|
|
for (dev = devices.dev; dev; dev = dev->next)
|
|
reset_device(dev);
|
|
|
|
/* If we saved off the original terminal settings, restore them now. */
|
|
if (orig_term.c_lflag & (ISIG|ICANON|ECHO))
|
|
tcsetattr(STDIN_FILENO, TCSANOW, &orig_term);
|
|
}
|
|
|
|
/* When the Guest tells us they updated the status field, we handle it. */
|
|
static void update_device_status(struct device *dev)
|
|
{
|
|
/* A zero status is a reset, otherwise it's a set of flags. */
|
|
if (dev->desc->status == 0)
|
|
reset_device(dev);
|
|
else if (dev->desc->status & VIRTIO_CONFIG_S_FAILED) {
|
|
warnx("Device %s configuration FAILED", dev->name);
|
|
if (dev->running)
|
|
reset_device(dev);
|
|
} else {
|
|
if (dev->running)
|
|
err(1, "Device %s features finalized twice", dev->name);
|
|
start_device(dev);
|
|
}
|
|
}
|
|
|
|
/*L:215
|
|
* This is the generic routine we call when the Guest uses LHCALL_NOTIFY. In
|
|
* particular, it's used to notify us of device status changes during boot.
|
|
*/
|
|
static void handle_output(unsigned long addr)
|
|
{
|
|
struct device *i;
|
|
|
|
/* Check each device. */
|
|
for (i = devices.dev; i; i = i->next) {
|
|
struct virtqueue *vq;
|
|
|
|
/*
|
|
* Notifications to device descriptors mean they updated the
|
|
* device status.
|
|
*/
|
|
if (from_guest_phys(addr) == i->desc) {
|
|
update_device_status(i);
|
|
return;
|
|
}
|
|
|
|
/* Devices should not be used before features are finalized. */
|
|
for (vq = i->vq; vq; vq = vq->next) {
|
|
if (addr != vq->config.pfn*getpagesize())
|
|
continue;
|
|
errx(1, "Notification on %s before setup!", i->name);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Early console write is done using notify on a nul-terminated string
|
|
* in Guest memory. It's also great for hacking debugging messages
|
|
* into a Guest.
|
|
*/
|
|
if (addr >= guest_limit)
|
|
errx(1, "Bad NOTIFY %#lx", addr);
|
|
|
|
write(STDOUT_FILENO, from_guest_phys(addr),
|
|
strnlen(from_guest_phys(addr), guest_limit - addr));
|
|
}
|
|
|
|
/*L:190
|
|
* Device Setup
|
|
*
|
|
* All devices need a descriptor so the Guest knows it exists, and a "struct
|
|
* device" so the Launcher can keep track of it. We have common helper
|
|
* routines to allocate and manage them.
|
|
*/
|
|
|
|
/*
|
|
* The layout of the device page is a "struct lguest_device_desc" followed by a
|
|
* number of virtqueue descriptors, then two sets of feature bits, then an
|
|
* array of configuration bytes. This routine returns the configuration
|
|
* pointer.
|
|
*/
|
|
static u8 *device_config(const struct device *dev)
|
|
{
|
|
return (void *)(dev->desc + 1)
|
|
+ dev->num_vq * sizeof(struct lguest_vqconfig)
|
|
+ dev->feature_len * 2;
|
|
}
|
|
|
|
/*
|
|
* This routine allocates a new "struct lguest_device_desc" from descriptor
|
|
* table page just above the Guest's normal memory. It returns a pointer to
|
|
* that descriptor.
|
|
*/
|
|
static struct lguest_device_desc *new_dev_desc(u16 type)
|
|
{
|
|
struct lguest_device_desc d = { .type = type };
|
|
void *p;
|
|
|
|
/* Figure out where the next device config is, based on the last one. */
|
|
if (devices.lastdev)
|
|
p = device_config(devices.lastdev)
|
|
+ devices.lastdev->desc->config_len;
|
|
else
|
|
p = devices.descpage;
|
|
|
|
/* We only have one page for all the descriptors. */
|
|
if (p + sizeof(d) > (void *)devices.descpage + getpagesize())
|
|
errx(1, "Too many devices");
|
|
|
|
/* p might not be aligned, so we memcpy in. */
|
|
return memcpy(p, &d, sizeof(d));
|
|
}
|
|
|
|
/*
|
|
* Each device descriptor is followed by the description of its virtqueues. We
|
|
* specify how many descriptors the virtqueue is to have.
|
|
*/
|
|
static void add_virtqueue(struct device *dev, unsigned int num_descs,
|
|
void (*service)(struct virtqueue *))
|
|
{
|
|
unsigned int pages;
|
|
struct virtqueue **i, *vq = malloc(sizeof(*vq));
|
|
void *p;
|
|
|
|
/* First we need some memory for this virtqueue. */
|
|
pages = (vring_size(num_descs, LGUEST_VRING_ALIGN) + getpagesize() - 1)
|
|
/ getpagesize();
|
|
p = get_pages(pages);
|
|
|
|
/* Initialize the virtqueue */
|
|
vq->next = NULL;
|
|
vq->last_avail_idx = 0;
|
|
vq->dev = dev;
|
|
|
|
/*
|
|
* This is the routine the service thread will run, and its Process ID
|
|
* once it's running.
