session.c

/*
  +----------------------------------------------------------------------+
  | Suhosin Version 1                            |
  +----------------------------------------------------------------------+
  | Copyright (c) 2006-2007 The Hardened-PHP Project             |
  | Copyright (c) 2007-2010 SektionEins GmbH                 |
  +----------------------------------------------------------------------+
  | This source file is subject to version 3.01 of the PHP license,  |
  | that is bundled with this package in the file LICENSE, and is    |
  | available through the world-wide-web at the following url:       |
  | http://www.php.net/license/3_01.txt                  |
  | If you did not receive a copy of the PHP license and are unable to   |
  | obtain it through the world-wide-web, please send a note to      |
  | license@php.net so we can mail you a copy immediately.       |
  +----------------------------------------------------------------------+
  | Author: Stefan Esser <sesser@sektioneins.de>             |
  +----------------------------------------------------------------------+
*/
/*
  $Id: session.c,v 1.1.1.1 2007-11-28 01:15:35 sesser Exp $ 
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "php.h"
#include "TSRM.h"
#include "SAPI.h"
#include "php_ini.h"
#include "php_suhosin.h"
#include "ext/standard/base64.h"
#include "ext/standard/php_smart_str.h"
#include "ext/standard/php_var.h"
#include "sha256.h"

#include <fcntl.h>

#if defined(HAVE_HASH_EXT) && !defined(COMPILE_DL_HASH)
# include "ext/hash/php_hash.h"
#endif

#define PS_OPEN_ARGS void **mod_data, const char *save_path, const char *session_name TSRMLS_DC
#define PS_CLOSE_ARGS void **mod_data TSRMLS_DC
#define PS_READ_ARGS void **mod_data, const char *key, char **val, int *vallen TSRMLS_DC
#define PS_WRITE_ARGS void **mod_data, const char *key, const char *val, const int vallen TSRMLS_DC
#define PS_DESTROY_ARGS void **mod_data, const char *key TSRMLS_DC
#define PS_GC_ARGS void **mod_data, int maxlifetime, int *nrdels TSRMLS_DC
#define PS_CREATE_SID_ARGS void **mod_data, int *newlen TSRMLS_DC

typedef struct ps_module_struct {
    const char *s_name;
    int (*s_open)(PS_OPEN_ARGS);
    int (*s_close)(PS_CLOSE_ARGS);
    int (*s_read)(PS_READ_ARGS);
    int (*s_write)(PS_WRITE_ARGS);
    int (*s_destroy)(PS_DESTROY_ARGS);
    int (*s_gc)(PS_GC_ARGS);
    char *(*s_create_sid)(PS_CREATE_SID_ARGS);
} ps_module;

typedef enum {
    php_session_disabled,
    php_session_none,
    php_session_active
} php_session_status;

#define PS_SERIALIZER_ENCODE_ARGS char **newstr, int *newlen TSRMLS_DC
#define PS_SERIALIZER_DECODE_ARGS const char *val, int vallen TSRMLS_DC

typedef struct ps_serializer_struct {
    const char *name;
    int (*encode)(PS_SERIALIZER_ENCODE_ARGS);
    int (*decode)(PS_SERIALIZER_DECODE_ARGS);
} ps_serializer;

typedef struct _php_ps_globals_43_44 {
    char *save_path;
    char *session_name;
    char *id;
    char *extern_referer_chk;
    char *entropy_file;
    char *cache_limiter;
    long entropy_length;
    long cookie_lifetime;
    char *cookie_path;
    char *cookie_domain;
    zend_bool  cookie_secure;
    ps_module *mod;
    void *mod_data;
    php_session_status session_status;
    long gc_probability;
    long gc_divisor;
    long gc_maxlifetime;
    int module_number;
    long cache_expire;
    zend_bool bug_compat; /* Whether to behave like PHP 4.2 and earlier */
    zend_bool bug_compat_warn; /* Whether to warn about it */
    const struct ps_serializer_struct *serializer;
    zval *http_session_vars;
    zend_bool auto_start;
    zend_bool use_cookies;
    zend_bool use_only_cookies;
    zend_bool use_trans_sid;    /* contains the INI value of whether to use trans-sid */
    zend_bool apply_trans_sid;  /* whether or not to enable trans-sid for the current request */
    int send_cookie;
    int define_sid;
} php_ps_globals_43_44;

