X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;ds=inline;f=src%2Fshared%2Fcapability.c;fp=src%2Fshared%2Fcapability.c;h=b1be0438037f7c2efcd35aad3cd72944f18588b8;hb=80b4378314cf62148fd053e97018cc5c78dd6af6;hp=65d7e038a7a39d305352bf9b4de8d865085a79da;hpb=2f0af4e120385e6078c96189f4a4d0cce0e12a3a;p=elogind.git

diff --git a/src/shared/capability.c b/src/shared/capability.c
index 65d7e038a..b1be04380 100644
--- a/src/shared/capability.c
+++ b/src/shared/capability.c
@@ -54,11 +54,25 @@ int have_effective_cap(int value) {
 unsigned long cap_last_cap(void) {
         static thread_local unsigned long saved;
         static thread_local bool valid = false;
+        _cleanup_free_ char *content = NULL;
         unsigned long p;
+        int r;
 
         if (valid)
                 return saved;
 
+        /* available since linux-3.2 */
+        r = read_one_line_file("/proc/sys/kernel/cap_last_cap", &content);
+        if (r >= 0) {
+                r = safe_atolu(content, &p);
+                if (r >= 0) {
+                        saved = p;
+                        valid = true;
+                        return p;
+                }
+        }
+
+        /* fall back to syscall-probing for pre linux-3.2 */
         p = (unsigned long) CAP_LAST_CAP;
 
         if (prctl(PR_CAPBSET_READ, p) < 0) {