Commit 394a9e04 authored by Eric Biggers's avatar Eric Biggers Committed by Herbert Xu
Browse files

crypto: cfb - add missing 'chunksize' property 



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: a7d85e06 ("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: default avatarEric Biggers <ebiggers@google.com>
Signed-off-by: default avatarHerbert Xu <herbert@gondor.apana.org.au>
parent 1bb64d86

crypto/cfb.c

+6 −0
Original line number Diff line number Diff line
@@ -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;

crypto/testmgr.h

+25 −0
Original line number Diff line number Diff line
@@ -12870,6 +12870,31 @@ 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,

	},

};



























































CRA Git | Maintained and supported by SUSTech CRA and CCSE