typedef struct _php_ps_globals_50_51 {
    char *save_path;
    char *session_name;
    char *id;
    char *extern_referer_chk;
    char *entropy_file;
    char *cache_limiter;
    long entropy_length;
    long cookie_lifetime;
    char *cookie_path;
    char *cookie_domain;
    zend_bool  cookie_secure;
    ps_module *mod;
    void *mod_data;
    php_session_status session_status;
    long gc_probability;
    long gc_divisor;
    long gc_maxlifetime;
    int module_number;
    long cache_expire;
    zend_bool bug_compat; /* Whether to behave like PHP 4.2 and earlier */
    zend_bool bug_compat_warn; /* Whether to warn about it */
    const struct ps_serializer_struct *serializer;
    zval *http_session_vars;
    zend_bool auto_start;
    zend_bool use_cookies;
    zend_bool use_only_cookies;
    zend_bool use_trans_sid;    /* contains the INI value of whether to use trans-sid */
    zend_bool apply_trans_sid;  /* whether or not to enable trans-sid for the current request */

    long hash_func;
    long hash_bits_per_character;
    int send_cookie;
    int define_sid;
} php_ps_globals_50_51;

typedef struct _php_ps_globals_52 {
    char *save_path;
    char *session_name;
    char *id;
    char *extern_referer_chk;
    char *entropy_file;
    char *cache_limiter;
    long entropy_length;
    long cookie_lifetime;
    char *cookie_path;
    char *cookie_domain;
    zend_bool  cookie_secure;
    zend_bool  cookie_httponly;
    ps_module *mod;
    void *mod_data;
    php_session_status session_status;
    long gc_probability;
    long gc_divisor;
    long gc_maxlifetime;
    int module_number;
    long cache_expire;
    zend_bool bug_compat; /* Whether to behave like PHP 4.2 and earlier */
    zend_bool bug_compat_warn; /* Whether to warn about it */
    const struct ps_serializer_struct *serializer;
    zval *http_session_vars;
    zend_bool auto_start;
    zend_bool use_cookies;
    zend_bool use_only_cookies;
    zend_bool use_trans_sid;    /* contains the INI value of whether to use trans-sid */
    zend_bool apply_trans_sid;  /* whether or not to enable trans-sid for the current request */

    long hash_func;
    long hash_bits_per_character;
    int send_cookie;
    int define_sid;
    zend_bool invalid_session_id;   /* allows the driver to report about an invalid session id and request id regeneration */
} php_ps_globals_52;

typedef struct _php_ps_globals_53 {
    char *save_path;
    char *session_name;
    char *id;
    char *extern_referer_chk;
    char *entropy_file;
    char *cache_limiter;
    long entropy_length;
    long cookie_lifetime;
    char *cookie_path;
    char *cookie_domain;
    zend_bool  cookie_secure;
    zend_bool  cookie_httponly;
    ps_module *mod;
    void *mod_data;
    php_session_status session_status;
    long gc_probability;
    long gc_divisor;
    long gc_maxlifetime;
    int module_number;
    long cache_expire;
    union {
        zval *names[6];
        struct {
            zval *ps_open;
            zval *ps_close;
            zval *ps_read;
            zval *ps_write;
            zval *ps_destroy;
            zval *ps_gc;
        } name;
    } mod_user_names;
    zend_bool bug_compat; /* Whether to behave like PHP 4.2 and earlier */
    zend_bool bug_compat_warn; /* Whether to warn about it */
    const struct ps_serializer_struct *serializer;
    zval *http_session_vars;
    zend_bool auto_start;
    zend_bool use_cookies;
    zend_bool use_only_cookies;
    zend_bool use_trans_sid;    /* contains the INI value of whether to use trans-sid */
    zend_bool apply_trans_sid;  /* whether or not to enable trans-sid for the current request */

    long hash_func;
#if defined(HAVE_HASH_EXT) && !defined(COMPILE_DL_HASH)
    php_hash_ops *hash_ops;
#endif
    long hash_bits_per_character;
    int send_cookie;
    int define_sid;
    zend_bool invalid_session_id;   /* allows the driver to report about an invalid session id and request id regeneration */
} php_ps_globals_53;

