1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
9 under the terms of the GNU Lesser General Public License as published by
10 the Free Software Foundation; either version 2.1 of the License, or
11 (at your option) any later version.
13 systemd is distributed in the hope that it will be useful, but
14 WITHOUT ANY WARRANTY; without even the implied warranty of
15 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
27 #include <sys/types.h>
30 #include <sys/capability.h>
31 #include <sys/prctl.h>
34 #include "capability.h"
38 int have_effective_cap(int value) {
47 if (cap_get_flag(cap, value, CAP_EFFECTIVE, &fv) < 0)
56 unsigned long cap_last_cap(void) {
57 static __thread unsigned long saved;
58 static __thread bool valid = false;
64 p = (unsigned long) CAP_LAST_CAP;
66 if (prctl(PR_CAPBSET_READ, p) < 0) {
68 /* Hmm, look downwards, until we find one that
70 for (p--; p > 0; p --)
71 if (prctl(PR_CAPBSET_READ, p) >= 0)
76 /* Hmm, look upwards, until we find one that doesn't
79 if (prctl(PR_CAPBSET_READ, p+1) < 0)
89 int capability_bounding_set_drop(uint64_t drop, bool right_now) {
91 cap_t after_cap = NULL, temp_cap = NULL;
95 /* If we are run as PID 1 we will lack CAP_SETPCAP by default
96 * in the effective set (yes, the kernel drops that when
97 * executing init!), so get it back temporarily so that we can
98 * call PR_CAPBSET_DROP. */
100 after_cap = cap_get_proc();
104 if (cap_get_flag(after_cap, CAP_SETPCAP, CAP_EFFECTIVE, &fv) < 0) {
110 static const cap_value_t v = CAP_SETPCAP;
112 temp_cap = cap_dup(after_cap);
118 if (cap_set_flag(temp_cap, CAP_EFFECTIVE, 1, &v, CAP_SET) < 0) {
123 if (cap_set_proc(temp_cap) < 0) {
129 for (i = 0; i <= cap_last_cap(); i++) {
131 if (drop & ((uint64_t) 1ULL << (uint64_t) i)) {
134 /* Drop it from the bounding set */
135 if (prctl(PR_CAPBSET_DROP, i) < 0) {
141 /* Also drop it from the inheritable set, so
142 * that anything we exec() loses the
143 * capability for good. */
144 if (cap_set_flag(after_cap, CAP_INHERITABLE, 1, &v, CAP_CLEAR) < 0) {
149 /* If we shall apply this right now drop it
150 * also from our own capability sets. */
152 if (cap_set_flag(after_cap, CAP_PERMITTED, 1, &v, CAP_CLEAR) < 0 ||
153 cap_set_flag(after_cap, CAP_EFFECTIVE, 1, &v, CAP_CLEAR) < 0) {
168 cap_set_proc(after_cap);
175 static int drop_from_file(const char *fn, uint64_t drop) {
178 uint64_t current, after;
181 r = read_one_line_file(fn, &p);
185 assert_cc(sizeof(hi) == sizeof(unsigned));
186 assert_cc(sizeof(lo) == sizeof(unsigned));
188 k = sscanf(p, "%u %u", &lo, &hi);
194 current = (uint64_t) lo | ((uint64_t) hi << 32ULL);
195 after = current & ~drop;
197 if (current == after)
200 lo = (unsigned) (after & 0xFFFFFFFFULL);
201 hi = (unsigned) ((after >> 32ULL) & 0xFFFFFFFFULL);
203 if (asprintf(&p, "%u %u", lo, hi) < 0)
206 r = write_one_line_file(fn, p);
212 int capability_bounding_set_drop_usermode(uint64_t drop) {
215 r = drop_from_file("/proc/sys/kernel/usermodehelper/inheritable", drop);
219 r = drop_from_file("/proc/sys/kernel/usermodehelper/bset", drop);