source: trunk/server/fedora/ref-prepatch/suexec.c @ 1225

Last change on this file since 1225 was 296, checked in by andersk, 16 years ago
Replace ref-prepatch/suexec.c with the actually unpatched version.
File size: 17.6 KB
Line 
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        gid = gr->gr_gid;
399        actual_gname = strdup(gr->gr_name);
400    }
401    else {
402        gid = atoi(target_gname);
403        actual_gname = strdup(target_gname);
404    }
405
406#ifdef _OSD_POSIX
407    /*
408     * Initialize BS2000 user environment
409     */
410    {
411        pid_t pid;
412        int status;
413
414        switch (pid = ufork(target_uname)) {
415        case -1:    /* Error */
416            log_err("failed to setup bs2000 environment for user %s: %s\n",
417                    target_uname, strerror(errno));
418            exit(150);
419        case 0:     /* Child */
420            break;
421        default:    /* Father */
422            while (pid != waitpid(pid, &status, 0))
423                ;
424            /* @@@ FIXME: should we deal with STOP signals as well? */
425            if (WIFSIGNALED(status)) {
426                kill (getpid(), WTERMSIG(status));
427            }
428            exit(WEXITSTATUS(status));
429        }
430    }
431#endif /*_OSD_POSIX*/
432
433    /*
434     * Save these for later since initgroups will hose the struct
435     */
436    uid = pw->pw_uid;
437    actual_uname = strdup(pw->pw_name);
438    target_homedir = strdup(pw->pw_dir);
439
440    /*
441     * Log the transaction here to be sure we have an open log
442     * before we setuid().
443     */
444    log_no_err("uid: (%s/%s) gid: (%s/%s) cmd: %s\n",
445               target_uname, actual_uname,
446               target_gname, actual_gname,
447               cmd);
448
449    /*
450     * Error out if attempt is made to execute as root or as
451     * a UID less than AP_UID_MIN.  Tsk tsk.
452     */
453    if ((uid == 0) || (uid < AP_UID_MIN)) {
454        log_err("cannot run as forbidden uid (%d/%s)\n", uid, cmd);
455        exit(107);
456    }
457
458    /*
459     * Error out if attempt is made to execute as root group
460     * or as a GID less than AP_GID_MIN.  Tsk tsk.
461     */
462    if ((gid == 0) || (gid < AP_GID_MIN)) {
463        log_err("cannot run as forbidden gid (%d/%s)\n", gid, cmd);
464        exit(108);
465    }
466
467    /*
468     * Change UID/GID here so that the following tests work over NFS.
469     *
470     * Initialize the group access list for the target user,
471     * and setgid() to the target group. If unsuccessful, error out.
472     */
473    if (((setgid(gid)) != 0) || (initgroups(actual_uname, gid) != 0)) {
474        log_err("failed to setgid (%ld: %s)\n", gid, cmd);
475        exit(109);
476    }
477
478    /*
479     * setuid() to the target user.  Error out on fail.
480     */
481    if ((setuid(uid)) != 0) {
482        log_err("failed to setuid (%ld: %s)\n", uid, cmd);
483        exit(110);
484    }
485
486    /*
487     * Get the current working directory, as well as the proper
488     * document root (dependant upon whether or not it is a
489     * ~userdir request).  Error out if we cannot get either one,
490     * or if the current working directory is not in the docroot.
491     * Use chdir()s and getcwd()s to avoid problems with symlinked
492     * directories.  Yuck.
493     */
494    if (getcwd(cwd, AP_MAXPATH) == NULL) {
495        log_err("cannot get current working directory\n");
496        exit(111);
497    }
498
499    if (userdir) {
500        if (((chdir(target_homedir)) != 0) ||
501            ((chdir(AP_USERDIR_SUFFIX)) != 0) ||
502            ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
503            ((chdir(cwd)) != 0)) {
504            log_err("cannot get docroot information (%s)\n", target_homedir);
505            exit(112);
506        }
507    }
508    else {
509        if (((chdir(AP_DOC_ROOT)) != 0) ||
510            ((getcwd(dwd, AP_MAXPATH)) == NULL) ||
511            ((chdir(cwd)) != 0)) {
512            log_err("cannot get docroot information (%s)\n", AP_DOC_ROOT);
513            exit(113);
514        }
515    }
516
517    if ((strncmp(cwd, dwd, strlen(dwd))) != 0) {
518        log_err("command not in docroot (%s/%s)\n", cwd, cmd);
519        exit(114);
520    }
521
522    /*
523     * Stat the cwd and verify it is a directory, or error out.
