From a62b01cd6cc1feb5e80d64d6937c291473ed82cb Mon Sep 17 00:00:00 2001 From: Ard Biesheuvel Date: Fri, 20 Sep 2013 09:55:40 +0200 Subject: crypto: create generic version of ablk_helper Create a generic version of ablk_helper so it can be reused by other architectures. Acked-by: Jussi Kivilinna Signed-off-by: Ard Biesheuvel Signed-off-by: Herbert Xu --- include/crypto/ablk_helper.h | 31 +++++++++++++++++++++++++++++++ 1 file changed, 31 insertions(+) create mode 100644 include/crypto/ablk_helper.h (limited to 'include/crypto') diff --git a/include/crypto/ablk_helper.h b/include/crypto/ablk_helper.h new file mode 100644 index 0000000..4f93df5 --- /dev/null +++ b/include/crypto/ablk_helper.h @@ -0,0 +1,31 @@ +/* + * Shared async block cipher helpers + */ + +#ifndef _CRYPTO_ABLK_HELPER_H +#define _CRYPTO_ABLK_HELPER_H + +#include +#include +#include + +struct async_helper_ctx { + struct cryptd_ablkcipher *cryptd_tfm; +}; + +extern int ablk_set_key(struct crypto_ablkcipher *tfm, const u8 *key, + unsigned int key_len); + +extern int __ablk_encrypt(struct ablkcipher_request *req); + +extern int ablk_encrypt(struct ablkcipher_request *req); + +extern int ablk_decrypt(struct ablkcipher_request *req); + +extern void ablk_exit(struct crypto_tfm *tfm); + +extern int ablk_init_common(struct crypto_tfm *tfm, const char *drv_name); + +extern int ablk_init(struct crypto_tfm *tfm); + +#endif /* _CRYPTO_ABLK_HELPER_H */ -- cgit v1.1 From 6bf37e5aa90f18baf5acf4874bca505dd667c37f Mon Sep 17 00:00:00 2001 From: James Yonan Date: Thu, 26 Sep 2013 02:20:39 -0600 Subject: crypto: crypto_memneq - add equality testing of memory regions w/o timing leaks When comparing MAC hashes, AEAD authentication tags, or other hash values in the context of authentication or integrity checking, it is important not to leak timing information to a potential attacker, i.e. when communication happens over a network. Bytewise memory comparisons (such as memcmp) are usually optimized so that they return a nonzero value as soon as a mismatch is found. E.g, on x86_64/i5 for 512 bytes this can be ~50 cyc for a full mismatch and up to ~850 cyc for a full match (cold). This early-return behavior can leak timing information as a side channel, allowing an attacker to iteratively guess the correct result. This patch adds a new method crypto_memneq ("memory not equal to each other") to the crypto API that compares memory areas of the same length in roughly "constant time" (cache misses could change the timing, but since they don't reveal information about the content of the strings being compared, they are effectively benign). Iow, best and worst case behaviour take the same amount of time to complete (in contrast to memcmp). Note that crypto_memneq (unlike memcmp) can only be used to test for equality or inequality, NOT for lexicographical order. This, however, is not an issue for its use-cases within the crypto API. We tried to locate all of the places in the crypto API where memcmp was being used for authentication or integrity checking, and convert them over to crypto_memneq. crypto_memneq is declared noinline, placed in its own source file, and compiled with optimizations that might increase code size disabled ("Os") because a smart compiler (or LTO) might notice that the return value is always compared against zero/nonzero, and might then reintroduce the same early-return optimization that we are trying to avoid. Using #pragma or __attribute__ optimization annotations of the code for disabling optimization was avoided as it seems to be considered broken or unmaintained for long time in GCC [1]. Therefore, we work around that by specifying the compile flag for memneq.o directly in the Makefile. We found that this seems to be most appropriate. As we use ("Os"), this patch also provides a loop-free "fast-path" for frequently used 16 byte digests. Similarly to kernel library string functions, leave an option for future even further optimized architecture specific assembler implementations. This was a joint work of James Yonan and Daniel Borkmann. Also thanks for feedback from Florian Weimer on this and earlier proposals [2]. [1] http://gcc.gnu.org/ml/gcc/2012-07/msg00211.html [2] https://lkml.org/lkml/2013/2/10/131 Signed-off-by: James Yonan Signed-off-by: Daniel Borkmann Cc: Florian Weimer Signed-off-by: Herbert Xu --- include/crypto/algapi.h | 18 +++++++++++++++++- 1 file changed, 17 insertions(+), 1 deletion(-) (limited to 'include/crypto') diff --git a/include/crypto/algapi.h b/include/crypto/algapi.h index 418d270..e73c19e 100644 --- a/include/crypto/algapi.h +++ b/include/crypto/algapi.h @@ -386,5 +386,21 @@ static inline int crypto_requires_sync(u32 type, u32 mask) return (type ^ CRYPTO_ALG_ASYNC) & mask & CRYPTO_ALG_ASYNC; } -#endif /* _CRYPTO_ALGAPI_H */ +noinline unsigned long __crypto_memneq(const void *a, const void *b, size_t size); + +/** + * crypto_memneq - Compare two areas of memory without leaking + * timing information. + * + * @a: One area of memory + * @b: Another area of memory + * @size: The size of the area. + * + * Returns 0 when data is equal, 1 otherwise. + */ +static inline int crypto_memneq(const void *a, const void *b, size_t size) +{ + return __crypto_memneq(a, b, size) != 0UL ? 1 : 0; +} +#endif /* _CRYPTO_ALGAPI_H */ -- cgit v1.1 From bc6e2bdb71056607141ada309a185f0a50b1aeaf Mon Sep 17 00:00:00 2001 From: Mathias Krause Date: Tue, 15 Oct 2013 13:49:30 +0200 Subject: crypto: authenc - Export key parsing helper function AEAD key parsing is duplicated to multiple places in the kernel. Add a common helper function to consolidate that functionality. Cc: Herbert Xu Cc: "David S. Miller" Signed-off-by: Mathias Krause Signed-off-by: Herbert Xu --- include/crypto/authenc.h | 12 +++++++++++- 1 file changed, 11 insertions(+), 1 deletion(-) (limited to 'include/crypto') diff --git a/include/crypto/authenc.h b/include/crypto/authenc.h index e47b044..6775059 100644 --- a/include/crypto/authenc.h +++ b/include/crypto/authenc.h @@ -23,5 +23,15 @@ struct crypto_authenc_key_param { __be32 enckeylen; }; -#endif /* _CRYPTO_AUTHENC_H */ +struct crypto_authenc_keys { + const u8 *authkey; + const u8 *enckey; + + unsigned int authkeylen; + unsigned int enckeylen; +}; +int crypto_authenc_extractkeys(struct crypto_authenc_keys *keys, const u8 *key, + unsigned int keylen); + +#endif /* _CRYPTO_AUTHENC_H */ -- cgit v1.1