Messages in this thread | | | Subject | Re: [PATCH] prctl: remove one-shot limitation for changing exe link | From | Stanislav Kinsburskiy <> | Date | Tue, 12 Jul 2016 18:52:29 +0200 |
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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 <oleg@redhat.com> >
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