Annotation of embedaddon/sudo/src/exec_common.c, revision 1.1.1.1
1.1 misho 1: /*
2: * Copyright (c) 2009-2012 Todd C. Miller <Todd.Miller@courtesan.com>
3: *
4: * Permission to use, copy, modify, and distribute this software for any
5: * purpose with or without fee is hereby granted, provided that the above
6: * copyright notice and this permission notice appear in all copies.
7: *
8: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15: */
16:
17: #include <config.h>
18:
19: #include <sys/types.h>
20: #include <sys/param.h>
21: #include <stdio.h>
22: #ifdef STDC_HEADERS
23: # include <stdlib.h>
24: # include <stddef.h>
25: #else
26: # ifdef HAVE_STDLIB_H
27: # include <stdlib.h>
28: # endif
29: #endif /* STDC_HEADERS */
30: #ifdef HAVE_STRING_H
31: # include <string.h>
32: #endif /* HAVE_STRING_H */
33: #ifdef HAVE_STRINGS_H
34: # include <strings.h>
35: #endif /* HAVE_STRINGS_H */
36: #ifdef HAVE_UNISTD_H
37: # include <unistd.h>
38: #endif /* HAVE_UNISTD_H */
39: #ifdef HAVE_PRIV_SET
40: # include <priv.h>
41: #endif
42: #include <errno.h>
43:
44: #include "sudo.h"
45: #include "sudo_exec.h"
46:
47: /*
48: * Disable execution of child processes in the command we are about
49: * to run. On systems with privilege sets, we can remove the exec
50: * privilege. On other systems we use LD_PRELOAD and the like.
51: */
52: static char * const *
53: disable_execute(char *const envp[])
54: {
55: #ifdef _PATH_SUDO_NOEXEC
56: char *preload, **nenvp = NULL;
57: int env_len, env_size;
58: int preload_idx = -1;
59: # ifdef RTLD_PRELOAD_ENABLE_VAR
60: bool enabled = false;
61: # endif
62: #endif /* _PATH_SUDO_NOEXEC */
63: debug_decl(disable_execute, SUDO_DEBUG_UTIL)
64:
65: #ifdef HAVE_PRIV_SET
66: /* Solaris privileges, remove PRIV_PROC_EXEC post-execve. */
67: if (priv_set(PRIV_OFF, PRIV_LIMIT, "PRIV_PROC_EXEC", NULL) == 0)
68: debug_return_ptr(envp);
69: warning(_("unable to remove PRIV_PROC_EXEC from PRIV_LIMIT"));
70: #endif /* HAVE_PRIV_SET */
71:
72: #ifdef _PATH_SUDO_NOEXEC
73: /*
74: * Preload a noexec file. For a list of LD_PRELOAD-alikes, see
75: * http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html
76: * XXX - need to support 32-bit and 64-bit variants
77: */
78:
79: /* Count entries in envp, looking for LD_PRELOAD as we go. */
80: for (env_len = 0; envp[env_len] != NULL; env_len++) {
81: if (strncmp(envp[env_len], RTLD_PRELOAD_VAR "=", sizeof(RTLD_PRELOAD_VAR)) == 0) {
82: preload_idx = env_len;
83: continue;
84: }
85: #ifdef RTLD_PRELOAD_ENABLE_VAR
86: if (strncmp(envp[env_len], RTLD_PRELOAD_ENABLE_VAR "=", sizeof(RTLD_PRELOAD_ENABLE_VAR)) == 0) {
87: enabled = true;
88: continue;
89: }
90: #endif
91: }
92:
93: /* Make a new copy of envp as needed. */
94: env_size = env_len + 1 + (preload_idx == -1);
95: #ifdef RTLD_PRELOAD_ENABLE_VAR
96: if (!enabled)
97: env_size++;
98: #endif
99: nenvp = emalloc2(env_size, sizeof(*envp));
100: memcpy(nenvp, envp, env_len * sizeof(*envp));
101: nenvp[env_len] = NULL;
102:
103: /* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
104: if (preload_idx == -1) {
105: # ifdef RTLD_PRELOAD_DEFAULT
106: easprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, sudo_conf_noexec_path(), RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
107: # else
108: preload = fmt_string(RTLD_PRELOAD_VAR, sudo_conf_noexec_path());
109: # endif
110: if (preload == NULL)
111: errorx(1, _("unable to allocate memory"));
112: nenvp[env_len++] = preload;
113: nenvp[env_len] = NULL;
114: } else {
115: easprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, sudo_conf_noexec_path(), RTLD_PRELOAD_DELIM, nenvp[preload_idx]);
116: nenvp[preload_idx] = preload;
117: }
118: # ifdef RTLD_PRELOAD_ENABLE_VAR
119: if (!enabled) {
120: nenvp[env_len++] = RTLD_PRELOAD_ENABLE_VAR "=";
121: nenvp[env_len] = NULL;
122: }
123: # endif
124:
125: /* Install new env pointer. */
126: envp = nenvp;
127: #endif /* _PATH_SUDO_NOEXEC */
128:
129: debug_return_ptr(envp);
130: }
131:
132: /*
133: * Like execve(2) but falls back to running through /bin/sh
134: * ala execvp(3) if we get ENOEXEC.
135: */
136: int
137: sudo_execve(const char *path, char *const argv[], char *const envp[], int noexec)
138: {
139: /* Modify the environment as needed to disable further execve(). */
140: if (noexec)
141: envp = disable_execute(envp);
142:
143: execve(path, argv, envp);
144: if (errno == ENOEXEC) {
145: int argc;
146: char **nargv;
147:
148: for (argc = 0; argv[argc] != NULL; argc++)
149: continue;
150: nargv = emalloc2(argc + 2, sizeof(char *));
151: nargv[0] = "sh";
152: nargv[1] = (char *)path;
153: memcpy(nargv + 2, argv + 1, argc * sizeof(char *));
154: execve(_PATH_BSHELL, nargv, envp);
155: efree(nargv);
156: }
157: return -1;
158: }
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