Adding upstream version 2.4.57.upstream/2.4.57

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 807 insertions, 0 deletions

diff --git a/modules/session/mod_session_crypto.c b/modules/session/mod_session_crypto.c
new file mode 100644
index 0000000..fe39f2c
--- /dev/null
+++ b/modules/session/mod_session_crypto.c
@@ -0,0 +1,807 @@
+/* Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You 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.
+ */
+
+#include "mod_session.h"
+#include "apu_version.h"
+#include "apr_base64.h"                /* for apr_base64_decode et al */
+#include "apr_lib.h"
+#include "apr_md5.h"
+#include "apr_strings.h"
+#include "http_log.h"
+#include "http_core.h"
+
+#if APU_MAJOR_VERSION == 1 && APU_MINOR_VERSION < 4
+
+#error session_crypto_module requires APU v1.4.0 or later
+
+#elif APU_HAVE_CRYPTO == 0
+
+#error Crypto support must be enabled in APR
+
+#else
+
+#include "apr_crypto.h"                /* for apr_*_crypt et al */
+
+#define CRYPTO_KEY "session_crypto_context"
+
+module AP_MODULE_DECLARE_DATA session_crypto_module;
+
+/**
+ * Structure to carry the per-dir session config.
+ */
+typedef struct {
+    apr_array_header_t *passphrases;
+    int passphrases_set;
+    const char *cipher;
+    int cipher_set;
+} session_crypto_dir_conf;
+
+/**
+ * Structure to carry the server wide session config.
+ */
+typedef struct {
+    const char *library;
+    const char *params;
+    int library_set;
+} session_crypto_conf;
+
+/* Wrappers around apr_siphash24() and apr_crypto_equals(),
+ * available in APU-1.6/APR-2.0 only.
+ */
+#if APU_MAJOR_VERSION > 1 || (APU_MAJOR_VERSION == 1 && APU_MINOR_VERSION >= 6)
+
+#include "apr_siphash.h"
+
+#define AP_SIPHASH_DSIZE    APR_SIPHASH_DSIZE
+#define AP_SIPHASH_KSIZE    APR_SIPHASH_KSIZE
+#define ap_siphash24_auth   apr_siphash24_auth
+
+#define ap_crypto_equals    apr_crypto_equals
+
+#else
+
+#define AP_SIPHASH_DSIZE    8
+#define AP_SIPHASH_KSIZE    16
+
+#define ROTL64(x, n) (((x) << (n)) | ((x) >> (64 - (n))))
+
+#define U8TO64_LE(p) \
+    (((apr_uint64_t)((p)[0])      ) | \
+     ((apr_uint64_t)((p)[1]) <<  8) | \
+     ((apr_uint64_t)((p)[2]) << 16) | \
+     ((apr_uint64_t)((p)[3]) << 24) | \
+     ((apr_uint64_t)((p)[4]) << 32) | \
+     ((apr_uint64_t)((p)[5]) << 40) | \
+     ((apr_uint64_t)((p)[6]) << 48) | \
+     ((apr_uint64_t)((p)[7]) << 56))
+
+#define U64TO8_LE(p, v) \
+do { \
+    (p)[0] = (unsigned char)((v)      ); \
+    (p)[1] = (unsigned char)((v) >>  8); \
+    (p)[2] = (unsigned char)((v) >> 16); \
+    (p)[3] = (unsigned char)((v) >> 24); \
+    (p)[4] = (unsigned char)((v) >> 32); \
+    (p)[5] = (unsigned char)((v) >> 40); \
+    (p)[6] = (unsigned char)((v) >> 48); \
+    (p)[7] = (unsigned char)((v) >> 56); \
+} while (0)
+
+#define SIPROUND() \
+do { \
+    v0 += v1; v1=ROTL64(v1,13); v1 ^= v0; v0=ROTL64(v0,32); \
