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Diffstat (limited to 'Documentation/userspace-api/seccomp_filter.rst')
| -rw-r--r-- | Documentation/userspace-api/seccomp_filter.rst | 12 |
1 files changed, 12 insertions, 0 deletions
diff --git a/Documentation/userspace-api/seccomp_filter.rst b/Documentation/userspace-api/seccomp_filter.rst index 6efb41cc8072..d61219889e49 100644 --- a/Documentation/userspace-api/seccomp_filter.rst +++ b/Documentation/userspace-api/seccomp_filter.rst @@ -259,6 +259,18 @@ and ``ioctl(SECCOMP_IOCTL_NOTIF_SEND)`` a response, indicating what should be returned to userspace. The ``id`` member of ``struct seccomp_notif_resp`` should be the same ``id`` as in ``struct seccomp_notif``. +Userspace can also add file descriptors to the notifying process via +``ioctl(SECCOMP_IOCTL_NOTIF_ADDFD)``. The ``id`` member of +``struct seccomp_notif_addfd`` should be the same ``id`` as in +``struct seccomp_notif``. The ``newfd_flags`` flag may be used to set flags +like O_EXEC on the file descriptor in the notifying process. If the supervisor +wants to inject the file descriptor with a specific number, the +``SECCOMP_ADDFD_FLAG_SETFD`` flag can be used, and set the ``newfd`` member to +the specific number to use. If that file descriptor is already open in the +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. + 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 |