| Message ID | 20220201003414.55380-1-ebiggers@kernel.org |
|---|---|
| Headers | show |
| Series | Fix bugs in public_key_verify_signature() | expand |
Hi Eric, On 2/1/22 8:34 AM, Eric Biggers wrote: > This patchset fixes some bugs in public_key_verify_signature() where it > could be tricked into using the wrong algorithm, as was discussed at > https://lore.kernel.org/linux-integrity/20211202215507.298415-1-zohar@linux.ibm.com/T/#t > > I'd appreciate it if the people who care about each of the supported > public key algorithms (RSA, ECDSA, ECRDSA, and SM2) would test this > patchset to make sure it still works for their use case(s). I've tested > that X.509 and PKCS#7 with RSA still work. > > Note, I have *not* included a fix for SM2 being implemented incorrectly. > That is another bug that I pointed out in the above thread. I think > that bug is for the people who actually care about SM2. > > This applies to v5.17-rc2. > Sorry for the late reply, thanks for your work. I did the test and the x509 certificate for SM2-with-SM3 is working fine. Tested-by: Tianjia Zhang <tianjia.zhang@linux.alibaba.com> Regarding the algorithm information in the signature data used by SM2, I will add a patch to fix this issue, thanks for pointing it out. Best regards, Tianjia > Eric Biggers (2): > KEYS: asymmetric: enforce that sig algo matches key algo > KEYS: asymmetric: properly validate hash_algo and encoding > > crypto/asymmetric_keys/pkcs7_verify.c | 6 -- > crypto/asymmetric_keys/public_key.c | 126 ++++++++++++++++------- > crypto/asymmetric_keys/x509_public_key.c | 6 -- > 3 files changed, 91 insertions(+), 47 deletions(-) > > > base-commit: 26291c54e111ff6ba87a164d85d4a4e134b7315c
On Mon, Jan 31, 2022 at 04:34:14PM -0800, Eric Biggers wrote: > From: Eric Biggers <ebiggers@google.com> > > It is insecure to allow arbitrary hash algorithms and signature > encodings to be used with arbitrary signature algorithms. Notably, > ECDSA, ECRDSA, and SM2 all sign/verify raw hash values and don't > disambiguate between different hash algorithms like RSA PKCS#1 v1.5 > padding does. Therefore, they need to be restricted to certain sets of > hash algorithms (ideally just one, but in practice small sets are used). > Additionally, the encoding is an integral part of modern signature > algorithms, and is not supposed to vary. > > Therefore, tighten the checks of hash_algo and encoding done by > software_key_determine_akcipher(). > > Also rearrange the parameters to software_key_determine_akcipher() to > put the public_key first, as this is the most important parameter and it > often determines everything else. > > Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") > Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification") > Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm") > Cc: stable@vger.kernel.org > Signed-off-by: Eric Biggers <ebiggers@google.com> > --- > crypto/asymmetric_keys/public_key.c | 111 +++++++++++++++++++--------- > 1 file changed, 76 insertions(+), 35 deletions(-) > > diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c > index aba7113d86c76..a603ee8afdb8d 100644 > --- a/crypto/asymmetric_keys/public_key.c > +++ b/crypto/asymmetric_keys/public_key.c > @@ -60,39 +60,83 @@ static void public_key_destroy(void *payload0, void *payload3) > } > > /* > - * Determine the crypto algorithm name. > + * Given a public_key, and an encoding and hash_algo to be used for signing > + * and/or verification with that key, determine the name of the corresponding > + * akcipher algorithm. Also check that encoding and hash_algo are allowed. > */ > -static > -int software_key_determine_akcipher(const char *encoding, > - const char *hash_algo, > - const struct public_key *pkey, > - char alg_name[CRYPTO_MAX_ALG_NAME]) > +static int > +software_key_determine_akcipher(const struct public_key *pkey, > + const char *encoding, const char *hash_algo, > + char alg_name[CRYPTO_MAX_ALG_NAME]) Why is changing parameter order necessary? BR, Jarkko
On Mon, Feb 21, 2022 at 02:46:26AM +0100, Jarkko Sakkinen wrote: > On Mon, Jan 31, 2022 at 04:34:14PM -0800, Eric Biggers wrote: > > From: Eric Biggers <ebiggers@google.com> > > > > It is insecure to allow arbitrary hash algorithms and signature > > encodings to be used with arbitrary signature algorithms. Notably, > > ECDSA, ECRDSA, and SM2 all sign/verify raw hash values and don't > > disambiguate between different hash algorithms like RSA PKCS#1 v1.5 > > padding does. Therefore, they need to be restricted to certain sets of > > hash algorithms (ideally just one, but in practice small sets are used). > > Additionally, the encoding is an integral part of modern signature > > algorithms, and is not supposed to vary. > > > > Therefore, tighten the checks of hash_algo and encoding done by > > software_key_determine_akcipher(). > > > > Also rearrange the parameters to software_key_determine_akcipher() to > > put the public_key first, as this is the most important parameter and it > > often determines everything else. > > > > Fixes: 299f561a6693 ("x509: Add support for parsing x509 certs with ECDSA keys") > > Fixes: 215525639631 ("X.509: support OSCCA SM2-with-SM3 certificate verification") > > Fixes: 0d7a78643f69 ("crypto: ecrdsa - add EC-RDSA (GOST 34.10) algorithm") > > Cc: stable@vger.kernel.org > > Signed-off-by: Eric Biggers <ebiggers@google.com> > > --- > > crypto/asymmetric_keys/public_key.c | 111 +++++++++++++++++++--------- > > 1 file changed, 76 insertions(+), 35 deletions(-) > > > > diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c > > index aba7113d86c76..a603ee8afdb8d 100644 > > --- a/crypto/asymmetric_keys/public_key.c > > +++ b/crypto/asymmetric_keys/public_key.c > > @@ -60,39 +60,83 @@ static void public_key_destroy(void *payload0, void *payload3) > > } > > > > /* > > - * Determine the crypto algorithm name. > > + * Given a public_key, and an encoding and hash_algo to be used for signing > > + * and/or verification with that key, determine the name of the corresponding > > + * akcipher algorithm. Also check that encoding and hash_algo are allowed. > > */ > > -static > > -int software_key_determine_akcipher(const char *encoding, > > - const char *hash_algo, > > - const struct public_key *pkey, > > - char alg_name[CRYPTO_MAX_ALG_NAME]) > > +static int > > +software_key_determine_akcipher(const struct public_key *pkey, > > + const char *encoding, const char *hash_algo, > > + char alg_name[CRYPTO_MAX_ALG_NAME]) > > Why is changing parameter order necessary? > It's mentioned in the commit message. It's obviously not necessary but this way makes much more sense IMO. - Eric