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 privileged 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 - unprivileged users can't delete these files */
44 gain_root_privilege();
45 gain_root_group_privilege();
48 if(sys_stat(outfile, &st) == 0) {
49 /* Check we're not deleting a device file. */
50 if(st.st_mode & S_IFREG)
55 /* now create the file */
56 fd = sys_open(outfile,flags,mode);
58 if (fd == -1) return False;
61 if (dup2(fd,1) != 0) {
62 DEBUG(2,("Failed to create stdout file descriptor\n"));
72 /****************************************************************************
73 run a command being careful about uid/gid handling and putting the output in
74 outfile (or discard it if outfile is NULL).
76 if shared is True then ensure the file will be writeable by all users
77 but created such that its owned by root. This overcomes a security hole.
79 if shared is not set then open the file with O_EXCL set
80 ****************************************************************************/
81 int smbrun(char *cmd,char *outfile,BOOL shared)
85 uid_t uid = current_user.uid;
86 gid_t gid = current_user.gid;
89 * Lose any kernel oplock capabilities we may have.
91 set_process_capability(KERNEL_OPLOCK_CAPABILITY, False);
92 set_inherited_process_capability(KERNEL_OPLOCK_CAPABILITY, False);
97 char *path = lp_smbrun();
99 /* in the old method we use system() to execute smbrun which then
100 executes the command (using system() again!). This involves lots
101 of shell launches and is very slow. It also suffers from a
102 potential security hole */
103 if (!file_exist(path,NULL)) {
104 DEBUG(0,("SMBRUN ERROR: Can't find %s. Installation problem?\n",path));
108 slprintf(syscmd,sizeof(syscmd)-1,"%s %d %d \"(%s 2>&1) > %s\"",
109 path,(int)uid,(int)gid,cmd,
110 outfile?outfile:"/dev/null");
112 DEBUG(5,("smbrun - running %s ",syscmd));
113 ret = system(syscmd);
114 DEBUG(5,("gave %d\n",ret));
117 /* in this newer method we will exec /bin/sh with the correct
118 arguments, after first setting stdout to point at the file */
121 * We need to temporarily stop CatchChild from eating
122 * SIGCLD signals as it also eats the exit status code. JRA.
125 CatchChildLeaveStatus();
127 if ((pid=fork()) < 0) {
128 DEBUG(0,("smbrun: fork failed with error %s\n", strerror(errno) ));
141 /* the parent just waits for the child to exit */
142 while((wpid = sys_waitpid(pid,&status,0)) < 0) {
153 DEBUG(2,("waitpid(%d) : %s\n",(int)pid,strerror(errno)));
156 #if defined(WIFEXITED) && defined(WEXITSTATUS)
157 if (WIFEXITED(status)) {
158 return WEXITSTATUS(status);
166 /* we are in the child. we exec /bin/sh to do the work for us. we
167 don't directly exec the command we want because it may be a
168 pipeline or anything else the config file specifies */
170 /* point our stdout at the file we want output to go into */
171 if (outfile && !setup_stdout_file(outfile,shared)) {
175 /* now completely lose our privileges. This is a fairly paranoid
176 way of doing it, but it does work on all systems that I know of */
178 become_user_permanently(uid, gid);
180 if (getuid() != uid || geteuid() != uid ||
181 getgid() != gid || getegid() != gid) {
182 /* we failed to lose our privileges - do not execute
184 exit(81); /* we can't print stuff at this stage,
185 instead use exit codes for debugging */
189 /* close all other file descriptors, leaving only 0, 1 and 2. 0 and
190 2 point to /dev/null from the startup code */
191 for (fd=3;fd<256;fd++) close(fd);
194 execl("/bin/sh","sh","-c",cmd,NULL);