code.delx.au - pulseaudio/blob - polyp/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 "log.h"
  36 #include "caps.h"
  37
  38 /* Drop root rights when called SUID root */
  39 void pa_drop_root(void) {
  40     uid_t uid = getuid();
  41
  42     if (uid == 0 || geteuid() != 0)
  43         return;
  44
  45     pa_log_info(__FILE__": dropping root rights.\n");
  46
  47 #if defined(HAVE_SETRESUID)
  48     setresuid(uid, uid, uid);
  49 #elif defined(HAVE_SETREUID)
  50     setreuid(uid, uid);
  51 #else
  52     setuid(uid);
  53     seteuid(uid);
  54 #endif
  55 }
  56
  57 #ifdef HAVE_SYS_CAPABILITY_H
  58
  59 /* Limit capabilities set to CAPSYS_NICE */
  60 int pa_limit_caps(void) {
  61     int r = -1;
  62     cap_t caps;
  63     cap_value_t nice_cap = CAP_SYS_NICE;
  64
  65     caps = cap_init();
  66     assert(caps);
  67
  68     cap_clear(caps);
  69
  70     cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET);
  71     cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET);
  72
  73     if (cap_set_proc(caps) < 0)
  74         goto fail;
  75
  76     pa_log_info(__FILE__": dropped capabilities successfully.\n");
  77
  78     r = 0;
  79
  80 fail:
  81     cap_free (caps);
  82
  83     return r;
  84 }
  85
  86 /* Drop all capabilities, effectively becoming a normal user */
  87 int pa_drop_caps(void) {
  88     cap_t caps;
  89     int r = -1;
  90
  91     caps = cap_init();
  92     assert(caps);
  93
  94     cap_clear(caps);
  95
  96     if (cap_set_proc(caps) < 0) {
  97         pa_log(__FILE__": failed to drop capabilities: %s\n", strerror(errno));
  98         goto fail;
  99     }
 100
 101     r = 0;
 102
 103 fail:
 104     cap_free (caps);
 105
 106     return r;
 107 }
 108
 109 #else
 110
 111 /* NOOPs in case capabilities are not available. */
 112 int pa_limit_caps(void) {
 113     return 0;
 114 }
 115
 116 int pa_drop_caps(void) {
 117     pa_drop_root();
 118     return 0;
 119 }
 120
 121 #endif
 122