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linux-next/arch/um/kernel/skas/process.c
Bodo Stroesser 8b51304ed3 [PATCH] uml: increase granularity of host capability checking 
This change enables SKAS0/SKAS3 to work with all combinations of /proc/mm and
PTRACE_FAULTINFO being available or not.

Also it changes the initialization of proc_mm and ptrace_faultinfo slightly,
to ease forcing SKAS0 on a patched host.  Forcing UML to run without /proc/mm
or PTRACE_FAULTINFO by cmdline parameter can be implemented with a setup
resetting the related variable.

Signed-off-by: Bodo Stroesser <bstroesser@fujitsu-siemens.com>
Signed-off-by: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-09-05 00:06:24 -07:00

571 lines
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/*
* Copyright (C) 2002- 2004 Jeff Dike (jdike@addtoit.com)
* Licensed under the GPL
*/
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <signal.h>
#include <setjmp.h>
#include <sched.h>
#include <sys/wait.h>
#include <sys/mman.h>
#include <sys/user.h>
#include <sys/time.h>
#include <asm/unistd.h>
#include <asm/types.h>
#include "user.h"
#include "ptrace_user.h"
#include "time_user.h"
#include "sysdep/ptrace.h"
#include "user_util.h"
#include "kern_util.h"
#include "skas.h"
#include "stub-data.h"
#include "mm_id.h"
#include "sysdep/sigcontext.h"
#include "sysdep/stub.h"
#include "os.h"
#include "proc_mm.h"
#include "skas_ptrace.h"
#include "chan_user.h"
#include "signal_user.h"
#include "registers.h"
#include "mem.h"
#include "uml-config.h"
#include "process.h"
int is_skas_winch(int pid, int fd, void *data)
{
if(pid != os_getpgrp())
return(0);
register_winch_irq(-1, fd, -1, data);
return(1);
}
void wait_stub_done(int pid, int sig, char * fname)
{
int n, status, err;
do {
if ( sig != -1 ) {
err = ptrace(PTRACE_CONT, pid, 0, sig);
if(err)
panic("%s : continue failed, errno = %d\n",
fname, errno);
}
sig = 0;
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
} while((n >= 0) && WIFSTOPPED(status) &&
((WSTOPSIG(status) == SIGVTALRM) ||
/* running UML inside a detached screen can cause
* SIGWINCHes
*/
(WSTOPSIG(status) == SIGWINCH)));
if((n < 0) || !WIFSTOPPED(status) ||
(WSTOPSIG(status) != SIGUSR1 && WSTOPSIG(status) != SIGTRAP)){
panic("%s : failed to wait for SIGUSR1/SIGTRAP, "
"pid = %d, n = %d, errno = %d, status = 0x%x\n",
fname, pid, n, errno, status);
}
}
void get_skas_faultinfo(int pid, struct faultinfo * fi)
{
int err;
if(ptrace_faultinfo){
err = ptrace(PTRACE_FAULTINFO, pid, 0, fi);
if(err)
panic("get_skas_faultinfo - PTRACE_FAULTINFO failed, "
"errno = %d\n", errno);
/* Special handling for i386, which has different structs */
if (sizeof(struct ptrace_faultinfo) < sizeof(struct faultinfo))
memset((char *)fi + sizeof(struct ptrace_faultinfo), 0,
sizeof(struct faultinfo) -
sizeof(struct ptrace_faultinfo));
}
else {
wait_stub_done(pid, SIGSEGV, "get_skas_faultinfo");
/* faultinfo is prepared by the stub-segv-handler at start of
* the stub stack page. We just have to copy it.
