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317e5d15 | 1 | /* $Id$ */ |
2 | ||
3 | /* | |
4 | * Copyright (c) 2005 Daniel Walsh <dwalsh@redhat.com> | |
5 | * Copyright (c) 2006 Damien Miller <djm@openbsd.org> | |
6 | * | |
7 | * Permission to use, copy, modify, and distribute this software for any | |
8 | * purpose with or without fee is hereby granted, provided that the above | |
9 | * copyright notice and this permission notice appear in all copies. | |
10 | * | |
11 | * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES | |
12 | * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF | |
13 | * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR | |
14 | * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES | |
15 | * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN | |
16 | * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF | |
17 | * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. | |
18 | */ | |
19 | ||
20 | /* | |
21 | * Linux-specific portability code - just SELinux support at present | |
22 | */ | |
23 | ||
24 | #include "includes.h" | |
25 | ||
26 | #include <errno.h> | |
27 | #include <stdarg.h> | |
28 | #include <string.h> | |
29 | ||
30 | #ifdef WITH_SELINUX | |
31 | #include "log.h" | |
32 | #include "port-linux.h" | |
33 | ||
34 | #include <selinux/selinux.h> | |
35 | #include <selinux/flask.h> | |
36 | #include <selinux/get_context_list.h> | |
37 | ||
38 | /* Wrapper around is_selinux_enabled() to log its return value once only */ | |
39 | static int | |
40 | ssh_selinux_enabled(void) | |
41 | { | |
42 | static int enabled = -1; | |
43 | ||
44 | if (enabled == -1) { | |
45 | enabled = is_selinux_enabled(); | |
46 | debug("SELinux support %s", enabled ? "enabled" : "disabled"); | |
47 | } | |
48 | ||
49 | return (enabled); | |
50 | } | |
51 | ||
52 | /* Return the default security context for the given username */ | |
53 | static security_context_t | |
54 | ssh_selinux_getctxbyname(char *pwname) | |
55 | { | |
56 | security_context_t sc; | |
57 | char *sename = NULL, *lvl = NULL; | |
58 | int r; | |
59 | ||
60 | #ifdef HAVE_GETSEUSERBYNAME | |
61 | if (getseuserbyname(pwname, &sename, &lvl) != 0) | |
62 | return NULL; | |
63 | #else | |
64 | sename = pwname; | |
65 | lvl = NULL; | |
66 | #endif | |
67 | ||
68 | #ifdef HAVE_GET_DEFAULT_CONTEXT_WITH_LEVEL | |
69 | r = get_default_context_with_level(sename, lvl, NULL, &sc); | |
70 | #else | |
71 | r = get_default_context(sename, NULL, &sc); | |
72 | #endif | |
73 | ||
74 | if (r != 0) { | |
75 | switch (security_getenforce()) { | |
76 | case -1: | |
77 | fatal("%s: ssh_selinux_getctxbyname: " | |
78 | "security_getenforce() failed", __func__); | |
79 | case 0: | |
80 | error("%s: Failed to get default SELinux security " | |
81 | "context for %s", __func__, pwname); | |
82 | default: | |
83 | fatal("%s: Failed to get default SELinux security " | |
84 | "context for %s (in enforcing mode)", | |
85 | __func__, pwname); | |
86 | } | |
87 | } | |
88 | ||
89 | #ifdef HAVE_GETSEUSERBYNAME | |
90 | if (sename != NULL) | |
91 | xfree(sename); | |
92 | if (lvl != NULL) | |
93 | xfree(lvl); | |
94 | #endif | |
95 | ||
96 | return (sc); | |
97 | } | |
98 | ||
99 | /* Set the execution context to the default for the specified user */ | |
100 | void | |
101 | ssh_selinux_setup_exec_context(char *pwname) | |
102 | { | |
103 | security_context_t user_ctx = NULL; | |
104 | ||
105 | if (!ssh_selinux_enabled()) | |
106 | return; | |
107 | ||
108 | debug3("%s: setting execution context", __func__); | |
109 | ||
110 | user_ctx = ssh_selinux_getctxbyname(pwname); | |
111 | if (setexeccon(user_ctx) != 0) { | |
112 | switch (security_getenforce()) { | |
113 | case -1: | |
114 | fatal("%s: security_getenforce() failed", __func__); | |
115 | case 0: | |
116 | error("%s: Failed to set SELinux execution " | |
117 | "context for %s", __func__, pwname); | |
118 | default: | |
119 | fatal("%s: Failed to set SELinux execution context " | |
120 | "for %s (in enforcing mode)", __func__, pwname); | |
121 | } | |
122 | } | |
123 | if (user_ctx != NULL) | |
124 | freecon(user_ctx); | |
125 | ||
126 | debug3("%s: done", __func__); | |
127 | } | |
128 | ||
129 | /* Set the TTY context for the specified user */ | |
130 | void | |
131 | ssh_selinux_setup_pty(char *pwname, const char *tty) | |
132 | { | |
133 | security_context_t new_tty_ctx = NULL; | |
134 | security_context_t user_ctx = NULL; | |
135 | security_context_t old_tty_ctx = NULL; | |
136 | ||
137 | if (!ssh_selinux_enabled()) | |
138 | return; | |
139 | ||
140 | debug3("%s: setting TTY context on %s", __func__, tty); | |
141 | ||
142 | user_ctx = ssh_selinux_getctxbyname(pwname); | |
143 | ||
144 | /* XXX: should these calls fatal() upon failure in enforcing mode? */ | |
145 | ||
146 | if (getfilecon(tty, &old_tty_ctx) == -1) { | |
147 | error("%s: getfilecon: %s", __func__, strerror(errno)); | |
148 | goto out; | |
149 | } | |
150 | ||
151 | if (security_compute_relabel(user_ctx, old_tty_ctx, | |
152 | SECCLASS_CHR_FILE, &new_tty_ctx) != 0) { | |
153 | error("%s: security_compute_relabel: %s", | |
154 | __func__, strerror(errno)); | |
155 | goto out; | |
156 | } | |
157 | ||
158 | if (setfilecon(tty, new_tty_ctx) != 0) | |
159 | error("%s: setfilecon: %s", __func__, strerror(errno)); | |
160 | out: | |
161 | if (new_tty_ctx != NULL) | |
162 | freecon(new_tty_ctx); | |
163 | if (old_tty_ctx != NULL) | |
164 | freecon(old_tty_ctx); | |
165 | if (user_ctx != NULL) | |
166 | freecon(user_ctx); | |
167 | debug3("%s: done", __func__); | |
168 | } | |
169 | #endif /* WITH_SELINUX */ |