Move more SSL3_RECORD oriented functions into ssl3_record.c

Reviewed-by: Richard Levitte <levitte@openssl.org>

1 files changed, 0 insertions, 220 deletions

diff --git a/ssl/s3_cbc.c b/ssl/s3_cbc.c
index 53e3c8764c..b20c564084 100644
--- a/ssl/s3_cbc.c
+++ b/ssl/s3_cbc.c
@@ -72,227 +72,7 @@
  */
 #define MAX_HASH_BLOCK_SIZE 128
 
-/*-
- * ssl3_cbc_remove_padding removes padding from the decrypted, SSLv3, CBC
- * record in |rec| by updating |rec->length| in constant time.
- *
- * block_size: the block size of the cipher used to encrypt the record.
- * returns:
- *   0: (in non-constant time) if the record is publicly invalid.
- *   1: if the padding was valid
- *  -1: otherwise.
- */
-int ssl3_cbc_remove_padding(const SSL *s,
-                            SSL3_RECORD *rec,
-                            unsigned block_size, unsigned mac_size)
-{
-    unsigned padding_length, good;
-    const unsigned overhead = 1 /* padding length byte */  + mac_size;
-
-    /*
-     * These lengths are all public so we can test them in non-constant time.
-     */
-    if (overhead > rec->length)
-        return 0;
-
-    padding_length = rec->data[rec->length - 1];
-    good = constant_time_ge(rec->length, padding_length + overhead);
-    /* SSLv3 requires that the padding is minimal. */
-    good &= constant_time_ge(block_size, padding_length + 1);
-    rec->length -= good & (padding_length + 1);
-    return constant_time_select_int(good, 1, -1);
-}
-
-/*-
- * tls1_cbc_remove_padding removes the CBC padding from the decrypted, TLS, CBC
- * record in |rec| in constant time and returns 1 if the padding is valid and
- * -1 otherwise. It also removes any explicit IV from the start of the record
- * without leaking any timing about whether there was enough space after the
- * padding was removed.
- *
- * block_size: the block size of the cipher used to encrypt the record.
- * returns:
- *   0: (in non-constant time) if the record is publicly invalid.
- *   1: if the padding was valid
- *  -1: otherwise.
- */
-int tls1_cbc_remove_padding(const SSL *s,
-                            SSL3_RECORD *rec,
-                            unsigned block_size, unsigned mac_size)
-{
-    unsigned padding_length, good, to_check, i;
-    const unsigned overhead = 1 /* padding length byte */  + mac_size;
-    /* Check if version requires explicit IV */
-    if (SSL_USE_EXPLICIT_IV(s)) {
-        /*
-         * These lengths are all public so we can test them in non-constant
-         * time.
-         */
-        if (overhead + block_size > rec->length)
-            return 0;
-        /* We can now safely skip explicit IV */
-        rec->data += block_size;
-        rec->input += block_size;
-        rec->length -= block_size;
-        rec->orig_len -= block_size;
-    } else if (overhead > rec->length)
-        return 0;
-
-    padding_length = rec->data[rec->length - 1];
-
-    /*
-     * NB: if compression is in operation the first packet may not be of even
-     * length so the padding bug check cannot be performed. This bug
-     * workaround has been around since SSLeay so hopefully it is either
-     * fixed now or no buggy implementation supports compression [steve]
-     */
-    if ((s->options & SSL_OP_TLS_BLOCK_PADDING_BUG) && !s->expand) {
-        /* First packet is even in size, so check */
-        if ((memcmp(s->s3->read_sequence, "\0\0\0\0\0\0\0\0", 8) == 0) &&
-            !(padding_length & 1)) {
-            s->s3->flags |= TLS1_FLAGS_TLS_PADDING_BUG;
-        }
-        if ((s->s3->flags & TLS1_FLAGS_TLS_PADDING_BUG) && padding_length > 0) {
-            padding_length--;
-        }
-    }
-
-    if (EVP_CIPHER_flags(s->enc_read_ctx->cipher) & EVP_CIPH_FLAG_AEAD_CIPHER) {
-        /* padding is already verified */
-        rec->length -= padding_length + 1;
-        return 1;
-    }
-
-    good = constant_time_ge(rec->length, overhead + padding_length);
-    /*
-     * The padding consists of a length byte at the end of the record and
-     * then that many bytes of padding, all with the same value as the length
-     * byte. Thus, with the length byte included, there are i+1 bytes of
-     * padding. We can't check just |padding_length+1| bytes because that
-     * leaks decrypted information. Therefore we always have to check the
-     * maximum amount of padding possible. (Again, the length of the record
-     * is public information so we can use it.)
-     */
-    to_check = 255;             /* maximum amount of padding. */
-    if (to_check > rec->length - 1)
-        to_check = rec->length - 1;
-
-    for (i = 0; i < to_check; i++) {
-        unsigned char mask = constant_time_ge_8(padding_length, i);
-        unsigned char b = rec->data[rec->length - 1 - i];
-        /*
-         * The final |padding_length+1| bytes should all have the value
-         * |padding_length|. Therefore the XOR should be zero.
-         */
-        good &= ~(mask & (padding_length ^ b));
-    }
-
-    /*
-     * If any of the final |padding_length+1| bytes had the wrong value, one
-     * or more of the lower eight bits of |good| will be cleared.
-     */
-    good = constant_time_eq(0xff, good & 0xff);
-    rec->length -= good & (padding_length + 1);
-
-    return constant_time_select_int(good, 1, -1);
-}
-
-/*-
- * ssl3_cbc_copy_mac copies |md_size| bytes from the end of |rec| to |out| in
- * constant time (independent of the concrete value of rec->length, which may
- * vary within a 256-byte window).
- *
- * ssl3_cbc_remove_padding or tls1_cbc_remove_padding must be called prior to
- * this function.
- *
- * On entry:
- *   rec->orig_len >= md_size
- *   md_size <= EVP_MAX_MD_SIZE
- *
- * If CBC_MAC_ROTATE_IN_PLACE is defined then the rotation is performed with
- * variable accesses in a 64-byte-aligned buffer. Assuming that this fits into
- * a single or pair of cache-lines, then the variable memory accesses don't
- * actually affect the timing. CPUs with smaller cache-lines [if any] are
- * not multi-core and are not considered vulnerable to cache-timing attacks.
- */
-#define CBC_MAC_ROTATE_IN_PLACE
-
-void ssl3_cbc_copy_mac(unsigned char *out,
-                       const SSL3_RECORD *rec, unsigned md_size)
-{
-#if defined(CBC_MAC_ROTATE_IN_PLACE)
-    unsigned char rotated_mac_buf[64 + EVP_MAX_MD_SIZE];
-    unsigned char *rotated_mac;
-#else
-    unsigned char rotated_mac[EVP_MAX_MD_SIZE];
-#endif
 
