suexec.c

Apache HTTP Server 是一个功能强大的灵活的与HTTP/1.1相兼容的web服务器.这里给出的是Apache HTTP服务器的源码。

/* Copyright 1999-2005 The Apache Software Foundation or its licensors, as
 * applicable.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

/*
 * suexec.c -- "Wrapper" support program for suEXEC behaviour for Apache
 *
 ***********************************************************************
 *
 * NOTE! : DO NOT edit this code!!!  Unless you know what you are doing,
 *         editing this code might open up your system in unexpected 
 *         ways to would-be crackers.  Every precaution has been taken 
 *         to make this code as safe as possible; alter it at your own
 *         risk.
 *
 ***********************************************************************
 *
 *
 */

#include "apr.h"
#include "ap_config.h"
#include "suexec.h"

#include <sys/param.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <string.h>
#include <time.h>
#if APR_HAVE_UNISTD_H
#include <unistd.h>
#endif

#include <stdio.h>
#include <stdarg.h>
#include <stdlib.h>

#ifdef HAVE_PWD_H
#include <pwd.h>
#endif

#ifdef HAVE_GRP_H
#include <grp.h>
#endif

/*
 ***********************************************************************
 * There is no initgroups() in QNX, so I believe this is safe :-)
 * Use cc -osuexec -3 -O -mf -DQNX suexec.c to compile.
 *
 * May 17, 1997.
 * Igor N. Kovalenko -- [e-mail]
 ***********************************************************************
 */

#if defined(NEED_INITGROUPS)
int initgroups(const char *name, gid_t basegid)
{
    /* QNX and MPE do not appear to support supplementary groups. */
    return 0;
}
#endif

#if defined(SUNOS4)
extern char *sys_errlist[];
#define strerror(x) sys_errlist[(x)]
#endif

#if defined(PATH_MAX)
#define AP_MAXPATH PATH_MAX
#elif defined(MAXPATHLEN)
#define AP_MAXPATH MAXPATHLEN
#else
#define AP_MAXPATH 8192
#endif

#define AP_ENVBUF 256

extern char **environ;
static FILE *log = NULL;

char *safe_env_lst[] =
{
    /* variable name starts with */
    "HTTP_",
    "SSL_",

    /* variable name is */
    "AUTH_TYPE=",
    "CONTENT_LENGTH=",
    "CONTENT_TYPE=",
    "DATE_GMT=",
    "DATE_LOCAL=",
    "DOCUMENT_NAME=",
    "DOCUMENT_PATH_INFO=",
    "DOCUMENT_ROOT=",
    "DOCUMENT_URI=",
    "FILEPATH_INFO=",
    "GATEWAY_INTERFACE=",
    "HTTPS=",
    "LAST_MODIFIED=",
    "PATH_INFO=",
    "PATH_TRANSLATED=",
    "QUERY_STRING=",
    "QUERY_STRING_UNESCAPED=",
    "REMOTE_ADDR=",
    "REMOTE_HOST=",
    "REMOTE_IDENT=",
    "REMOTE_PORT=",
    "REMOTE_USER=",
    "REDIRECT_QUERY_STRING=",
    "REDIRECT_REMOTE_USER=",
    "REDIRECT_STATUS=",
    "REDIRECT_URL=",
    "REQUEST_METHOD=",
    "REQUEST_URI=",
    "SCRIPT_FILENAME=",
    "SCRIPT_NAME=",
    "SCRIPT_URI=",
    "SCRIPT_URL=",
    "SERVER_ADMIN=",
    "SERVER_NAME=",
    "SERVER_ADDR=",
    "SERVER_PORT=",
    "SERVER_PROTOCOL=",
    "SERVER_SIGNATURE=",
    "SERVER_SOFTWARE=",
    "UNIQUE_ID=",
    "USER_NAME=",
    "TZ=",
    NULL
};


static void err_output(const char *fmt, va_list ap)
{
#ifdef AP_LOG_EXEC
    time_t timevar;
    struct tm *lt;

    if (!log) {
        if ((log = fopen(AP_LOG_EXEC, "a")) == NULL) {
            fprintf(stderr, "failed to open log file\n");
            perror("fopen");
            exit(1);
        }
    }

    time(&timevar);
    lt = localtime(&timevar);

    fprintf(log, "[%d-%.2d-%.2d %.2d:%.2d:%.2d]: ",
            lt->tm_year + 1900, lt->tm_mon + 1, lt->tm_mday,
            lt->tm_hour, lt->tm_min, lt->tm_sec);

    vfprintf(log, fmt, ap);

    fflush(log);
#endif /* AP_LOG_EXEC */
    return;
}

static void log_err(const char *fmt,...)
{
#ifdef AP_LOG_EXEC
    va_list ap;

    va_start(ap, fmt);
    err_output(fmt, ap);
    va_end(ap);
#endif /* AP_LOG_EXEC */
    return;
}

static void clean_env(void)
{
    char pathbuf[512];
    char **cleanenv;
    char **ep;
    int cidx = 0;
    int idx;

