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

   1 /* $Id$ */
   2
   3 /***
   4   This file is part of PulseAudio.
   5
   6   Copyright 2004-2006 Lennart Poettering
   7   Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB
   8
   9   PulseAudio is free software; you can redistribute it and/or modify
  10   it under the terms of the GNU Lesser General Public License as published
  11   by the Free Software Foundation; either version 2 of the License,
  12   or (at your option) any later version.
  13
  14   PulseAudio is distributed in the hope that it will be useful, but
  15   WITHOUT ANY WARRANTY; without even the implied warranty of
  16   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  17   General Public License for more details.
  18
  19   You should have received a copy of the GNU Lesser General Public License
  20   along with PulseAudio; if not, write to the Free Software
  21   Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  22   USA.
  23 ***/
  24
  25 #ifdef HAVE_CONFIG_H
  26 #include <config.h>
  27 #endif
  28
  29 #include <unistd.h>
  30 #include <errno.h>
  31 #include <string.h>
  32 #include <sys/types.h>
  33 #include <pulsecore/macro.h>
  34
  35 #ifdef HAVE_SYS_CAPABILITY_H
  36 #include <sys/capability.h>
  37 #endif
  38 #ifdef HAVE_SYS_PRCTL_H
  39 #include <sys/prctl.h>
  40 #endif
  41
  42 #include <pulsecore/core-error.h>
  43
  44 #include <pulsecore/log.h>
  45
  46 #include "caps.h"
  47
  48 /* Glibc <= 2.2 has broken unistd.h */
  49 #if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
  50 int setresgid(gid_t r, gid_t e, gid_t s);
  51 int setresuid(uid_t r, uid_t e, uid_t s);
  52 #endif
  53
  54 #ifdef HAVE_GETUID
  55
  56 /* Drop root rights when called SUID root */
  57 void pa_drop_root(void) {
  58     uid_t uid = getuid();
  59
  60     if (uid == 0 || geteuid() != 0)
  61         return;
  62
  63     pa_log_info("Dropping root priviliges.");
  64
  65 #if defined(HAVE_SETRESUID)
  66     pa_assert_se(setresuid(uid, uid, uid) >= 0);
  67 #elif defined(HAVE_SETREUID)
  68     pa_assert_se(setreuid(uid, uid) >= 0);
  69 #else
  70     pa_assert_se(setuid(uid) >= 0);
  71     pa_assert_se(seteuid(uid) >= 0);
  72 #endif
  73
  74     pa_assert_se(getuid() == uid);
  75     pa_assert_se(geteuid() == uid);
  76 }
  77
  78 #else
  79
  80 void pa_drop_root(void) {
  81 }
  82
  83 #endif
  84
  85 #if defined(HAVE_SYS_CAPABILITY_H) && defined(HAVE_SYS_PRCTL_H)
  86
  87 /* Limit permitted capabilities set to CAPSYS_NICE */
  88 void pa_limit_caps(void) {
  89     cap_t caps;
  90     cap_value_t nice_cap = CAP_SYS_NICE;
  91
  92     pa_assert_se(caps = cap_init());
  93     pa_assert_se(cap_clear(caps) == 0);
  94     pa_assert_se(cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET) == 0);
  95     pa_assert_se(cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET) == 0);
  96     pa_assert_se(cap_set_proc(caps) == 0);
  97
  98     pa_assert_se(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0);
  99
 100     pa_log_info("Dropped capabilities successfully.");
 101
 102     pa_assert_se(cap_free(caps) == 0);
 103 }
 104
 105 /* Drop all capabilities, effectively becoming a normal user */
 106 void pa_drop_caps(void) {
 107     cap_t caps;
 108
 109     pa_assert_se(prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) == 0);
 110
 111     pa_assert_se(caps = cap_init());
 112     pa_assert_se(cap_clear(caps) == 0);
 113     pa_assert_se(cap_set_proc(caps) == 0);
 114     pa_assert_se(cap_free(caps) == 0);
 115 }
 116
 117 #else
 118
 119 /* NOOPs in case capabilities are not available. */
 120 int pa_limit_caps(void) {
 121     return 0;
 122 }
 123
 124 void pa_drop_caps(void) {
 125     pa_drop_root();
 126 }
 127
 128 #endif