diff options
Diffstat (limited to 'freebsd/crypto/openssl/crypto/rsa/rsa_ssl.c')
| -rw-r--r-- | freebsd/crypto/openssl/crypto/rsa/rsa_ssl.c | 138 |
1 files changed, 100 insertions, 38 deletions
diff --git a/freebsd/crypto/openssl/crypto/rsa/rsa_ssl.c b/freebsd/crypto/openssl/crypto/rsa/rsa_ssl.c index d57a43ed..b5d91c90 100644 --- a/freebsd/crypto/openssl/crypto/rsa/rsa_ssl.c +++ b/freebsd/crypto/openssl/crypto/rsa/rsa_ssl.c @@ -1,7 +1,7 @@ #include <machine/rtems-bsd-user-space.h> /* - * Copyright 1995-2018 The OpenSSL Project Authors. All Rights Reserved. + * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved. * * Licensed under the OpenSSL license (the "License"). You may not use * this file except in compliance with the License. You can obtain a copy @@ -14,6 +14,7 @@ #include <openssl/bn.h> #include <openssl/rsa.h> #include <openssl/rand.h> +#include "internal/constant_time_locl.h" int RSA_padding_add_SSLv23(unsigned char *to, int tlen, const unsigned char *from, int flen) @@ -54,57 +55,118 @@ int RSA_padding_add_SSLv23(unsigned char *to, int tlen, return 1; } +/* + * Copy of RSA_padding_check_PKCS1_type_2 with a twist that rejects padding + * if nul delimiter is not preceded by 8 consecutive 0x03 bytes. It also + * preserves error code reporting for backward compatibility. + */ int RSA_padding_check_SSLv23(unsigned char *to, int tlen, const unsigned char *from, int flen, int num) { - int i, j, k; - const unsigned char *p; + int i; + /* |em| is the encoded message, zero-padded to exactly |num| bytes */ + unsigned char *em = NULL; + unsigned int good, found_zero_byte, mask, threes_in_row; + int zero_index = 0, msg_index, mlen = -1, err; + + if (tlen <= 0 || flen <= 0) + return -1; - p = from; - if (flen < 10) { + if (flen > num || num < 11) { RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_SMALL); return -1; } - /* Accept even zero-padded input */ - if (flen == num) { - if (*(p++) != 0) { - RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_BLOCK_TYPE_IS_NOT_02); - return -1; - } - flen--; - } - if ((num != (flen + 1)) || (*(p++) != 02)) { - RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_BLOCK_TYPE_IS_NOT_02); + + em = OPENSSL_malloc(num); + if (em == NULL) { + RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, ERR_R_MALLOC_FAILURE); return -1; } + /* + * Caller is encouraged to pass zero-padded message created with + * BN_bn2binpad. Trouble is that since we can't read out of |from|'s + * bounds, it's impossible to have an invariant memory access pattern + * in case |from| was not zero-padded in advance. + */ + for (from += flen, em += num, i = 0; i < num; i++) { + mask = ~constant_time_is_zero(flen); + flen -= 1 & mask; + from -= 1 & mask; + *--em = *from & mask; + } + + good = constant_time_is_zero(em[0]); + good &= constant_time_eq(em[1], 2); + err = constant_time_select_int(good, 0, RSA_R_BLOCK_TYPE_IS_NOT_02); + mask = ~good; /* scan over padding data */ - j = flen - 1; /* one for type */ - for (i = 0; i < j; i++) - if (*(p++) == 0) - break; - - if ((i == j) || (i < 8)) { - RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, - RSA_R_NULL_BEFORE_BLOCK_MISSING); - return -1; + found_zero_byte = 0; + threes_in_row = 0; + for (i = 2; i < num; i++) { + unsigned int equals0 = constant_time_is_zero(em[i]); + + zero_index = constant_time_select_int(~found_zero_byte & equals0, + i, zero_index); + found_zero_byte |= equals0; + + threes_in_row += 1 & ~found_zero_byte; + threes_in_row &= found_zero_byte | constant_time_eq(em[i], 3); } - for (k = -9; k < -1; k++) { - if (p[k] != 0x03) - break; + + /* + * PS must be at least 8 bytes long, and it starts two bytes into |em|. + * If we never found a 0-byte, then |zero_index| is 0 and the check + * also fails. + */ + good &= constant_time_ge(zero_index, 2 + 8); + err = constant_time_select_int(mask | good, err, + RSA_R_NULL_BEFORE_BLOCK_MISSING); + mask = ~good; + + good &= constant_time_ge(threes_in_row, 8); + err = constant_time_select_int(mask | good, err, + RSA_R_SSLV3_ROLLBACK_ATTACK); + mask = ~good; + + /* + * Skip the zero byte. This is incorrect if we never found a zero-byte + * but in this case we also do not copy the message out. + */ + msg_index = zero_index + 1; + mlen = num - msg_index; + + /* + * For good measure, do this check in constant time as well. + */ + good &= constant_time_ge(tlen, mlen); + err = constant_time_select_int(mask | good, err, RSA_R_DATA_TOO_LARGE); + + /* + * Move the result in-place by |num|-11-|mlen| bytes to the left. + * Then if |good| move |mlen| bytes from |em|+11 to |to|. + * Otherwise leave |to| unchanged. + * Copy the memory back in a way that does not reveal the size of + * the data being copied via a timing side channel. This requires copying + * parts of the buffer multiple times based on the bits set in the real + * length. Clear bits do a non-copy with identical access pattern. + * The loop below has overall complexity of O(N*log(N)). + */ + tlen = constant_time_select_int(constant_time_lt(num - 11, tlen), + num - 11, tlen); + for (msg_index = 1; msg_index < num - 11; msg_index <<= 1) { + mask = ~constant_time_eq(msg_index & (num - 11 - mlen), 0); + for (i = 11; i < num - msg_index; i++) + em[i] = constant_time_select_8(mask, em[i + msg_index], em[i]); } - if (k == -1) { - RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_SSLV3_ROLLBACK_ATTACK); - return -1; + for (i = 0; i < tlen; i++) { + mask = good & constant_time_lt(i, mlen); + to[i] = constant_time_select_8(mask, em[i + 11], to[i]); } - i++; /* Skip over the '\0' */ - j -= i; - if (j > tlen) { - RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, RSA_R_DATA_TOO_LARGE); - return -1; - } - memcpy(to, p, (unsigned int)j); + OPENSSL_clear_free(em, num); + RSAerr(RSA_F_RSA_PADDING_CHECK_SSLV23, err); + err_clear_last_constant_time(1 & good); - return j; + return constant_time_select_int(good, mlen, -1); } |