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author | Linus Torvalds <torvalds@linux-foundation.org> | 2019-04-29 22:24:34 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2019-04-29 22:24:34 +0200 |
commit | 83a50840e72a5a964b4704fcdc2fbb2d771015ab (patch) | |
tree | 9cbd662133d250f7e199a4e7a38a66dc67a7c935 /kernel/seccomp.c | |
parent | x86: make ZERO_PAGE() at least parse its argument (diff) | |
parent | seccomp: Make NEW_LISTENER and TSYNC flags exclusive (diff) | |
download | linux-83a50840e72a5a964b4704fcdc2fbb2d771015ab.tar.xz linux-83a50840e72a5a964b4704fcdc2fbb2d771015ab.zip |
Merge tag 'seccomp-v5.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull seccomp fixes from Kees Cook:
"Syzbot found a use-after-free bug in seccomp due to flags that should
not be allowed to be used together.
Tycho fixed this, I updated the self-tests, and the syzkaller PoC has
been running for several days without triggering KASan (before this
fix, it would reproduce). These patches have also been in -next for
almost a week, just to be sure.
- Add logic for making some seccomp flags exclusive (Tycho)
- Update selftests for exclusivity testing (Kees)"
* tag 'seccomp-v5.1-rc8' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux:
seccomp: Make NEW_LISTENER and TSYNC flags exclusive
selftests/seccomp: Prepare for exclusive seccomp flags
Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r-- | kernel/seccomp.c | 17 |
1 files changed, 15 insertions, 2 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c index df27e499956a..3582eeb59893 100644 --- a/kernel/seccomp.c +++ b/kernel/seccomp.c @@ -502,7 +502,10 @@ out: * * Caller must be holding current->sighand->siglock lock. * - * Returns 0 on success, -ve on error. + * Returns 0 on success, -ve on error, or + * - in TSYNC mode: the pid of a thread which was either not in the correct + * seccomp mode or did not have an ancestral seccomp filter + * - in NEW_LISTENER mode: the fd of the new listener */ static long seccomp_attach_filter(unsigned int flags, struct seccomp_filter *filter) @@ -1258,6 +1261,16 @@ static long seccomp_set_mode_filter(unsigned int flags, if (flags & ~SECCOMP_FILTER_FLAG_MASK) return -EINVAL; + /* + * In the successful case, NEW_LISTENER returns the new listener fd. + * But in the failure case, TSYNC returns the thread that died. If you + * combine these two flags, there's no way to tell whether something + * succeeded or failed. So, let's disallow this combination. + */ + if ((flags & SECCOMP_FILTER_FLAG_TSYNC) && + (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER)) + return -EINVAL; + /* Prepare the new filter before holding any locks. */ prepared = seccomp_prepare_user_filter(filter); if (IS_ERR(prepared)) @@ -1304,7 +1317,7 @@ out: mutex_unlock(¤t->signal->cred_guard_mutex); out_put_fd: if (flags & SECCOMP_FILTER_FLAG_NEW_LISTENER) { - if (ret < 0) { + if (ret) { listener_f->private_data = NULL; fput(listener_f); put_unused_fd(listener); |