1 /*
2 * This file is part of ltrace.
3 * Copyright (C) 2011,2012 Petr Machata, Red Hat Inc.
4 * Copyright (C) 2010 Joe Damato
5 * Copyright (C) 1998,1999,2003,2008,2009 Juan Cespedes
6 * Copyright (C) 2006 Ian Wienand
7 *
8 * This program is free software; you can redistribute it and/or
9 * modify it under the terms of the GNU General Public License as
10 * published by the Free Software Foundation; either version 2 of the
11 * License, or (at your option) any later version.
12 *
13 * This program is distributed in the hope that it will be useful, but
14 * WITHOUT ANY WARRANTY; without even the implied warranty of
15 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
16 * General Public License for more details.
17 *
18 * You should have received a copy of the GNU General Public License
19 * along with this program; if not, write to the Free Software
20 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
21 * 02110-1301 USA
22 */
23 #include "config.h"
24
25 #include <stdio.h>
26 #include <stdlib.h>
27 #include <sys/types.h>
28 #include <sys/stat.h>
29 #include <unistd.h>
30 #include <errno.h>
31 #include <string.h>
32 #include <pwd.h>
33 #include <grp.h>
34
35 #include "backend.h"
36 #include "options.h"
37 #include "debug.h"
38
39 static void
change_uid(const char * command)40 change_uid(const char * command)
41 {
42 uid_t run_uid, run_euid;
43 gid_t run_gid, run_egid;
44
45 if (options.user) {
46 struct passwd *pent;
47
48 if (getuid() != 0 || geteuid() != 0) {
49 fprintf(stderr,
50 "you must be root to use the -u option\n");
51 exit(1);
52 }
53 if ((pent = getpwnam(options.user)) == NULL) {
54 fprintf(stderr, "cannot find user `%s'\n", options.user);
55 exit(1);
56 }
57 run_uid = pent->pw_uid;
58 run_gid = pent->pw_gid;
59
60 if (initgroups(options.user, run_gid) < 0) {
61 perror("ltrace: initgroups");
62 exit(1);
63 }
64 } else {
65 run_uid = getuid();
66 run_gid = getgid();
67 }
68 if (options.user || !geteuid()) {
69 struct stat statbuf;
70 run_euid = run_uid;
71 run_egid = run_gid;
72
73 if (!stat(command, &statbuf)) {
74 if (statbuf.st_mode & S_ISUID) {
75 run_euid = statbuf.st_uid;
76 }
77 if (statbuf.st_mode & S_ISGID) {
78 run_egid = statbuf.st_gid;
79 }
80 }
81 if (setregid(run_gid, run_egid) < 0) {
82 perror("ltrace: setregid");
83 exit(1);
84 }
85 if (setreuid(run_uid, run_euid) < 0) {
86 perror("ltrace: setreuid");
87 exit(1);
88 }
89 }
90 }
91
92 pid_t
execute_program(const char * command,char ** argv)93 execute_program(const char * command, char **argv)
94 {
95 pid_t pid;
96
97 debug(1, "Executing `%s'...", command);
98
99 pid = fork();
100 if (pid < 0) {
101 fail:
102 perror("ltrace: fork");
103 exit(1);
104 } else if (!pid) { /* child */
105 change_uid(command);
106 trace_me();
107 execvp(command, argv);
108 fprintf(stderr, "Can't execute `%s': %s\n", command,
109 strerror(errno));
110 _exit(1);
111 }
112
113 if (wait_for_proc(pid) < 0)
114 goto fail;
115
116 debug(1, "PID=%d", pid);
117 return pid;
118 }
119