|
|
*/
|
|
vq->service = service;
|
|
vq->thread = (pid_t)-1;
|
|
|
|
/* Initialize the configuration. */
|
|
vq->config.num = num_descs;
|
|
vq->config.irq = devices.next_irq++;
|
|
vq->config.pfn = to_guest_phys(p) / getpagesize();
|
|
|
|
/* Initialize the vring. */
|
|
vring_init(&vq->vring, num_descs, p, LGUEST_VRING_ALIGN);
|
|
|
|
/*
|
|
* Append virtqueue to this device's descriptor. We use
|
|
* device_config() to get the end of the device's current virtqueues;
|
|
* we check that we haven't added any config or feature information
|
|
* yet, otherwise we'd be overwriting them.
|
|
*/
|
|
assert(dev->desc->config_len == 0 && dev->desc->feature_len == 0);
|
|
memcpy(device_config(dev), &vq->config, sizeof(vq->config));
|
|
dev->num_vq++;
|
|
dev->desc->num_vq++;
|
|
|
|
verbose("Virtqueue page %#lx\n", to_guest_phys(p));
|
|
|
|
/*
|
|
* Add to tail of list, so dev->vq is first vq, dev->vq->next is
|
|
* second.
|
|
*/
|
|
for (i = &dev->vq; *i; i = &(*i)->next);
|
|
*i = vq;
|
|
}
|
|
|
|
/*
|
|
* The first half of the feature bitmask is for us to advertise features. The
|
|
* second half is for the Guest to accept features.
|
|
*/
|
|
static void add_feature(struct device *dev, unsigned bit)
|
|
{
|
|
u8 *features = get_feature_bits(dev);
|
|
|
|
/* We can't extend the feature bits once we've added config bytes */
|
|
if (dev->desc->feature_len <= bit / CHAR_BIT) {
|
|
assert(dev->desc->config_len == 0);
|
|
dev->feature_len = dev->desc->feature_len = (bit/CHAR_BIT) + 1;
|
|
}
|
|
|
|
features[bit / CHAR_BIT] |= (1 << (bit % CHAR_BIT));
|
|
}
|
|
|
|
/*
|
|
* This routine sets the configuration fields for an existing device's
|
|
* descriptor. It only works for the last device, but that's OK because that's
|
|
* how we use it.
|
|
*/
|
|
static void set_config(struct device *dev, unsigned len, const void *conf)
|
|
{
|
|
/* Check we haven't overflowed our single page. */
|
|
if (device_config(dev) + len > devices.descpage + getpagesize())
|
|
errx(1, "Too many devices");
|
|
|
|
/* Copy in the config information, and store the length. */
|
|
memcpy(device_config(dev), conf, len);
|
|
dev->desc->config_len = len;
|
|
|
|
/* Size must fit in config_len field (8 bits)! */
|
|
assert(dev->desc->config_len == len);
|
|
}
|
|
|
|
/*
|
|
* This routine does all the creation and setup of a new device, including
|
|
* calling new_dev_desc() to allocate the descriptor and device memory. We
|
|
* don't actually start the service threads until later.
|
|
*
|
|
* See what I mean about userspace being boring?
|
|
*/
|
|
static struct device *new_device(const char *name, u16 type)
|
|
{
|
|
struct device *dev = malloc(sizeof(*dev));
|
|
|
|
/* Now we populate the fields one at a time. */
|
|
dev->desc = new_dev_desc(type);
|
|
dev->name = name;
|
|
dev->vq = NULL;
|
|
dev->feature_len = 0;
|
|
dev->num_vq = 0;
|
|
dev->running = false;
|
|
dev->next = NULL;
|
|
|
|
/*
|
|
* Append to device list. Prepending to a single-linked list is
|
|
* easier, but the user expects the devices to be arranged on the bus
|
|
* in command-line order. The first network device on the command line
|
|
* is eth0, the first block device /dev/vda, etc.
|
|
*/
|
|
if (devices.lastdev)
|
|
devices.lastdev->next = dev;
|
|
else
|
|
devices.dev = dev;
|
|
devices.lastdev = dev;
|
|
|
|
return dev;
|
|
}
|
|
|
|
/*
|
|
* Our first setup routine is the console. It's a fairly simple device, but
|
|
* UNIX tty handling makes it uglier than it could be.
|
|
*/
|
|
static void setup_console(void)
|
|
{
|
|
struct device *dev;
|
|
|
|
/* If we can save the initial standard input settings... */
|
|
if (tcgetattr(STDIN_FILENO, &orig_term) == 0) {
|
|
struct termios term = orig_term;
|
|
/*
|
|
* Then we turn off echo, line buffering and ^C etc: We want a
|
|
* raw input stream to the Guest.