#ifdef ZTS
static ts_rsrc_id session_globals_id = 0;
# if (PHP_MAJOR_VERSION == 5 && PHP_MINOR_VERSION >= 3)
#  define SESSION_G(v) TSRMG(session_globals_id, php_ps_globals_53 *, v)
# elif (PHP_MAJOR_VERSION == 5 && PHP_MINOR_VERSION >= 2)
#  define SESSION_G(v) TSRMG(session_globals_id, php_ps_globals_52 *, v)
# elif (PHP_MAJOR_VERSION == 5)
#  define SESSION_G(v) TSRMG(session_globals_id, php_ps_globals_50_51 *, v)
# elif (PHP_MAJOR_VERSION == 4 && PHP_MINOR_VERSION >= 3)
#  define SESSION_G(v) TSRMG(session_globals_id, php_ps_globals_43_44 *, v)
# else 
    UNSUPPORTED PHP VERSION
# endif
#else
# if (PHP_MAJOR_VERSION == 5 && PHP_MINOR_VERSION >= 3)
static php_ps_globals_53 *session_globals = NULL;
# elif (PHP_MAJOR_VERSION == 5 && PHP_MINOR_VERSION >= 2)
static php_ps_globals_52 *session_globals = NULL;
# elif (PHP_MAJOR_VERSION == 5)
static php_ps_globals_50_51 *session_globals = NULL;
# elif (PHP_MAJOR_VERSION == 4 && PHP_MINOR_VERSION >= 3)
static php_ps_globals_43_44 *session_globals = NULL;
# else 
    UNSUPPORTED PHP VERSION
# endif
#define SESSION_G(v) (session_globals->v)
#endif

ps_serializer *(*suhosin_find_ps_serializer)(char *name TSRMLS_DC) = NULL;

#define PS_ENCODE_VARS                                          \
    char *key;                                                  \
    uint key_length;                                            \
    ulong num_key;                                              \
    zval **struc;

#define PS_ENCODE_LOOP(code) do {                                   \
        HashTable *_ht = Z_ARRVAL_P(SESSION_G(http_session_vars));          \
        int key_type;                                               \
                                                                    \
        for (zend_hash_internal_pointer_reset(_ht);                 \
                (key_type = zend_hash_get_current_key_ex(_ht, &key, &key_length, &num_key, 0, NULL)) != HASH_KEY_NON_EXISTANT; \
                    zend_hash_move_forward(_ht)) {                  \
            if (key_type == HASH_KEY_IS_LONG) {                     \
                php_error_docref(NULL TSRMLS_CC, E_NOTICE, "Skipping numeric key %ld", num_key);    \
                continue;                                           \
            }                                                       \
            key_length--;                                           \
            if (suhosin_get_session_var(key, key_length, &struc TSRMLS_CC) == SUCCESS) {    \
                code;                                               \
            }                                                       \
        }                                                           \
    } while(0)

static int suhosin_get_session_var(char *name, size_t namelen, zval ***state_var TSRMLS_DC) /* {{{ */
{
    int ret = FAILURE;

    if (SESSION_G(http_session_vars) && SESSION_G(http_session_vars)->type == IS_ARRAY) {
        ret = zend_hash_find(Z_ARRVAL_P(SESSION_G(http_session_vars)), name, namelen + 1, (void **) state_var);

        /* If register_globals is enabled, and
         * if there is an entry for the slot in $_SESSION, and
         * if that entry is still set to NULL, and
         * if the global var exists, then
         * we prefer the same key in the global sym table. */

        if (PG(register_globals) && ret == SUCCESS && Z_TYPE_PP(*state_var) == IS_NULL) {
            zval **tmp;

            if (zend_hash_find(&EG(symbol_table), name, namelen + 1, (void **) &tmp) == SUCCESS) {
                *state_var = tmp;
            }
        }
    }
    return ret;
}

#define PS_DELIMITER '|'
#define PS_UNDEF_MARKER '!'

int suhosin_session_encode(char **newstr, int *newlen TSRMLS_DC)
{
    smart_str buf = {0};
    php_serialize_data_t var_hash;
    PS_ENCODE_VARS;

