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

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   PulseAudio is free software; you can redistribute it and/or modify
   7   it under the terms of the GNU Lesser General Public License as published
   8   by the Free Software Foundation; either version 2 of the License,
   9   or (at your option) any later version.
  10
  11   PulseAudio is distributed in the hope that it will be useful, but
  12   WITHOUT ANY WARRANTY; without even the implied warranty of
  13   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  14   General Public License for more details.
  15
  16   You should have received a copy of the GNU Lesser General Public License
  17   along with PulseAudio; if not, write to the Free Software
  18   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  19   USA.
  20 ***/
  21
  22 #ifdef HAVE_CONFIG_H
  23 #include <config.h>
  24 #endif
  25
  26 #include <assert.h>
  27 #include <unistd.h>
  28 #include <errno.h>
  29 #include <string.h>
  30 #include <sys/types.h>
  31
  32 #ifdef HAVE_SYS_CAPABILITY_H
  33 #include <sys/capability.h>
  34 #endif
  35
  36 #include <pulsecore/core-error.h>
  37
  38 #include <pulsecore/log.h>
  39
  40 #include "caps.h"
  41
  42 /* Glibc <= 2.2 has broken unistd.h */
  43 #if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
  44 int setresgid(gid_t r, gid_t e, gid_t s);
  45 int setresuid(uid_t r, uid_t e, uid_t s);
  46 #endif
  47
  48 #ifdef HAVE_GETUID
  49
  50 /* Drop root rights when called SUID root */
  51 void pa_drop_root(void) {
  52     uid_t uid = getuid();
  53
  54     if (uid == 0 || geteuid() != 0)
  55         return;
  56
  57     pa_log_info("dropping root rights.");
  58
  59 #if defined(HAVE_SETRESUID)
  60     setresuid(uid, uid, uid);
  61 #elif defined(HAVE_SETREUID)
  62     setreuid(uid, uid);
  63 #else
  64     setuid(uid);
  65     seteuid(uid);
  66 #endif
  67 }
  68
  69 #else
  70
  71 void pa_drop_root(void) {
  72 }
  73
  74 #endif
  75
  76 #ifdef HAVE_SYS_CAPABILITY_H
  77
  78 /* Limit capabilities set to CAPSYS_NICE */
  79 int pa_limit_caps(void) {
  80     int r = -1;
  81     cap_t caps;
  82     cap_value_t nice_cap = CAP_SYS_NICE;
  83
  84     /* Only drop caps when called SUID */
  85     if (getuid() == 0)
  86         return 0;
  87
  88     caps = cap_init();
  89     assert(caps);
  90
  91     cap_clear(caps);
  92
  93     cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET);
  94     cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET);
  95
  96     if (cap_set_proc(caps) < 0)
  97         goto fail;
  98
  99     pa_log_info("dropped capabilities successfully.");
 100
 101     r = 0;
 102
 103 fail:
 104     cap_free (caps);
 105
 106     return r;
 107 }
 108
 109 /* Drop all capabilities, effectively becoming a normal user */
 110 int pa_drop_caps(void) {
 111     cap_t caps;
 112     int r = -1;
 113
 114     /* Only drop caps when called SUID */
 115     if (getuid() == 0)
 116         return 0;
 117
 118     caps = cap_init();
 119     assert(caps);
 120
 121     cap_clear(caps);
 122
 123     if (cap_set_proc(caps) < 0) {
 124         pa_log("failed to drop capabilities: %s", pa_cstrerror(errno));
 125         goto fail;
 126     }
 127
 128     r = 0;
 129
 130 fail:
 131     cap_free (caps);
 132
 133     return r;
 134 }
 135
 136 #else
 137
 138 /* NOOPs in case capabilities are not available. */
 139 int pa_limit_caps(void) {
 140     return 0;
 141 }
 142
 143 int pa_drop_caps(void) {
 144     pa_drop_root();
 145     return 0;
 146 }
 147
 148 #endif
 149