Subject: [merged] proc-make-proc_fd_permission-thread-friendly.patch removed from -mm tree
To: oleg@xxxxxxxxxx,mm-commits@xxxxxxxxxxxxxxx
From: akpm@xxxxxxxxxxxxxxxxxxxx
Date: Thu, 12 Sep 2013 12:48:35 -0700
The patch titled
Subject: proc: make proc_fd_permission() thread-friendly
has been removed from the -mm tree. Its filename was
proc-make-proc_fd_permission-thread-friendly.patch
This patch was dropped because it was merged into mainline or a subsystem tree
------------------------------------------------------
From: Oleg Nesterov <oleg@xxxxxxxxxx>
Subject: 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@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/fd.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff -puN fs/proc/fd.c~proc-make-proc_fd_permission-thread-friendly fs/proc/fd.c
--- a/fs/proc/fd.c~proc-make-proc_fd_permission-thread-friendly
+++ a/fs/proc/fd.c
@@ -286,7 +286,7 @@ int proc_fd_permission(struct inode *ino
int rv = generic_permission(inode, mask);
if (rv == 0)
return 0;
- if (task_pid(current) == proc_pid(inode))
+ if (task_tgid(current) == proc_pid(inode))
rv = 0;
return rv;
}
_
Patches currently in -mm which might be from oleg@xxxxxxxxxx are
origin.patch
anon_inodefs-forbid-open-via-proc.patch
autofs4-allow-autofs-to-work-outside-the-initial-pid-namespace.patch
autofs4-translate-pids-to-the-right-namespace-for-the-daemon.patch
signals-eventpoll-set-saved_sigmask-at-the-start.patch
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