    PHP_VAR_SERIALIZE_INIT(var_hash);

    PS_ENCODE_LOOP(
            smart_str_appendl(&buf, key, key_length);
            if (key[0] == PS_UNDEF_MARKER || memchr(key, PS_DELIMITER, key_length)) {
                PHP_VAR_SERIALIZE_DESTROY(var_hash);
                smart_str_free(&buf);
                return FAILURE;
            }
            smart_str_appendc(&buf, PS_DELIMITER);

            php_var_serialize(&buf, struc, &var_hash TSRMLS_CC);
        } else {
            smart_str_appendc(&buf, PS_UNDEF_MARKER);
            smart_str_appendl(&buf, key, key_length);
            smart_str_appendc(&buf, PS_DELIMITER);
    );

    if (newlen) {
        *newlen = buf.len;
    }
    smart_str_0(&buf);
    *newstr = buf.c;

    PHP_VAR_SERIALIZE_DESTROY(var_hash);
    return SUCCESS;
}

static void suhosin_send_cookie(TSRMLS_D)
{
    int  * session_send_cookie = &SESSION_G(send_cookie);
    char * base;
    zend_ini_entry *ini_entry;
    
    /* The following is requires to be 100% compatible to PHP 
       versions where the hash extension is not available by default */
#if (PHP_MAJOR_VERSION >= 5 && PHP_MINOR_VERSION >= 3)
    if (zend_hash_find(EG(ini_directives), "session.hash_bits_per_character", sizeof("session.hash_bits_per_character"), (void **) &ini_entry) == SUCCESS) {
#ifndef ZTS
        base = (char *) ini_entry->mh_arg2;
#else
        base = (char *) ts_resource(*((int *) ini_entry->mh_arg2));
#endif
        session_send_cookie = (int *) (base+(size_t) ini_entry->mh_arg1+sizeof(long));
    }
#endif
    *session_send_cookie = 1;
}

void suhosin_get_ipv4(char *buf TSRMLS_DC)
{
    char *raddr = sapi_getenv("REMOTE_ADDR", sizeof("REMOTE_ADDR")-1 TSRMLS_CC);
    int i;


    if (raddr == NULL) {
        memset(buf, 0, 4);
        return;
    }
    
    for (i=0; i<4; i++) {
        if (raddr[0] == 0) {
            buf[i] = 0;
        } else {
            buf[i] = strtol(raddr, &raddr, 10);
            if (raddr[0] == '.') {
                raddr++;
            }
        }
    }
}

char *suhosin_encrypt_string(char *str, int len, char *var, int vlen, char *key TSRMLS_DC)
{
    int padded_len, i, slen;
    unsigned char *crypted, *tmp;
    unsigned int check = 0x13579BDF;
    
    if (str == NULL) {
    return NULL;
    }
    if (len == 0) {
        return estrndup("", 0);
    }


    suhosin_aes_gkey(4,8,key TSRMLS_CC);

    padded_len = ((len+15) & ~0xF);
    crypted = emalloc(16+padded_len+1);
    memset(crypted, 0xff, 16+padded_len+1);
    memcpy(crypted+16, str, len+1);

    /* calculate check value */
    for (i = 0; i<vlen; i++) {
        check = (check << 3) | (check >> (32-3));
        check += check << 1;
        check ^= (unsigned char)var[i];
    }
    for (i = 0; i<len; i++) {
        check = (check << 3) | (check >> (32-3));
        check += check << 1;
        check ^= (unsigned char)str[i];
    }
    
    /* store ip value */
    suhosin_get_ipv4(crypted+4 TSRMLS_CC);
    
    /* store check value */
    crypted[8] = check & 0xff;
    crypted[9] = (check >> 8) & 0xff;
    crypted[10] = (check >> 16) & 0xff;
    crypted[11] = (check >> 24) & 0xff;

