diff --git a/modules/session/mod_session_crypto.c b/modules/session/mod_session_crypto.c
index 4d65bb8..9231a5e 100644
--- a/modules/session/mod_session_crypto.c
+++ b/modules/session/mod_session_crypto.c
@@ -18,6 +18,7 @@
#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"
@@ -57,6 +58,146 @@ typedef struct {
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.
*
@@ -128,21 +269,14 @@ static apr_status_t encrypt_string(request_rec * r, const apr_crypto_t *f,
apr_crypto_block_t *block = NULL;
unsigned char *encrypt = NULL;
unsigned char *combined = NULL;
- apr_size_t encryptlen, tlen;
+ 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;
-
- /* by default, return an empty string */
- *out = "";
-
- /* don't attempt to encrypt an empty string, trying to do so causes a segfault */
- if (!in || !*in) {
- return APR_SUCCESS;
- }
+ apr_size_t passlen;
/* use a uuid as a salt value, and prepend it to our result */
apr_uuid_get(&salt);
@@ -152,9 +286,9 @@ static apr_status_t encrypt_string(request_rec * r, const apr_crypto_t *f,
}
/* encrypt using the first passphrase in the list */
- passphrase = APR_ARRAY_IDX(dconf->passphrases, 0, char *);
- res = apr_crypto_passphrase(&key, &ivSize, passphrase,
- strlen(passphrase),
+ 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)) {
@@ -183,8 +317,9 @@ static apr_status_t encrypt_string(request_rec * r, const apr_crypto_t *f,
}
/* encrypt the given string */
- res = apr_crypto_block_encrypt(&encrypt, &encryptlen, (unsigned char *)in,
- strlen(in), block);
+ 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");
@@ -198,18 +333,20 @@ static apr_status_t encrypt_string(request_rec * r, const apr_crypto_t *f,
}
encryptlen += tlen;
- /* prepend the salt and the iv to the result */
- combined = apr_palloc(r->pool, ivSize + encryptlen + sizeof(apr_uuid_t));
- memcpy(combined, &salt, sizeof(apr_uuid_t));
- memcpy(combined + sizeof(apr_uuid_t), iv, ivSize);
- memcpy(combined + sizeof(apr_uuid_t) + ivSize, encrypt, encryptlen);
-
- /* base64 encode the result */
- base64 = apr_palloc(r->pool, apr_base64_encode_len(ivSize + encryptlen +
- sizeof(apr_uuid_t) + 1)
- * sizeof(char));
- apr_base64_encode(base64, (const char *) combined,
- ivSize + encryptlen + sizeof(apr_uuid_t));
+ /* 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;
@@ -234,6 +371,7 @@ static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
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 */
@@ -241,6 +379,13 @@ static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
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()
+ "too short to decrypt, aborting");
+ return APR_ECRYPT;
+ }
+
res = crypt_init(r, f, &cipher, dconf);
if (res != APR_SUCCESS) {
return res;
@@ -249,14 +394,25 @@ static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
/* try each passphrase in turn */
for (; i < dconf->passphrases->nelts; i++) {
const char *passphrase = APR_ARRAY_IDX(dconf->passphrases, i, char *);
- apr_size_t len = decodedlen;
- char *slider = decoded;
+ 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()
+ "auth does not match, skipping");
+ continue;
+ }
/* encrypt using the first passphrase in the list */
- res = apr_crypto_passphrase(&key, &ivSize, passphrase,
- strlen(passphrase),
- (unsigned char *)decoded, sizeof(apr_uuid_t),
- *cipher, APR_MODE_CBC, 1, 4096, f, r->pool);
+ 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)
"the passphrase '%s' was empty", passphrase);
@@ -279,7 +435,7 @@ static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
}
/* sanity check - decoded too short? */
- if (decodedlen < (sizeof(apr_uuid_t) + ivSize)) {
+ 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;
@@ -290,8 +446,8 @@ static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
slider += sizeof(apr_uuid_t);
len -= sizeof(apr_uuid_t);
- res = apr_crypto_block_decrypt_init(&block, &blockSize, (unsigned char *)slider, key,
- r->pool);
+ 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");
@@ -304,7 +460,7 @@ static apr_status_t decrypt_string(request_rec * r, const apr_crypto_t *f,
/* decrypt the given string */
res = apr_crypto_block_decrypt(&decrypted, &decryptedlen,
- (unsigned char *)slider, len, block);
+ slider, len, block);
if (res) {
ap_log_rerror(APLOG_MARK, APLOG_DEBUG, res, r, APLOGNO(01838)
"apr_crypto_block_decrypt failed");