diff options
author | David Benjamin <davidben@chromium.org> | 2015-08-11 18:47:56 +0300 |
---|---|---|
committer | Adam Langley <agl@google.com> | 2015-08-17 23:26:47 +0300 |
commit | 0257cffb4e5eaed6b89746c37a770eff2683becf (patch) | |
tree | 95ea8b50c9c4c6f4dfdcc8c1f8868517a520e04b /crypto/bn | |
parent | 2b9ec7055844ae2d0b0a9567191fcf6de110c70f (diff) |
Tidy up BN decimal and hex decode functions.
Move the bn_expand call inside decode_hex; it's an implementation detail of
hex-decoding. decode_dec instead works with BN_mul_word and BN_add_word so it
can just rely on BN internally expanding things and check the return value.
Also clean up the decode_hex loop so it's somewhat more readable and check for
INT_MAX in bn_x2bn. It uses int over size_t rather pervasively, but while I'm
here at least make that function check overflow.
BUG=517474
Change-Id: I4f043973ee43071a02ea5d4313a8fdaf12404e84
Reviewed-on: https://boringssl-review.googlesource.com/5679
Reviewed-by: Adam Langley <agl@google.com>
Diffstat (limited to 'crypto/bn')
-rw-r--r-- | crypto/bn/convert.c | 88 |
1 files changed, 51 insertions, 37 deletions
diff --git a/crypto/bn/convert.c b/crypto/bn/convert.c index 4c707473..610dc9fd 100644 --- a/crypto/bn/convert.c +++ b/crypto/bn/convert.c @@ -56,7 +56,9 @@ #include <openssl/bn.h> +#include <assert.h> #include <ctype.h> +#include <limits.h> #include <stdio.h> #include <string.h> @@ -227,47 +229,59 @@ char *BN_bn2hex(const BIGNUM *bn) { return buf; } -/* decode_hex decodes |i| bytes of hex data from |in| and updates |bn|. */ -static void decode_hex(BIGNUM *bn, const char *in, int i) { - int h, m, j, k, c; - BN_ULONG l=0; - - j = i; /* least significant 'hex' */ - h = 0; - while (j > 0) { - m = ((BN_BYTES * 2) <= j) ? (BN_BYTES * 2) : j; - l = 0; - for (;;) { - c = in[j - m]; - if ((c >= '0') && (c <= '9')) { - k = c - '0'; - } else if ((c >= 'a') && (c <= 'f')) { - k = c - 'a' + 10; - } else if ((c >= 'A') && (c <= 'F')) { - k = c - 'A' + 10; - } else { - k = 0; /* paranoia */ - } +/* decode_hex decodes |in_len| bytes of hex data from |in| and updates |bn|. */ +static int decode_hex(BIGNUM *bn, const char *in, int in_len) { + if (in_len > INT_MAX/4) { + OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG); + return 0; + } + /* |in_len| is the number of hex digits. */ + if (bn_expand(bn, in_len * 4) == NULL) { + return 0; + } - l = (l << 4) | k; + int i = 0; + while (in_len > 0) { + /* Decode one |BN_ULONG| at a time. */ + int todo = BN_BYTES * 2; + if (todo > in_len) { + todo = in_len; + } - if (--m <= 0) { - bn->d[h++] = l; - break; + BN_ULONG word = 0; + int j; + for (j = todo; j > 0; j--) { + char c = in[in_len - j]; + + BN_ULONG hex; + if (c >= '0' && c <= '9') { + hex = c - '0'; + } else if (c >= 'a' && c <= 'f') { + hex = c - 'a' + 10; + } else if (c >= 'A' && c <= 'F') { + hex = c - 'A' + 10; + } else { + hex = 0; + /* This shouldn't happen. The caller checks |isxdigit|. */ + assert(0); } + word = (word << 4) | hex; } - j -= (BN_BYTES * 2); + bn->d[i++] = word; + in_len -= todo; } - - bn->top = h; + assert(i <= bn->dmax); + bn->top = i; + return 1; } /* decode_dec decodes |in_len| bytes of decimal data from |in| and updates |bn|. */ -static void decode_dec(BIGNUM *bn, const char *in, int in_len) { +static int decode_dec(BIGNUM *bn, const char *in, int in_len) { int i, j; BN_ULONG l = 0; + /* Decode |BN_DEC_NUM| digits at a time. */ j = BN_DEC_NUM - (in_len % BN_DEC_NUM); if (j == BN_DEC_NUM) { j = 0; @@ -277,15 +291,18 @@ static void decode_dec(BIGNUM *bn, const char *in, int in_len) { l *= 10; l += in[i] - '0'; if (++j == BN_DEC_NUM) { - BN_mul_word(bn, BN_DEC_CONV); - BN_add_word(bn, l); + if (!BN_mul_word(bn, BN_DEC_CONV) || + !BN_add_word(bn, l)) { + return 0; + } l = 0; j = 0; } } + return 1; } -typedef void (*decode_func) (BIGNUM *bn, const char *in, int i); +typedef int (*decode_func) (BIGNUM *bn, const char *in, int in_len); typedef int (*char_test_func) (int c); static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_func want_char) { @@ -302,7 +319,7 @@ static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_ in++; } - for (i = 0; want_char((unsigned char)in[i]); i++) {} + for (i = 0; want_char((unsigned char)in[i]) && i + neg < INT_MAX; i++) {} num = i + neg; if (outp == NULL) { @@ -320,13 +337,10 @@ static int bn_x2bn(BIGNUM **outp, const char *in, decode_func decode, char_test_ BN_zero(ret); } - /* i is the number of hex digests; */ - if (bn_expand(ret, i * 4) == NULL) { + if (!decode(ret, in, i)) { goto err; } - decode(ret, in, i); - bn_correct_top(ret); if (!BN_is_zero(ret)) { ret->neg = neg; |