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Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/userspace-api/seccomp_filter.rst | 10 |
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 |