X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fshared%2Fcapability.c;h=4840c3ebf4149fc7658e7f3f2c204fb6219f8235;hb=27cc6f166bdebc0e698fb692993b801db2618866;hp=65d7e038a7a39d305352bf9b4de8d865085a79da;hpb=dd5ae4c36c89da5dbe8d1628939b26c00db98753;p=elogind.git
diff --git a/src/shared/capability.c b/src/shared/capability.c
index 65d7e038a..4840c3ebf 100644
--- a/src/shared/capability.c
+++ b/src/shared/capability.c
@@ -19,14 +19,9 @@
along with systemd; If not, see .
***/
-#include
-#include
#include
#include
#include
-#include
-#include
-#include
#include
#include
#include "grp.h"
@@ -54,11 +49,25 @@ 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) {
@@ -216,8 +225,8 @@ int capability_bounding_set_drop_usermode(uint64_t drop) {
}
int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) {
-
_cleanup_cap_free_ cap_t d = NULL;
+ unsigned i, j = 0;
int r;
/* Unfortunately we cannot leave privilege dropping to PID 1
@@ -233,6 +242,7 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) {
if (setgroups(0, NULL) < 0)
return log_error_errno(errno, "Failed to drop auxiliary groups list: %m");
+ /* Ensure we keep the permitted caps across the setresuid() */
if (prctl(PR_SET_KEEPCAPS, 1) < 0)
return log_error_errno(errno, "Failed to enable keep capabilities flag: %m");
@@ -243,31 +253,37 @@ int drop_privileges(uid_t uid, gid_t gid, uint64_t keep_capabilities) {
if (prctl(PR_SET_KEEPCAPS, 0) < 0)
return log_error_errno(errno, "Failed to disable keep capabilities flag: %m");
+ /* Drop all caps from the bounding set, except the ones we want */
r = capability_bounding_set_drop(~keep_capabilities, true);
if (r < 0)
return log_error_errno(r, "Failed to drop capabilities: %m");
+ /* Now upgrade the permitted caps we still kept to effective caps */
d = cap_init();
if (!d)
return log_oom();
if (keep_capabilities) {
- cap_value_t bits[sizeof(keep_capabilities)*8];
- unsigned i, j = 0;
+ cap_value_t bits[u64log2(keep_capabilities) + 1];
- for (i = 0; i < sizeof(keep_capabilities)*8; i++)
+ for (i = 0; i < ELEMENTSOF(bits); i++)
if (keep_capabilities & (1ULL << i))
bits[j++] = i;
+ /* 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) {
log_error_errno(errno, "Failed to enable capabilities bits: %m");
return -errno;
}
- }
- if (cap_set_proc(d) < 0)
- return log_error_errno(errno, "Failed to increase capabilities: %m");
+ if (cap_set_proc(d) < 0)
+ return log_error_errno(errno, "Failed to increase capabilities: %m");
+ }
return 0;
}