|
|
*/
|
|
term.c_lflag &= ~(ISIG|ICANON|ECHO);
|
|
tcsetattr(STDIN_FILENO, TCSANOW, &term);
|
|
}
|
|
|
|
dev = new_device("console", VIRTIO_ID_CONSOLE);
|
|
|
|
/* We store the console state in dev->priv, and initialize it. */
|
|
dev->priv = malloc(sizeof(struct console_abort));
|
|
((struct console_abort *)dev->priv)->count = 0;
|
|
|
|
/*
|
|
* The console needs two virtqueues: the input then the output. When
|
|
* they put something the input queue, we make sure we're listening to
|
|
* stdin. When they put something in the output queue, we write it to
|
|
* stdout.
|
|
*/
|
|
add_virtqueue(dev, VIRTQUEUE_NUM, console_input);
|
|
add_virtqueue(dev, VIRTQUEUE_NUM, console_output);
|
|
|
|
verbose("device %u: console\n", ++devices.device_num);
|
|
}
|
|
/*:*/
|
|
|
|
/*M:010
|
|
* Inter-guest networking is an interesting area. Simplest is to have a
|
|
* --sharenet=<name> option which opens or creates a named pipe. This can be
|
|
* used to send packets to another guest in a 1:1 manner.
|
|
*
|
|
* More sophisticated is to use one of the tools developed for project like UML
|
|
* to do networking.
|
|
*
|
|
* Faster is to do virtio bonding in kernel. Doing this 1:1 would be
|
|
* completely generic ("here's my vring, attach to your vring") and would work
|
|
* for any traffic. Of course, namespace and permissions issues need to be
|
|
* dealt with. A more sophisticated "multi-channel" virtio_net.c could hide
|
|
* multiple inter-guest channels behind one interface, although it would
|
|
* require some manner of hotplugging new virtio channels.
|
|
*
|
|
* Finally, we could use a virtio network switch in the kernel, ie. vhost.
|
|
:*/
|
|
|
|
static u32 str2ip(const char *ipaddr)
|
|
{
|
|
unsigned int b[4];
|
|
|
|
if (sscanf(ipaddr, "%u.%u.%u.%u", &b[0], &b[1], &b[2], &b[3]) != 4)
|
|
errx(1, "Failed to parse IP address '%s'", ipaddr);
|
|
return (b[0] << 24) | (b[1] << 16) | (b[2] << 8) | b[3];
|
|
}
|
|
|
|
static void str2mac(const char *macaddr, unsigned char mac[6])
|
|
{
|
|
unsigned int m[6];
|
|
if (sscanf(macaddr, "%02x:%02x:%02x:%02x:%02x:%02x",
|
|
&m[0], &m[1], &m[2], &m[3], &m[4], &m[5]) != 6)
|
|
errx(1, "Failed to parse mac address '%s'", macaddr);
|
|
mac[0] = m[0];
|
|
mac[1] = m[1];
|
|
mac[2] = m[2];
|
|
mac[3] = m[3];
|
|
mac[4] = m[4];
|
|
mac[5] = m[5];
|
|
}
|
|
|
|
/*
|
|
* This code is "adapted" from libbridge: it attaches the Host end of the
|
|
* network device to the bridge device specified by the command line.
|
|
*
|
|
* This is yet another James Morris contribution (I'm an IP-level guy, so I
|
|
* dislike bridging), and I just try not to break it.
|
|
*/
|
|
static void add_to_bridge(int fd, const char *if_name, const char *br_name)
|
|
{
|
|
int ifidx;
|
|
struct ifreq ifr;
|
|
|
|
if (!*br_name)
|
|
errx(1, "must specify bridge name");
|
|
|
|
ifidx = if_nametoindex(if_name);
|
|
if (!ifidx)
|
|
errx(1, "interface %s does not exist!", if_name);
|
|
|
|
strncpy(ifr.ifr_name, br_name, IFNAMSIZ);
|
|
ifr.ifr_name[IFNAMSIZ-1] = '\0';
|
|
ifr.ifr_ifindex = ifidx;
|
|
if (ioctl(fd, SIOCBRADDIF, &ifr) < 0)
|
|
err(1, "can't add %s to bridge %s", if_name, br_name);
|
|
}
|
|
|
|
/*
|
|
* This sets up the Host end of the network device with an IP address, brings
|
|
* it up so packets will flow, the copies the MAC address into the hwaddr
|
|
* pointer.
|
|
*/
|
|
static void configure_device(int fd, const char *tapif, u32 ipaddr)
|
|
{
|
|
struct ifreq ifr;
|
|
struct sockaddr_in sin;
|
|
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
strcpy(ifr.ifr_name, tapif);
|
|
|
|
/* Don't read these incantations. Just cut & paste them like I did! */
|
|
sin.sin_family = AF_INET;
|
|
sin.sin_addr.s_addr = htonl(ipaddr);
|
|
memcpy(&ifr.ifr_addr, &sin, sizeof(sin));
|
|
if (ioctl(fd, SIOCSIFADDR, &ifr) != 0)
|
|
err(1, "Setting %s interface address", tapif);
|
|
ifr.ifr_flags = IFF_UP;
|
|
if (ioctl(fd, SIOCSIFFLAGS, &ifr) != 0)
|
|
err(1, "Bringing interface %s up", tapif);
|
|
}
|
|
|
|
static int get_tun_device(char tapif[IFNAMSIZ])
|
|
{
|
|
struct ifreq ifr;
|
|
int netfd;
|
|
|
|
/* Start with this zeroed. Messy but sure. */
|
|
memset(&ifr, 0, sizeof(ifr));
|
|
|
|
/*
|
|
* We open the /dev/net/tun device and tell it we want a tap device. A
|
|
* tap device is like a tun device, only somehow different. To tell
|
|
* the truth, I completely blundered my way through this code, but it
|
|
* works now!