*/
memcpy(fi, (void *)current_stub_stack(), sizeof(*fi));
}
}
static void handle_segv(int pid, union uml_pt_regs * regs)
{
get_skas_faultinfo(pid, &regs->skas.faultinfo);
segv(regs->skas.faultinfo, 0, 1, NULL);
}
/*To use the same value of using_sysemu as the caller, ask it that value (in local_using_sysemu)*/
static void handle_trap(int pid, union uml_pt_regs *regs, int local_using_sysemu)
{
int err, status;
/* Mark this as a syscall */
UPT_SYSCALL_NR(regs) = PT_SYSCALL_NR(regs->skas.regs);
if (!local_using_sysemu)
{
err = ptrace(PTRACE_POKEUSR, pid, PT_SYSCALL_NR_OFFSET, __NR_getpid);
if(err < 0)
panic("handle_trap - nullifying syscall failed errno = %d\n",
errno);
err = ptrace(PTRACE_SYSCALL, pid, 0, 0);
if(err < 0)
panic("handle_trap - continuing to end of syscall failed, "
"errno = %d\n", errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if((err < 0) || !WIFSTOPPED(status) ||
(WSTOPSIG(status) != SIGTRAP + 0x80))
panic("handle_trap - failed to wait at end of syscall, "
"errno = %d, status = %d\n", errno, status);
}
handle_syscall(regs);
}
extern int __syscall_stub_start;
int stub_code_fd = -1;
__u64 stub_code_offset;
static int userspace_tramp(void *stack)
{
void *addr;
ptrace(PTRACE_TRACEME, 0, 0, 0);
init_new_thread_signals(1);
enable_timer();
if(!proc_mm){
/* This has a pte, but it can't be mapped in with the usual
* tlb_flush mechanism because this is part of that mechanism
*/
addr = mmap64((void *) UML_CONFIG_STUB_CODE, page_size(),
PROT_EXEC, MAP_FIXED | MAP_PRIVATE,
stub_code_fd, stub_code_offset);
if(addr == MAP_FAILED){
printk("mapping stub code failed, errno = %d\n",
errno);
exit(1);
}
if(stack != NULL){
int fd;
__u64 offset;
fd = phys_mapping(to_phys(stack), &offset);
addr = mmap((void *) UML_CONFIG_STUB_DATA, page_size(),
PROT_READ | PROT_WRITE,
MAP_FIXED | MAP_SHARED, fd, offset);
if(addr == MAP_FAILED){
printk("mapping stub stack failed, "
"errno = %d\n", errno);
exit(1);
}
}
}
if(!ptrace_faultinfo){
unsigned long v = UML_CONFIG_STUB_CODE +
(unsigned long) stub_segv_handler -
(unsigned long) &__syscall_stub_start;
set_sigstack((void *) UML_CONFIG_STUB_DATA, page_size());
set_handler(SIGSEGV, (void *) v, SA_ONSTACK,
SIGIO, SIGWINCH, SIGALRM, SIGVTALRM,
SIGUSR1, -1);
}
os_stop_process(os_getpid());
return(0);
}
/* Each element set once, and only accessed by a single processor anyway */
#undef NR_CPUS
#define NR_CPUS 1
int userspace_pid[NR_CPUS];
int start_userspace(unsigned long stub_stack)
{
void *stack;
unsigned long sp;
int pid, status, n, flags;
if ( stub_code_fd == -1 )
stub_code_fd = phys_mapping(to_phys(&__syscall_stub_start),
&stub_code_offset);
stack = mmap(NULL, PAGE_SIZE, PROT_READ | PROT_WRITE | PROT_EXEC,
MAP_PRIVATE | MAP_ANONYMOUS, -1, 0);
if(stack == MAP_FAILED)
panic("start_userspace : mmap failed, errno = %d", errno);
sp = (unsigned long) stack + PAGE_SIZE - sizeof(void *);
flags = CLONE_FILES | SIGCHLD;
if(proc_mm) flags |= CLONE_VM;
pid = clone(userspace_tramp, (void *) sp, flags, (void *) stub_stack);
if(pid < 0)
panic("start_userspace : clone failed, errno = %d", errno);
do {
CATCH_EINTR(n = waitpid(pid, &status, WUNTRACED));
if(n < 0)
panic("start_userspace : wait failed, errno = %d",
errno);
} while(WIFSTOPPED(status) && (WSTOPSIG(status) == SIGVTALRM));
if(!WIFSTOPPED(status) || (WSTOPSIG(status) != SIGSTOP))
panic("start_userspace : expected SIGSTOP, got status = %d",
status);
if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL, (void *)PTRACE_O_TRACESYSGOOD) < 0)
panic("start_userspace : PTRACE_SETOPTIONS failed, errno=%d\n",
errno);
if(munmap(stack, PAGE_SIZE) < 0)
panic("start_userspace : munmap failed, errno = %d\n", errno);
return(pid);
}
void userspace(union uml_pt_regs *regs)
{
int err, status, op, pid = userspace_pid[0];
int local_using_sysemu; /*To prevent races if using_sysemu changes under us.*/
while(1){
restore_registers(pid, regs);
/* Now we set local_using_sysemu to be used for one loop */
local_using_sysemu = get_using_sysemu();
op = SELECT_PTRACE_OPERATION(local_using_sysemu, singlestepping(NULL));
err = ptrace(op, pid, 0, 0);
if(err)
panic("userspace - could not resume userspace process, "
"pid=%d, ptrace operation = %d, errno = %d\n",
op, errno);
CATCH_EINTR(err = waitpid(pid, &status, WUNTRACED));
if(err < 0)
panic("userspace - waitpid failed, errno = %d\n",
errno);
regs->skas.is_user = 1;
