summaryrefslogtreecommitdiffstats
path: root/src/daemon/caps.c
blob: 5b4008a58d8bd043d9429d1f5c90ae4c1be5c4d4 (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
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
/* $Id$ */

/***
  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)
    setresuid(uid, uid, uid);
#elif defined(HAVE_SETREUID)
    setreuid(uid, uid);
#else
    setuid(uid);
    seteuid(uid);
#endif
}

#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 */
int pa_limit_caps(void) {
    int r = -1;
    cap_t caps;
    cap_value_t nice_cap = CAP_SYS_NICE;

    caps = cap_init();
    pa_assert(caps);
    cap_clear(caps);
    cap_set_flag(caps, CAP_EFFECTIVE, 1, &nice_cap, CAP_SET);
    cap_set_flag(caps, CAP_PERMITTED, 1, &nice_cap, CAP_SET);

    if (cap_set_proc(caps) < 0)
        goto fail;

    if (prctl(PR_SET_KEEPCAPS, 1, 0, 0, 0) < 0)
        goto fail;

    pa_log_info("Dropped capabilities successfully.");

    r = 1;

fail:
    cap_free(caps);

    return r;
}

/* Drop all capabilities, effectively becoming a normal user */
int pa_drop_caps(void) {
    cap_t caps;
    int r = -1;

    caps = cap_init();
    pa_assert(caps);

    cap_clear(caps);

    prctl(PR_SET_KEEPCAPS, 0, 0, 0, 0);

    if (cap_set_proc(caps) < 0) {
        pa_log("Failed to drop capabilities: %s", pa_cstrerror(errno));
        goto fail;
    }

    r = 0;

fail:
    cap_free(caps);

    return r;
}

#else

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

int pa_drop_caps(void) {
    pa_drop_root();
    return 0;
}

#endif