    /* store original length */
    crypted[12] = len & 0xff;
    crypted[13] = (len >> 8) & 0xff;
    crypted[14] = (len >> 16) & 0xff;
    crypted[15] = (len >> 24) & 0xff;
    
    for (i=0, tmp=crypted; i<padded_len+16; i+=16, tmp+=16) {
        if (i > 0) {
            int j;
            for (j=0; j<16; j++) tmp[j] ^= tmp[j-16];
        }
        suhosin_aes_encrypt((char *)tmp TSRMLS_CC);
    }
    
    tmp = php_base64_encode(crypted, padded_len+16, NULL);
    efree(crypted);
    slen=strlen((char *)tmp);
    for (i=0; i<slen; i++) {
        switch (tmp[i]) {
        case '/': tmp[i]='-'; break;
        case '=': tmp[i]='.'; break;
        case '+': tmp[i]='_'; break;
        }
    }
    return (char *)tmp;
}

char *suhosin_decrypt_string(char *str, int padded_len, char *var, int vlen, char *key, int *orig_len, int check_ra TSRMLS_DC)
{
    int len, i, o_len, invalid = 0;
    unsigned char *decrypted, *tmp;
    unsigned int check = 0x13579BDF;
    char buf[4];
    
    if (str == NULL) {
    return NULL;
    }
    
    if (padded_len == 0) {
        if (orig_len) {
            *orig_len = 0;
        }
        return estrndup("", 0);
    }
    suhosin_aes_gkey(4,8,key TSRMLS_CC);

    for (i=0; i<padded_len; i++) {
        switch (str[i]) {
        case '-': str[i]='/'; break;
        case '.': str[i]='='; break;
        case '_': str[i]='+'; break;
        }
    }
    
    decrypted = php_base64_decode((unsigned char *)str, padded_len, &len);
    if (decrypted == NULL || len < 2*16 || (len % 16) != 0) {
error_out:
        if (decrypted != NULL) {
            efree(decrypted);
        }
        if (orig_len) {
            *orig_len = 0;
        }
        return NULL;
    }
    
    for (i=len-16, tmp=decrypted+i; i>=0; i-=16, tmp-=16) {
    suhosin_aes_decrypt((char *)tmp TSRMLS_CC);
    if (i > 0) {
        int j;
        for (j=0; j<16; j++) tmp[j] ^= tmp[j-16];
    }
    }
    
    /* retrieve orig_len */
    o_len = decrypted[15];
    o_len <<= 8;
    o_len |= decrypted[14];
    o_len <<= 8;
    o_len |= decrypted[13];
    o_len <<= 8;
    o_len |= decrypted[12];
    
    if (o_len < 0 || o_len > len-16) {
        goto error_out;
    }

    /* calculate check value */
    for (i = 0; i<vlen; i++) {
        check = (check << 3) | (check >> (32-3));
        check += check << 1;
        check ^= (unsigned char)var[i];
    }
    for (i = 0; i<o_len; i++) {
        check = (check << 3) | (check >> (32-3));
        check += check << 1;
        check ^= decrypted[16+i];
    }
    
    /* check value */
    invalid = (decrypted[8] != (check & 0xff)) || 
           (decrypted[9] != ((check >> 8) & 0xff)) || 
               (decrypted[10] != ((check >> 16) & 0xff)) || 
               (decrypted[11] != ((check >> 24) & 0xff));
    
    /* check IP */
    if (check_ra > 0) {
        if (check_ra > 4) {
            check_ra = 4;
        }
        suhosin_get_ipv4(&buf TSRMLS_CC);
        if (memcmp(buf, decrypted+4, check_ra) != 0) {
            goto error_out;
        }
    }
    
    if (invalid) {
        goto error_out;
    }
    
    if (orig_len) {
        *orig_len = o_len;
    }
    
    memmove(decrypted, decrypted+16, o_len);
    decrypted[o_len] = 0;
    /* we do not realloc() here because 16 byte less 
       is simply not worth the overhead */  
    return (char *)decrypted;
}

char *suhosin_generate_key(char *key, zend_bool ua, zend_bool dr, long raddr, char *cryptkey TSRMLS_DC)
{
    char *_ua = NULL;
    char *_dr = NULL;
    char *_ra = NULL;
    suhosin_SHA256_CTX ctx;
    
    if (ua) {
        _ua = sapi_getenv("HTTP_USER_AGENT", sizeof("HTTP_USER_AGENT")-1 TSRMLS_CC);
    }
    
    if (dr) {
        _dr = sapi_getenv("DOCUMENT_ROOT", sizeof("DOCUMENT_ROOT")-1 TSRMLS_CC);
    }
    
    if (raddr > 0) {
        _ra = sapi_getenv("REMOTE_ADDR", sizeof("REMOTE_ADDR")-1 TSRMLS_CC);
    }
    