|
|
*/
|
|
netfd = open_or_die("/dev/net/tun", O_RDWR);
|
|
ifr.ifr_flags = IFF_TAP | IFF_NO_PI | IFF_VNET_HDR;
|
|
strcpy(ifr.ifr_name, "tap%d");
|
|
if (ioctl(netfd, TUNSETIFF, &ifr) != 0)
|
|
err(1, "configuring /dev/net/tun");
|
|
|
|
if (ioctl(netfd, TUNSETOFFLOAD,
|
|
TUN_F_CSUM|TUN_F_TSO4|TUN_F_TSO6|TUN_F_TSO_ECN) != 0)
|
|
err(1, "Could not set features for tun device");
|
|
|
|
/*
|
|
* We don't need checksums calculated for packets coming in this
|
|
* device: trust us!
|
|
*/
|
|
ioctl(netfd, TUNSETNOCSUM, 1);
|
|
|
|
memcpy(tapif, ifr.ifr_name, IFNAMSIZ);
|
|
return netfd;
|
|
}
|
|
|
|
/*L:195
|
|
* Our network is a Host<->Guest network. This can either use bridging or
|
|
* routing, but the principle is the same: it uses the "tun" device to inject
|
|
* packets into the Host as if they came in from a normal network card. We
|
|
* just shunt packets between the Guest and the tun device.
|
|
*/
|
|
static void setup_tun_net(char *arg)
|
|
{
|
|
struct device *dev;
|
|
struct net_info *net_info = malloc(sizeof(*net_info));
|
|
int ipfd;
|
|
u32 ip = INADDR_ANY;
|
|
bool bridging = false;
|
|
char tapif[IFNAMSIZ], *p;
|
|
struct virtio_net_config conf;
|
|
|
|
net_info->tunfd = get_tun_device(tapif);
|
|
|
|
/* First we create a new network device. */
|
|
dev = new_device("net", VIRTIO_ID_NET);
|
|
dev->priv = net_info;
|
|
|
|
/* Network devices need a recv and a send queue, just like console. */
|
|
add_virtqueue(dev, VIRTQUEUE_NUM, net_input);
|
|
add_virtqueue(dev, VIRTQUEUE_NUM, net_output);
|
|
|
|
/*
|
|
* We need a socket to perform the magic network ioctls to bring up the
|
|
* tap interface, connect to the bridge etc. Any socket will do!
|
|
*/
|
|
ipfd = socket(PF_INET, SOCK_DGRAM, IPPROTO_IP);
|
|
if (ipfd < 0)
|
|
err(1, "opening IP socket");
|
|
|
|
/* If the command line was --tunnet=bridge:<name> do bridging. */
|
|
if (!strncmp(BRIDGE_PFX, arg, strlen(BRIDGE_PFX))) {
|
|
arg += strlen(BRIDGE_PFX);
|
|
bridging = true;
|
|
}
|
|
|
|
/* A mac address may follow the bridge name or IP address */
|
|
p = strchr(arg, ':');
|
|
if (p) {
|
|
str2mac(p+1, conf.mac);
|
|
add_feature(dev, VIRTIO_NET_F_MAC);
|
|
*p = '\0';
|
|
}
|
|
|
|
/* arg is now either an IP address or a bridge name */
|
|
if (bridging)
|
|
add_to_bridge(ipfd, tapif, arg);
|
|
else
|
|
ip = str2ip(arg);
|
|
|
|
/* Set up the tun device. */
|
|
configure_device(ipfd, tapif, ip);
|
|
|
|
/* Expect Guest to handle everything except UFO */
|
|
add_feature(dev, VIRTIO_NET_F_CSUM);
|
|
add_feature(dev, VIRTIO_NET_F_GUEST_CSUM);
|
|
add_feature(dev, VIRTIO_NET_F_GUEST_TSO4);
|
|
add_feature(dev, VIRTIO_NET_F_GUEST_TSO6);
|
|
add_feature(dev, VIRTIO_NET_F_GUEST_ECN);
|
|
add_feature(dev, VIRTIO_NET_F_HOST_TSO4);
|
|
add_feature(dev, VIRTIO_NET_F_HOST_TSO6);
|
|
add_feature(dev, VIRTIO_NET_F_HOST_ECN);
|
|
/* We handle indirect ring entries */
|
|
add_feature(dev, VIRTIO_RING_F_INDIRECT_DESC);
|
|
/* We're compliant with the damn spec. */
|
|
add_feature(dev, VIRTIO_F_ANY_LAYOUT);
|
|
set_config(dev, sizeof(conf), &conf);
|
|
|
|
/* We don't need the socket any more; setup is done. */
|
|
close(ipfd);
|
|
|
|
devices.device_num++;
|
|
|
|
if (bridging)
|
|
verbose("device %u: tun %s attached to bridge: %s\n",
|
|
devices.device_num, tapif, arg);
|
|
else
|
|
verbose("device %u: tun %s: %s\n",
|
|
devices.device_num, tapif, arg);
|
|
}
|
|
/*:*/
|
|
|
|
/* This hangs off device->priv. */
|
|
struct vblk_info {
|
|
/* The size of the file. */
|
|
off64_t len;
|
|
|
|
/* The file descriptor for the file. */
|
|
int fd;
|
|
|
|
};
|
|
|
|
/*L:210
|
|
* The Disk
|
|
*
|
|
* The disk only has one virtqueue, so it only has one thread. It is really
|
|
* simple: the Guest asks for a block number and we read or write that position
|
|
* in the file.
