1/* Licensed to the Apache Software Foundation (ASF) under one or more
2 * contributor license agreements.  See the NOTICE file distributed with
3 * this work for additional information regarding copyright ownership.
4 * The ASF licenses this file to You under the Apache License, Version 2.0
5 * (the "License"); you may not use this file except in compliance with
6 * the License.  You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17/*
18 * suexec.c -- "Wrapper" support program for suEXEC behaviour for Apache
19 *
20 ***********************************************************************
21 *
22 * NOTE! : DO NOT edit this code!!!  Unless you know what you are doing,
23 *         editing this code might open up your system in unexpected
24 *         ways to would-be crackers.  Every precaution has been taken
25 *         to make this code as safe as possible; alter it at your own
26 *         risk.
27 *
28 ***********************************************************************
29 *
30 *
31 */
32
33#include "apr.h"
34#include "ap_config.h"
35#include "suexec.h"
36
37#include <sys/param.h>
38#include <sys/stat.h>
39#include <sys/types.h>
40#include <string.h>
41#include <time.h>
42#if APR_HAVE_UNISTD_H
43#include <unistd.h>
44#endif
45
46#include <stdio.h>
47#include <stdarg.h>
48#include <stdlib.h>
49
50#ifdef HAVE_PWD_H
51#include <pwd.h>
52#endif
53
54#ifdef HAVE_GRP_H
55#include <grp.h>
56#endif
57
58/*
59 ***********************************************************************
60 * There is no initgroups() in QNX, so I believe this is safe :-)
61 * Use cc -osuexec -3 -O -mf -DQNX suexec.c to compile.
62 *
63 * May 17, 1997.
64 * Igor N. Kovalenko -- infoh mail.wplus.net
65 ***********************************************************************
66 */
67
68#if defined(NEED_INITGROUPS)
69int initgroups(const char *name, gid_t basegid)
70{
71    /* QNX and MPE do not appear to support supplementary groups. */
72    return 0;
73}
74#endif
75
76#if defined(SUNOS4)
77extern char *sys_errlist[];
78#define strerror(x) sys_errlist[(x)]
79#endif
80
81#if defined(PATH_MAX)
82#define AP_MAXPATH PATH_MAX
83#elif defined(MAXPATHLEN)
84#define AP_MAXPATH MAXPATHLEN
85#else
86#define AP_MAXPATH 8192
87#endif
88
89#define AP_ENVBUF 256
90
91extern char **environ;
92static FILE *log = NULL;
93
94static const char *const safe_env_lst[] =
95{
96    /* variable name starts with */
97    "HTTP_",
98    "SSL_",
99
100    /* variable name is */
101    "AUTH_TYPE=",
102    "CONTENT_LENGTH=",
103    "CONTENT_TYPE=",
104    "DATE_GMT=",
105    "DATE_LOCAL=",
106    "DOCUMENT_NAME=",
107    "DOCUMENT_PATH_INFO=",
108    "DOCUMENT_ROOT=",
109    "DOCUMENT_URI=",
110    "GATEWAY_INTERFACE=",
111    "HTTPS=",
112    "LAST_MODIFIED=",
113    "PATH_INFO=",
114    "PATH_TRANSLATED=",
115    "QUERY_STRING=",
116    "QUERY_STRING_UNESCAPED=",
117    "REMOTE_ADDR=",
118    "REMOTE_HOST=",
119    "REMOTE_IDENT=",
120    "REMOTE_PORT=",
121    "REMOTE_USER=",
122    "REDIRECT_HANDLER=",
123    "REDIRECT_QUERY_STRING=",
124    "REDIRECT_REMOTE_USER=",
125    "REDIRECT_STATUS=",
126    "REDIRECT_URL=",
127    "REQUEST_METHOD=",
128    "REQUEST_URI=",
129    "SCRIPT_FILENAME=",
130    "SCRIPT_NAME=",
131    "SCRIPT_URI=",
132    "SCRIPT_URL=",
133    "SERVER_ADMIN=",
134    "SERVER_NAME=",
135    "SERVER_ADDR=",
136    "SERVER_PORT=",
137    "SERVER_PROTOCOL=",
138    "SERVER_SIGNATURE=",
139    "SERVER_SOFTWARE=",
140    "UNIQUE_ID=",
141    "USER_NAME=",
142    "TZ=",
143    NULL
144};
145
146
147static void err_output(int is_error, const char *fmt, va_list ap)
148{
149#ifdef AP_LOG_EXEC
150    time_t timevar;
151    struct tm *lt;
152
153    if (!log) {
154        if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
