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

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of polypaudio.
   5
   6   polypaudio 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   polypaudio 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 polypaudio; 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 <polypcore/log.h>
  36
  37 #include "caps.h"
  38
  39 /* Glibc <= 2.2 has broken unistd.h */
  40 #if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
  41 int setresgid(gid_t r, gid_t e, gid_t s);
  42 int setresuid(uid_t r, uid_t e, uid_t s);
  43 #endif
  44
  45 #ifdef HAVE_GETUID
  46
  47 /* Drop root rights when called SUID root */
  48 void pa_drop_root(void) {
  49     uid_t uid = getuid();
  50
  51     if (uid == 0 || geteuid() != 0)
  52         return;
  53
  54     pa_log_info(__FILE__": dropping root rights.");
  55
  56 #if defined(HAVE_SETRESUID)
  57     setresuid(uid, uid, uid);
  58 #elif defined(HAVE_SETREUID)
  59     setreuid(uid, uid);
  60 #else
  61     setuid(uid);
  62     seteuid(uid);
  63 #endif
  64 }
  65
  66 #else
  67
  68 void pa_drop_root(void) {
  69 }
  70
  71 #endif
  72
  73 #ifdef HAVE_SYS_CAPABILITY_H
  74
  75 /* Limit capabilities set to CAPSYS_NICE */
  76 int pa_limit_caps(void) {
  77     int r = -1;
  78     cap_t caps;
  79     cap_value_t nice_cap = CAP_SYS_NICE;
  80
  81     caps = cap_init();
  82     assert(caps);
  83
  84     cap_clear(caps);
  85
  86     cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET);
  87     cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET);
  88
  89     if (cap_set_proc(caps) < 0)
  90         goto fail;
  91
  92     pa_log_info(__FILE__": dropped capabilities successfully.");
  93
  94     r = 0;
  95
  96 fail:
  97     cap_free (caps);
  98
  99     return r;
 100 }
 101
 102 /* Drop all capabilities, effectively becoming a normal user */
 103 int pa_drop_caps(void) {
 104     cap_t caps;
 105     int r = -1;
 106
 107     caps = cap_init();
 108     assert(caps);
 109
 110     cap_clear(caps);
 111
 112     if (cap_set_proc(caps) < 0) {
 113         pa_log(__FILE__": failed to drop capabilities: %s", strerror(errno));
 114         goto fail;
 115     }
 116
 117     r = 0;
 118
 119 fail:
 120     cap_free (caps);
 121
 122     return r;
 123 }
 124
 125 #else
 126
 127 /* NOOPs in case capabilities are not available. */
 128 int pa_limit_caps(void) {
 129     return 0;
 130 }
 131
 132 int pa_drop_caps(void) {
 133     pa_drop_root();
 134     return 0;
 135 }
 136
 137 #endif
 138