|
|
*
|
|
* Before we serviced each virtqueue in a separate thread, that was unacceptably
|
|
* slow: the Guest waits until the read is finished before running anything
|
|
* else, even if it could have been doing useful work.
|
|
*
|
|
* We could have used async I/O, except it's reputed to suck so hard that
|
|
* characters actually go missing from your code when you try to use it.
|
|
*/
|
|
static void blk_request(struct virtqueue *vq)
|
|
{
|
|
struct vblk_info *vblk = vq->dev->priv;
|
|
unsigned int head, out_num, in_num, wlen;
|
|
int ret, i;
|
|
u8 *in;
|
|
struct virtio_blk_outhdr out;
|
|
struct iovec iov[vq->vring.num];
|
|
off64_t off;
|
|
|
|
/*
|
|
* Get the next request, where we normally wait. It triggers the
|
|
* interrupt to acknowledge previously serviced requests (if any).
|
|
*/
|
|
head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
|
|
|
|
/* Copy the output header from the front of the iov (adjusts iov) */
|
|
iov_consume(iov, out_num, &out, sizeof(out));
|
|
|
|
/* Find and trim end of iov input array, for our status byte. */
|
|
in = NULL;
|
|
for (i = out_num + in_num - 1; i >= out_num; i--) {
|
|
if (iov[i].iov_len > 0) {
|
|
in = iov[i].iov_base + iov[i].iov_len - 1;
|
|
iov[i].iov_len--;
|
|
break;
|
|
}
|
|
}
|
|
if (!in)
|
|
errx(1, "Bad virtblk cmd with no room for status");
|
|
|
|
/*
|
|
* For historical reasons, block operations are expressed in 512 byte
|
|
* "sectors".
|
|
*/
|
|
off = out.sector * 512;
|
|
|
|
/*
|
|
* In general the virtio block driver is allowed to try SCSI commands.
|
|
* It'd be nice if we supported eject, for example, but we don't.
|
|
*/
|
|
if (out.type & VIRTIO_BLK_T_SCSI_CMD) {
|
|
fprintf(stderr, "Scsi commands unsupported\n");
|
|
*in = VIRTIO_BLK_S_UNSUPP;
|
|
wlen = sizeof(*in);
|
|
} else if (out.type & VIRTIO_BLK_T_OUT) {
|
|
/*
|
|
* Write
|
|
*
|
|
* Move to the right location in the block file. This can fail
|
|
* if they try to write past end.
|
|
*/
|
|
if (lseek64(vblk->fd, off, SEEK_SET) != off)
|
|
err(1, "Bad seek to sector %llu", out.sector);
|
|
|
|
ret = writev(vblk->fd, iov, out_num);
|
|
verbose("WRITE to sector %llu: %i\n", out.sector, ret);
|
|
|
|
/*
|
|
* Grr... Now we know how long the descriptor they sent was, we
|
|
* make sure they didn't try to write over the end of the block
|
|
* file (possibly extending it).
|
|
*/
|
|
if (ret > 0 && off + ret > vblk->len) {
|
|
/* Trim it back to the correct length */
|
|
ftruncate64(vblk->fd, vblk->len);
|
|
/* Die, bad Guest, die. */
|
|
errx(1, "Write past end %llu+%u", off, ret);
|
|
}
|
|
|
|
wlen = sizeof(*in);
|
|
*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
|
|
} else if (out.type & VIRTIO_BLK_T_FLUSH) {
|
|
/* Flush */
|
|
ret = fdatasync(vblk->fd);
|
|
verbose("FLUSH fdatasync: %i\n", ret);
|
|
wlen = sizeof(*in);
|
|
*in = (ret >= 0 ? VIRTIO_BLK_S_OK : VIRTIO_BLK_S_IOERR);
|
|
} else {
|
|
/*
|
|
* Read
|
|
*
|
|
* Move to the right location in the block file. This can fail
|
|
* if they try to read past end.