    /* While cleaning the environment, the environment should be clean.
     * (e.g. malloc() may get the name of a file for writing debugging info.
     * Bad news if MALLOC_DEBUG_FILE is set to /etc/passwd.  Sprintf() may be
     * susceptible to bad locale settings....)
     * (from PR 2790)
     */
    char **envp = environ;
    char *empty_ptr = NULL;
 
    environ = &empty_ptr; /* VERY safe environment */

    if ((cleanenv = (char **) calloc(AP_ENVBUF, sizeof(char *))) == NULL) {
        log_err("failed to malloc memory for environment\n");
        exit(120);
    }

    sprintf(pathbuf, "PATH=%s", AP_SAFE_PATH);
    cleanenv[cidx] = strdup(pathbuf);
    cidx++;

    for (ep = envp; *ep && cidx < AP_ENVBUF-1; ep++) {
        for (idx = 0; safe_env_lst[idx]; idx++) {
            if (!strncmp(*ep, safe_env_lst[idx],
                         strlen(safe_env_lst[idx]))) {
                cleanenv[cidx] = *ep;
                cidx++;
                break;
            }
        }
    }

    cleanenv[cidx] = NULL;

    environ = cleanenv;
}

int main(int argc, char *argv[])
{
    int userdir = 0;        /* ~userdir flag             */
    uid_t uid;              /* user information          */
    gid_t gid;              /* target group placeholder  */
    char *target_uname;     /* target user name          */
    char *target_gname;     /* target group name         */
    char *target_homedir;   /* target home directory     */
    char *actual_uname;     /* actual user name          */
    char *actual_gname;     /* actual group name         */
    char *prog;             /* name of this program      */
    char *cmd;              /* command to be executed    */
    char cwd[AP_MAXPATH];   /* current working directory */
    char dwd[AP_MAXPATH];   /* docroot working directory */
    struct passwd *pw;      /* password entry holder     */
    struct group *gr;       /* group entry holder        */
    struct stat dir_info;   /* directory info holder     */
    struct stat prg_info;   /* program info holder       */

    /*
     * Start with a "clean" environment
     */
    clean_env();

    prog = argv[0];
    /*
     * Check existence/validity of the UID of the user
     * running this program.  Error out if invalid.
     */
    uid = getuid();
    if ((pw = getpwuid(uid)) == NULL) {
        log_err("crit: invalid uid: (%ld)\n", uid);
        exit(102);
    }
    /*
     * See if this is a 'how were you compiled' request, and
     * comply if so.
     */
    if ((argc > 1)
        && (! strcmp(argv[1], "-V"))
        && ((uid == 0)
#ifdef _OSD_POSIX
        /* User name comparisons are case insensitive on BS2000/OSD */
            || (! strcasecmp(AP_HTTPD_USER, pw->pw_name)))
#else  /* _OSD_POSIX */
            || (! strcmp(AP_HTTPD_USER, pw->pw_name)))
#endif /* _OSD_POSIX */
        ) {
#ifdef AP_DOC_ROOT
        fprintf(stderr, " -D AP_DOC_ROOT=\"%s\"\n", AP_DOC_ROOT);
#endif
#ifdef AP_GID_MIN
        fprintf(stderr, " -D AP_GID_MIN=%d\n", AP_GID_MIN);
#endif
#ifdef AP_HTTPD_USER
        fprintf(stderr, " -D AP_HTTPD_USER=\"%s\"\n", AP_HTTPD_USER);
#endif
#ifdef AP_LOG_EXEC
        fprintf(stderr, " -D AP_LOG_EXEC=\"%s\"\n", AP_LOG_EXEC);
#endif
#ifdef AP_SAFE_PATH
        fprintf(stderr, " -D AP_SAFE_PATH=\"%s\"\n", AP_SAFE_PATH);
#endif
#ifdef AP_SUEXEC_UMASK
        fprintf(stderr, " -D AP_SUEXEC_UMASK=%03o\n", AP_SUEXEC_UMASK);
#endif
#ifdef AP_UID_MIN
        fprintf(stderr, " -D AP_UID_MIN=%d\n", AP_UID_MIN);
#endif
#ifdef AP_USERDIR_SUFFIX
        fprintf(stderr, " -D AP_USERDIR_SUFFIX=\"%s\"\n", AP_USERDIR_SUFFIX);
#endif
        exit(0);
    }
    /*
     * If there are a proper number of arguments, set
     * all of them to variables.  Otherwise, error out.
     */
    if (argc < 4) {
        log_err("too few arguments\n");