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authorPrzemyslaw Kedzierski <p.kedzierski@samsung.com>2014-12-09 12:17:24 +0100
committerLennart Poettering <lennart@poettering.net>2014-12-09 18:23:24 +0100
commitdd5ae4c36c89da5dbe8d1628939b26c00db98753 (patch)
tree70732de11f8d613b3c3a5117009f9802301774e7 /src/shared
parent4c213d6cf416917c61f82d8bee795b8f3a4c5372 (diff)
bus-proxy: cloning smack label
When dbus client connects to systemd-bus-proxyd through Unix domain socket proxy takes client's smack label and sets for itself. It is done before and independent of dropping privileges. The reason of such soluton is fact that tests of access rights performed by lsm may take place inside kernel, not only in userspace of recipient of message. The bus-proxyd needs CAP_MAC_ADMIN to manipulate its label. In case of systemd running in system mode, CAP_MAC_ADMIN should be added to CapabilityBoundingSet in service file of bus-proxyd. In case of systemd running in user mode ('systemd --user') it can be achieved by addition Capabilities=cap_mac_admin=i and SecureBits=keep-caps to user@.service file and setting cap_mac_admin+ei on bus-proxyd binary.
Diffstat (limited to 'src/shared')
-rw-r--r--src/shared/capability.c18
-rw-r--r--src/shared/capability.h2
2 files changed, 20 insertions, 0 deletions
diff --git a/src/shared/capability.c b/src/shared/capability.c
index 5d156ab3cd..65d7e038a7 100644
--- a/src/shared/capability.c
+++ b/src/shared/capability.c
@@ -271,3 +271,21 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) {
return 0;
}
+
+int drop_capability(cap_value_t cv) {
+ _cleanup_cap_free_ cap_t tmp_cap = NULL;
+
+ tmp_cap = cap_get_proc();
+ if (!tmp_cap)
+ return -errno;
+
+ if ((cap_set_flag(tmp_cap, CAP_INHERITABLE, 1, &cv, CAP_CLEAR) < 0) ||
+ (cap_set_flag(tmp_cap, CAP_PERMITTED, 1, &cv, CAP_CLEAR) < 0) ||
+ (cap_set_flag(tmp_cap, CAP_EFFECTIVE, 1, &cv, CAP_CLEAR) < 0))
+ return -errno;
+
+ if (cap_set_proc(tmp_cap) < 0)
+ return -errno;
+
+ return 0;
+}
diff --git a/src/shared/capability.h b/src/shared/capability.h
index 3e6d9995f5..6f2f6f997d 100644
--- a/src/shared/capability.h
+++ b/src/shared/capability.h
@@ -34,6 +34,8 @@ int capability_bounding_set_drop_usermode(uint64_t drop);
int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilites);
+int drop_capability(cap_value_t cv);
+
DEFINE_TRIVIAL_CLEANUP_FUNC(cap_t, cap_free);
#define _cleanup_cap_free_ _cleanup_(cap_freep)