    SDEBUG("(suhosin_generate_key) KEY: %s - UA: %s - DR: %s - RA: %s", key,_ua,_dr,_ra);
    
    suhosin_SHA256Init(&ctx);
    if (key == NULL) {
        suhosin_SHA256Update(&ctx, (unsigned char*)"D3F4UL7", sizeof("D3F4UL7"));
    } else {
        suhosin_SHA256Update(&ctx, (unsigned char*)key, strlen(key));
    }
    if (_ua) {
        suhosin_SHA256Update(&ctx, (unsigned char*)_ua, strlen(_ua));
    }
    if (_dr) {
        suhosin_SHA256Update(&ctx, (unsigned char*)_dr, strlen(_dr));
    }
    if (_ra) {
        if (raddr >= 4) {
            suhosin_SHA256Update(&ctx, (unsigned char*)_ra, strlen(_ra));
        } else {
            long dots = 0;
            char *tmp = _ra;
            
            while (*tmp) {
                if (*tmp == '.') {
                    dots++;
                    if (dots == raddr) {
                        break;
                    }
                }
                tmp++;
            }
            suhosin_SHA256Update(&ctx, (unsigned char*)_ra, tmp-_ra);
        }
    }
    suhosin_SHA256Final((unsigned char *)cryptkey, &ctx);
    cryptkey[32] = 0; /* uhmm... not really a string */
    
    return cryptkey;
}


static int (*old_OnUpdateSaveHandler)(zend_ini_entry *entry, char *new_value, uint new_value_length, void *mh_arg1, void *mh_arg2, void *mh_arg3, int stage TSRMLS_DC) = NULL;
static int (*old_SessionRINIT)(INIT_FUNC_ARGS) = NULL;

static int suhosin_hook_s_read(void **mod_data, const char *key, char **val, int *vallen TSRMLS_DC)
{
    int r;
    
    int i;char *v,*KEY=(char *)key;

    /* protect session vars */
/*  if (SESSION_G(http_session_vars) && SESSION_G(http_session_vars)->type == IS_ARRAY) {
        SESSION_G(http_session_vars)->refcount++;
    }*/
    
    /* protect dumb session handlers */
    if (key == NULL || !key[0] || *mod_data == NULL) {
regenerate:
        SDEBUG("regenerating key is %s", key);
        KEY = SESSION_G(id) = SESSION_G(mod)->s_create_sid(&SESSION_G(mod_data), NULL TSRMLS_CC);
        suhosin_send_cookie(TSRMLS_C);
    } else if (strlen(key) > SUHOSIN_G(session_max_id_length)) {
        suhosin_log(S_SESSION, "session id ('%s') exceeds maximum length - regenerating", KEY);
        if (!SUHOSIN_G(simulation)) {
            goto regenerate;
        }
    }
#if (PHP_MAJOR_VERSION < 5) || (PHP_MAJOR_VERSION == 5 && PHP_MINOR_VERSION < 2)
      else if (strpbrk(KEY, "\r\n\t <>'\"\\")) {
        suhosin_log(S_SESSION, "session id ('%s') contains invalid chars - regenerating", KEY);
        if (!SUHOSIN_G(simulation)) {
            goto regenerate;
        }
    }
#endif

    r = SUHOSIN_G(old_s_read)(mod_data, KEY, val, vallen TSRMLS_CC);

    if (r == SUCCESS && SUHOSIN_G(session_encrypt) && *vallen > 0) {
        char cryptkey[33];
    
