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execve updates for v5.20-rc1

Browse Source 
- Allow unsharing time namespace on vfork+exec (Andrei Vagin)
 
 - Replace usage of deprecated kmap APIs (Fabio M. De Francesco)
 
 - Fix spelling mistake (Zhang Jiaming)
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Merge tag 'execve-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux

Pull execve updates from Kees Cook:

 - Allow unsharing time namespace on vfork+exec (Andrei Vagin)

 - Replace usage of deprecated kmap APIs (Fabio M. De Francesco)

 - Fix spelling mistake (Zhang Jiaming)

* tag 'execve-v5.20-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
  exec: Call kmap_local_page() in copy_string_kernel()
  exec: Fix a spelling mistake
  selftests/timens: add a test for vfork+exit
  fs/exec: allow to unshare a time namespace on vfork+exec
This commit is contained in:
Linus Torvalds 2022-08-02 14:36:19 -07:00
commit d7b767b508
5 changed files with 106 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

15
fs/exec.c
View File

@ -65,6 +65,7 @@
#include <linux/io_uring.h>
#include <linux/syscall_user_dispatch.h>
#include <linux/coredump.h>
#include <linux/time_namespace.h>
#include <linux/uaccess.h>
#include <asm/mmu_context.h>
@ -630,7 +631,6 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
unsigned int bytes_to_copy = min_t(unsigned int, len,
min_not_zero(offset_in_page(pos), PAGE_SIZE));
struct page *page;
char *kaddr;
pos -= bytes_to_copy;
arg -= bytes_to_copy;
@ -639,11 +639,8 @@ int copy_string_kernel(const char *arg, struct linux_binprm *bprm)
page = get_arg_page(bprm, pos, 1);
if (!page)
return -E2BIG;
kaddr = kmap_atomic(page);
flush_arg_page(bprm, pos & PAGE_MASK, page);
memcpy(kaddr + offset_in_page(pos), arg, bytes_to_copy);
flush_dcache_page(page);
kunmap_atomic(kaddr);
memcpy_to_page(page, offset_in_page(pos), arg, bytes_to_copy);
put_arg_page(page);
}
@ -982,10 +979,12 @@ static int exec_mmap(struct mm_struct *mm)
{
struct task_struct *tsk;
struct mm_struct *old_mm, *active_mm;
bool vfork;
int ret;
/* Notify parent that we're no longer interested in the old VM */
tsk = current;
vfork = !!tsk->vfork_done;
old_mm = current->mm;
exec_mm_release(tsk, old_mm);
if (old_mm)
@ -1030,6 +1029,10 @@ static int exec_mmap(struct mm_struct *mm)
tsk->mm->vmacache_seqnum = 0;
vmacache_flush(tsk);
task_unlock(tsk);
if (vfork)
timens_on_fork(tsk->nsproxy, tsk);
if (old_mm) {
mmap_read_unlock(old_mm);
BUG_ON(active_mm != old_mm);
@ -1149,7 +1152,7 @@ static int de_thread(struct task_struct *tsk)
/*
* We are going to release_task()->ptrace_unlink() silently,
* the tracer can sleep in do_wait(). EXIT_DEAD guarantees
* the tracer wont't block again waiting for this thread.
* the tracer won't block again waiting for this thread.
*/
if (unlikely(leader->ptrace))
__wake_up_parent(leader, leader->parent);

5
kernel/fork.c
View File

@ -2033,8 +2033,11 @@ static __latent_entropy struct task_struct *copy_process(
/*
* If the new process will be in a different time namespace
* do not allow it to share VM or a thread group with the forking task.
*
* On vfork, the child process enters the target time namespace only
* after exec.
*/
if (clone_flags & (CLONE_THREAD | CLONE_VM)) {
if ((clone_flags & (CLONE_VM | CLONE_VFORK)) == CLONE_VM) {
if (nsp->time_ns != nsp->time_ns_for_children)
return ERR_PTR(-EINVAL);
}

3
kernel/nsproxy.c
View File

@ -179,7 +179,8 @@ int copy_namespaces(unsigned long flags, struct task_struct *tsk)
if (IS_ERR(new_ns))
return PTR_ERR(new_ns);
timens_on_fork(new_ns, tsk);
if ((flags & CLONE_VM) == 0)
timens_on_fork(new_ns, tsk);
tsk->nsproxy = new_ns;
return 0;

2
tools/testing/selftests/timens/Makefile
View File

@ -1,4 +1,4 @@
TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex
TEST_GEN_PROGS := timens timerfd timer clock_nanosleep procfs exec futex vfork_exec
TEST_GEN_PROGS_EXTENDED := gettime_perf
CFLAGS := -Wall -Werror -pthread

90
tools/testing/selftests/timens/vfork_exec.c Normal file
View File

@ -0,0 +1,90 @@
// SPDX-License-Identifier: GPL-2.0
#define _GNU_SOURCE
#include <errno.h>
#include <fcntl.h>
#include <sched.h>
#include <stdio.h>
#include <stdbool.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <time.h>
#include <unistd.h>
#include <string.h>
#include "log.h"
#include "timens.h"
#define OFFSET (36000)
int main(int argc, char *argv[])
{
struct timespec now, tst;
int status, i;
pid_t pid;
if (argc > 1) {
if (sscanf(argv[1], "%ld", &now.tv_sec) != 1)
return pr_perror("sscanf");
for (i = 0; i < 2; i++) {
_gettime(CLOCK_MONOTONIC, &tst, i);
if (abs(tst.tv_sec - now.tv_sec) > 5)
return pr_fail("%ld %ld\n", now.tv_sec, tst.tv_sec);
}
return 0;
}
nscheck();
ksft_set_plan(1);
clock_gettime(CLOCK_MONOTONIC, &now);
if (unshare_timens())
return 1;
if (_settime(CLOCK_MONOTONIC, OFFSET))
return 1;
for (i = 0; i < 2; i++) {
_gettime(CLOCK_MONOTONIC, &tst, i);
if (abs(tst.tv_sec - now.tv_sec) > 5)
return pr_fail("%ld %ld\n",
now.tv_sec, tst.tv_sec);
}
pid = vfork();
if (pid < 0)
return pr_perror("fork");
if (pid == 0) {
char now_str[64];
char *cargv[] = {"exec", now_str, NULL};
char *cenv[] = {NULL};
// Check that we are still in the source timens.
for (i = 0; i < 2; i++) {
_gettime(CLOCK_MONOTONIC, &tst, i);
if (abs(tst.tv_sec - now.tv_sec) > 5)
return pr_fail("%ld %ld\n",
now.tv_sec, tst.tv_sec);
}
/* Check for proper vvar offsets after execve. */
snprintf(now_str, sizeof(now_str), "%ld", now.tv_sec + OFFSET);
execve("/proc/self/exe", cargv, cenv);
return pr_perror("execve");
}
if (waitpid(pid, &status, 0) != pid)
return pr_perror("waitpid");
if (status)
ksft_exit_fail();
ksft_test_result_pass("exec\n");
ksft_exit_pass();
return 0;
}