155            fprintf(stderr, "suexec failure: could not open log file\n");
156            perror("fopen");
157            exit(1);
158        }
159    }
160
161    if (is_error) {
162        fprintf(stderr, "suexec policy violation: see suexec log for more "
163                        "details\n");
164    }
165
166    time(&timevar);
167    lt = localtime(&timevar);
168
169    fprintf(log, "[%d-%.2d-%.2d %.2d:%.2d:%.2d]: ",
170            lt->tm_year + 1900, lt->tm_mon + 1, lt->tm_mday,
171            lt->tm_hour, lt->tm_min, lt->tm_sec);
172
173    vfprintf(log, fmt, ap);
174
175    fflush(log);
176#endif /* AP_LOG_EXEC */
177    return;
178}
179
180static void log_err(const char *fmt,...)
181{
182#ifdef AP_LOG_EXEC
183    va_list ap;
184
185    va_start(ap, fmt);
186    err_output(1, fmt, ap); /* 1 == is_error */
187    va_end(ap);
188#endif /* AP_LOG_EXEC */
189    return;
190}
191
192static void log_no_err(const char *fmt,...)
193{
194#ifdef AP_LOG_EXEC
195    va_list ap;
196
197    va_start(ap, fmt);
198    err_output(0, fmt, ap); /* 0 == !is_error */
199    va_end(ap);
200#endif /* AP_LOG_EXEC */
201    return;
202}
203
204static void clean_env(void)
205{
206    char pathbuf[512];
207    char **cleanenv;
208    char **ep;
209    int cidx = 0;
210    int idx;
211
212    /* While cleaning the environment, the environment should be clean.
213     * (e.g. malloc() may get the name of a file for writing debugging info.
214     * Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd.  Sprintf() may be
215     * susceptible to bad locale settings....)
216     * (from PR 2790)
217     */
218    char **envp = environ;
219    char *empty_ptr = NULL;
220
221    environ = &empty_ptr; /* VERY safe environment */
222
223    if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
224        log_err("failed to malloc memory for environment\n");
225        exit(120);
226    }
227
228    sprintf(pathbuf, "PATH=%s", AP_SAFE_PATH);
229    cleanenv[cidx] = strdup(pathbuf);
230    cidx++;
231
232    for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) {
233        for (idx = 0; safe_env_lst[idx]; idx++) {
234            if (!strncmp(*ep, safe_env_lst[idx],
235                         strlen(safe_env_lst[idx]))) {
236                cleanenv[cidx] = *ep;
237                cidx++;
238                break;
239            }
240        }
241    }
242
243    cleanenv[cidx] = NULL;
244
245    environ = cleanenv;
246}
247
248int main(int argc, char *argv[])
249{
250    int userdir = 0;        /* ~userdir flag             */
251    uid_t uid;              /* user information          */
252    gid_t gid;              /* target group placeholder  */
253    char *target_uname;     /* target user name          */
254    char *target_gname;     /* target group name         */
255    char *target_homedir;   /* target home directory     */
256    char *actual_uname;     /* actual user name          */
257    char *actual_gname;     /* actual group name         */
258    char *prog;             /* name of this program      */
259    char *cmd;              /* command to be executed    */
260    char cwd[AP_MAXPATH];   /* current working directory */
261    char dwd[AP_MAXPATH];   /* docroot working directory */
262    struct passwd *pw;      /* password entry holder     */
263    struct group *gr;       /* group entry holder        */
264    struct stat dir_info;   /* directory info holder     */
265    struct stat prg_info;   /* program info holder       */
266
267    /*
268     * Start with a "clean" environment
269     */
270    clean_env();
271
272    prog = argv[0];
273    /*
274     * Check existence/validity of the UID of the user
275     * running this program.  Error out if invalid.