+    v2 += v3; v3=ROTL64(v3,16); v3 ^= v2; \
+    v0 += v3; v3=ROTL64(v3,21); v3 ^= v0; \
+    v2 += v1; v1=ROTL64(v1,17); v1 ^= v2; v2=ROTL64(v2,32); \
+} while(0)
+
+static apr_uint64_t ap_siphash24(const void *src, apr_size_t len,
+                                 const unsigned char key[AP_SIPHASH_KSIZE])
+{
+    const unsigned char *ptr, *end;
+    apr_uint64_t v0, v1, v2, v3, m;
+    apr_uint64_t k0, k1;
+    unsigned int rem;
+
+    k0 = U8TO64_LE(key + 0);
+    k1 = U8TO64_LE(key + 8);
+    v3 = k1 ^ (apr_uint64_t)0x7465646279746573ULL;
+    v2 = k0 ^ (apr_uint64_t)0x6c7967656e657261ULL;
+    v1 = k1 ^ (apr_uint64_t)0x646f72616e646f6dULL;
+    v0 = k0 ^ (apr_uint64_t)0x736f6d6570736575ULL;
+
+    rem = (unsigned int)(len & 0x7);
+    for (ptr = src, end = ptr + len - rem; ptr < end; ptr += 8) {
+        m = U8TO64_LE(ptr);
+        v3 ^= m;
+        SIPROUND();
+        SIPROUND();
+        v0 ^= m;
+    }
+    m = (apr_uint64_t)(len & 0xff) << 56;
+    switch (rem) {
+        case 7: m |= (apr_uint64_t)ptr[6] << 48;
+        case 6: m |= (apr_uint64_t)ptr[5] << 40;
+        case 5: m |= (apr_uint64_t)ptr[4] << 32;
+        case 4: m |= (apr_uint64_t)ptr[3] << 24;
+        case 3: m |= (apr_uint64_t)ptr[2] << 16;
+        case 2: m |= (apr_uint64_t)ptr[1] << 8;
+        case 1: m |= (apr_uint64_t)ptr[0];
+        case 0: break;
+    }
+    v3 ^= m;
+    SIPROUND();
+    SIPROUND();
+    v0 ^= m;
+
+    v2 ^= 0xff;
+    SIPROUND();
+    SIPROUND();
+    SIPROUND();
+    SIPROUND();
+
+    return v0 ^ v1 ^ v2 ^ v3;
+}
+
+static void ap_siphash24_auth(unsigned char out[AP_SIPHASH_DSIZE],
+                              const void *src, apr_size_t len,
+                              const unsigned char key[AP_SIPHASH_KSIZE])
+{
+    apr_uint64_t h;
+    h = ap_siphash24(src, len, key);
+    U64TO8_LE(out, h);
+}
+
+static int ap_crypto_equals(const void *buf1, const void *buf2,
+                            apr_size_t size)
+{
+    const unsigned char *p1 = buf1;
+    const unsigned char *p2 = buf2;
+    unsigned char diff = 0;
+    apr_size_t i;
+
+    for (i = 0; i < size; ++i) {
+        diff |= p1[i] ^ p2[i];
+    }
+
+    return 1 & ((diff - 1) >> 8);
+}
+
+#endif
+
+static void compute_auth(const void *src, apr_size_t len,
+                         const char *passphrase, apr_size_t passlen,
+                         unsigned char auth[AP_SIPHASH_DSIZE])
+{
+    unsigned char key[APR_MD5_DIGESTSIZE];
+
+    /* XXX: if we had a way to get the raw bytes from an apr_crypto_key_t
+     *      we could use them directly (not available in APR-1.5.x).
+     * MD5 is 128bit too, so use it to get a suitable siphash key
+     * from the passphrase.
+     */
+    apr_md5(key, passphrase, passlen);
+
+    ap_siphash24_auth(auth, src, len, key);
+}
+
+/**
+ * Initialise the encryption as per the current config.
+ *
+ * Returns APR_SUCCESS if successful.
