Annotation of embedaddon/sudo/src/exec_common.c, revision 1.1.1.4
1.1 misho 1: /*
1.1.1.3 misho 2: * Copyright (c) 2009-2013 Todd C. Miller <Todd.Miller@courtesan.com>
1.1 misho 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 <stdio.h>
21: #ifdef STDC_HEADERS
22: # include <stdlib.h>
23: # include <stddef.h>
24: #else
25: # ifdef HAVE_STDLIB_H
26: # include <stdlib.h>
27: # endif
28: #endif /* STDC_HEADERS */
29: #ifdef HAVE_STRING_H
30: # include <string.h>
31: #endif /* HAVE_STRING_H */
32: #ifdef HAVE_STRINGS_H
33: # include <strings.h>
34: #endif /* HAVE_STRINGS_H */
35: #ifdef HAVE_UNISTD_H
36: # include <unistd.h>
37: #endif /* HAVE_UNISTD_H */
38: #ifdef HAVE_PRIV_SET
39: # include <priv.h>
40: #endif
41: #include <errno.h>
1.1.1.3 misho 42: #include <fcntl.h>
1.1.1.2 misho 43: #include <signal.h>
1.1 misho 44:
45: #include "sudo.h"
46: #include "sudo_exec.h"
47:
48: /*
49: * Disable execution of child processes in the command we are about
50: * to run. On systems with privilege sets, we can remove the exec
51: * privilege. On other systems we use LD_PRELOAD and the like.
52: */
53: static char * const *
54: disable_execute(char *const envp[])
55: {
56: #ifdef _PATH_SUDO_NOEXEC
57: char *preload, **nenvp = NULL;
58: int env_len, env_size;
59: int preload_idx = -1;
60: # ifdef RTLD_PRELOAD_ENABLE_VAR
61: bool enabled = false;
62: # endif
63: #endif /* _PATH_SUDO_NOEXEC */
64: debug_decl(disable_execute, SUDO_DEBUG_UTIL)
65:
66: #ifdef HAVE_PRIV_SET
67: /* Solaris privileges, remove PRIV_PROC_EXEC post-execve. */
68: if (priv_set(PRIV_OFF, PRIV_LIMIT, "PRIV_PROC_EXEC", NULL) == 0)
69: debug_return_ptr(envp);
70: warning(_("unable to remove PRIV_PROC_EXEC from PRIV_LIMIT"));
71: #endif /* HAVE_PRIV_SET */
72:
73: #ifdef _PATH_SUDO_NOEXEC
74: /*
75: * Preload a noexec file. For a list of LD_PRELOAD-alikes, see
76: * http://www.fortran-2000.com/ArnaudRecipes/sharedlib.html
77: * XXX - need to support 32-bit and 64-bit variants
78: */
79:
80: /* Count entries in envp, looking for LD_PRELOAD as we go. */
81: for (env_len = 0; envp[env_len] != NULL; env_len++) {
82: if (strncmp(envp[env_len], RTLD_PRELOAD_VAR "=", sizeof(RTLD_PRELOAD_VAR)) == 0) {
83: preload_idx = env_len;
84: continue;
85: }
86: #ifdef RTLD_PRELOAD_ENABLE_VAR
87: if (strncmp(envp[env_len], RTLD_PRELOAD_ENABLE_VAR "=", sizeof(RTLD_PRELOAD_ENABLE_VAR)) == 0) {
88: enabled = true;
89: continue;
90: }
91: #endif
92: }
93:
94: /* Make a new copy of envp as needed. */
95: env_size = env_len + 1 + (preload_idx == -1);
96: #ifdef RTLD_PRELOAD_ENABLE_VAR
97: if (!enabled)
98: env_size++;
99: #endif
100: nenvp = emalloc2(env_size, sizeof(*envp));
101: memcpy(nenvp, envp, env_len * sizeof(*envp));
102: nenvp[env_len] = NULL;
103:
104: /* Prepend our LD_PRELOAD to existing value or add new entry at the end. */
105: if (preload_idx == -1) {
106: # ifdef RTLD_PRELOAD_DEFAULT
107: easprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, sudo_conf_noexec_path(), RTLD_PRELOAD_DELIM, RTLD_PRELOAD_DEFAULT);
108: # else
109: preload = fmt_string(RTLD_PRELOAD_VAR, sudo_conf_noexec_path());
110: # endif
111: if (preload == NULL)
1.1.1.4 ! misho 112: fatal(NULL);
1.1 misho 113: nenvp[env_len++] = preload;
114: nenvp[env_len] = NULL;
115: } else {
116: easprintf(&preload, "%s=%s%s%s", RTLD_PRELOAD_VAR, sudo_conf_noexec_path(), RTLD_PRELOAD_DELIM, nenvp[preload_idx]);
117: nenvp[preload_idx] = preload;
118: }
119: # ifdef RTLD_PRELOAD_ENABLE_VAR
120: if (!enabled) {
121: nenvp[env_len++] = RTLD_PRELOAD_ENABLE_VAR "=";
122: nenvp[env_len] = NULL;
123: }
124: # endif
125:
126: /* Install new env pointer. */
127: envp = nenvp;
128: #endif /* _PATH_SUDO_NOEXEC */
129:
130: debug_return_ptr(envp);
131: }
132:
133: /*
134: * Like execve(2) but falls back to running through /bin/sh
135: * ala execvp(3) if we get ENOEXEC.
136: */
137: int
138: sudo_execve(const char *path, char *const argv[], char *const envp[], int noexec)
139: {
140: /* Modify the environment as needed to disable further execve(). */
141: if (noexec)
142: envp = disable_execute(envp);
143:
144: execve(path, argv, envp);
145: if (errno == ENOEXEC) {
146: int argc;
147: char **nargv;
148:
149: for (argc = 0; argv[argc] != NULL; argc++)
150: continue;
151: nargv = emalloc2(argc + 2, sizeof(char *));
152: nargv[0] = "sh";
153: nargv[1] = (char *)path;
154: memcpy(nargv + 2, argv + 1, argc * sizeof(char *));
155: execve(_PATH_BSHELL, nargv, envp);
156: efree(nargv);
157: }
158: return -1;
159: }
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