276     */
277    uid = getuid();
278    if ((pw = getpwuid(uid)) == NULL) {
279        log_err("crit: invalid uid: (%ld)\n", uid);
280        exit(102);
281    }
282    /*
283     * See if this is a 'how were you compiled' request, and
284     * comply if so.
285     */
286    if ((argc > 1)
287        && (! strcmp(argv[1], "-V"))
288        && ((uid == 0)
289#ifdef _OSD_POSIX
290        /* User name comparisons are case insensitive on BS2000/OSD */
291            || (! strcasecmp(AP_HTTPD_USER, pw->pw_name)))
292#else  /* _OSD_POSIX */
293            || (! strcmp(AP_HTTPD_USER, pw->pw_name)))
294#endif /* _OSD_POSIX */
295        ) {
296#ifdef AP_DOC_ROOT
297        fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
298#endif
299#ifdef AP_GID_MIN
300        fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
301#endif
302#ifdef AP_HTTPD_USER
303        fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
304#endif
305#ifdef AP_LOG_EXEC
306        fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
307#endif
308#ifdef AP_SAFE_PATH
309        fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
310#endif
311#ifdef AP_SUEXEC_UMASK
312        fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
313#endif
314#ifdef AP_UID_MIN
315        fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
316#endif
317#ifdef AP_USERDIR_SUFFIX
318        fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX);
319#endif
320        exit(0);
321    }
322    /*
323     * If there are a proper number of arguments, set
324     * all of them to variables.  Otherwise, error out.
325     */
326    if (argc < 4) {
327        log_err("too few arguments\n");
328        exit(101);
329    }
330    target_uname = argv[1];
331    target_gname = argv[2];
332    cmd = argv[3];
333
334    /*
335     * Check to see if the user running this program
336     * is the user allowed to do so as defined in
337     * suexec.h.  If not the allowed user, error out.
338     */
339#ifdef _OSD_POSIX
340    /* User name comparisons are case insensitive on BS2000/OSD */
341    if (strcasecmp(AP_HTTPD_USER, pw->pw_name)) {
342        log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
343        exit(103);
344    }
345#else  /*_OSD_POSIX*/
346    if (strcmp(AP_HTTPD_USER, pw->pw_name)) {
347        log_err("user mismatch (%s instead of %s)\n", pw->pw_name, AP_HTTPD_USER);
348        exit(103);
349    }
350#endif /*_OSD_POSIX*/
351
352    /*
353     * Check for a leading '/' (absolute path) in the command to be executed,
354     * or attempts to back up out of the current directory,
355     * to protect against attacks.  If any are
356     * found, error out.  Naughty naughty crackers.
357     */
358    if ((cmd[0] == '/') || (!strncmp(cmd, "../", 3))
359        || (strstr(cmd, "/../") != NULL)) {
360        log_err("invalid command (%s)\n", cmd);
361        exit(104);
362    }
363
364    /*
365     * Check to see if this is a ~userdir request.  If
366     * so, set the flag, and remove the '~' from the
367     * target username.
368     */
369    if (!strncmp("~", target_uname, 1)) {
370        target_uname++;
371        userdir = 1;
372    }
373
374    /*
375     * Error out if the target username is invalid.
376     */
377    if (strspn(target_uname, "1234567890") != strlen(target_uname)) {
378        if ((pw = getpwnam(target_uname)) == NULL) {
379            log_err("invalid target user name: (%s)\n", target_uname);
380            exit(105);
381        }
382    }
383    else {
384        if ((pw = getpwuid(atoi(target_uname))) == NULL) {
385            log_err("invalid target user id: (%s)\n", target_uname);
386            exit(121);
387        }
388    }
389
390    /*
391     * Error out if the target group name is invalid.
