From: Zbigniew Jędrzejewski-Szmek <zbyszek@in.waw.pl>
Date: Wed, 4 Feb 2015 15:24:02 +0000 (-0500)
Subject: shared/capabilities: simplify assertions about bits
X-Git-Tag: v219~147
X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=2c9fc26670ef85a14d16a72bc16e7368f76c28f4

shared/capabilities: simplify assertions about bits

The assert added in 7d328b5446 was wrong. Also update the comments
and make sure we don't try to shift by type size.
---

diff --git a/src/shared/capability.c b/src/shared/capability.c
index 57f392a4d..915ceb9d9 100644
--- a/src/shared/capability.c
+++ b/src/shared/capability.c
@@ -275,10 +275,10 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) {
                         if (keep_capabilities & (1ULL << i))
                                 bits[j++] = i;
 
-                /* don't keep too many bits */
-                assert((keep_capabilities & (~1ULL << i)) == 0);
-                /* don't throw away too many bits */
-                assert(((keep_capabilities >> i) & (~1ULL >> i)) == 0);
+                /* use enough bits */
+                assert(i == 64 || (keep_capabilities >> i) == 0);
+                /* don't use too many bits */
+                assert(keep_capabilities & (1ULL << (i - 1)));
 
                 if (cap_set_flag(d, CAP_EFFECTIVE, j, bits, CAP_SET) < 0 ||
                     cap_set_flag(d, CAP_PERMITTED, j, bits, CAP_SET) < 0) {