+ */
+static apr_status_t crypt_init(request_rec *r,
+        const apr_crypto_t *f, apr_crypto_block_key_type_e **cipher,
+        session_crypto_dir_conf * dconf)
+{
+    apr_status_t res;
+    apr_hash_t *ciphers;
+
+    res = apr_crypto_get_block_key_types(&ciphers, f);
+    if (APR_SUCCESS != res) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01823)
+                "no ciphers returned by APR. "
+                "session encryption not possible");
+        return res;
+    }
+
+    *cipher = apr_hash_get(ciphers, dconf->cipher, APR_HASH_KEY_STRING);
+    if (!(*cipher)) {
+        apr_hash_index_t *hi;
+        const void *key;
+        apr_ssize_t klen;
+        int sum = 0;
+        int offset = 0;
+        char *options = NULL;
+
+        for (hi = apr_hash_first(r->pool, ciphers); hi; hi = apr_hash_next(hi)) {
+            apr_hash_this(hi, NULL, &klen, NULL);
+            sum += klen + 2;
+        }
+        for (hi = apr_hash_first(r->pool, ciphers); hi; hi = apr_hash_next(hi)) {
+            apr_hash_this(hi, &key, &klen, NULL);
+            if (!options) {
+                options = apr_palloc(r->pool, sum + 1);
+            }
+            else {
+                options[offset++] = ',';
+                options[offset++] = ' ';
+            }
+            strncpy(options + offset, key, klen);
+            offset += klen;
+        }
+        options[offset] = 0;
+
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01824)
+                "cipher '%s' not recognised by crypto driver. "
+                "session encryption not possible, options: %s", dconf->cipher, options);
+
+        return APR_EGENERAL;
+    }
+
+    return APR_SUCCESS;
+}
+
+/**
+ * Encrypt the string given as per the current config.
+ *
+ * Returns APR_SUCCESS if successful.
+ */
+static apr_status_t encrypt_string(request_rec * r, const apr_crypto_t *f,
+        session_crypto_dir_conf *dconf, const char *in, char **out)
+{
+    apr_status_t res;
+    apr_crypto_key_t *key = NULL;
+    apr_size_t ivSize = 0;
+    apr_crypto_block_t *block = NULL;
+    unsigned char *encrypt = NULL;
+    unsigned char *combined = NULL;
+    apr_size_t encryptlen, tlen, combinedlen;
+    char *base64;
+    apr_size_t blockSize = 0;
+    const unsigned char *iv = NULL;
+    apr_uuid_t salt;
+    apr_crypto_block_key_type_e *cipher;
+    const char *passphrase;
+    apr_size_t passlen;
+
+    /* use a uuid as a salt value, and prepend it to our result */
+    apr_uuid_get(&salt);
+    res = crypt_init(r, f, &cipher, dconf);
+    if (res != APR_SUCCESS) {
+        return res;
+    }
+
+    /* encrypt using the first passphrase in the list */
+    passphrase = APR_ARRAY_IDX(dconf->passphrases, 0, const char *);
+    passlen = strlen(passphrase);
+    res = apr_crypto_passphrase(&key, &ivSize, passphrase, passlen,
+            (unsigned char *) (&salt), sizeof(apr_uuid_t),
+            *cipher, APR_MODE_CBC, 1, 4096, f, r->pool);
+    if (APR_STATUS_IS_ENOKEY(res)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01825)
+                "failure generating key from passphrase");
+    }
+    if (APR_STATUS_IS_EPADDING(res)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01826)
+                "padding is not supported for cipher");
+    }
+    if (APR_STATUS_IS_EKEYTYPE(res)) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01827)
+                "the key type is not known");
+    }
+    if (APR_SUCCESS != res) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01828)
+                "encryption could not be configured.");
+        return res;
+    }
+
+    res = apr_crypto_block_encrypt_init(&block, &iv, key, &blockSize, r->pool);
+    if (APR_SUCCESS != res) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01829)
+                "apr_crypto_block_encrypt_init failed");
+        return res;
+    }
+
+    /* encrypt the given string */
+    res = apr_crypto_block_encrypt(&encrypt, &encryptlen,
+                                   (const unsigned char *)in, strlen(in),
+                                   block);
+    if (APR_SUCCESS != res) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01830)
+                "apr_crypto_block_encrypt failed");
+        return res;
+    }
+    res = apr_crypto_block_encrypt_finish(encrypt + encryptlen, &tlen, block);
+    if (APR_SUCCESS != res) {
+        ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01831)
+                "apr_crypto_block_encrypt_finish failed");
+        return res;
+    }
+    encryptlen += tlen;
+
+    /* prepend the salt and the iv to the result (keep room for the MAC) */
+    combinedlen = AP_SIPHASH_DSIZE + sizeof(apr_uuid_t) + ivSize + encryptlen;
+    combined = apr_palloc(r->pool, combinedlen);
+    memcpy(combined + AP_SIPHASH_DSIZE, &salt, sizeof(apr_uuid_t));
+    memcpy(combined + AP_SIPHASH_DSIZE + sizeof(apr_uuid_t), iv, ivSize);
+    memcpy(combined + AP_SIPHASH_DSIZE + sizeof(apr_uuid_t) + ivSize,
+           encrypt, encryptlen);
+    /* authenticate the whole salt+IV+ciphertext with a leading MAC */
+    compute_auth(combined + AP_SIPHASH_DSIZE, combinedlen - AP_SIPHASH_DSIZE,
+                 passphrase, passlen, combined);
+
+    /* base64 encode the result (APR handles the trailing '\0') */
+    base64 = apr_palloc(r->pool, apr_base64_encode_len(combinedlen));
+    apr_base64_encode(base64, (const char *) combined, combinedlen);
+    *out = base64;
+
+    return res;
+
+}
+
+/**
+ * Decrypt the string given as per the current config.