|
|
*/
|
|
if (lseek64(vblk->fd, off, SEEK_SET) != off)
|
|
err(1, "Bad seek to sector %llu", out.sector);
|
|
|
|
ret = readv(vblk->fd, iov + out_num, in_num);
|
|
if (ret >= 0) {
|
|
wlen = sizeof(*in) + ret;
|
|
*in = VIRTIO_BLK_S_OK;
|
|
} else {
|
|
wlen = sizeof(*in);
|
|
*in = VIRTIO_BLK_S_IOERR;
|
|
}
|
|
}
|
|
|
|
/* Finished that request. */
|
|
add_used(vq, head, wlen);
|
|
}
|
|
|
|
/*L:198 This actually sets up a virtual block device. */
|
|
static void setup_block_file(const char *filename)
|
|
{
|
|
struct device *dev;
|
|
struct vblk_info *vblk;
|
|
struct virtio_blk_config conf;
|
|
|
|
/* Creat the device. */
|
|
dev = new_device("block", VIRTIO_ID_BLOCK);
|
|
|
|
/* The device has one virtqueue, where the Guest places requests. */
|
|
add_virtqueue(dev, VIRTQUEUE_NUM, blk_request);
|
|
|
|
/* Allocate the room for our own bookkeeping */
|
|
vblk = dev->priv = malloc(sizeof(*vblk));
|
|
|
|
/* First we open the file and store the length. */
|
|
vblk->fd = open_or_die(filename, O_RDWR|O_LARGEFILE);
|
|
vblk->len = lseek64(vblk->fd, 0, SEEK_END);
|
|
|
|
/* We support FLUSH. */
|
|
add_feature(dev, VIRTIO_BLK_F_FLUSH);
|
|
|
|
/* Tell Guest how many sectors this device has. */
|
|
conf.capacity = cpu_to_le64(vblk->len / 512);
|
|
|
|
/*
|
|
* Tell Guest not to put in too many descriptors at once: two are used
|
|
* for the in and out elements.
|
|
*/
|
|
add_feature(dev, VIRTIO_BLK_F_SEG_MAX);
|
|
conf.seg_max = cpu_to_le32(VIRTQUEUE_NUM - 2);
|
|
|
|
/* Don't try to put whole struct: we have 8 bit limit. */
|
|
set_config(dev, offsetof(struct virtio_blk_config, geometry), &conf);
|
|
|
|
verbose("device %u: virtblock %llu sectors\n",
|
|
++devices.device_num, le64_to_cpu(conf.capacity));
|
|
}
|
|
|
|
/*L:211
|
|
* Our random number generator device reads from /dev/random into the Guest's
|
|
* input buffers. The usual case is that the Guest doesn't want random numbers
|
|
* and so has no buffers although /dev/random is still readable, whereas
|
|
* console is the reverse.
|
|
*
|
|
* The same logic applies, however.
|
|
*/
|
|
struct rng_info {
|
|
int rfd;
|
|
};
|
|
|
|
static void rng_input(struct virtqueue *vq)
|
|
{
|
|
int len;
|
|
unsigned int head, in_num, out_num, totlen = 0;
|
|
struct rng_info *rng_info = vq->dev->priv;
|
|
struct iovec iov[vq->vring.num];
|
|
|
|
/* First we need a buffer from the Guests's virtqueue. */
|
|
head = wait_for_vq_desc(vq, iov, &out_num, &in_num);
|
|
if (out_num)
|
|
errx(1, "Output buffers in rng?");
|
|
|
|
/*
|
|
* Just like the console write, we loop to cover the whole iovec.
|
|
* In this case, short reads actually happen quite a bit.
|
|
*/
|
|
while (!iov_empty(iov, in_num)) {
|
|
len = readv(rng_info->rfd, iov, in_num);
|
|
if (len <= 0)
|
|
err(1, "Read from /dev/random gave %i", len);
|
|
iov_consume(iov, in_num, NULL, len);
|
|
totlen += len;
|
|
}
|
|
|
|
/* Tell the Guest about the new input. */
|
|
add_used(vq, head, totlen);
|
|
}
|
|
|
|
/*L:199
|
|
* This creates a "hardware" random number device for the Guest.
|
|
*/
|
|
static void setup_rng(void)
|
|
{
|
|
struct device *dev;
|
|
struct rng_info *rng_info = malloc(sizeof(*rng_info));
|
|
|
|
/* Our device's privat info simply contains the /dev/random fd. */
|
|
rng_info->rfd = open_or_die("/dev/random", O_RDONLY);
|
|
|
|
/* Create the new device. */
|
|
dev = new_device("rng", VIRTIO_ID_RNG);
|
|
dev->priv = rng_info;
|
|
|
|
/* The device has one virtqueue, where the Guest places inbufs. */
|
|
add_virtqueue(dev, VIRTQUEUE_NUM, rng_input);
|
|
|
|
verbose("device %u: rng\n", devices.device_num++);
|
|
}
|
|
/* That's the end of device setup. */
|
|
|
|
/*L:230 Reboot is pretty easy: clean up and exec() the Launcher afresh. */
|
|
static void __attribute__((noreturn)) restart_guest(void)
|
|
{
|
|
unsigned int i;
|
|
|
|
/*
|
|
* Since we don't track all open fds, we simply close everything beyond
|
|
* stderr.
|
|
*/
|
|
for (i = 3; i < FD_SETSIZE; i++)
|
|
close(i);
|
|
|
|
/* Reset all the devices (kills all threads). */
|
|
cleanup_devices();
|
|
|
|
execv(main_args[0], main_args);
|
|
err(1, "Could not exec %s", main_args[0]);
|
|
}
|
|
|
|
/*L:220
|
|
* Finally we reach the core of the Launcher which runs the Guest, serves
|
|
* its input and output, and finally, lays it to rest.
