1 /*
2 **
3 ** Copyright 2008, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 ** http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17
18 #define LOG_TAG "su"
19
20 #include <stdio.h>
21 #include <stdlib.h>
22 #include <string.h>
23 #include <sys/types.h>
24 #include <dirent.h>
25 #include <errno.h>
26
27 #include <unistd.h>
28 #include <time.h>
29
30 #include <pwd.h>
31
32 #include <private/android_filesystem_config.h>
33
34
pwtoid(const char * tok,uid_t * uid,gid_t * gid)35 void pwtoid(const char *tok, uid_t *uid, gid_t *gid)
36 {
37 struct passwd *pw;
38 pw = getpwnam(tok);
39 if (pw) {
40 if (uid) *uid = pw->pw_uid;
41 if (gid) *gid = pw->pw_gid;
42 } else {
43 uid_t tmpid = atoi(tok);
44 if (uid) *uid = tmpid;
45 if (gid) *gid = tmpid;
46 }
47 }
48
extract_uidgids(const char * uidgids,uid_t * uid,gid_t * gid,gid_t * gids,int * gids_count)49 void extract_uidgids(const char *uidgids, uid_t *uid, gid_t *gid, gid_t *gids,
50 int *gids_count)
51 {
52 char *clobberablegids;
53 char *nexttok;
54 char *tok;
55 int gids_found;
56
57 if (!uidgids || !*uidgids) {
58 *gid = *uid = 0;
59 *gids_count = 0;
60 return;
61 }
62 clobberablegids = strdup(uidgids);
63 strcpy(clobberablegids, uidgids);
64 nexttok = clobberablegids;
65 tok = strsep(&nexttok, ",");
66 pwtoid(tok, uid, gid);
67 tok = strsep(&nexttok, ",");
68 if (!tok) {
69 /* gid is already set above */
70 *gids_count = 0;
71 free(clobberablegids);
72 return;
73 }
74 pwtoid(tok, NULL, gid);
75 gids_found = 0;
76 while ((gids_found < *gids_count) && (tok = strsep(&nexttok, ","))) {
77 pwtoid(tok, NULL, gids);
78 gids_found++;
79 gids++;
80 }
81 if (nexttok && gids_found == *gids_count) {
82 fprintf(stderr, "too many group ids\n");
83 }
84 *gids_count = gids_found;
85 free(clobberablegids);
86 }
87
88 /*
89 * SU can be given a specific command to exec. UID _must_ be
90 * specified for this (ie argc => 3).
91 *
92 * Usage:
93 * su 1000
94 * su 1000 ls -l
95 * or
96 * su [uid[,gid[,group1]...] [cmd]]
97 * E.g.
98 * su 1000,shell,net_bw_acct,net_bw_stats id
99 * will return
100 * uid=1000(system) gid=2000(shell) groups=3006(net_bw_stats),3007(net_bw_acct)
101 */
main(int argc,char ** argv)102 int main(int argc, char **argv)
103 {
104 struct passwd *pw;
105 uid_t uid, myuid;
106 gid_t gid, gids[10];
107
108 /* Until we have something better, only root and the shell can use su. */
109 myuid = getuid();
110 if (myuid != AID_ROOT && myuid != AID_SHELL) {
111 fprintf(stderr,"su: uid %d not allowed to su\n", myuid);
112 return 1;
113 }
114
115 if(argc < 2) {
116 uid = gid = 0;
117 } else {
118 int gids_count = sizeof(gids)/sizeof(gids[0]);
119 extract_uidgids(argv[1], &uid, &gid, gids, &gids_count);
120 if(gids_count) {
121 if(setgroups(gids_count, gids)) {
122 fprintf(stderr, "su: failed to set groups\n");
123 return 1;
124 }
125 }
126 }
127
128 if(setgid(gid) || setuid(uid)) {
129 fprintf(stderr,"su: permission denied\n");
130 return 1;
131 }
132
133 /* User specified command for exec. */
134 if (argc == 3 ) {
135 if (execlp(argv[2], argv[2], NULL) < 0) {
136 int saved_errno = errno;
137 fprintf(stderr, "su: exec failed for %s Error:%s\n", argv[2],
138 strerror(errno));
139 return -saved_errno;
140 }
141 } else if (argc > 3) {
142 /* Copy the rest of the args from main. */
143 char *exec_args[argc - 1];
144 memset(exec_args, 0, sizeof(exec_args));
145 memcpy(exec_args, &argv[2], sizeof(exec_args));
146 if (execvp(argv[2], exec_args) < 0) {
147 int saved_errno = errno;
148 fprintf(stderr, "su: exec failed for %s Error:%s\n", argv[2],
149 strerror(errno));
150 return -saved_errno;
151 }
152 }
153
154 /* Default exec shell. */
155 execlp("/system/bin/sh", "sh", NULL);
156
157 fprintf(stderr, "su: exec failed\n");
158 return 1;
159 }
160