+ *
+ * Returns APR_SUCCESS if successful.
+ */
+static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
+        session_crypto_dir_conf *dconf, const char *in, char **out)
+{
+    apr_status_t res;
+    apr_crypto_key_t *key = NULL;
+    apr_size_t ivSize = 0;
+    apr_crypto_block_t *block = NULL;
+    unsigned char *decrypted = NULL;
+    apr_size_t decryptedlen, tlen;
+    apr_size_t decodedlen;
+    char *decoded;
+    apr_size_t blockSize = 0;
+    apr_crypto_block_key_type_e *cipher;
+    unsigned char auth[AP_SIPHASH_DSIZE];
+    int i = 0;
+
+    /* strip base64 from the string */
+    decoded = apr_palloc(r->pool, apr_base64_decode_len(in));
+    decodedlen = apr_base64_decode(decoded, in);
+    decoded[decodedlen] = '\0';
+
+    /* sanity check - decoded too short? */
+    if (decodedlen < (AP_SIPHASH_DSIZE + sizeof(apr_uuid_t))) {
+        ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(10005)
+                "too short to decrypt, aborting");
+        return APR_ECRYPT;
+    }
+
+    res = crypt_init(r, f, &cipher, dconf);
+    if (res != APR_SUCCESS) {
+        return res;
+    }
+
+    res = APR_ECRYPT; /* in case we exhaust all passphrases */
+
+    /* try each passphrase in turn */
+    for (; i < dconf->passphrases->nelts; i++) {
+        const char *passphrase = APR_ARRAY_IDX(dconf->passphrases, i, char *);
+        apr_size_t passlen = strlen(passphrase);
+        apr_size_t len = decodedlen - AP_SIPHASH_DSIZE;
+        unsigned char *slider = (unsigned char *)decoded + AP_SIPHASH_DSIZE;
+
+        /* Verify authentication of the whole salt+IV+ciphertext by computing
+         * the MAC and comparing it (timing safe) with the one in the payload.
+         */
+        compute_auth(slider, len, passphrase, passlen, auth);
+        if (!ap_crypto_equals(auth, decoded, AP_SIPHASH_DSIZE)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(10006)
+                    "auth does not match, skipping");
+            continue;
+        }
+
+        /* encrypt using the first passphrase in the list */
+        res = apr_crypto_passphrase(&key, &ivSize, passphrase, passlen,
+                                    slider, sizeof(apr_uuid_t),
+                                    *cipher, APR_MODE_CBC, 1, 4096,
+                                    f, r->pool);
+        if (APR_STATUS_IS_ENOKEY(res)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01832)
+                    "failure generating key from passphrase");
+            continue;
+        }
+        else if (APR_STATUS_IS_EPADDING(res)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01833)
+                    "padding is not supported for cipher");
+            continue;
+        }
+        else if (APR_STATUS_IS_EKEYTYPE(res)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01834)
+                    "the key type is not known");
+            continue;
+        }
+        else if (APR_SUCCESS != res) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01835)
+                    "encryption could not be configured.");
+            continue;
+        }
+
+        /* sanity check - decoded too short? */
+        if (len < (sizeof(apr_uuid_t) + ivSize)) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, APR_SUCCESS, r, APLOGNO(01836)
+                    "too short to decrypt, skipping");
+            res = APR_ECRYPT;
+            continue;
+        }
+
+        /* bypass the salt at the start of the decoded block */
+        slider += sizeof(apr_uuid_t);
+        len -= sizeof(apr_uuid_t);
+
+        res = apr_crypto_block_decrypt_init(&block, &blockSize, slider, key,
+                                            r->pool);
+        if (APR_SUCCESS != res) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01837)
+                    "apr_crypto_block_decrypt_init failed");
+            continue;
+        }
+
+        /* bypass the iv at the start of the decoded block */
+        slider += ivSize;
+        len -= ivSize;
+
+        /* decrypt the given string */
+        res = apr_crypto_block_decrypt(&decrypted, &decryptedlen,
+                                       slider, len, block);
+        if (res) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01838)
+                    "apr_crypto_block_decrypt failed");
+            continue;
+        }
+        *out = (char *) decrypted;
+
+        res = apr_crypto_block_decrypt_finish(decrypted + decryptedlen, &tlen, block);
+        if (APR_SUCCESS != res) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01839)
+                    "apr_crypto_block_decrypt_finish failed");
+            continue;
+        }
+        decryptedlen += tlen;
+        decrypted[decryptedlen] = 0;
+
+        break;
+    }
+
+    if (APR_SUCCESS != res) {
+        ap_log_rerror(APLOG_MARK, APLOG_INFO, res, r, APLOGNO(01840)
+                "decryption failed");
+    }
+
+    return res;
+
+}
+
+/**
+ * Crypto encoding for the session.
