12.07.2016 18:42, Oleg Nesterov пишет:
On 07/12, Stanislav Kinsburskiy wrote:
--- a/kernel/sys.c
+++ b/kernel/sys.c
@@ -1696,16 +1696,6 @@ static int prctl_set_mm_exe_file(struct mm_struct *mm,
unsigned int fd)
fput(exe_file);
}
- /*
- * The symlink can be changed only once, just to disallow arbitrary
- * transitions malicious software might bring in. This means one
- * could make a snapshot over all processes running and monitor
- * /proc/pid/exe changes to notice unusual activity if needed.
- */
- err = -EPERM;
- if (test_and_set_bit(MMF_EXE_FILE_CHANGED, &mm->flags))
- goto exit;
-
I didn't even try to read the changelog so I do not know why do you
want this change ;)
But I would like to ack it in any case. I never understood why do we
want/need this MMF_EXE_FILE_CHANGED check, I suggested to remove it
many times.
And can't resist, please note the xchg() below. Currently (before this
patch) we do not need it. I was specially added to ensure that we can
just remove this test_and_set_bit(MMF_EXE_FILE_CHANGED) without adding
a race.
Thanks, Oleg. I'll take a look.
But should this be addressed in this patch? Especially if it's not
needed even now (before this patch)?
Acked-by: Oleg Nesterov <[email protected]>
