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"
39 int have_effective_cap(int value) {
48 if (cap_get_flag(cap, value, CAP_EFFECTIVE, &fv) < 0)
57 unsigned long cap_last_cap(void) {
58 static __thread unsigned long saved;
59 static __thread bool valid = false;
65 p = (unsigned long) CAP_LAST_CAP;
67 if (prctl(PR_CAPBSET_READ, p) < 0) {
69 /* Hmm, look downwards, until we find one that
71 for (p--; p > 0; p --)
72 if (prctl(PR_CAPBSET_READ, p) >= 0)
77 /* Hmm, look upwards, until we find one that doesn't
80 if (prctl(PR_CAPBSET_READ, p+1) < 0)
90 int capability_bounding_set_drop(uint64_t drop, bool right_now) {
92 cap_t after_cap = NULL, temp_cap = NULL;
96 /* If we are run as PID 1 we will lack CAP_SETPCAP by default
97 * in the effective set (yes, the kernel drops that when
98 * executing init!), so get it back temporarily so that we can
99 * call PR_CAPBSET_DROP. */
101 after_cap = cap_get_proc();
105 if (cap_get_flag(after_cap, CAP_SETPCAP, CAP_EFFECTIVE, &fv) < 0) {
111 static const cap_value_t v = CAP_SETPCAP;
113 temp_cap = cap_dup(after_cap);
119 if (cap_set_flag(temp_cap, CAP_EFFECTIVE, 1, &v, CAP_SET) < 0) {
124 if (cap_set_proc(temp_cap) < 0) {
130 for (i = 0; i <= cap_last_cap(); i++) {
132 if (drop & ((uint64_t) 1ULL << (uint64_t) i)) {
135 /* Drop it from the bounding set */
136 if (prctl(PR_CAPBSET_DROP, i) < 0) {
142 /* Also drop it from the inheritable set, so
143 * that anything we exec() loses the
144 * capability for good. */
145 if (cap_set_flag(after_cap, CAP_INHERITABLE, 1, &v, CAP_CLEAR) < 0) {
150 /* If we shall apply this right now drop it
151 * also from our own capability sets. */
153 if (cap_set_flag(after_cap, CAP_PERMITTED, 1, &v, CAP_CLEAR) < 0 ||
154 cap_set_flag(after_cap, CAP_EFFECTIVE, 1, &v, CAP_CLEAR) < 0) {
169 cap_set_proc(after_cap);
176 static int drop_from_file(const char *fn, uint64_t drop) {
179 uint64_t current, after;
182 r = read_one_line_file(fn, &p);
186 assert_cc(sizeof(hi) == sizeof(unsigned));
187 assert_cc(sizeof(lo) == sizeof(unsigned));
189 k = sscanf(p, "%u %u", &lo, &hi);
195 current = (uint64_t) lo | ((uint64_t) hi << 32ULL);
196 after = current & ~drop;
198 if (current == after)
201 lo = (unsigned) (after & 0xFFFFFFFFULL);
202 hi = (unsigned) ((after >> 32ULL) & 0xFFFFFFFFULL);
204 if (asprintf(&p, "%u %u", lo, hi) < 0)
207 r = write_string_file(fn, p);
213 int capability_bounding_set_drop_usermode(uint64_t drop) {
216 r = drop_from_file("/proc/sys/kernel/usermodehelper/inheritable", drop);
220 r = drop_from_file("/proc/sys/kernel/usermodehelper/bset", drop);