-/***
- This file is part of systemd.
-
- Copyright 2010 Lennart Poettering
-
- systemd is free software; you can redistribute it and/or modify it
- under the terms of the GNU Lesser General Public License as published by
- the Free Software Foundation; either version 2.1 of the License, or
- (at your option) any later version.
-
- systemd is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- Lesser General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with systemd; If not, see <http://www.gnu.org/licenses/>.
-***/
+/* SPDX-License-Identifier: LGPL-2.1+ */
#include <errno.h>
#include <grp.h>
#include "log.h"
#include "macro.h"
#include "parse-util.h"
+#include "user-util.h"
#include "util.h"
#if 0 /// UNNEEDED by elogind
}
int capability_bounding_set_drop(uint64_t keep, bool right_now) {
- _cleanup_cap_free_ cap_t after_cap = NULL;
+ _cleanup_cap_free_ cap_t before_cap = NULL, after_cap = NULL;
cap_flag_value_t fv;
unsigned long i;
int r;
* executing init!), so get it back temporarily so that we can
* call PR_CAPBSET_DROP. */
- after_cap = cap_get_proc();
- if (!after_cap)
+ before_cap = cap_get_proc();
+ if (!before_cap)
return -errno;
- if (cap_get_flag(after_cap, CAP_SETPCAP, CAP_EFFECTIVE, &fv) < 0)
+ if (cap_get_flag(before_cap, CAP_SETPCAP, CAP_EFFECTIVE, &fv) < 0)
return -errno;
if (fv != CAP_SET) {
_cleanup_cap_free_ cap_t temp_cap = NULL;
static const cap_value_t v = CAP_SETPCAP;
- temp_cap = cap_dup(after_cap);
- if (!temp_cap) {
- r = -errno;
- goto finish;
- }
+ temp_cap = cap_dup(before_cap);
+ if (!temp_cap)
+ return -errno;
- if (cap_set_flag(temp_cap, CAP_EFFECTIVE, 1, &v, CAP_SET) < 0) {
- r = -errno;
- goto finish;
- }
+ if (cap_set_flag(temp_cap, CAP_EFFECTIVE, 1, &v, CAP_SET) < 0)
+ return -errno;
- if (cap_set_proc(temp_cap) < 0) {
- r = -errno;
- goto finish;
- }
+ if (cap_set_proc(temp_cap) < 0)
+ log_debug_errno(errno, "Can't acquire effective CAP_SETPCAP bit, ignoring: %m");
+
+ /* If we didn't manage to acquire the CAP_SETPCAP bit, we continue anyway, after all this just means
+ * we'll fail later, when we actually intend to drop some capabilities. */
}
+ after_cap = cap_dup(before_cap);
+ if (!after_cap)
+ return -errno;
+
for (i = 0; i <= cap_last_cap(); i++) {
+ cap_value_t v;
- if (!(keep & (UINT64_C(1) << i))) {
- cap_value_t v;
+ if ((keep & (UINT64_C(1) << i)))
+ continue;
- /* Drop it from the bounding set */
- if (prctl(PR_CAPBSET_DROP, i) < 0) {
- r = -errno;
+ /* Drop it from the bounding set */
+ if (prctl(PR_CAPBSET_DROP, i) < 0) {
+ r = -errno;
+
+ /* If dropping the capability failed, let's see if we didn't have it in the first place. If so,
+ * continue anyway, as dropping a capability we didn't have in the first place doesn't really
+ * matter anyway. */
+ if (prctl(PR_CAPBSET_READ, i) != 0)
goto finish;
- }
- v = (cap_value_t) i;
+ }
+ v = (cap_value_t) i;
- /* Also drop it from the inheritable set, so
- * that anything we exec() loses the
- * capability for good. */
- if (cap_set_flag(after_cap, CAP_INHERITABLE, 1, &v, CAP_CLEAR) < 0) {
+ /* Also drop it from the inheritable set, so
+ * that anything we exec() loses the
+ * capability for good. */
+ if (cap_set_flag(after_cap, CAP_INHERITABLE, 1, &v, CAP_CLEAR) < 0) {
+ r = -errno;
+ goto finish;
+ }
+
+ /* If we shall apply this right now drop it
+ * also from our own capability sets. */
+ if (right_now) {
+ if (cap_set_flag(after_cap, CAP_PERMITTED, 1, &v, CAP_CLEAR) < 0 ||
+ cap_set_flag(after_cap, CAP_EFFECTIVE, 1, &v, CAP_CLEAR) < 0) {
r = -errno;
goto finish;
}
-
- /* If we shall apply this right now drop it
- * also from our own capability sets. */
- if (right_now) {
- if (cap_set_flag(after_cap, CAP_PERMITTED, 1, &v, CAP_CLEAR) < 0 ||
- cap_set_flag(after_cap, CAP_EFFECTIVE, 1, &v, CAP_CLEAR) < 0) {
- r = -errno;
- goto finish;
- }
- }
}
}
r = 0;
finish:
- if (cap_set_proc(after_cap) < 0)
- return -errno;
+ if (cap_set_proc(after_cap) < 0) {
+ /* If there are no actual changes anyway then let's ignore this error. */
+ if (cap_compare(before_cap, after_cap) != 0)
+ r = -errno;
+ }
return r;
}
static int drop_from_file(const char *fn, uint64_t keep) {
- int r, k;
- uint32_t hi, lo;
+ _cleanup_free_ char *p = NULL;
uint64_t current, after;
- char *p;
+ uint32_t hi, lo;
+ int r, k;
r = read_one_line_file(fn, &p);
if (r < 0)
assert_cc(sizeof(lo) == sizeof(unsigned));
k = sscanf(p, "%u %u", &lo, &hi);
- free(p);
-
if (k != 2)
return -EIO;
lo = (unsigned) (after & 0xFFFFFFFFULL);
hi = (unsigned) ((after >> 32ULL) & 0xFFFFFFFFULL);
- if (asprintf(&p, "%u %u", lo, hi) < 0)
- return -ENOMEM;
-
- r = write_string_file(fn, p, WRITE_STRING_FILE_CREATE);
- free(p);
-
- return r;
+ return write_string_filef(fn, WRITE_STRING_FILE_CREATE, "%u %u", lo, hi);
}
int capability_bounding_set_drop_usermode(uint64_t keep) {
if (setresgid(gid, gid, gid) < 0)
return log_error_errno(errno, "Failed to change group ID: %m");
- if (setgroups(0, NULL) < 0)
- return log_error_errno(errno, "Failed to drop auxiliary groups list: %m");
+ r = maybe_setgroups(0, NULL);
+ if (r < 0)
+ return log_error_errno(r, "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");
- r = setresuid(uid, uid, uid);
- if (r < 0)
+ if (setresuid(uid, uid, uid) < 0)
return log_error_errno(errno, "Failed to change user ID: %m");
if (prctl(PR_SET_KEEPCAPS, 0) < 0)
return 0;
}
+
+bool ambient_capabilities_supported(void) {
+ static int cache = -1;
+
+ if (cache >= 0)
+ return cache;
+
+ /* If PR_CAP_AMBIENT returns something valid, or an unexpected error code we assume that ambient caps are
+ * available. */
+
+ cache = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, CAP_KILL, 0, 0) >= 0 ||
+ !IN_SET(errno, EINVAL, EOPNOTSUPP, ENOSYS);
+
+ return cache;
+}
#endif // 0
~ianmdlvl / elogind.git / blobdiff