-/* SPDX-License-Identifier: LGPL-2.1+ */
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
#include <errno.h>
-#include <grp.h>
#include <stdio.h>
#include <stdlib.h>
-#include <sys/capability.h>
#include <sys/prctl.h>
#include <unistd.h>
#include "alloc-util.h"
#include "capability-util.h"
+#include "cap-list.h"
#include "fileio.h"
#include "log.h"
#include "macro.h"
return fv == CAP_SET;
}
-unsigned long cap_last_cap(void) {
- static thread_local unsigned long saved;
+unsigned cap_last_cap(void) {
+ static thread_local unsigned saved;
static thread_local bool valid = false;
_cleanup_free_ char *content = NULL;
unsigned long p = 0;
}
/* fall back to syscall-probing for pre linux-3.2 */
- p = (unsigned long) CAP_LAST_CAP;
+ p = MIN((unsigned long) CAP_LAST_CAP, 63U);
if (prctl(PR_CAPBSET_READ, p) < 0) {
/* Hmm, look downwards, until we find one that works */
- for (p--; p > 0; p --)
+ for (p--; p > 0; p--)
if (prctl(PR_CAPBSET_READ, p) >= 0)
break;
}
int capability_update_inherited_set(cap_t caps, uint64_t set) {
- unsigned long i;
+ /* Add capabilities in the set to the inherited caps, drops capabilities not in the set.
+ * Do not apply them yet. */
- /* Add capabilities in the set to the inherited caps. Do not apply
- * them yet. */
-
- for (i = 0; i < cap_last_cap(); i++) {
-
- if (set & (UINT64_C(1) << i)) {
- cap_value_t v;
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
+ cap_flag_value_t flag = set & (UINT64_C(1) << i) ? CAP_SET : CAP_CLEAR;
+ cap_value_t v;
- v = (cap_value_t) i;
+ v = (cap_value_t) i;
- /* Make the capability inheritable. */
- if (cap_set_flag(caps, CAP_INHERITABLE, 1, &v, CAP_SET) < 0)
- return -errno;
- }
+ if (cap_set_flag(caps, CAP_INHERITABLE, 1, &v, flag) < 0)
+ return -errno;
}
return 0;
int capability_ambient_set_apply(uint64_t set, bool also_inherit) {
_cleanup_cap_free_ cap_t caps = NULL;
- unsigned long i;
int r;
- /* Add the capabilities to the ambient set. */
+ /* Remove capabilities requested in ambient set, but not in the bounding set */
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
+ if (set == 0)
+ break;
+
+ if (FLAGS_SET(set, (UINT64_C(1) << i)) && prctl(PR_CAPBSET_READ, i) != 1) {
+ log_debug("Ambient capability %s requested but missing from bounding set,"
+ " suppressing automatically.", capability_to_name(i));
+ set &= ~(UINT64_C(1) << i);
+ }
+ }
+
+ /* Add the capabilities to the ambient set (an possibly also the inheritable set) */
+
+ /* Check that we can use PR_CAP_AMBIENT or quit early. */
+ if (!ambient_capabilities_supported())
+ return (set & all_capabilities()) == 0 ?
+ 0 : -EOPNOTSUPP; /* if actually no ambient caps are to be set, be silent,
+ * otherwise fail recognizably */
if (also_inherit) {
caps = cap_get_proc();
return -errno;
}
- for (i = 0; i < cap_last_cap(); i++) {
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
if (set & (UINT64_C(1) << i)) {
/* Add the capability to the ambient set. */
if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_RAISE, i, 0, 0) < 0)
return -errno;
+ } else {
+
+ /* Drop the capability so we don't inherit capabilities we didn't ask for. */
+ r = prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_IS_SET, i, 0, 0);
+ if (r < 0)
+ return -errno;
+
+ if (r)
+ if (prctl(PR_CAP_AMBIENT, PR_CAP_AMBIENT_LOWER, i, 0, 0) < 0)
+ return -errno;
+
}
}
return 0;
}
-int capability_bounding_set_drop(uint64_t keep, bool right_now) {
- _cleanup_cap_free_ cap_t before_cap = NULL, after_cap = NULL;
+int capability_gain_cap_setpcap(cap_t *ret_before_caps) {
+ _cleanup_cap_free_ cap_t caps = NULL;
cap_flag_value_t fv;
- unsigned long i;
- int r;
-
- /* If we are run as PID 1 we will lack CAP_SETPCAP by default
- * in the effective set (yes, the kernel drops that when
- * executing init!), so get it back temporarily so that we can
- * call PR_CAPBSET_DROP. */
-
- before_cap = cap_get_proc();
- if (!before_cap)
+ caps = cap_get_proc();
+ if (!caps)
return -errno;
- if (cap_get_flag(before_cap, CAP_SETPCAP, CAP_EFFECTIVE, &fv) < 0)
+ if (cap_get_flag(caps, 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(before_cap);
+ temp_cap = cap_dup(caps);
if (!temp_cap)
return -errno;
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. */
+ * we'll fail later, when we actually intend to drop some capabilities or try to set securebits. */
}
+ if (ret_before_caps)
+ /* Return the capabilities as they have been before setting CAP_SETPCAP */
+ *ret_before_caps = TAKE_PTR(caps);
+
+ return 0;
+}
+