save_registers(pid, regs);
UPT_SYSCALL_NR(regs) = -1; /* Assume: It's not a syscall */
if(WIFSTOPPED(status)){
switch(WSTOPSIG(status)){
case SIGSEGV:
if(PTRACE_FULL_FAULTINFO || !ptrace_faultinfo)
user_signal(SIGSEGV, regs, pid);
else handle_segv(pid, regs);
break;
case SIGTRAP + 0x80:
handle_trap(pid, regs, local_using_sysemu);
break;
case SIGTRAP:
relay_signal(SIGTRAP, regs);
break;
case SIGIO:
case SIGVTALRM:
case SIGILL:
case SIGBUS:
case SIGFPE:
case SIGWINCH:
user_signal(WSTOPSIG(status), regs, pid);
break;
default:
printk("userspace - child stopped with signal "
"%d\n", WSTOPSIG(status));
}
pid = userspace_pid[0];
interrupt_end();
/* Avoid -ERESTARTSYS handling in host */
PT_SYSCALL_NR(regs->skas.regs) = -1;
}
}
}
#define INIT_JMP_NEW_THREAD 0
#define INIT_JMP_REMOVE_SIGSTACK 1
#define INIT_JMP_CALLBACK 2
#define INIT_JMP_HALT 3
#define INIT_JMP_REBOOT 4
int copy_context_skas0(unsigned long new_stack, int pid)
{
int err;
unsigned long regs[MAX_REG_NR];
unsigned long current_stack = current_stub_stack();
struct stub_data *data = (struct stub_data *) current_stack;
struct stub_data *child_data = (struct stub_data *) new_stack;
__u64 new_offset;
int new_fd = phys_mapping(to_phys((void *)new_stack), &new_offset);
/* prepare offset and fd of child's stack as argument for parent's
* and child's mmap2 calls
*/
*data = ((struct stub_data) { .offset = MMAP_OFFSET(new_offset),
.fd = new_fd,
.timer = ((struct itimerval)
{ { 0, 1000000 / hz() },
{ 0, 1000000 / hz() }})});
get_safe_registers(regs);
/* Set parent's instruction pointer to start of clone-stub */
regs[REGS_IP_INDEX] = UML_CONFIG_STUB_CODE +
(unsigned long) stub_clone_handler -
(unsigned long) &__syscall_stub_start;
regs[REGS_SP_INDEX] = UML_CONFIG_STUB_DATA + PAGE_SIZE -
sizeof(void *);
err = ptrace_setregs(pid, regs);
if(err < 0)
panic("copy_context_skas0 : PTRACE_SETREGS failed, "
"pid = %d, errno = %d\n", pid, errno);
/* set a well known return code for detection of child write failure */
child_data->err = 12345678;
/* Wait, until parent has finished its work: read child's pid from
* parent's stack, and check, if bad result.
*/
wait_stub_done(pid, 0, "copy_context_skas0");
pid = data->err;
if(pid < 0)
panic("copy_context_skas0 - stub-parent reports error %d\n",
pid);
/* Wait, until child has finished too: read child's result from
* child's stack and check it.
*/
wait_stub_done(pid, -1, "copy_context_skas0");
if (child_data->err != UML_CONFIG_STUB_DATA)
panic("copy_context_skas0 - stub-child reports error %d\n",
child_data->err);
if (ptrace(PTRACE_OLDSETOPTIONS, pid, NULL,
(void *)PTRACE_O_TRACESYSGOOD) < 0)
panic("copy_context_skas0 : PTRACE_SETOPTIONS failed, "
"errno = %d\n", errno);
return pid;
}
/*
* This is used only, if proc_mm is available, while PTRACE_FAULTINFO
* isn't. Opening /proc/mm creates a new mm_context, which lacks the stub-pages
* Thus, we map them using /proc/mm-fd
*/
void map_stub_pages(int fd, unsigned long code,
unsigned long data, unsigned long stack)
{
struct proc_mm_op mmop;
int n;
mmop = ((struct proc_mm_op) { .op = MM_MMAP,
.u =
{ .mmap =
{ .addr = code,
.len = PAGE_SIZE,
.prot = PROT_EXEC,
.flags = MAP_FIXED | MAP_PRIVATE,
.fd = stub_code_fd,
.offset = stub_code_offset
} } });
n = os_write_file(fd, &mmop, sizeof(mmop));
if(n != sizeof(mmop))
panic("map_stub_pages : /proc/mm map for code failed, "
"err = %d\n", -n);
if ( stack ) {
__u64 map_offset;
int map_fd = phys_mapping(to_phys((void *)stack), &map_offset);
mmop = ((struct proc_mm_op)
{ .op = MM_MMAP,
.u =
{ .mmap =
{ .addr = data,
.len = PAGE_SIZE,
.prot = PROT_READ | PROT_WRITE,
.flags = MAP_FIXED | MAP_SHARED,
.fd = map_fd,
.offset = map_offset
} } });
n = os_write_file(fd, &mmop, sizeof(mmop));
if(n != sizeof(mmop))
panic("map_stub_pages : /proc/mm map for data failed, "
"err = %d\n", -n);
}
}
void new_thread(void *stack, void **switch_buf_ptr, void **fork_buf_ptr,
void (*handler)(int))
{
unsigned long flags;
sigjmp_buf switch_buf, fork_buf;
*switch_buf_ptr = &switch_buf;
*fork_buf_ptr = &fork_buf;
/* Somewhat subtle - siglongjmp restores the signal mask before doing
* the longjmp. This means that when jumping from one stack to another
* when the target stack has interrupts enabled, an interrupt may occur
* on the source stack. This is bad when starting up a process because
* it's not supposed to get timer ticks until it has been scheduled.