+ *
+ * @param r The request pointer.
+ * @param z A pointer to where the session will be written.
+ */
+static apr_status_t session_crypto_encode(request_rec * r, session_rec * z)
+{
+
+    char *encoded = NULL;
+    apr_status_t res;
+    const apr_crypto_t *f = NULL;
+    session_crypto_dir_conf *dconf = ap_get_module_config(r->per_dir_config,
+            &session_crypto_module);
+
+    if (dconf->passphrases_set && z->encoded && *z->encoded) {
+        apr_pool_userdata_get((void **)&f, CRYPTO_KEY, r->server->process->pconf);
+        res = encrypt_string(r, f, dconf, z->encoded, &encoded);
+        if (res != OK) {
+            ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01841)
+                    "encrypt session failed");
+            return res;
+        }
+        z->encoded = encoded;
+    }
+
+    return OK;
+
+}
+
+/**
+ * Crypto decoding for the session.
+ *
+ * @param r The request pointer.
+ * @param z A pointer to where the session will be written.
+ */
+static apr_status_t session_crypto_decode(request_rec * r,
+        session_rec * z)
+{
+
+    char *encoded = NULL;
+    apr_status_t res;
+    const apr_crypto_t *f = NULL;
+    session_crypto_dir_conf *dconf = ap_get_module_config(r->per_dir_config,
+            &session_crypto_module);
+
+    if ((dconf->passphrases_set) && z->encoded && *z->encoded) {
+        apr_pool_userdata_get((void **)&f, CRYPTO_KEY,
+                r->server->process->pconf);
+        res = decrypt_string(r, f, dconf, z->encoded, &encoded);
+        if (res != APR_SUCCESS) {
+            ap_log_rerror(APLOG_MARK, APLOG_ERR, res, r, APLOGNO(01842)
+                    "decrypt session failed, wrong passphrase?");
+            return res;
+        }
+        z->encoded = encoded;
+    }
+
+    return OK;
+
+}
+
+/**
+ * Initialise the SSL in the post_config hook.