+int capability_bounding_set_drop(uint64_t keep, bool right_now) {
+ _cleanup_cap_free_ cap_t before_cap = NULL, after_cap = NULL;
+ int r;
+
+ /* If we are run as PID 1 we will lack CAP_SETPCAP by default
+ * in the effective set (yes, the kernel drops that when
+ * executing init!), so get it back temporarily so that we can
+ * call PR_CAPBSET_DROP. */
+
+ r = capability_gain_cap_setpcap(&before_cap);
+ if (r < 0)
+ return r;
after_cap = cap_dup(before_cap);
if (!after_cap)
return -errno;
- for (i = 0; i <= cap_last_cap(); i++) {
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
cap_value_t v;
if ((keep & (UINT64_C(1) << i)))
if (r < 0)
return r;
- assert_cc(sizeof(hi) == sizeof(unsigned));
- assert_cc(sizeof(lo) == sizeof(unsigned));
-
- k = sscanf(p, "%u %u", &lo, &hi);
+ k = sscanf(p, "%" PRIu32 " %" PRIu32, &lo, &hi);
if (k != 2)
return -EIO;
- current = (uint64_t) lo | ((uint64_t) hi << 32ULL);
+ current = (uint64_t) lo | ((uint64_t) hi << 32);
after = current & keep;
if (current == after)
return 0;
- lo = (unsigned) (after & 0xFFFFFFFFULL);
- hi = (unsigned) ((after >> 32ULL) & 0xFFFFFFFFULL);
+ lo = after & UINT32_C(0xFFFFFFFF);
+ hi = (after >> 32) & UINT32_C(0xFFFFFFFF);
- return write_string_filef(fn, WRITE_STRING_FILE_CREATE, "%u %u", lo, hi);
+ return write_string_filef(fn, 0, "%" PRIu32 " %" PRIu32, lo, hi);
}
int capability_bounding_set_drop_usermode(uint64_t keep) {
return cache;
}
+bool capability_quintet_mangle(CapabilityQuintet *q) {
+ uint64_t combined, drop = 0;
+ bool ambient_supported;
+
+ assert(q);
+
+ combined = q->effective | q->bounding | q->inheritable | q->permitted;
+
+ ambient_supported = q->ambient != (uint64_t) -1;
+ if (ambient_supported)
+ combined |= q->ambient;
+
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
+ unsigned long bit = UINT64_C(1) << i;
+ if (!FLAGS_SET(combined, bit))
+ continue;
+
+ if (prctl(PR_CAPBSET_READ, i) > 0)
+ continue;
+
+ drop |= bit;
+
+ log_debug("Not in the current bounding set: %s", capability_to_name(i));
+ }
+
+ q->effective &= ~drop;
+ q->bounding &= ~drop;
+ q->inheritable &= ~drop;
+ q->permitted &= ~drop;
+
+ if (ambient_supported)
+ q->ambient &= ~drop;
+
+ return drop != 0; /* Let the caller know we changed something */
+}
+
int capability_quintet_enforce(const CapabilityQuintet *q) {
- _cleanup_cap_free_ cap_t c = NULL;
- bool need_set_proc_again = false;
+ _cleanup_cap_free_ cap_t c = NULL, modified = NULL;
int r;
if (q->ambient != (uint64_t) -1) {
- unsigned long i;
bool changed = false;
c = cap_get_proc();
if (!c)
return -errno;
- /* In order to raise the ambient caps set we first need to raise the matching inheritable + permitted
- * cap */
- for (i = 0; i <= cap_last_cap(); i++) {
+ /* In order to raise the ambient caps set we first need to raise the matching
+ * inheritable + permitted cap */
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
uint64_t m = UINT64_C(1) << i;
cap_value_t cv = (cap_value_t) i;
cap_flag_value_t old_value_inheritable, old_value_permitted;
if (q->inheritable != (uint64_t) -1 || q->permitted != (uint64_t) -1 || q->effective != (uint64_t) -1) {
bool changed = false;
- unsigned long i;
if (!c) {
c = cap_get_proc();
return -errno;
}
- for (i = 0; i <= cap_last_cap(); i++) {
+ for (unsigned i = 0; i <= cap_last_cap(); i++) {
uint64_t m = UINT64_C(1) << i;
cap_value_t cv = (cap_value_t) i;
}
if (changed) {
- _cleanup_cap_free_ cap_t modified = NULL;
-
/* In order to change the bounding caps, we need to keep CAP_SETPCAP for a bit
* longer. Let's add it to our list hence for now. */
if (q->bounding != (uint64_t) -1) {
/* Now, let's enforce the caps for the first time. Note that this is where we acquire
* caps in any of the sets we currently don't have. We have to do this before
- * droppoing the bounding caps below, since at that point we can never acquire new
- * caps in inherited/permitted/effective anymore, but only lose them.*/
+ * dropping the bounding caps below, since at that point we can never acquire new
+ * caps in inherited/permitted/effective anymore, but only lose them. */
if (cap_set_proc(modified ?: c) < 0)
return -errno;
-
- need_set_proc_again = !!modified;
}
}
* we have already set only in the CAP_SETPCAP bit, which we needed for dropping the bounding
* bits. This call only undoes bits and doesn't acquire any which means the bounding caps don't
* matter. */
- if (need_set_proc_again)
+ if (modified)
if (cap_set_proc(c) < 0)
return -errno;
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