392     */
393    if (strspn(target_gname, "1234567890") != strlen(target_gname)) {
394        if ((gr = getgrnam(target_gname)) == NULL) {
395            log_err("invalid target group name: (%s)\n", target_gname);
396            exit(106);
397        }
398    }
399    else {
400        if ((gr = getgrgid(atoi(target_gname))) == NULL) {
401            log_err("invalid target group id: (%s)\n", target_gname);
402            exit(106);
403        }
404    }
405    gid = gr->gr_gid;
406    actual_gname = strdup(gr->gr_name);
407
408#ifdef _OSD_POSIX
409    /*
410     * Initialize BS2000 user environment
411     */
412    {
413        pid_t pid;
414        int status;
415
416        switch (pid = ufork(target_uname)) {
417        case -1:    /* Error */
418            log_err("failed to setup bs2000 environment for user %s: %s\n",
419                    target_uname, strerror(errno));
420            exit(150);
421        case 0:     /* Child */
422            break;
423        default:    /* Father */
424            while (pid != waitpid(pid, &status, 0))
425                ;
426            /* @@@ FIXME: should we deal with STOP signals as well? */
427            if (WIFSIGNALED(status)) {
428                kill (getpid(), WTERMSIG(status));
429            }
430            exit(WEXITSTATUS(status));
431        }
432    }
433#endif /*_OSD_POSIX*/
434
435    /*
436     * Save these for later since initgroups will hose the struct
437     */
438    uid = pw->pw_uid;
439    actual_uname = strdup(pw->pw_name);
440    target_homedir = strdup(pw->pw_dir);
441
442    /*
443     * Log the transaction here to be sure we have an open log
444     * before we setuid().
445     */
446    log_no_err("uid: (%s/%s) gid: (%s/%s) cmd: %s\n",
447               target_uname, actual_uname,
448               target_gname, actual_gname,
449               cmd);
450
451    /*
452     * Error out if attempt is made to execute as root or as
453     * a UID less than AP_UID_MIN.  Tsk tsk.
454     */
455    if ((uid == 0) || (uid < AP_UID_MIN)) {
456        log_err("cannot run as forbidden uid (%d/%s)\n", uid, cmd);
457        exit(107);
458    }
459
460    /*
461     * Error out if attempt is made to execute as root group
462     * or as a GID less than AP_GID_MIN.  Tsk tsk.
463     */
464    if ((gid == 0) || (gid < AP_GID_MIN)) {
465        log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd);
466        exit(108);
467    }
468
469    /*
470     * Change UID/GID here so that the following tests work over NFS.
471     *
472     * Initialize the group access list for the target user,
473     * and setgid() to the target group. If unsuccessful, error out.
474     */
475    if (((setgid(gid)) != 0) || (initgroups(actual_uname, gid) != 0)) {
476        log_err("failed to setgid (%ld: %s)\n", gid, cmd);
477        exit(109);
478    }
479
480    /*
481     * setuid() to the target user.  Error out on fail.
482     */
483    if ((setuid(uid)) != 0) {
484        log_err("failed to setuid (%ld: %s)\n", uid, cmd);
485        exit(110);
486    }
487
488    /*
489     * Get the current working directory, as well as the proper
490     * document root (dependant upon whether or not it is a
491     * ~userdir request).  Error out if we cannot get either one,
492     * or if the current working directory is not in the docroot.
493     * Use chdir()s and getcwd()s to avoid problems with symlinked
494     * directories.  Yuck.
495     */
496    if (getcwd(cwd, AP_MAXPATH) == NULL) {
497        log_err("cannot get current working directory\n");
498        exit(111);
499    }
500
501    if (userdir) {
502        if (((chdir(target_homedir)) != 0) ||
503            ((chdir(AP_USERDIR_SUFFIX)) != 0) ||
504            ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
505            ((chdir(cwd)) != 0)) {
506            log_err("cannot get docroot information (%s)\n", target_homedir);
507            exit(112);
508        }
509    }
510    else {
511        if (((chdir(AP_DOC_ROOT)) != 0) ||
512            ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
513            ((chdir(cwd)) != 0)) {
514            log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT);
515            exit(113);
516        }
517    }
518
519    if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
520        log_err("command not in docroot (%s/%s)\n", cwd, cmd);
521        exit(114);
522    }
523
524    /*
525     * Stat the cwd and verify it is a directory, or error out.
