diff options
author | Andy Polyakov <appro@openssl.org> | 2016-08-21 23:30:37 +0200 |
---|---|---|
committer | Andy Polyakov <appro@openssl.org> | 2016-08-21 23:34:12 +0200 |
commit | c1a7dcbe16c6bff38390db1964b76c16b6802c7d (patch) | |
tree | abdc328320d1f0ace4f69c679daad02a2a55f826 /crypto | |
parent | 2e929e538caee6be857ae78ed4e03404857a074a (diff) |
evp/bio_enc.c: refine non-overlapping logic.
RT#4628
Reviewed-by: Rich Salz <rsalz@openssl.org>
Diffstat (limited to 'crypto')
-rw-r--r-- | crypto/evp/bio_enc.c | 69 |
1 files changed, 42 insertions, 27 deletions
diff --git a/crypto/evp/bio_enc.c b/crypto/evp/bio_enc.c index 47d0384b4d..e3aaadb11e 100644 --- a/crypto/evp/bio_enc.c +++ b/crypto/evp/bio_enc.c @@ -27,7 +27,8 @@ static int enc_new(BIO *h); static int enc_free(BIO *data); static long enc_callback_ctrl(BIO *h, int cmd, bio_info_cb *fps); #define ENC_BLOCK_SIZE (1024*4) -#define BUF_OFFSET (EVP_MAX_BLOCK_LENGTH*2) +#define ENC_MIN_CHUNK (256) +#define BUF_OFFSET (ENC_MIN_CHUNK + EVP_MAX_BLOCK_LENGTH) typedef struct enc_struct { int buf_len; @@ -36,11 +37,12 @@ typedef struct enc_struct { int finished; int ok; /* bad decrypt */ EVP_CIPHER_CTX *cipher; + unsigned char *read_start, *read_end; /* * buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate can return * up to a block more data than is presented to it */ - unsigned char buf[ENC_BLOCK_SIZE + BUF_OFFSET + 2]; + unsigned char buf[BUF_OFFSET + ENC_BLOCK_SIZE]; } BIO_ENC_CTX; static const BIO_METHOD methods_enc = { @@ -75,6 +77,7 @@ static int enc_new(BIO *bi) } ctx->cont = 1; ctx->ok = 1; + ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]); BIO_set_data(bi, ctx); BIO_set_init(bi, 1); @@ -102,7 +105,7 @@ static int enc_free(BIO *a) static int enc_read(BIO *b, char *out, int outl) { - int ret = 0, i; + int ret = 0, i, blocksize; BIO_ENC_CTX *ctx; BIO *next; @@ -130,27 +133,24 @@ static int enc_read(BIO *b, char *out, int outl) } } + blocksize = EVP_CIPHER_CTX_block_size(ctx->cipher); + if (blocksize == 1) + blocksize = 0; + /* * At this point, we have room of outl bytes and an empty buffer, so we * should read in some more. */ while (outl > 0) { - int buf_len; - if (ctx->cont <= 0) break; - buf_len = outl + EVP_MAX_BLOCK_LENGTH - 1; - buf_len -= buf_len % EVP_MAX_BLOCK_LENGTH; - if (buf_len > ENC_BLOCK_SIZE) { - buf_len = ENC_BLOCK_SIZE; + if (ctx->read_start == ctx->read_end) { /* time to read more data */ + ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]); + ctx->read_end += BIO_read(next, ctx->read_start, ENC_BLOCK_SIZE); } - - /* - * read in at IV offset, read the EVP_Cipher documentation about why - */ - i = BIO_read(next, &(ctx->buf[BUF_OFFSET]), buf_len); + i = ctx->read_end - ctx->read_start; if (i <= 0) { /* Should be continue next time we are called? */ @@ -164,26 +164,41 @@ static int enc_read(BIO *b, char *out, int outl) ret = (ret == 0) ? i : ret; break; } - } else if (outl >= EVP_MAX_BLOCK_LENGTH) { - if (!EVP_CipherUpdate(ctx->cipher, - (unsigned char *)out, &buf_len, - &(ctx->buf[BUF_OFFSET]), i)) { - BIO_clear_retry_flags(b); - return 0; - } - ret += buf_len; - outl -= buf_len; - out += buf_len; - - continue; } else { + if (outl > ENC_MIN_CHUNK) { + /* + * Depending on flags block cipher decrypt can write + * one extra block and then back off, i.e. output buffer + * has to accommodate extra block... + */ + int j = outl - blocksize, buf_len; + + if (!EVP_CipherUpdate(ctx->cipher, + (unsigned char *)out, &buf_len, + ctx->read_start, i > j ? j : i)) { + BIO_clear_retry_flags(b); + return 0; + } + ret += buf_len; + out += buf_len; + outl -= buf_len; + + if ((i -= j) <= 0) { + ctx->read_start = ctx->read_end; + continue; + } + ctx->read_start += j; + } + if (i > ENC_MIN_CHUNK) + i = ENC_MIN_CHUNK; if (!EVP_CipherUpdate(ctx->cipher, ctx->buf, &ctx->buf_len, - &(ctx->buf[BUF_OFFSET]), i)) { + ctx->read_start, i)) { BIO_clear_retry_flags(b); ctx->ok = 0; return 0; } + ctx->read_start += i; ctx->cont = 1; /* * Note: it is possible for EVP_CipherUpdate to decrypt zero |