|
|
*/
|
|
static void __attribute__((noreturn)) run_guest(void)
|
|
{
|
|
for (;;) {
|
|
unsigned long notify_addr;
|
|
int readval;
|
|
|
|
/* We read from the /dev/lguest device to run the Guest. */
|
|
readval = pread(lguest_fd, ¬ify_addr,
|
|
sizeof(notify_addr), cpu_id);
|
|
|
|
/* One unsigned long means the Guest did HCALL_NOTIFY */
|
|
if (readval == sizeof(notify_addr)) {
|
|
verbose("Notify on address %#lx\n", notify_addr);
|
|
handle_output(notify_addr);
|
|
/* ENOENT means the Guest died. Reading tells us why. */
|
|
} else if (errno == ENOENT) {
|
|
char reason[1024] = { 0 };
|
|
pread(lguest_fd, reason, sizeof(reason)-1, cpu_id);
|
|
errx(1, "%s", reason);
|
|
/* ERESTART means that we need to reboot the guest */
|
|
} else if (errno == ERESTART) {
|
|
restart_guest();
|
|
/* Anything else means a bug or incompatible change. */
|
|
} else
|
|
err(1, "Running guest failed");
|
|
}
|
|
}
|
|
/*L:240
|
|
* This is the end of the Launcher. The good news: we are over halfway
|
|
* through! The bad news: the most fiendish part of the code still lies ahead
|
|
* of us.
|
|
*
|
|
* Are you ready? Take a deep breath and join me in the core of the Host, in
|
|
* "make Host".
|
|
:*/
|
|
|
|
static struct option opts[] = {
|
|
{ "verbose", 0, NULL, 'v' },
|
|
{ "tunnet", 1, NULL, 't' },
|
|
{ "block", 1, NULL, 'b' },
|
|
{ "rng", 0, NULL, 'r' },
|
|
{ "initrd", 1, NULL, 'i' },
|
|
{ "username", 1, NULL, 'u' },
|
|
{ "chroot", 1, NULL, 'c' },
|
|
{ NULL },
|
|
};
|
|
static void usage(void)
|
|
{
|
|
errx(1, "Usage: lguest [--verbose] "
|
|
"[--tunnet=(<ipaddr>:<macaddr>|bridge:<bridgename>:<macaddr>)\n"
|
|
"|--block=<filename>|--initrd=<filename>]...\n"
|
|
"<mem-in-mb> vmlinux [args...]");
|
|
}
|
|
|
|
/*L:105 The main routine is where the real work begins: */
|
|
int main(int argc, char *argv[])
|
|
{
|
|
/* Memory, code startpoint and size of the (optional) initrd. */
|
|
unsigned long mem = 0, start, initrd_size = 0;
|
|
/* Two temporaries. */
|
|
int i, c;
|
|
/* The boot information for the Guest. */
|
|
struct boot_params *boot;
|
|
/* If they specify an initrd file to load. */
|
|
const char *initrd_name = NULL;
|
|
|
|
/* Password structure for initgroups/setres[gu]id */
|
|
struct passwd *user_details = NULL;
|
|
|
|
/* Directory to chroot to */
|
|
char *chroot_path = NULL;
|
|
|
|
/* Save the args: we "reboot" by execing ourselves again. */
|
|
main_args = argv;
|
|
|
|
/*
|
|
* First we initialize the device list. We keep a pointer to the last
|
|
* device, and the next interrupt number to use for devices (1:
|
|
* remember that 0 is used by the timer).
|
|
*/
|
|
devices.lastdev = NULL;
|
|
devices.next_irq = 1;
|
|
|
|
/* We're CPU 0. In fact, that's the only CPU possible right now. */
|
|
cpu_id = 0;
|
|
|
|
/*
|
|
* We need to know how much memory so we can set up the device
|
|
* descriptor and memory pages for the devices as we parse the command
|
|
* line. So we quickly look through the arguments to find the amount
|
|
* of memory now.
|
|
*/
|
|
for (i = 1; i < argc; i++) {
|
|
if (argv[i][0] != '-') {
|
|
mem = atoi(argv[i]) * 1024 * 1024;
|
|
/*
|
|
* We start by mapping anonymous pages over all of
|
|
* guest-physical memory range. This fills it with 0,
|
|
* and ensures that the Guest won't be killed when it
|
|
* tries to access it.
