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author | Oleg Nesterov <oleg@redhat.com> | 2013-09-11 14:24:37 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-09-11 15:59:03 -0700 |
commit | 96d0df79f2644fc823f26c06491e182d87a90c2a (patch) | |
tree | 09f0d82a4ac4e0410a0067466eb04ab138db3e4f /fs/exec.c | |
parent | a3c039929d01f793c47922017b6c0ae438e11598 (diff) | |
download | linux-96d0df79f2644fc823f26c06491e182d87a90c2a.tar.gz linux-96d0df79f2644fc823f26c06491e182d87a90c2a.tar.bz2 linux-96d0df79f2644fc823f26c06491e182d87a90c2a.zip |
proc: make proc_fd_permission() thread-friendly
proc_fd_permission() says "process can still access /proc/self/fd after it
has executed a setuid()", but the "task_pid() = proc_pid() check only
helps if the task is group leader, /proc/self points to
/proc/<leader-pid>.
Change this check to use task_tgid() so that the whole thread group can
access its /proc/self/fd or /proc/<tid-of-sub-thread>/fd.
Notes:
- CLONE_THREAD does not require CLONE_FILES so task->files
can differ, but I don't think this can lead to any security
problem. And this matches same_thread_group() in
__ptrace_may_access().
- /proc/self should probably point to /proc/<thread-tid>, but
it is too late to change the rules. Perhaps it makes sense
to add /proc/thread though.
Test-case:
void *tfunc(void *arg)
{
assert(opendir("/proc/self/fd"));
return NULL;
}
int main(void)
{
pthread_t t;
pthread_create(&t, NULL, tfunc, NULL);
pthread_join(t, NULL);
return 0;
}
fails if, say, this executable is not readable and suid_dumpable = 0.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'fs/exec.c')
0 files changed, 0 insertions, 0 deletions