524     */
525    if (((lstat(cwd, &dir_info)) != 0) || !(S_ISDIR(dir_info.st_mode))) {
526        log_err("cannot stat directory: (%s)\n", cwd);
527        exit(115);
528    }
529
530    /*
531     * Error out if cwd is writable by others.
532     */
533    if ((dir_info.st_mode & S_IWOTH) || (dir_info.st_mode & S_IWGRP)) {
534        log_err("directory is writable by others: (%s)\n", cwd);
535        exit(116);
536    }
537
538    /*
539     * Error out if we cannot stat the program.
540     */
541    if (((lstat(cmd, &prg_info)) != 0) || (S_ISLNK(prg_info.st_mode))) {
542        log_err("cannot stat program: (%s)\n", cmd);
543        exit(117);
544    }
545
546    /*
547     * Error out if the program is writable by others.
548     */
549    if ((prg_info.st_mode & S_IWOTH) || (prg_info.st_mode & S_IWGRP)) {
550        log_err("file is writable by others: (%s/%s)\n", cwd, cmd);
551        exit(118);
552    }
553
554    /*
555     * Error out if the file is setuid or setgid.
556     */
557    if ((prg_info.st_mode & S_ISUID) || (prg_info.st_mode & S_ISGID)) {
558        log_err("file is either setuid or setgid: (%s/%s)\n", cwd, cmd);
559        exit(119);
560    }
561
562    /*
563     * Error out if the target name/group is different from
564     * the name/group of the cwd or the program.
565     */
566    if ((uid != dir_info.st_uid) ||
567        (gid != dir_info.st_gid) ||
568        (uid != prg_info.st_uid) ||
569        (gid != prg_info.st_gid)) {
570        log_err("target uid/gid (%ld/%ld) mismatch "
571                "with directory (%ld/%ld) or program (%ld/%ld)\n",
572                uid, gid,
573                dir_info.st_uid, dir_info.st_gid,
574                prg_info.st_uid, prg_info.st_gid);
575        exit(120);
576    }
577    /*
578     * Error out if the program is not executable for the user.
579     * Otherwise, she won't find any error in the logs except for
580     * "[error] Premature end of script headers: ..."
581     */
582    if (!(prg_info.st_mode & S_IXUSR)) {
583        log_err("file has no execute permission: (%s/%s)\n", cwd, cmd);
584        exit(121);
585    }
586
587#ifdef AP_SUEXEC_UMASK
588    /*
589     * umask() uses inverse logic; bits are CLEAR for allowed access.
590     */
591    if ((~AP_SUEXEC_UMASK) & 0022) {
592        log_err("notice: AP_SUEXEC_UMASK of %03o allows "
593                "write permission to group and/or other\n", AP_SUEXEC_UMASK);
594    }
595    umask(AP_SUEXEC_UMASK);
596#endif /* AP_SUEXEC_UMASK */
597
598    /*
599     * Be sure to close the log file so the CGI can't
600     * mess with it.  If the exec fails, it will be reopened
601     * automatically when log_err is called.  Note that the log
602     * might not actually be open if AP_LOG_EXEC isn't defined.
603     * However, the "log" cell isn't ifdef'd so let's be defensive
604     * and assume someone might have done something with it
605     * outside an ifdef'd AP_LOG_EXEC block.
606     */
607    if (log != NULL) {
608        fclose(log);
609        log = NULL;
610    }
611
612    /*
613     * Execute the command, replacing our image with its own.
614     */
615#ifdef NEED_HASHBANG_EMUL
616    /* We need the #! emulation when we want to execute scripts */
617    {
618        extern char **environ;
619
620        ap_execve(cmd, &argv[3], environ);
621    }
622#else /*NEED_HASHBANG_EMUL*/
623    execv(cmd, &argv[3]);
624#endif /*NEED_HASHBANG_EMUL*/
625
626    /*
627     * (I can't help myself...sorry.)
628     *
629     * Uh oh.  Still here.  Where's the kaboom?  There was supposed to be an
630     * EARTH-shattering kaboom!
631     *
632     * Oh well, log the failure and error out.
633     */
634    log_err("(%d)%s: exec failed (%s)\n", errno, strerror(errno), cmd);
635    exit(255);
636}
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