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/*
35 * SU can be given a specific command to exec. UID _must_ be
36 * specified for this (ie argc => 3).
37 *
38 * Usage:
39 * su 1000
40 * su 1000 ls -l
41 */
42int main(int argc, char **argv)
43{
44    struct passwd *pw;
45    int uid, gid, myuid;
46
47    /* Until we have something better, only root and the shell can use su. */
48    myuid = getuid();
49    if (myuid != AID_ROOT && myuid != AID_SHELL) {
50        fprintf(stderr,"su: uid %d not allowed to su\n", myuid);
51        return 1;
52    }
53
54    if(argc < 2) {
55        uid = gid = 0;
56    } else {
57        pw = getpwnam(argv[1]);
58
59        if(pw == 0) {
60            uid = gid = atoi(argv[1]);
61        } else {
62            uid = pw->pw_uid;
63            gid = pw->pw_gid;
64        }
65    }
66
67    if(setgid(gid) || setuid(uid)) {
68        fprintf(stderr,"su: permission denied\n");
69        return 1;
70    }
71
72    /* User specified command for exec. */
73    if (argc == 3 ) {
74        if (execlp(argv[2], argv[2], NULL) < 0) {
75            fprintf(stderr, "su: exec failed for %s Error:%s\n", argv[2],
76                    strerror(errno));
77            return -errno;
78        }
79    } else if (argc > 3) {
80        /* Copy the rest of the args from main. */
81        char *exec_args[argc - 1];
82        memset(exec_args, 0, sizeof(exec_args));
83        memcpy(exec_args, &argv[2], sizeof(exec_args));
84        if (execvp(argv[2], exec_args) < 0) {
85            fprintf(stderr, "su: exec failed for %s Error:%s\n", argv[2],
86                    strerror(errno));
87            return -errno;
88        }
89    }
90
91    /* Default exec shell. */
92    execlp("/system/bin/sh", "sh", NULL);
93
94    fprintf(stderr, "su: exec failed\n");
95    return 1;
96}
97