        SUHOSIN_G(do_not_scan) = 1;
        suhosin_generate_key(SUHOSIN_G(session_cryptkey), SUHOSIN_G(session_cryptua), SUHOSIN_G(session_cryptdocroot), SUHOSIN_G(session_cryptraddr), (char *)&cryptkey TSRMLS_CC);
    
        v = *val;
        i = *vallen;
        *val = suhosin_decrypt_string(v, i, "", 0, (char *)&cryptkey, vallen, SUHOSIN_G(session_checkraddr) TSRMLS_CC);
        SUHOSIN_G(do_not_scan) = 0;
    if (*val == NULL) {
        *val = estrndup("", 0);
        *vallen = 0;
    }
        efree(v);
    }
    
    return r;
}

static int suhosin_hook_s_write(void **mod_data, const char *key, const char *val, const int vallen TSRMLS_DC)
{
    int r;
/*  int nullify = 0;*/
    char *v = (char *)val;

    /* protect dumb session handlers */
    if (key == NULL || !key[0] || val == NULL || strlen(key) > SUHOSIN_G(session_max_id_length) || *mod_data == NULL) {
        r = FAILURE;
        goto return_write;
    }
    
    r = vallen;

    if (r > 0 && SUHOSIN_G(session_encrypt)) {
        char cryptkey[33];

        SUHOSIN_G(do_not_scan) = 1;
    
        suhosin_generate_key(SUHOSIN_G(session_cryptkey), SUHOSIN_G(session_cryptua), SUHOSIN_G(session_cryptdocroot), SUHOSIN_G(session_cryptraddr), (char *)&cryptkey TSRMLS_CC);
        
        v = suhosin_encrypt_string(v, vallen, "", 0, (char *)&cryptkey TSRMLS_CC);
        
        SUHOSIN_G(do_not_scan) = 0;
        r = strlen(v);
    }

    r = SUHOSIN_G(old_s_write)(mod_data, key, v, r TSRMLS_CC);
    
return_write:
    /* protect session vars */
/*  if (SESSION_G(http_session_vars) && SESSION_G(http_session_vars)->type == IS_ARRAY) {
        if (SESSION_G(http_session_vars)->refcount==1) {
            nullify = 1;
        }
        zval_ptr_dtor(&SESSION_G(http_session_vars));
        if (nullify) {
            suhosin_log(S_SESSION, "possible session variables double free attack stopped");
            SESSION_G(http_session_vars) = NULL;
        }
    }*/

    return r;
}

static int suhosin_hook_s_destroy(void **mod_data, const char *key TSRMLS_DC)
{
    int r;

    /* protect dumb session handlers */
    if (key == NULL || !key[0] || strlen(key) > SUHOSIN_G(session_max_id_length) || *mod_data == NULL) {
        return FAILURE;
    }
    
    r = SUHOSIN_G(old_s_destroy)(mod_data, key TSRMLS_CC);
    
    return r;
}

static void suhosin_hook_session_module(TSRMLS_D)
{
    ps_module *old_mod = SESSION_G(mod), *mod;

    if (old_mod == NULL || SUHOSIN_G(s_module) == old_mod) {
        return;
    }
    if (SUHOSIN_G(s_module) == NULL) {
        SUHOSIN_G(s_module) = mod = malloc(sizeof(ps_module));
        if (mod == NULL) {
            return;
        }
    }
    mod = SUHOSIN_G(s_module);
    memcpy(mod, old_mod, sizeof(ps_module));
    
    SUHOSIN_G(old_s_read) = mod->s_read;
    mod->s_read = suhosin_hook_s_read;
    SUHOSIN_G(old_s_write) = mod->s_write;
    mod->s_write = suhosin_hook_s_write;
    SUHOSIN_G(old_s_destroy) = mod->s_destroy;
    mod->s_destroy = suhosin_hook_s_destroy;
    
    SESSION_G(mod) = mod;
}

static PHP_INI_MH(suhosin_OnUpdateSaveHandler)
{
    int r;

    r = old_OnUpdateSaveHandler(entry, new_value, new_value_length, mh_arg1, mh_arg2, mh_arg3, stage TSRMLS_CC);
    
    suhosin_hook_session_module(TSRMLS_C);
    
    return r;
}


static int suhosin_hook_session_RINIT(INIT_FUNC_ARGS)
{
    if (SESSION_G(mod) == NULL) {
        char *value = zend_ini_string("session.save_handler", sizeof("session.save_handler"), 0);
        