* So, we disable interrupts around the sigsetjmp to ensure that
* they can't happen until we get back here where they are safe.
*/
flags = get_signals();
block_signals();
if(sigsetjmp(fork_buf, 1) == 0)
new_thread_proc(stack, handler);
remove_sigstack();
set_signals(flags);
}
void thread_wait(void *sw, void *fb)
{
sigjmp_buf buf, **switch_buf = sw, *fork_buf;
*switch_buf = &buf;
fork_buf = fb;
if(sigsetjmp(buf, 1) == 0)
siglongjmp(*fork_buf, INIT_JMP_REMOVE_SIGSTACK);
}
void switch_threads(void *me, void *next)
{
sigjmp_buf my_buf, **me_ptr = me, *next_buf = next;
*me_ptr = &my_buf;
if(sigsetjmp(my_buf, 1) == 0)
siglongjmp(*next_buf, 1);
}
static sigjmp_buf initial_jmpbuf;
/* XXX Make these percpu */
static void (*cb_proc)(void *arg);
static void *cb_arg;
static sigjmp_buf *cb_back;
int start_idle_thread(void *stack, void *switch_buf_ptr, void **fork_buf_ptr)
{
sigjmp_buf **switch_buf = switch_buf_ptr;
int n;
set_handler(SIGWINCH, (__sighandler_t) sig_handler,
SA_ONSTACK | SA_RESTART, SIGUSR1, SIGIO, SIGALRM,
SIGVTALRM, -1);
*fork_buf_ptr = &initial_jmpbuf;
n = sigsetjmp(initial_jmpbuf, 1);
switch(n){
case INIT_JMP_NEW_THREAD:
new_thread_proc((void *) stack, new_thread_handler);
break;
case INIT_JMP_REMOVE_SIGSTACK:
remove_sigstack();
break;
case INIT_JMP_CALLBACK:
(*cb_proc)(cb_arg);
siglongjmp(*cb_back, 1);
break;
case INIT_JMP_HALT:
kmalloc_ok = 0;
return(0);
case INIT_JMP_REBOOT:
kmalloc_ok = 0;
return(1);
default:
panic("Bad sigsetjmp return in start_idle_thread - %d\n", n);
}
siglongjmp(**switch_buf, 1);
}
void remove_sigstack(void)
{
stack_t stack = ((stack_t) { .ss_flags = SS_DISABLE,
.ss_sp = NULL,
.ss_size = 0 });
if(sigaltstack(&stack, NULL) != 0)
panic("disabling signal stack failed, errno = %d\n", errno);
}
void initial_thread_cb_skas(void (*proc)(void *), void *arg)
{
sigjmp_buf here;
cb_proc = proc;
cb_arg = arg;
cb_back = &here;
block_signals();
if(sigsetjmp(here, 1) == 0)
siglongjmp(initial_jmpbuf, INIT_JMP_CALLBACK);
unblock_signals();
cb_proc = NULL;
cb_arg = NULL;
cb_back = NULL;
}
void halt_skas(void)
{
block_signals();
siglongjmp(initial_jmpbuf, INIT_JMP_HALT);
}
void reboot_skas(void)
{
block_signals();
siglongjmp(initial_jmpbuf, INIT_JMP_REBOOT);
}
void switch_mm_skas(struct mm_id *mm_idp)
{
int err;
#warning need cpu pid in switch_mm_skas
if(proc_mm){
err = ptrace(PTRACE_SWITCH_MM, userspace_pid[0], 0,
mm_idp->u.mm_fd);
if(err)
panic("switch_mm_skas - PTRACE_SWITCH_MM failed, "
"errno = %d\n", errno);
}
else userspace_pid[0] = mm_idp->u.pid;
}
/*
* Overrides for Emacs so that we follow Linus's tabbing style.
* Emacs will notice this stuff at the end of the file and automatically
* adjust the settings for this buffer only. This must remain at the end
* of the file.
* ---------------------------------------------------------------------------
* Local variables:
* c-file-style: "linux"
* End:
*/
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