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authorLinus Torvalds <torvalds@linux-foundation.org>2022-05-24 22:37:24 +0300
committerLinus Torvalds <torvalds@linux-foundation.org>2022-05-24 22:37:24 +0300
commitdc8af1ffd657c90733088e0093c7990305b2b4e9 (patch)
treebc48bacb34bb92f3b31146f07a3dfd0c2eb2cbb6 /Documentation/userspace-api
parent0bf13a84362e750a90008af259b098d7c0e0755b (diff)
parent5e91d2a4146946ea0abc984ca957f12b70632901 (diff)
downloadlinux-dc8af1ffd657c90733088e0093c7990305b2b4e9.tar.xz
Merge tag 'seccomp-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux
Pull seccomp updates from Kees Cook: - Rework USER_NOTIF notification ordering and kill logic (Sargun Dhillon) - Improved PTRACE_O_SUSPEND_SECCOMP selftest (Jann Horn) - Gracefully handle failed unshare() in selftests (Yang Guang) - Spelling fix (Colin Ian King) * tag 'seccomp-v5.19-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/kees/linux: selftests/seccomp: Fix spelling mistake "Coud" -> "Could" selftests/seccomp: Add test for wait killable notifier selftests/seccomp: Refactor get_proc_stat to split out file reading code seccomp: Add wait_killable semantic to seccomp user notifier selftests/seccomp: Ensure that notifications come in FIFO order seccomp: Use FIFO semantics to order notifications selftests/seccomp: Add SKIP for failed unshare() selftests/seccomp: Test PTRACE_O_SUSPEND_SECCOMP without CAP_SYS_ADMIN
Diffstat (limited to 'Documentation/userspace-api')
-rw-r--r--Documentation/userspace-api/seccomp_filter.rst10
1 files changed, 10 insertions, 0 deletions
diff --git a/Documentation/userspace-api/seccomp_filter.rst b/Documentation/userspace-api/seccomp_filter.rst
index 539e9d4a4860..d1e2b9193f09 100644
--- a/Documentation/userspace-api/seccomp_filter.rst
+++ b/Documentation/userspace-api/seccomp_filter.rst
@@ -271,6 +271,16 @@ notifying process it will be replaced. The supervisor can also add an FD, and
respond atomically by using the ``SECCOMP_ADDFD_FLAG_SEND`` flag and the return
value will be the injected file descriptor number.
+The notifying process can be preempted, resulting in the notification being
+aborted. This can be problematic when trying to take actions on behalf of the
+notifying process that are long-running and typically retryable (mounting a
+filesytem). Alternatively, at filter installation time, the
+``SECCOMP_FILTER_FLAG_WAIT_KILLABLE_RECV`` flag can be set. This flag makes it
+such that when a user notification is received by the supervisor, the notifying
+process will ignore non-fatal signals until the response is sent. Signals that
+are sent prior to the notification being received by userspace are handled
+normally.
+
It is worth noting that ``struct seccomp_data`` contains the values of register
arguments to the syscall, but does not contain pointers to memory. The task's
memory is accessible to suitably privileged traces via ``ptrace()`` or