Merge pull request #4087 from fsateler/detect-seccomp-filter

seccomp: also detect if seccomp filtering is available

1 files changed, 15 insertions, 4 deletions

diff --git a/src/shared/seccomp-util.c b/src/shared/seccomp-util.c
index 6c489284d1..2f42381fc1 100644
--- a/src/shared/seccomp-util.c
+++ b/src/shared/seccomp-util.c
@@ -20,9 +20,9 @@
 #include <errno.h>
 #include <seccomp.h>
 #include <stddef.h>
+#include <sys/prctl.h>
+#include <linux/seccomp.h>
 
-#include "alloc-util.h"
-#include "fileio.h"
 #include "macro.h"
 #include "seccomp-util.h"
 #include "string-util.h"
@@ -91,11 +91,22 @@ int seccomp_add_secondary_archs(scmp_filter_ctx *c) {
 
 }
 
+static bool is_basic_seccomp_available(void) {
+        int r;
+        r = prctl(PR_GET_SECCOMP, 0, 0, 0, 0);
+        return r >= 0;
+}
+
+static bool is_seccomp_filter_available(void) {
+        int r;
+        r = prctl(PR_SET_SECCOMP, SECCOMP_MODE_FILTER, NULL, 0, 0);
+        return r < 0 && errno == EFAULT;
+}
+
 bool is_seccomp_available(void) {
-        _cleanup_free_ char* field = NULL;
         static int cached_enabled = -1;
         if (cached_enabled < 0)
-                cached_enabled = get_proc_field("/proc/self/status", "Seccomp", "\n", &field) == 0;
+                cached_enabled = is_basic_seccomp_available() && is_seccomp_filter_available();
         return cached_enabled;
 }