Andrew Morton [akpm@xxxxxxxxxxxxxxxxxxxx] wrote:
|
| (switched to email. Please respond via emailed reply-to-all, not via the
| bugzilla web interface).
|
| On Thu, 11 Dec 2008 08:16:55 -0800 (PST) bugme-daemon@xxxxxxxxxxxxxxxxxxx wrote:
|
| > http://bugzilla.kernel.org/show_bug.cgi?id=12199
| >
| > Summary: /proc/1/exe entry of PID namespace init process links to
| > wrong executable
| > Product: Process Management
| > Version: 2.5
| > KernelVersion: 2.6.27.8
| > Platform: All
| > OS/Version: Linux
| > Tree: Mainline
| > Status: NEW
| > Severity: low
| > Priority: P1
| > Component: Other
| > AssignedTo: process_other@xxxxxxxxxxxxxxxxxxxx
| > ReportedBy: robert.rex@xxxxxxxxxx
| >
| >
| > Latest working kernel version:
| >
| > None known.
| >
| > Earliest failing kernel version:
| >
| > 2.6.25.4, 2.6.27.4 and 2.6.27.8 show this behaviour, but I assume that it
| > exists since 2.6.24 with the introduction of PID namespaces.
Hmm. I am able to repro the behavior with attached test case and with
CLONE_NEWPID removed. Ran this in a chroot shell and it shows complete
path. I tried on Ubuntu 8.04 (2.6.22-15, which has no pid namespace
support).
$ mount /dev/sda3 /tmp/target
$ chroot /tmp/target
$ ./pid_namespace_chroot2
/proc/self/exe is /tmp/target/tmp/pid_namespace_chroot2
set_mm_exe_file() call from flush_old_exec() sets 'mm->exe_file' to
'linux_bprm.file' and proc_exe_link() picks it up from there.
Could this be related how linux_bprm.file is populated after chroot ?
I have not traced that yet.
Sukadev
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/wait.h>
#define CLONE_NEWNS 0x00020000
#define CLONE_NEWPID 0x20000000
/** Compile with "gcc -o pid_namespace_chroot2 pid_namespace_chroot2.c" */
int do_child(void)
{
int status;
char buf[256];
if (mount("none", "/proc", "proc", 0, NULL)) {
perror("mount");
return 1;
}
if (readlink("/proc/self/exe", buf, sizeof(buf)) < 0) {
perror("READLINK");
return 1;
}
printf("/proc/self/exe is %s\n", buf);
if (umount("/proc")) {
perror("umount");
return 1;
}
return 0;
}
int main(void)
{
int status, pid;
void *stack = malloc(getpagesize());
if (!stack) {
perror("malloc");
return 1;
}
pid = clone(do_child, stack + getpagesize(), CLONE_NEWNS, NULL);
if (pid == -1) {
perror("clone");
return 1;
}
if (waitpid(pid, &status, __WALL) < 0) {
perror("waitpid");
return 1;
}
return 0;
}
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