+ */
+static int session_crypto_init(apr_pool_t *p, apr_pool_t *plog,
+        apr_pool_t *ptemp, server_rec *s)
+{
+    const apr_crypto_driver_t *driver = NULL;
+    apr_crypto_t *f = NULL;
+
+    session_crypto_conf *conf = ap_get_module_config(s->module_config,
+            &session_crypto_module);
+
+    /* session_crypto_init() will be called twice. Don't bother
+     * going through all of the initialization on the first call
+     * because it will just be thrown away.*/
+    if (ap_state_query(AP_SQ_MAIN_STATE) == AP_SQ_MS_CREATE_PRE_CONFIG) {
+        return OK;
+    }
+
+    if (conf->library) {
+
+        const apu_err_t *err = NULL;
+        apr_status_t rv;
+
+        rv = apr_crypto_init(p);
+        if (APR_SUCCESS != rv) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(01843)
+                    "APR crypto could not be initialised");
+            return rv;
+        }
+
+        rv = apr_crypto_get_driver(&driver, conf->library, conf->params, &err, p);
+        if (APR_EREINIT == rv) {
+            ap_log_error(APLOG_MARK, APLOG_WARNING, rv, s, APLOGNO(01844)
+                    "warning: crypto for '%s' was already initialised, "
+                    "using existing configuration", conf->library);
+            rv = APR_SUCCESS;
+        }
+        if (APR_SUCCESS != rv && err) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(01845)
+                    "The crypto library '%s' could not be loaded: %s (%s: %d)", conf->library, err->msg, err->reason, err->rc);
+            return rv;
+        }
+        if (APR_ENOTIMPL == rv) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(01846)
+                    "The crypto library '%s' could not be found",
+                    conf->library);
+            return rv;
+        }
+        if (APR_SUCCESS != rv || !driver) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(01847)
+                    "The crypto library '%s' could not be loaded",
+                    conf->library);
+            return rv;
+        }
+
+        rv = apr_crypto_make(&f, driver, conf->params, p);
+        if (APR_SUCCESS != rv) {
+            ap_log_error(APLOG_MARK, APLOG_ERR, rv, s, APLOGNO(01848)
+                    "The crypto library '%s' could not be initialised",
+                    conf->library);
+            return rv;
+        }
+
+        ap_log_error(APLOG_MARK, APLOG_INFO, rv, s, APLOGNO(01849)
+                "The crypto library '%s' was loaded successfully",
+                conf->library);
+
+        apr_pool_userdata_set((const void *)f, CRYPTO_KEY,
+                apr_pool_cleanup_null, s->process->pconf);
+
+    }
+
+    return OK;
+}
+
+static void *create_session_crypto_config(apr_pool_t * p, server_rec *s)
+{
+    session_crypto_conf *new =
+    (session_crypto_conf *) apr_pcalloc(p, sizeof(session_crypto_conf));
+
+    /* if no library has been configured, set the recommended library
+     * as a sensible default.
+     */
+#ifdef APU_CRYPTO_RECOMMENDED_DRIVER
+    new->library = APU_CRYPTO_RECOMMENDED_DRIVER;
+#endif
+
+    return (void *) new;
+}
+
+static void *create_session_crypto_dir_config(apr_pool_t * p, char *dummy)
+{
+    session_crypto_dir_conf *new =
+    (session_crypto_dir_conf *) apr_pcalloc(p, sizeof(session_crypto_dir_conf));
+
+    new->passphrases = apr_array_make(p, 10, sizeof(char *));
+
+    /* default cipher AES256-SHA */
+    new->cipher = "aes256";
+
+    return (void *) new;
+}
+
+static void *merge_session_crypto_dir_config(apr_pool_t * p, void *basev, void *addv)
+{
+    session_crypto_dir_conf *new = (session_crypto_dir_conf *) apr_pcalloc(p, sizeof(session_crypto_dir_conf));
+    session_crypto_dir_conf *add = (session_crypto_dir_conf *) addv;
+    session_crypto_dir_conf *base = (session_crypto_dir_conf *) basev;
+
+    new->passphrases = (add->passphrases_set == 0) ? base->passphrases : add->passphrases;
+    new->passphrases_set = add->passphrases_set || base->passphrases_set;
+    new->cipher = (add->cipher_set == 0) ? base->cipher : add->cipher;
+    new->cipher_set = add->cipher_set || base->cipher_set;
+
+    return new;
+}
+
+static const char *set_crypto_driver(cmd_parms * cmd, void *config, const char *arg)
+{
+    session_crypto_conf *conf =
+    (session_crypto_conf *)ap_get_module_config(cmd->server->module_config,
+            &session_crypto_module);
+