526     */
527    if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) {
528        log_err("cannot stat directory: (%s)\n", cwd);
529        exit(115);
530    }
531
532    /*
533     * Error out if cwd is writable by others.
534     */
535    if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) {
536        log_err("directory is writable by others: (%s)\n", cwd);
537        exit(116);
538    }
539
540    /*
541     * Error out if we cannot stat the program.
542     */
543    if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) {
544        log_err("cannot stat program: (%s)\n", cmd);
545        exit(117);
546    }
547
548    /*
549     * Error out if the program is writable by others.
550     */
551    if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) {
552        log_err("file is writable by others: (%s/%s)\n", cwd, cmd);
553        exit(118);
554    }
555
556    /*
557     * Error out if the file is setuid or setgid.
558     */
559    if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) {
560        log_err("file is either setuid or setgid: (%s/%s)\n", cwd, cmd);
561        exit(119);
562    }
563
564    /*
565     * Error out if the target name/group is different from
566     * the name/group of the cwd or the program.
567     */
568    if ((uid != dir_info.st_uid) ||
569        (gid != dir_info.st_gid) ||
570        (uid != prg_info.st_uid) ||
571        (gid != prg_info.st_gid)) {
572        log_err("target uid/gid (%ld/%ld) mismatch "
573                "with directory (%ld/%ld) or program (%ld/%ld)\n",
574                uid, gid,
575                dir_info.st_uid, dir_info.st_gid,
576                prg_info.st_uid, prg_info.st_gid);
577        exit(120);
578    }
579    /*
580     * Error out if the program is not executable for the user.
581     * Otherwise, she won't find any error in the logs except for
582     * "[error] Premature end of script headers: ..."
583     */
584    if (!(prg_info.st_mode & S_IXUSR)) {
585        log_err("file has no execute permission: (%s/%s)\n", cwd, cmd);
586        exit(121);
587    }
588
589#ifdef AP_SUEXEC_UMASK
590    /*
591     * umask() uses inverse logic; bits are CLEAR for allowed access.
592     */
593    if ((~AP_SUEXEC_UMASK) & 0022) {
594        log_err("notice: AP_SUEXEC_UMASK of %03o allows "
595                "write permission to group and/or other\n", AP_SUEXEC_UMASK);
596    }
597    umask(AP_SUEXEC_UMASK);
598#endif /* AP_SUEXEC_UMASK */
599
600    /*
601     * Be sure to close the log file so the CGI can't
602     * mess with it.  If the exec fails, it will be reopened
603     * automatically when log_err is called.  Note that the log
604     * might not actually be open if AP_LOG_EXEC isn't defined.
605     * However, the "log" cell isn't ifdef'd so let's be defensive
606     * and assume someone might have done something with it
607     * outside an ifdef'd AP_LOG_EXEC block.
608     */
609    if (log != NULL) {
610        fclose(log);
611        log = NULL;
612    }
613
614    /*
615     * Execute the command, replacing our image with its own.
616     */
617#ifdef NEED_HASHBANG_EMUL
618    /* We need the #! emulation when we want to execute scripts */
619    {
620        extern char **environ;
621
622        ap_execve(cmd, &argv[3], environ);
623    }
624#else /*NEED_HASHBANG_EMUL*/
625    execv(cmd, &argv[3]);
626#endif /*NEED_HASHBANG_EMUL*/
627
628    /*
629     * (I can't help myself...sorry.)
630     *
631     * Uh oh.  Still here.  Where's the kaboom?  There was supposed to be an
632     * EARTH-shattering kaboom!
633     *
634     * Oh well, log the failure and error out.
635     */
636    log_err("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);
637    exit(255);
638}
639