2 Unix SMB/Netbios implementation.
4 run a command as a specified user
5 Copyright (C) Andrew Tridgell 1992-1998
7 This program is free software; you can redistribute it and/or modify
8 it under the terms of the GNU General Public License as published by
9 the Free Software Foundation; either version 2 of the License, or
10 (at your option) any later version.
12 This program is distributed in the hope that it will be useful,
13 but WITHOUT ANY WARRANTY; without even the implied warranty of
14 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 GNU General Public License for more details.
17 You should have received a copy of the GNU General Public License
18 along with this program; if not, write to the Free Software
19 Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
24 /* need to move this from here!! need some sleep ... */
25 struct current_user current_user;
27 extern int DEBUGLEVEL;
29 /****************************************************************************
30 This is a utility function of smbrun(). It must be called only from
31 the child as it may leave the caller in a privilaged state.
32 ****************************************************************************/
33 static BOOL setup_stdout_file(char *outfile,BOOL shared)
37 mode_t mode = S_IWUSR|S_IRUSR|S_IRGRP|S_IROTH;
38 int flags = O_RDWR|O_CREAT|O_TRUNC|O_EXCL;
43 /* become root - unprivilaged users can't delete these files */
53 if(sys_stat(outfile, &st) == 0) {
54 /* Check we're not deleting a device file. */
55 if(st.st_mode & S_IFREG)
60 /* now create the file */
61 fd = sys_open(outfile,flags,mode);
63 if (fd == -1) return False;
66 if (dup2(fd,1) != 0) {
67 DEBUG(2,("Failed to create stdout file descriptor\n"));
77 /****************************************************************************
78 run a command being careful about uid/gid handling and putting the output in
79 outfile (or discard it if outfile is NULL).
81 if shared is True then ensure the file will be writeable by all users
82 but created such that its owned by root. This overcomes a security hole.
84 if shared is not set then open the file with O_EXCL set
85 ****************************************************************************/
86 int smbrun(char *cmd,char *outfile,BOOL shared)
89 int uid = current_user.uid;
90 int gid = current_user.gid;
93 * Lose any kernel oplock capabilities we may have.
95 set_process_capability(KERNEL_OPLOCK_CAPABILITY, False);
96 set_inherited_process_capability(KERNEL_OPLOCK_CAPABILITY, False);
101 char *path = lp_smbrun();
103 /* in the old method we use system() to execute smbrun which then
104 executes the command (using system() again!). This involves lots
105 of shell launches and is very slow. It also suffers from a
106 potential security hole */
107 if (!file_exist(path,NULL)) {
108 DEBUG(0,("SMBRUN ERROR: Can't find %s. Installation problem?\n",path));
112 slprintf(syscmd,sizeof(syscmd)-1,"%s %d %d \"(%s 2>&1) > %s\"",
114 outfile?outfile:"/dev/null");
116 DEBUG(5,("smbrun - running %s ",syscmd));
117 ret = system(syscmd);
118 DEBUG(5,("gave %d\n",ret));
121 /* in this newer method we will exec /bin/sh with the correct
122 arguments, after first setting stdout to point at the file */
126 /* the parent just waits for the child to exit */
127 if (sys_waitpid(pid,&status,0) != pid) {
128 DEBUG(2,("waitpid(%d) : %s\n",pid,strerror(errno)));
135 /* we are in the child. we exec /bin/sh to do the work for us. we
136 don't directly exec the command we want because it may be a
137 pipeline or anything else the config file specifies */
139 /* point our stdout at the file we want output to go into */
140 if (outfile && !setup_stdout_file(outfile,shared)) {
144 /* now completely lose our privilages. This is a fairly paranoid
145 way of doing it, but it does work on all systems that I know of */
146 #ifdef HAVE_SETRESUID
149 setresgid(gid,gid,gid);
150 setresuid(uid,uid,uid);
160 if (getuid() != uid || geteuid() != uid ||
161 getgid() != gid || getegid() != gid) {
162 /* we failed to lose our privilages - do not execute
164 exit(81); /* we can't print stuff at this stage,
165 instead use exit codes for debugging */
168 /* close all other file descriptors, leaving only 0, 1 and 2. 0 and
169 2 point to /dev/null from the startup code */
170 for (fd=3;fd<256;fd++) close(fd);
172 execl("/bin/sh","sh","-c",cmd,NULL);