115 lines
3 KiB
C
115 lines
3 KiB
C
/***
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This file is part of avahi.
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avahi is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as
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published by the Free Software Foundation; either version 2.1 of the
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License, or (at your option) any later version.
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avahi is distributed in the hope that it will be useful, but WITHOUT
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ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General
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Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with avahi; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
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USA.
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***/
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#ifdef HAVE_CONFIG_H
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#include <config.h>
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#endif
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#include <sys/types.h>
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#include <assert.h>
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#include <errno.h>
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#include <string.h>
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#include <sys/capability.h>
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#include <sys/prctl.h>
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#include <avahi-core/log.h>
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#include "caps.h"
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int avahi_caps_reduce(void) {
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int ret = 0;
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cap_t caps;
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static cap_value_t cap_values[] = { CAP_SYS_CHROOT, CAP_SETUID, CAP_SETGID };
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/* Let's reduce our caps to the minimum set and tell Linux to keep
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* them across setuid(). This is called before we drop
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* privileges. */
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caps = cap_init();
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assert(caps);
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cap_clear(caps);
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cap_set_flag(caps, CAP_EFFECTIVE, 3, cap_values, CAP_SET);
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cap_set_flag(caps, CAP_PERMITTED, 3, cap_values, CAP_SET);
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if (cap_set_proc(caps) < 0) {
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avahi_log_error("cap_set_proc() failed: %s", strerror(errno));
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ret = -1;
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}
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cap_free(caps);
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/* Retain capabilities across setuid() */
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if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0) {
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avahi_log_error("prctl(PR_SET_KEEPCAPS) failed: %s", strerror(errno));
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ret = -1;
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}
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return ret;
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}
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int avahi_caps_reduce2(void) {
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int ret = 0;
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cap_t caps;
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static cap_value_t cap_values[] = { CAP_SYS_CHROOT };
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/* Reduce our caps to the bare minimum and tell Linux not to keep
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* them across setuid(). This is called after we drop
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* privileges. */
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/* No longer retain caps across setuid() */
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if (prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) < 0) {
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avahi_log_error("prctl(PR_SET_KEEPCAPS) failed: %s", strerror(errno));
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ret = -1;
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}
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caps = cap_init();
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assert(caps);
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cap_clear(caps);
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/* setuid() zeroed our effective caps, let's get them back */
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cap_set_flag(caps, CAP_EFFECTIVE, 1, cap_values, CAP_SET);
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cap_set_flag(caps, CAP_PERMITTED, 1, cap_values, CAP_SET);
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if (cap_set_proc(caps) < 0) {
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avahi_log_error("cap_set_proc() failed: %s", strerror(errno));
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ret = -1;
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}
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cap_free(caps);
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return ret;
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}
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int avahi_caps_drop_all(void) {
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cap_t caps;
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int ret = 0;
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/* Drop all capabilities and turn ourselves into a normal user process */
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caps = cap_init();
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assert(caps);
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cap_clear(caps);
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if (cap_set_proc(caps) < 0) {
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avahi_log_error("cap_set_proc() failed: %s", strerror(errno));
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ret = -1;
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}
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cap_free(caps);
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return ret;
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}
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