-    /*
-     * mac_end is the index of |rec->data| just after the end of the MAC.
-     */
-    unsigned mac_end = rec->length;
-    unsigned mac_start = mac_end - md_size;
-    /*
-     * scan_start contains the number of bytes that we can ignore because the
-     * MAC's position can only vary by 255 bytes.
-     */
-    unsigned scan_start = 0;
-    unsigned i, j;
-    unsigned div_spoiler;
-    unsigned rotate_offset;
-
-    OPENSSL_assert(rec->orig_len >= md_size);
-    OPENSSL_assert(md_size <= EVP_MAX_MD_SIZE);
-
-#if defined(CBC_MAC_ROTATE_IN_PLACE)
-    rotated_mac = rotated_mac_buf + ((0 - (size_t)rotated_mac_buf) & 63);
-#endif
-
-    /* This information is public so it's safe to branch based on it. */
-    if (rec->orig_len > md_size + 255 + 1)
-        scan_start = rec->orig_len - (md_size + 255 + 1);
-    /*
-     * div_spoiler contains a multiple of md_size that is used to cause the
-     * modulo operation to be constant time. Without this, the time varies
-     * based on the amount of padding when running on Intel chips at least.
-     * The aim of right-shifting md_size is so that the compiler doesn't
-     * figure out that it can remove div_spoiler as that would require it to
-     * prove that md_size is always even, which I hope is beyond it.
-     */
-    div_spoiler = md_size >> 1;
-    div_spoiler <<= (sizeof(div_spoiler) - 1) * 8;
-    rotate_offset = (div_spoiler + mac_start - scan_start) % md_size;
-
-    memset(rotated_mac, 0, md_size);
-    for (i = scan_start, j = 0; i < rec->orig_len; i++) {
-        unsigned char mac_started = constant_time_ge_8(i, mac_start);
-        unsigned char mac_ended = constant_time_ge_8(i, mac_end);
-        unsigned char b = rec->data[i];
-        rotated_mac[j++] |= b & mac_started & ~mac_ended;
-        j &= constant_time_lt(j, md_size);
-    }
-
-    /* Now rotate the MAC */
-#if defined(CBC_MAC_ROTATE_IN_PLACE)
-    j = 0;
-    for (i = 0; i < md_size; i++) {
-        /* in case cache-line is 32 bytes, touch second line */
-        ((volatile unsigned char *)rotated_mac)[rotate_offset ^ 32];
-        out[j++] = rotated_mac[rotate_offset++];
-        rotate_offset &= constant_time_lt(rotate_offset, md_size);
-    }
-#else
-    memset(out, 0, md_size);
-    rotate_offset = md_size - rotate_offset;
-    rotate_offset &= constant_time_lt(rotate_offset, md_size);
-    for (i = 0; i < md_size; i++) {
-        for (j = 0; j < md_size; j++)
-            out[j] |= rotated_mac[i] & constant_time_eq_8(j, rotate_offset);
-        rotate_offset++;
-        rotate_offset &= constant_time_lt(rotate_offset, md_size);
-    }
-#endif
-}
 
 /*
  * u32toLE serialises an unsigned, 32-bit number (n) as four bytes at (p) in