From 939b8f14dcd9312140d001b55b4e7a87173682ef Mon Sep 17 00:00:00 2001
From: Lennart Poettering <lennart@poettering.net>
Date: Tue, 29 May 2012 23:33:38 +0200
Subject: capabilities: when dropping capabilities system-wide also drop them
 from usermode helpers

This hooks things up with /proc/sys/kernel/usermodehelper/bset and
/proc/sys/kernel/usermodehelper/inheritable.
---
 src/shared/capability.c | 51 +++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

(limited to 'src/shared/capability.c')

diff --git a/src/shared/capability.c b/src/shared/capability.c
index 08b7a209da..9b743e86d0 100644
--- a/src/shared/capability.c
+++ b/src/shared/capability.c
@@ -171,3 +171,54 @@ finish:
 
         return r;
 }
+
+static int drop_from_file(const char *fn, uint64_t drop) {
+        int r, k;
+        uint32_t hi, lo;
+        uint64_t current, after;
+        char *p;
+
+        r = read_one_line_file(fn, &p);
+        if (r < 0)
+                return r;
+
+        assert_cc(sizeof(hi) == sizeof(unsigned));
+        assert_cc(sizeof(lo) == sizeof(unsigned));
+
+        k = sscanf(p, "%u %u", &lo, &hi);
+        free(p);
+
+        if (k != 2)
+                return -EIO;
+
+        current = (uint64_t) lo | ((uint64_t) hi << 32ULL);
+        after = current & ~drop;
+
+        if (current == after)
+                return 0;
+
+        lo = (unsigned) (after & 0xFFFFFFFFULL);
+        hi = (unsigned) ((after >> 32ULL) & 0xFFFFFFFFULL);
+
+        if (asprintf(&p, "%u %u", lo, hi) < 0)
+                return -ENOMEM;
+
+        r = write_one_line_file(fn, p);
+        free(p);
+
+        return r;
+}
+
+int capability_bounding_set_drop_usermode(uint64_t drop) {
+        int r;
+
+        r = drop_from_file("/proc/sys/kernel/usermodehelper/inheritable", drop);
+        if (r < 0)
+                return r;
+
+        r = drop_from_file("/proc/sys/kernel/usermodehelper/bset", drop);
+        if (r < 0)
+                return r;
+
+        return r;
+}
-- 
cgit v1.2.3-54-g00ecf