BACKPORT: seccomp: add "seccomp" syscall

This adds the new "seccomp" syscall with both an "operation" and "flags"
parameter for future expansion. The third argument is a pointer value,
used with the SECCOMP_SET_MODE_FILTER operation. Currently, flags must
be 0. This is functionally equivalent to prctl(PR_SET_SECCOMP, ...).

In addition to the TSYNC flag later in this patch series, there is a
non-zero chance that this syscall could be used for configuring a fixed
argument area for seccomp-tracer-aware processes to pass syscall arguments
in the future. Hence, the use of "seccomp" not simply "seccomp_add_filter"
for this syscall. Additionally, this syscall uses operation, flags,
and user pointer for arguments because strictly passing arguments via
a user pointer would mean seccomp itself would be unable to trivially
filter the seccomp syscall itself.

Signed-off-by: Kees Cook <>
Reviewed-by: Oleg Nesterov <>
Reviewed-by: Andy Lutomirski <>

Bug: 28020023
Patchset: seccomp

(cherry picked from kernel/msm commit c7ff43e528a0b84d7bf73f7ab46a8bd447f4549d)
Signed-off-by: Kees Cook <>
Change-Id: I27ef0c7ca6c8216db0bf478130ccfa452094771a
8 files changed