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evp/bio_enc.c: refine non-overlapping logic.
RT#4628 Reviewed-by: Rich Salz <rsalz@openssl.org>
This commit is contained in:
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2e929e538c
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@ -27,7 +27,8 @@ static int enc_new(BIO *h);
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static int enc_free(BIO *data);
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static int enc_free(BIO *data);
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static long enc_callback_ctrl(BIO *h, int cmd, bio_info_cb *fps);
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static long enc_callback_ctrl(BIO *h, int cmd, bio_info_cb *fps);
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#define ENC_BLOCK_SIZE (1024*4)
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#define ENC_BLOCK_SIZE (1024*4)
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#define BUF_OFFSET (EVP_MAX_BLOCK_LENGTH*2)
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#define ENC_MIN_CHUNK (256)
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#define BUF_OFFSET (ENC_MIN_CHUNK + EVP_MAX_BLOCK_LENGTH)
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typedef struct enc_struct {
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typedef struct enc_struct {
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int buf_len;
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int buf_len;
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@ -36,11 +37,12 @@ typedef struct enc_struct {
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int finished;
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int finished;
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int ok; /* bad decrypt */
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int ok; /* bad decrypt */
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EVP_CIPHER_CTX *cipher;
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EVP_CIPHER_CTX *cipher;
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unsigned char *read_start, *read_end;
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/*
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/*
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* buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate can return
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* buf is larger than ENC_BLOCK_SIZE because EVP_DecryptUpdate can return
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* up to a block more data than is presented to it
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* up to a block more data than is presented to it
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*/
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*/
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unsigned char buf[ENC_BLOCK_SIZE + BUF_OFFSET + 2];
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unsigned char buf[BUF_OFFSET + ENC_BLOCK_SIZE];
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} BIO_ENC_CTX;
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} BIO_ENC_CTX;
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static const BIO_METHOD methods_enc = {
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static const BIO_METHOD methods_enc = {
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@ -75,6 +77,7 @@ static int enc_new(BIO *bi)
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}
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}
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ctx->cont = 1;
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ctx->cont = 1;
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ctx->ok = 1;
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ctx->ok = 1;
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ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
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BIO_set_data(bi, ctx);
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BIO_set_data(bi, ctx);
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BIO_set_init(bi, 1);
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BIO_set_init(bi, 1);
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@ -102,7 +105,7 @@ static int enc_free(BIO *a)
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static int enc_read(BIO *b, char *out, int outl)
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static int enc_read(BIO *b, char *out, int outl)
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{
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{
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int ret = 0, i;
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int ret = 0, i, blocksize;
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BIO_ENC_CTX *ctx;
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BIO_ENC_CTX *ctx;
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BIO *next;
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BIO *next;
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@ -130,27 +133,24 @@ static int enc_read(BIO *b, char *out, int outl)
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}
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}
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}
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}
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blocksize = EVP_CIPHER_CTX_block_size(ctx->cipher);
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if (blocksize == 1)
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blocksize = 0;
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/*
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/*
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* At this point, we have room of outl bytes and an empty buffer, so we
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* At this point, we have room of outl bytes and an empty buffer, so we
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* should read in some more.
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* should read in some more.
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*/
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*/
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while (outl > 0) {
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while (outl > 0) {
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int buf_len;
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if (ctx->cont <= 0)
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if (ctx->cont <= 0)
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break;
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break;
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buf_len = outl + EVP_MAX_BLOCK_LENGTH - 1;
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if (ctx->read_start == ctx->read_end) { /* time to read more data */
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buf_len -= buf_len % EVP_MAX_BLOCK_LENGTH;
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ctx->read_end = ctx->read_start = &(ctx->buf[BUF_OFFSET]);
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if (buf_len > ENC_BLOCK_SIZE) {
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ctx->read_end += BIO_read(next, ctx->read_start, ENC_BLOCK_SIZE);
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buf_len = ENC_BLOCK_SIZE;
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}
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}
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i = ctx->read_end - ctx->read_start;
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/*
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* read in at IV offset, read the EVP_Cipher documentation about why
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*/
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i = BIO_read(next, &(ctx->buf[BUF_OFFSET]), buf_len);
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if (i <= 0) {
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if (i <= 0) {
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/* Should be continue next time we are called? */
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/* Should be continue next time we are called? */
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@ -164,26 +164,41 @@ static int enc_read(BIO *b, char *out, int outl)
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ret = (ret == 0) ? i : ret;
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ret = (ret == 0) ? i : ret;
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break;
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break;
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}
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}
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} else if (outl >= EVP_MAX_BLOCK_LENGTH) {
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if (!EVP_CipherUpdate(ctx->cipher,
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(unsigned char *)out, &buf_len,
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&(ctx->buf[BUF_OFFSET]), i)) {
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BIO_clear_retry_flags(b);
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return 0;
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}
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ret += buf_len;
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outl -= buf_len;
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out += buf_len;
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continue;
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} else {
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} else {
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if (outl > ENC_MIN_CHUNK) {
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/*
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* Depending on flags block cipher decrypt can write
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* one extra block and then back off, i.e. output buffer
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* has to accommodate extra block...
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*/
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int j = outl - blocksize, buf_len;
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if (!EVP_CipherUpdate(ctx->cipher,
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(unsigned char *)out, &buf_len,
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ctx->read_start, i > j ? j : i)) {
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BIO_clear_retry_flags(b);
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return 0;
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}
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ret += buf_len;
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out += buf_len;
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outl -= buf_len;
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if ((i -= j) <= 0) {
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ctx->read_start = ctx->read_end;
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continue;
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}
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ctx->read_start += j;
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}
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if (i > ENC_MIN_CHUNK)
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i = ENC_MIN_CHUNK;
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if (!EVP_CipherUpdate(ctx->cipher,
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if (!EVP_CipherUpdate(ctx->cipher,
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ctx->buf, &ctx->buf_len,
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ctx->buf, &ctx->buf_len,
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&(ctx->buf[BUF_OFFSET]), i)) {
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ctx->read_start, i)) {
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BIO_clear_retry_flags(b);
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BIO_clear_retry_flags(b);
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ctx->ok = 0;
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ctx->ok = 0;
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return 0;
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return 0;
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}
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}
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ctx->read_start += i;
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ctx->cont = 1;
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ctx->cont = 1;
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/*
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/*
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* Note: it is possible for EVP_CipherUpdate to decrypt zero
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* Note: it is possible for EVP_CipherUpdate to decrypt zero
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