        if (value) {
            suhosin_OnUpdateSaveHandler(NULL, value, strlen(value), NULL, NULL, NULL, 0 TSRMLS_CC);
        }
    }
    return old_SessionRINIT(INIT_FUNC_ARGS_PASSTHRU);
}

void suhosin_hook_session(TSRMLS_D)
{
    ps_serializer *serializer;
    zend_ini_entry *ini_entry;
    zend_module_entry *module;
#ifdef ZTS
    ts_rsrc_id *ps_globals_id_ptr;
#endif
    
    if (zend_hash_find(&module_registry, "session", sizeof("session"), (void**)&module) == FAILURE) {
        return;
    }
    /* retrieve globals from module entry struct if possible */
#if PHP_VERSION_ID >= 50200
#ifdef ZTS
    if (session_globals_id == 0) {
    session_globals_id = *module->globals_id_ptr;
    }
#else
    if (session_globals == NULL) {
    session_globals = module->globals_ptr;
    }
#endif
#else
    /* retrieve globals from symbols if PHP version is old */
#ifdef ZTS
    if (session_globals_id == 0) {
        ps_globals_id_ptr = DL_FETCH_SYMBOL(module->handle, "ps_globals_id");
        if (ps_globals_id_ptr == NULL) {
            ps_globals_id_ptr = DL_FETCH_SYMBOL(module->handle, "_ps_globals_id");
        }
        if (ps_globals_id_ptr == NULL) {
            return;
        }
        
        session_globals_id = *ps_globals_id_ptr;
    }
#else
    if (session_globals == NULL) {
        session_globals = DL_FETCH_SYMBOL(module->handle, "ps_globals");
        if (session_globals == NULL) {
            session_globals = DL_FETCH_SYMBOL(module->handle, "_ps_globals");
        }
        if (session_globals == NULL) {
            return;
        }
    }
#endif
#endif
    if (old_OnUpdateSaveHandler != NULL) {
        return;
    }
    
    /* hook request startup function of session module */
    old_SessionRINIT = module->request_startup_func;
    module->request_startup_func = suhosin_hook_session_RINIT;
    
    /* retrieve pointer to session.save_handler ini entry */
    if (zend_hash_find(EG(ini_directives), "session.save_handler", sizeof("session.save_handler"), (void **) &ini_entry) == FAILURE) {
        return;
    }
    SUHOSIN_G(s_module) = NULL;

    /* replace OnUpdateMemoryLimit handler */
    old_OnUpdateSaveHandler = ini_entry->on_modify;
    ini_entry->on_modify = suhosin_OnUpdateSaveHandler;
    
    suhosin_hook_session_module(TSRMLS_C);
    
    /* Protect the PHP serializer from ! attacks */
# if PHP_MAJOR_VERSION > 5 || (PHP_MAJOR_VERSION == 5 && PHP_MINOR_VERSION >= 2)
    serializer = SESSION_G(serializer);
    if (serializer != NULL && strcmp(serializer->name, "php")==0) {
        serializer->encode = suhosin_session_encode;
    }
#endif

    /* increase session identifier entropy */
    if (SESSION_G(entropy_length) == 0 || SESSION_G(entropy_file) == NULL) {
        
        /* ensure that /dev/urandom exists */
        int fd = VCWD_OPEN("/dev/urandom", O_RDONLY);
        if (fd >= 0) {
            close(fd);
            SESSION_G(entropy_length) = 16;
            SESSION_G(entropy_file) = pestrdup("/dev/urandom", 1);
        }
    }
}

void suhosin_unhook_session(TSRMLS_D)
{
    if (old_OnUpdateSaveHandler != NULL) {
        zend_ini_entry *ini_entry;
        
        /* retrieve pointer to session.save_handler ini entry */
        if (zend_hash_find(EG(ini_directives), "session.save_handler", sizeof("session.save_handler"), (void **) &ini_entry) == FAILURE) {
            return;
        }
        ini_entry->on_modify = old_OnUpdateSaveHandler;
    
        old_OnUpdateSaveHandler = NULL; 
    }

}

/*
 * Local variables:
 * tab-width: 4
 * c-basic-offset: 4
 * End:
 * vim600: sw=4 ts=4 fdm=marker
 * vim<600: sw=4 ts=4
 */