|
|
*/
|
|
guest_base = map_zeroed_pages(mem / getpagesize()
|
|
+ DEVICE_PAGES);
|
|
guest_limit = mem;
|
|
guest_max = mem + DEVICE_PAGES*getpagesize();
|
|
devices.descpage = get_pages(1);
|
|
break;
|
|
}
|
|
}
|
|
|
|
/* The options are fairly straight-forward */
|
|
while ((c = getopt_long(argc, argv, "v", opts, NULL)) != EOF) {
|
|
switch (c) {
|
|
case 'v':
|
|
verbose = true;
|
|
break;
|
|
case 't':
|
|
setup_tun_net(optarg);
|
|
break;
|
|
case 'b':
|
|
setup_block_file(optarg);
|
|
break;
|
|
case 'r':
|
|
setup_rng();
|
|
break;
|
|
case 'i':
|
|
initrd_name = optarg;
|
|
break;
|
|
case 'u':
|
|
user_details = getpwnam(optarg);
|
|
if (!user_details)
|
|
err(1, "getpwnam failed, incorrect username?");
|
|
break;
|
|
case 'c':
|
|
chroot_path = optarg;
|
|
break;
|
|
default:
|
|
warnx("Unknown argument %s", argv[optind]);
|
|
usage();
|
|
}
|
|
}
|
|
/*
|
|
* After the other arguments we expect memory and kernel image name,
|
|
* followed by command line arguments for the kernel.
|
|
*/
|
|
if (optind + 2 > argc)
|
|
usage();
|
|
|
|
verbose("Guest base is at %p\n", guest_base);
|
|
|
|
/* We always have a console device */
|
|
setup_console();
|
|
|
|
/* Now we load the kernel */
|
|
start = load_kernel(open_or_die(argv[optind+1], O_RDONLY));
|
|
|
|
/* Boot information is stashed at physical address 0 */
|
|
boot = from_guest_phys(0);
|
|
|
|
/* Map the initrd image if requested (at top of physical memory) */
|
|
if (initrd_name) {
|
|
initrd_size = load_initrd(initrd_name, mem);
|
|
/*
|
|
* These are the location in the Linux boot header where the
|
|
* start and size of the initrd are expected to be found.
|
|
*/
|
|
boot->hdr.ramdisk_image = mem - initrd_size;
|
|
boot->hdr.ramdisk_size = initrd_size;
|
|
/* The bootloader type 0xFF means "unknown"; that's OK. */
|
|
boot->hdr.type_of_loader = 0xFF;
|
|
}
|
|
|
|
/*
|
|
* The Linux boot header contains an "E820" memory map: ours is a
|
|
* simple, single region.
|
|
*/
|
|
boot->e820_entries = 1;
|
|
boot->e820_map[0] = ((struct e820entry) { 0, mem, E820_RAM });
|
|
/*
|
|
* The boot header contains a command line pointer: we put the command
|
|
* line after the boot header.
|
|
*/
|
|
boot->hdr.cmd_line_ptr = to_guest_phys(boot + 1);
|
|
/* We use a simple helper to copy the arguments separated by spaces. */
|
|
concat((char *)(boot + 1), argv+optind+2);
|
|
|
|
/* Set kernel alignment to 16M (CONFIG_PHYSICAL_ALIGN) */
|
|
boot->hdr.kernel_alignment = 0x1000000;
|
|
|
|
/* Boot protocol version: 2.07 supports the fields for lguest. */
|
|
boot->hdr.version = 0x207;
|
|
|
|
/* The hardware_subarch value of "1" tells the Guest it's an lguest. */
|
|
boot->hdr.hardware_subarch = 1;
|
|
|
|
/* Tell the entry path not to try to reload segment registers. */
|
|
boot->hdr.loadflags |= KEEP_SEGMENTS;
|
|
|
|
/* We tell the kernel to initialize the Guest. */
|
|
tell_kernel(start);
|
|
|
|
/* Ensure that we terminate if a device-servicing child dies. */
|
|
signal(SIGCHLD, kill_launcher);
|
|
|
|
/* If we exit via err(), this kills all the threads, restores tty. */
|
|
atexit(cleanup_devices);
|
|
|
|
/* If requested, chroot to a directory */
|
|
if (chroot_path) {
|
|
if (chroot(chroot_path) != 0)
|
|
err(1, "chroot(\"%s\") failed", chroot_path);
|
|
|
|
if (chdir("/") != 0)
|
|
err(1, "chdir(\"/\") failed");
|
|
|
|
verbose("chroot done\n");
|
|
}
|
|
|
|
/* If requested, drop privileges */
|
|
if (user_details) {
|
|
uid_t u;
|
|
gid_t g;
|
|
|
|
u = user_details->pw_uid;
|
|
g = user_details->pw_gid;
|
|
|
|
if (initgroups(user_details->pw_name, g) != 0)
|
|
err(1, "initgroups failed");
|
|
|
|
if (setresgid(g, g, g) != 0)
|
|
err(1, "setresgid failed");
|
|
|
|
if (setresuid(u, u, u) != 0)
|
|
err(1, "setresuid failed");
|
|
|
|
verbose("Dropping privileges completed\n");
|
|
}
|
|
|
|
/* Finally, run the Guest. This doesn't return. */
|
|
run_guest();
|
|
}
|
|
/*:*/
|
|
|
|
/*M:999
|
|
* Mastery is done: you now know everything I do.
|
|
*
|
|
* But surely you have seen code, features and bugs in your wanderings which
|
|
* you now yearn to attack? That is the real game, and I look forward to you
|
|
* patching and forking lguest into the Your-Name-Here-visor.
|
|
*
|
|
* Farewell, and good coding!
|
|
* Rusty Russell.
|
|
*/
|