code.delx.au - pulseaudio/blob - src/daemon/caps.c

   1 /***
   2   This file is part of PulseAudio.
   3
   4   Copyright 2004-2006 Lennart Poettering
   5   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   6
   7   PulseAudio is free software; you can redistribute it and/or modify
   8   it under the terms of the GNU Lesser General Public License as published
   9   by the Free Software Foundation; either version 2 of the License,
  10   or (at your option) any later version.
  11
  12   PulseAudio is distributed in the hope that it will be useful, but
  13   WITHOUT ANY WARRANTY; without even the implied warranty of
  14   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  15   General Public License for more details.
  16
  17   You should have received a copy of the GNU Lesser General Public License
  18   along with PulseAudio; if not, write to the Free Software
  19   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  20   USA.
  21 ***/
  22
  23 #ifdef HAVE_CONFIG_H
  24 #include <config.h>
  25 #endif
  26
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <string.h>
  30 #include <sys/types.h>
  31
  32 #include <pulse/i18n.h>
  33
  34 #include <pulsecore/macro.h>
  35 #include <pulsecore/core-error.h>
  36 #include <pulsecore/log.h>
  37 #include <pulsecore/core-util.h>
  38
  39 #ifdef HAVE_SYS_CAPABILITY_H
  40 #include <sys/capability.h>
  41 #endif
  42 #ifdef HAVE_SYS_PRCTL_H
  43 #include <sys/prctl.h>
  44 #endif
  45
  46 #include "caps.h"
  47
  48 /* Glibc <= 2.2 has broken unistd.h */
  49 #if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
  50 int setresgid(gid_t r, gid_t e, gid_t s);
  51 int setresuid(uid_t r, uid_t e, uid_t s);
  52 #endif
  53
  54 #ifdef HAVE_GETUID
  55
  56 /* Drop root rights when called SUID root */
  57 void pa_drop_root(void) {
  58     uid_t uid = getuid();
  59
  60     if (uid == 0 || geteuid() != 0)
  61         return;
  62
  63     pa_log_info(_("Dropping root privileges."));
  64
  65 #if defined(HAVE_SETRESUID)
  66     pa_assert_se(setresuid(uid, uid, uid) >= 0);
  67 #elif defined(HAVE_SETREUID)
  68     pa_assert_se(setreuid(uid, uid) >= 0);
  69 #else
  70     pa_assert_se(setuid(uid) >= 0);
  71     pa_assert_se(seteuid(uid) >= 0);
  72 #endif
  73
  74     pa_assert_se(getuid() == uid);
  75     pa_assert_se(geteuid() == uid);
  76 }
  77
  78 #else
  79
  80 void pa_drop_root(void) {
  81 }
  82
  83 #endif
  84
  85 #if defined(HAVE_SYS_CAPABILITY_H) && defined(HAVE_SYS_PRCTL_H)
  86
  87 /* Limit permitted capabilities set to CAPSYS_NICE */
  88 void pa_limit_caps(void) {
  89     cap_t caps;
  90     cap_value_t nice_cap = CAP_SYS_NICE;
  91
  92     pa_assert_se(caps = cap_init());
  93     pa_assert_se(cap_clear(caps) == 0);
  94     pa_assert_se(cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET) == 0);
  95     pa_assert_se(cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET) == 0);
  96
  97     if (cap_set_proc(caps) < 0)
  98         /* Hmm, so we couldn't limit our caps, which probably means we
  99          * hadn't any in the first place, so let's just make sure of
 100          * that */
 101         pa_drop_caps();
 102     else
 103         pa_log_info(_("Limited capabilities successfully to CAP_SYS_NICE."));
 104
 105     pa_assert_se(cap_free(caps) == 0);
 106
 107     pa_assert_se(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0);
 108 }
 109
 110 /* Drop all capabilities, effectively becoming a normal user */
 111 void pa_drop_caps(void) {
 112     cap_t caps;
 113
 114 #ifndef __OPTIMIZE__
 115     /* Valgrind doesn't not know set_caps, so we bypass it here -- but
 116      * only in development builds.*/
 117
 118     if (pa_in_valgrind() && !pa_have_caps())
 119         return;
 120 #endif
 121
 122     pa_assert_se(prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) == 0);
 123
 124     pa_assert_se(caps = cap_init());
 125     pa_assert_se(cap_clear(caps) == 0);
 126     pa_assert_se(cap_set_proc(caps) == 0);
 127     pa_assert_se(cap_free(caps) == 0);
 128
 129     pa_assert_se(!pa_have_caps());
 130 }
 131
 132 pa_bool_t pa_have_caps(void) {
 133     cap_t caps;
 134     cap_flag_value_t flag = CAP_CLEAR;
 135
 136 #ifdef __OPTIMIZE__
 137     pa_assert_se(caps = cap_get_proc());
 138 #else
 139     if (!(caps = cap_get_proc()))
 140         return FALSE;
 141 #endif
 142     pa_assert_se(cap_get_flag(caps, CAP_SYS_NICE, CAP_EFFECTIVE, &flag) >= 0);
 143     pa_assert_se(cap_free(caps) == 0);
 144
 145     return flag == CAP_SET;
 146 }
 147
 148 #else
 149
 150 /* NOOPs in case capabilities are not available. */
 151 void pa_limit_caps(void) {
 152 }
 153
 154 void pa_drop_caps(void) {
 155     pa_drop_root();
 156 }
 157
 158 pa_bool_t pa_have_caps(void) {
 159     return FALSE;
 160 }
 161
 162 #endif