arm64: add seccomp support

secure_computing() is called first in syscall_trace_enter() so that
a system call will be aborted quickly without doing succeeding syscall
tracing if seccomp rules want to deny that system call.

On compat task, syscall numbers for system calls allowed in seccomp mode 1
are different from those on normal tasks, and so _NR_seccomp_xxx_32's need
to be redefined.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Signed-off-by: Will Deacon <will.deacon@arm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm64/kernel/ptrace.c b/arch/arm64/kernel/ptrace.c
index f576781d8d3b..d882b833dbdb 100644
--- a/arch/arm64/kernel/ptrace.c
+++ b/arch/arm64/kernel/ptrace.c
@@ -27,6 +27,7 @@
 #include <linux/smp.h>
 #include <linux/ptrace.h>
 #include <linux/user.h>
+#include <linux/seccomp.h>
 #include <linux/security.h>
 #include <linux/init.h>
 #include <linux/signal.h>
@@ -1149,6 +1150,10 @@ static void tracehook_report_syscall(struct pt_regs *regs,
 
 asmlinkage int syscall_trace_enter(struct pt_regs *regs)
 {
+        /* Do the secure computing check first; failures should be fast. */
+        if (secure_computing() == -1)
+                return -1;
+
         if (test_thread_flag(TIF_SYSCALL_TRACE))
                 tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);