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
  31 #ifdef HAVE_SYS_CAPABILITY_H
  32 #include <sys/capability.h>
  33 #endif
  34
  35 #include <pulsecore/core-error.h>
  36
  37 #include <pulsecore/log.h>
  38
  39 #include "caps.h"
  40
  41 /* Glibc <= 2.2 has broken unistd.h */
  42 #if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
  43 int setresgid(gid_t r, gid_t e, gid_t s);
  44 int setresuid(uid_t r, uid_t e, uid_t s);
  45 #endif
  46
  47 #ifdef HAVE_GETUID
  48
  49 /* Drop root rights when called SUID root */
  50 void pa_drop_root(void) {
  51     uid_t uid = getuid();
  52
  53     if (uid == 0 || geteuid() != 0)
  54         return;
  55
  56     pa_log_info(__FILE__": dropping root rights.");
  57
  58 #if defined(HAVE_SETRESUID)
  59     setresuid(uid, uid, uid);
  60 #elif defined(HAVE_SETREUID)
  61     setreuid(uid, uid);
  62 #else
  63     setuid(uid);
  64     seteuid(uid);
  65 #endif
  66 }
  67
  68 #else
  69
  70 void pa_drop_root(void) {
  71 }
  72
  73 #endif
  74
  75 #ifdef HAVE_SYS_CAPABILITY_H
  76
  77 /* Limit capabilities set to CAPSYS_NICE */
  78 int pa_limit_caps(void) {
  79     int r = -1;
  80     cap_t caps;
  81     cap_value_t nice_cap = CAP_SYS_NICE;
  82
  83     caps = cap_init();
  84     assert(caps);
  85
  86     cap_clear(caps);
  87
  88     cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET);
  89     cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET);
  90
  91     if (cap_set_proc(caps) < 0)
  92         goto fail;
  93
  94     pa_log_info(__FILE__": dropped capabilities successfully.");
  95
  96     r = 0;
  97
  98 fail:
  99     cap_free (caps);
 100
 101     return r;
 102 }
 103
 104 /* Drop all capabilities, effectively becoming a normal user */
 105 int pa_drop_caps(void) {
 106     cap_t caps;
 107     int r = -1;
 108
 109     caps = cap_init();
 110     assert(caps);
 111
 112     cap_clear(caps);
 113
 114     if (cap_set_proc(caps) < 0) {
 115         pa_log(__FILE__": failed to drop capabilities: %s", pa_cstrerror(errno));
 116         goto fail;
 117     }
 118
 119     r = 0;
 120
 121 fail:
 122     cap_free (caps);
 123
 124     return r;
 125 }
 126
 127 #else
 128
 129 /* NOOPs in case capabilities are not available. */
 130 int pa_limit_caps(void) {
 131     return 0;
 132 }
 133
 134 int pa_drop_caps(void) {
 135     pa_drop_root();
 136     return 0;
 137 }
 138
 139 #endif
 140