release/src/router/samba3/source/lib/smbrun.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    run a command as a specified user
   4    Copyright (C) Andrew Tridgell 1992-1998
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 /* need to move this from here!! need some sleep ... */
  24 struct current_user current_user;
  25
  26 /****************************************************************************
  27 This is a utility function of smbrun().
  28 ****************************************************************************/
  29
  30 static int setup_out_fd(void)
  31 {
  32         int fd;
  33         pstring path;
  34
  35         slprintf(path, sizeof(path)-1, "%s/smb.XXXXXX", tmpdir());
  36
  37         /* now create the file */
  38         fd = smb_mkstemp(path);
  39
  40         if (fd == -1) {
  41                 DEBUG(0,("setup_out_fd: Failed to create file %s. (%s)\n",
  42                         path, strerror(errno) ));
  43                 return -1;
  44         }
  45
  46         DEBUG(10,("setup_out_fd: Created tmp file %s\n", path ));
  47
  48         /* Ensure file only kept around by open fd. */
  49         unlink(path);
  50         return fd;
  51 }
  52
  53 /****************************************************************************
  54 run a command being careful about uid/gid handling and putting the output in
  55 outfd (or discard it if outfd is NULL).
  56 ****************************************************************************/
  57
  58 static int smbrun_internal(const char *cmd, int *outfd, BOOL sanitize)
  59 {
  60         pid_t pid;
  61         uid_t uid = current_user.ut.uid;
  62         gid_t gid = current_user.ut.gid;
  63
  64         /*
  65          * Lose any elevated privileges.
  66          */
  67         drop_effective_capability(KERNEL_OPLOCK_CAPABILITY);
  68         drop_effective_capability(DMAPI_ACCESS_CAPABILITY);
  69
  70         /* point our stdout at the file we want output to go into */
  71
  72         if (outfd && ((*outfd = setup_out_fd()) == -1)) {
  73                 return -1;
  74         }
  75
  76         /* in this method we will exec /bin/sh with the correct
  77            arguments, after first setting stdout to point at the file */
  78
  79         /*
  80          * We need to temporarily stop CatchChild from eating
  81          * SIGCLD signals as it also eats the exit status code. JRA.
  82          */
  83
  84         CatchChildLeaveStatus();
  85
  86         if ((pid=sys_fork()) < 0) {
  87                 DEBUG(0,("smbrun: fork failed with error %s\n", strerror(errno) ));
  88                 CatchChild();
  89                 if (outfd) {
  90                         close(*outfd);
  91                         *outfd = -1;
  92                 }
  93                 return errno;
  94         }
  95
  96         if (pid) {
  97                 /*
  98                  * Parent.
  99                  */
 100                 int status=0;
 101                 pid_t wpid;
 102
 103
 104                 /* the parent just waits for the child to exit */
 105                 while((wpid = sys_waitpid(pid,&status,0)) < 0) {
 106                         if(errno == EINTR) {
 107                                 errno = 0;
 108                                 continue;
 109                         }
 110                         break;
 111                 }
 112
 113                 CatchChild();
 114
 115                 if (wpid != pid) {
 116                         DEBUG(2,("waitpid(%d) : %s\n",(int)pid,strerror(errno)));
 117                         if (outfd) {
 118                                 close(*outfd);
 119                                 *outfd = -1;
 120                         }
 121                         return -1;
 122                 }
 123
 124                 /* Reset the seek pointer. */
 125                 if (outfd) {
 126                         sys_lseek(*outfd, 0, SEEK_SET);
 127                 }
 128
 129 #if defined(WIFEXITED) && defined(WEXITSTATUS)
 130                 if (WIFEXITED(status)) {
 131                         return WEXITSTATUS(status);
 132                 }
 133 #endif
 134
 135                 return status;
 136         }
 137
 138         CatchChild();
 139
 140         /* we are in the child. we exec /bin/sh to do the work for us. we
 141            don't directly exec the command we want because it may be a
 142            pipeline or anything else the config file specifies */
 143
 144         /* point our stdout at the file we want output to go into */
 145         if (outfd) {
 146                 close(1);
 147                 if (sys_dup2(*outfd,1) != 1) {
 148                         DEBUG(2,("Failed to create stdout file descriptor\n"));
 149                         close(*outfd);
 150                         exit(80);
 151                 }
 152         }
 153
 154         /* now completely lose our privileges. This is a fairly paranoid
 155            way of doing it, but it does work on all systems that I know of */
 156
 157         become_user_permanently(uid, gid);
 158
 159         if (getuid() != uid || geteuid() != uid ||
 160             getgid() != gid || getegid() != gid) {
 161                 /* we failed to lose our privileges - do not execute
 162                    the command */
 163                 exit(81); /* we can't print stuff at this stage,
 164                              instead use exit codes for debugging */
 165         }
 166
 167 #ifndef __INSURE__
 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         {
 171         int fd;
 172         for (fd=3;fd<256;fd++) close(fd);
 173         }
 174 #endif
 175
 176         {
 177                 const char *newcmd = sanitize ? escape_shell_string(cmd) : cmd;
 178                 if (!newcmd) {
 179                         exit(82);
 180                 }
 181                 execl("/bin/sh","sh","-c",newcmd,NULL);
 182         }
 183
 184         /* not reached */
 185         exit(83);
 186         return 1;
 187 }
 188
 189 /****************************************************************************