+    const char *err = ap_check_cmd_context(cmd, GLOBAL_ONLY);
+
+    if (err != NULL) {
+        return err;
+    }
+
+    conf->library = ap_getword_conf(cmd->pool, &arg);
+    conf->params = arg;
+    conf->library_set = 1;
+
+    return NULL;
+}
+
+static const char *set_crypto_passphrase(cmd_parms * cmd, void *config, const char *arg)
+{
+    int arglen = strlen(arg);
+    char **argv;
+    char *result;
+    const char **passphrase;
+    session_crypto_dir_conf *dconf = (session_crypto_dir_conf *) config;
+
+    passphrase = apr_array_push(dconf->passphrases);
+
+    if ((arglen > 5) && strncmp(arg, "exec:", 5) == 0) {
+        if (apr_tokenize_to_argv(arg+5, &argv, cmd->temp_pool) != APR_SUCCESS) {
+            return apr_pstrcat(cmd->pool,
+                               "Unable to parse exec arguments from ",
+                               arg+5, NULL);
+        }
+        argv[0] = ap_server_root_relative(cmd->temp_pool, argv[0]);
+
+        if (!argv[0]) {
+            return apr_pstrcat(cmd->pool,
+                               "Invalid SessionCryptoPassphrase exec location:",
+                               arg+5, NULL);
+        }
+        result = ap_get_exec_line(cmd->pool,
+                                  (const char*)argv[0], (const char * const *)argv);
+
+        if(!result) {
+            return apr_pstrcat(cmd->pool,
+                               "Unable to get bind password from exec of ",
+                               arg+5, NULL);
+        }
+        *passphrase = result;
+    }
+    else {
+        *passphrase = arg;
+    }
+
+    dconf->passphrases_set = 1;
+
+    return NULL;
+}
+
+static const char *set_crypto_passphrase_file(cmd_parms *cmd, void *config,
+                                  const char *filename)
+{
+    char buffer[MAX_STRING_LEN];
+    char *arg;
+    const char *args;
+    ap_configfile_t *file;
+    apr_status_t rv;
+
+    filename = ap_server_root_relative(cmd->temp_pool, filename);
+    rv = ap_pcfg_openfile(&file, cmd->temp_pool, filename);
+    if (rv != APR_SUCCESS) {
+        return apr_psprintf(cmd->pool, "%s: Could not open file %s: %pm",
+                            cmd->cmd->name, filename, &rv);
+    }
+
+    while (!(ap_cfg_getline(buffer, sizeof(buffer), file))) {
+        args = buffer;
+        while (*(arg = ap_getword_conf(cmd->pool, &args)) != '\0') {
+            if (*arg == '#') {
+                break;
+            }
+            set_crypto_passphrase(cmd, config, arg);
+        }
+    }
+
+    ap_cfg_closefile(file);
+
+    return NULL;
+}
+
+static const char *set_crypto_cipher(cmd_parms * cmd, void *config, const char *cipher)
+{
+    session_crypto_dir_conf *dconf = (session_crypto_dir_conf *) config;
+
+    dconf->cipher = cipher;
+    dconf->cipher_set = 1;
+
+    return NULL;
+}
+
+static const command_rec session_crypto_cmds[] =
+{
+    AP_INIT_ITERATE("SessionCryptoPassphrase", set_crypto_passphrase, NULL, RSRC_CONF|OR_AUTHCFG,
+            "The passphrase(s) used to encrypt the session. First will be used for encryption, all phrases will be accepted for decryption"),
+    AP_INIT_TAKE1("SessionCryptoPassphraseFile", set_crypto_passphrase_file, NULL, RSRC_CONF|ACCESS_CONF,
+            "File containing passphrase(s) used to encrypt the session, one per line. First will be used for encryption, all phrases will be accepted for decryption"),
+    AP_INIT_TAKE1("SessionCryptoCipher", set_crypto_cipher, NULL, RSRC_CONF|OR_AUTHCFG,
+            "The underlying crypto cipher to use"),
+    AP_INIT_RAW_ARGS("SessionCryptoDriver", set_crypto_driver, NULL, RSRC_CONF,
+            "The underlying crypto library driver to use"),
+    { NULL }
+};
+
+static void register_hooks(apr_pool_t * p)
+{
+    ap_hook_session_encode(session_crypto_encode, NULL, NULL, APR_HOOK_LAST);
+    ap_hook_session_decode(session_crypto_decode, NULL, NULL, APR_HOOK_FIRST);
+    ap_hook_post_config(session_crypto_init, NULL, NULL, APR_HOOK_LAST);
+}
+
+AP_DECLARE_MODULE(session_crypto) =
+{
+    STANDARD20_MODULE_STUFF,
+    create_session_crypto_dir_config, /* dir config creater */
+    merge_session_crypto_dir_config, /* dir merger --- default is to override */
+    create_session_crypto_config, /* server config */
+    NULL, /* merge server config */
+    session_crypto_cmds, /* command apr_table_t */
+    register_hooks /* register hooks */
+};
+
+#endif