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crypto: cfb - add missing 'chunksize' property

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commit 394a9e044702e6a8958a5e89d2a291605a587a2a upstream.

Like some other block cipher mode implementations, the CFB
implementation assumes that while walking through the scatterlist, a
partial block does not occur until the end.  But the walk is incorrectly
being done with a blocksize of 1, as 'cra_blocksize' is set to 1 (since
CFB is a stream cipher) but no 'chunksize' is set.  This bug causes
incorrect encryption/decryption for some scatterlist layouts.

Fix it by setting the 'chunksize'.  Also extend the CFB test vectors to
cover this bug as well as cases where the message length is not a
multiple of the block size.

Fixes: a7d85e06ed ("crypto: cfb - add support for Cipher FeedBack mode")
Cc: <stable@vger.kernel.org> # v4.17+
Cc: James Bottomley <James.Bottomley@HansenPartnership.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Eric Biggers 2019-01-03 20:16:10 -08:00 committed by Greg Kroah-Hartman
parent 6ed42ccca5
commit 0b1871d041
2 changed files with 31 additions and 0 deletions
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6
crypto/cfb.c
View file

@ -298,6 +298,12 @@ static int crypto_cfb_create(struct crypto_template *tmpl, struct rtattr **tb)
inst->alg.base.cra_blocksize = 1;
inst->alg.base.cra_alignmask = alg->cra_alignmask;
/*
* To simplify the implementation, configure the skcipher walk to only
* give a partial block at the very end, never earlier.
*/
inst->alg.chunksize = alg->cra_blocksize;
inst->alg.ivsize = alg->cra_blocksize;
inst->alg.min_keysize = alg->cra_cipher.cia_min_keysize;
inst->alg.max_keysize = alg->cra_cipher.cia_max_keysize;

25
crypto/testmgr.h
View file

@ -11416,6 +11416,31 @@ static const struct cipher_testvec aes_cfb_tv_template[] = {
"\x75\xa3\x85\x74\x1a\xb9\xce\xf8"
"\x20\x31\x62\x3d\x55\xb1\xe4\x71",
.len = 64,
.also_non_np = 1,
.np = 2,
.tap = { 31, 33 },
}, { /* > 16 bytes, not a multiple of 16 bytes */
.key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
"\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
.klen = 16,
.iv = "\x00\x01\x02\x03\x04\x05\x06\x07"
"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
.ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f\x96"
"\xe9\x3d\x7e\x11\x73\x93\x17\x2a"
"\xae",
.ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad\x20"
"\x33\x34\x49\xf8\xe8\x3c\xfb\x4a"
"\xc8",
.len = 17,
}, { /* < 16 bytes */
.key = "\x2b\x7e\x15\x16\x28\xae\xd2\xa6"
"\xab\xf7\x15\x88\x09\xcf\x4f\x3c",
.klen = 16,
.iv = "\x00\x01\x02\x03\x04\x05\x06\x07"
"\x08\x09\x0a\x0b\x0c\x0d\x0e\x0f",
.ptext = "\x6b\xc1\xbe\xe2\x2e\x40\x9f",
.ctext = "\x3b\x3f\xd9\x2e\xb7\x2d\xad",
.len = 7,
},
};