summaryrefslogtreecommitdiffstats
path: root/src/daemon/caps.c
blob: e936d6bb37a2b7d3772dc0257591ce28ace0c876 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
/* $Id$ */

/***
  This file is part of PulseAudio.

  Copyright 2004-2006 Lennart Poettering
  Copyright 2006 Pierre Ossman <ossman@cendio.se> for Cendio AB

  PulseAudio is free software; you can redistribute it and/or modify
  it under the terms of the GNU Lesser General Public License as published
  by the Free Software Foundation; either version 2 of the License,
  or (at your option) any later version.

  PulseAudio is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with PulseAudio; if not, write to the Free Software
  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
  USA.
***/

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include <unistd.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <pulsecore/macro.h>

#ifdef HAVE_SYS_CAPABILITY_H
#include <sys/capability.h>
#endif
#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#endif

#include <pulsecore/core-error.h>

#include <pulsecore/log.h>

#include "caps.h"

/* Glibc <= 2.2 has broken unistd.h */
#if defined(linux) && (__GLIBC__ <= 2 && __GLIBC_MINOR__ <= 2)
int setresgid(gid_t r, gid_t e, gid_t s);
int setresuid(uid_t r, uid_t e, uid_t s);
#endif

#ifdef HAVE_GETUID

/* Drop root rights when called SUID root */
void pa_drop_root(void) {
    uid_t uid = getuid();

    if (uid == 0 || geteuid() != 0)
        return;

    pa_log_info("Dropping root priviliges.");

#if defined(HAVE_SETRESUID)
    pa_assert_se(setresuid(uid, uid, uid) >= 0);
#elif defined(HAVE_SETREUID)
    pa_assert_se(setreuid(uid, uid) >= 0);
#else
    pa_assert_se(setuid(uid) >= 0);
    pa_assert_se(seteuid(uid) >= 0);
#endif

    pa_assert_se(getuid() == uid);
    pa_assert_se(geteuid() == uid);
}

#else

void pa_drop_root(void) {
}

#endif

#if defined(HAVE_SYS_CAPABILITY_H) && defined(HAVE_SYS_PRCTL_H)

/* Limit permitted capabilities set to CAPSYS_NICE */
void pa_limit_caps(void) {
    cap_t caps;
    cap_value_t nice_cap = CAP_SYS_NICE;

    pa_assert_se(caps = cap_init());
    pa_assert_se(cap_clear(caps) == 0);
    pa_assert_se(cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET) == 0);
    pa_assert_se(cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET) == 0);
    pa_assert_se(cap_set_proc(caps) == 0);

    pa_assert_se(prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) == 0);

    pa_log_info("Dropped capabilities successfully.");

    pa_assert_se(cap_free(caps) == 0);
}

/* Drop all capabilities, effectively becoming a normal user */
void pa_drop_caps(void) {
    cap_t caps;

    pa_assert_se(prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0) == 0);

    pa_assert_se(caps = cap_init());
    pa_assert_se(cap_clear(caps) == 0);
    pa_assert_se(cap_set_proc(caps) == 0);
    pa_assert_se(cap_free(caps) == 0);
}

#else

/* NOOPs in case capabilities are not available. */
int pa_limit_caps(void) {
    return 0;
}

void pa_drop_caps(void) {
    pa_drop_root();
}

#endif