 190  Use only in known safe shell calls (printing).
 191 ****************************************************************************/
 192
 193 int smbrun_no_sanitize(const char *cmd, int *outfd)
 194 {
 195         return smbrun_internal(cmd, outfd, False);
 196 }
 197
 198 /****************************************************************************
 199  By default this now sanitizes shell expansion.
 200 ****************************************************************************/
 201
 202 int smbrun(const char *cmd, int *outfd)
 203 {
 204         return smbrun_internal(cmd, outfd, True);
 205 }
 206
 207 /****************************************************************************
 208 run a command being careful about uid/gid handling and putting the output in
 209 outfd (or discard it if outfd is NULL).
 210 sends the provided secret to the child stdin.
 211 ****************************************************************************/
 212
 213 int smbrunsecret(const char *cmd, const char *secret)
 214 {
 215         pid_t pid;
 216         uid_t uid = current_user.ut.uid;
 217         gid_t gid = current_user.ut.gid;
 218         int ifd[2];
 219
 220         /*
 221          * Lose any elevated privileges.
 222          */
 223         drop_effective_capability(KERNEL_OPLOCK_CAPABILITY);
 224         drop_effective_capability(DMAPI_ACCESS_CAPABILITY);
 225
 226         /* build up an input pipe */
 227         if(pipe(ifd)) {
 228                 return -1;
 229         }
 230
 231         /* in this method we will exec /bin/sh with the correct
 232            arguments, after first setting stdout to point at the file */
 233
 234         /*
 235          * We need to temporarily stop CatchChild from eating
 236          * SIGCLD signals as it also eats the exit status code. JRA.
 237          */
 238
 239         CatchChildLeaveStatus();
 240
 241         if ((pid=sys_fork()) < 0) {
 242                 DEBUG(0, ("smbrunsecret: fork failed with error %s\n", strerror(errno)));
 243                 CatchChild();
 244                 return errno;
 245         }
 246
 247         if (pid) {
 248                 /*
 249                  * Parent.
 250                  */
 251                 int status = 0;
 252                 pid_t wpid;
 253                 size_t towrite;
 254                 ssize_t wrote;
 255
 256                 close(ifd[0]);
 257                 /* send the secret */
 258                 towrite = strlen(secret);
 259                 wrote = write(ifd[1], secret, towrite);
 260                 if ( wrote != towrite ) {
 261                     DEBUG(0,("smbrunsecret: wrote %ld of %lu bytes\n",(long)wrote,(unsigned long)towrite));
 262                 }
 263                 fsync(ifd[1]);
 264                 close(ifd[1]);
 265
 266                 /* the parent just waits for the child to exit */
 267                 while((wpid = sys_waitpid(pid, &status, 0)) < 0) {
 268                         if(errno == EINTR) {
 269                                 errno = 0;
 270                                 continue;
 271                         }
 272                         break;
 273                 }
 274
 275                 CatchChild();
 276
 277                 if (wpid != pid) {
 278                         DEBUG(2, ("waitpid(%d) : %s\n", (int)pid, strerror(errno)));
 279                         return -1;
 280                 }
 281
 282 #if defined(WIFEXITED) && defined(WEXITSTATUS)
 283                 if (WIFEXITED(status)) {
 284                         return WEXITSTATUS(status);
 285                 }
 286 #endif
 287
 288                 return status;
 289         }
 290
 291         CatchChild();
 292
 293         /* we are in the child. we exec /bin/sh to do the work for us. we
 294            don't directly exec the command we want because it may be a
 295            pipeline or anything else the config file specifies */
 296
 297         close(ifd[1]);
 298         close(0);
 299         if (sys_dup2(ifd[0], 0) != 0) {
 300                 DEBUG(2,("Failed to create stdin file descriptor\n"));
 301                 close(ifd[0]);
 302                 exit(80);
 303         }
 304
 305         /* now completely lose our privileges. This is a fairly paranoid
 306            way of doing it, but it does work on all systems that I know of */
 307
 308         become_user_permanently(uid, gid);
 309
 310         if (getuid() != uid || geteuid() != uid ||
 311             getgid() != gid || getegid() != gid) {
 312                 /* we failed to lose our privileges - do not execute
 313                    the command */
 314                 exit(81); /* we can't print stuff at this stage,
 315                              instead use exit codes for debugging */
 316         }
 317
 318 #ifndef __INSURE__
 319         /* close all other file descriptors, leaving only 0, 1 and 2. 0 and
 320            2 point to /dev/null from the startup code */
 321         {
 322                 int fd;
 323                 for (fd = 3; fd < 256; fd++) close(fd);
 324         }
 325 #endif
 326
 327         execl("/bin/sh", "sh", "-c", cmd, NULL);
 328
 329         /* not reached */
 330         exit(82);
 331         return 1;
 332 }