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
  38 #ifdef HAVE_SYS_CAPABILITY_H
  39 #include <sys/capability.h>
  40 #endif
  41 #ifdef HAVE_SYS_PRCTL_H
  42 #include <sys/prctl.h>
  43 #endif
  44
  45 #include "caps.h"
  46
  47 /* Glibc <= 2.2 has broken unistd.h */
  48 #if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
  49 int setresgid(gid_t r, gid_t e, gid_t s);
  50 int setresuid(uid_t r, uid_t e, uid_t s);
  51 #endif
  52
  53 #ifdef HAVE_GETUID
  54
  55 /* Drop root rights when called SUID root */
  56 void pa_drop_root(void) {
  57     uid_t uid = getuid();
  58
  59     if (uid == 0 || geteuid() != 0)
  60         return;
  61
  62     pa_log_info(_("Dropping root priviliges."));
  63
  64 #if defined(HAVE_SETRESUID)
  65     pa_assert_se(setresuid(uid, uid, uid) >= 0);
  66 #elif defined(HAVE_SETREUID)
  67     pa_assert_se(setreuid(uid, uid) >= 0);
  68 #else
  69     pa_assert_se(setuid(uid) >= 0);
  70     pa_assert_se(seteuid(uid) >= 0);
  71 #endif
  72
  73     pa_assert_se(getuid() == uid);
  74     pa_assert_se(geteuid() == uid);
  75 }
  76
  77 #else
  78
  79 void pa_drop_root(void) {
  80 }
  81
  82 #endif
  83
  84 #if defined(HAVE_SYS_CAPABILITY_H) && defined(HAVE_SYS_PRCTL_H)
  85
  86 /* Limit permitted capabilities set to CAPSYS_NICE */
  87 void pa_limit_caps(void) {
  88     cap_t caps;
  89     cap_value_t nice_cap = CAP_SYS_NICE;
  90
  91     pa_assert_se(caps = cap_init());
  92     pa_assert_se(cap_clear(caps) == 0);
  93     pa_assert_se(cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET) == 0);
  94     pa_assert_se(cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET) == 0);
  95
  96     if (cap_set_proc(caps) < 0)
  97         /* Hmm, so we couldn't limit our caps, which probably means we
  98          * hadn't any in the first place, so let's just make sure of
  99          * that */
 100         pa_drop_caps();
 101     else
 102         pa_log_info(_("Limited capabilities successfully to CAP_SYS_NICE."));
 103
 104     pa_assert_se(cap_free(caps) == 0);
 105
 106     pa_assert_se(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0);
 107 }
 108
 109 /* Drop all capabilities, effectively becoming a normal user */
 110 void pa_drop_caps(void) {
 111     cap_t caps;
 112
 113 #ifndef __OPTIMIZE__
 114     /* Valgrind doesn't not know set_caps, so we bypass it here -- but
 115      *  only in development builts.*/
 116
 117     if (getenv("VALGRIND") && !pa_have_caps())
 118         return;
 119 #endif
 120
 121     pa_assert_se(prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) == 0);
 122
 123     pa_assert_se(caps = cap_init());
 124     pa_assert_se(cap_clear(caps) == 0);
 125     pa_assert_se(cap_set_proc(caps) == 0);
 126     pa_assert_se(cap_free(caps) == 0);
 127
 128     pa_assert_se(!pa_have_caps());
 129 }
 130
 131 pa_bool_t pa_have_caps(void) {
 132     cap_t caps;
 133     cap_flag_value_t flag = CAP_CLEAR;
 134
 135 #ifdef __OPTIMIZE__
 136     pa_assert_se(caps = cap_get_proc());
 137 #else
 138     if (!(caps = cap_get_proc()))
 139         return FALSE;
 140 #endif
 141     pa_assert_se(cap_get_flag(caps, CAP_SYS_NICE, CAP_EFFECTIVE, &flag) >= 0);
 142     pa_assert_se(cap_free(caps) == 0);
 143
 144     return flag == CAP_SET;
 145 }
 146
 147 #else
 148
 149 /* NOOPs in case capabilities are not available. */
 150 void pa_limit_caps(void) {
 151 }
 152
 153 void pa_drop_caps(void) {
 154     pa_drop_root();
 155 }
 156
 157 pa_bool_t pa_have_caps(void) {
 158     return FALSE;
 159 }
 160
 161 #endif