[PATCH v2 06/19] crypto: rsassa-pkcs1 - Migrate to sig_alg backend
Klara Modin
klarasmodin at gmail.com
Mon Oct 28 11:45:41 UTC 2024
On 2024-10-25 09:17, Lukas Wunner wrote:
> On Wed, Oct 23, 2024 at 12:19:45PM +0200, Klara Modin wrote:
>> On 2024-10-21 21:02, Lukas Wunner wrote:
>>> On Mon, Oct 21, 2024 at 06:08:03PM +0200, Klara Modin wrote:
>>>> This commit (1e562deacecca1f1bec7d23da526904a1e87525e in next-20241021)
>>>> seems to break connecting to wpa2-enterprise with iwd.
> [...]
>>> There is a *second* issue I discovered last week. I cooked up
>>> a fix this morning, but haven't written a commit message yet.
>>> The patch is included below and it could indeed solve the
>>> problem because it fixes an issue introduced by the commit you
>>> identified as culprit.
> [...]
>> Tested on top of yesterday's next-20241022.
>>
>> With the first patch only there is no change, same behavior as previously.
>>
>> With the second patch only I get an oops, similar as the one you mentioned
>> in the first fix
>>
>> With both patches everything seems to work as expected. Thanks!
>
> Thanks a lot for your testing efforts, this helps greatly!
>
> I've dug into the source code of iwd (Intel Wireless Daemon) and
> the ell library it uses (Embedded Linux Library).
>
> It turns out that the patch I sent you is sufficient when using
> TLS 1.2 or newer for EAP (which I assume is true in your case).
> But the patch is *not* sufficient for TLS 1.1 or earlier.
>
> Normally RSA PKCS#1 encoding requires that the hash is prepended
> by a Full Hash Prefix (an ASN.1 sequence which identifies the
> hash algorithm used). But it turns out there are legacy protocols
> such as TLS 1.1 or earlier as well as IKEv1 which omit the
> Full Hash Prefix.
>
> The kernel supported this prior to 1e562deacecc. Although TLS 1.1
> was deprecated in 2021 by RFC 8996, I think we cannot just remove
> support without advance notice.
>
> So below is a new patch which reinstates support for these legacy
> protocols. It should also fix the issue you're seeing with TLS 1.2
> or newer (which is caused by invoking KEYCTL_PKEY_QUERY without
> specifying a hash algorithm).
>
> The patch below replaces the one I sent on Monday. You'll still
> need the other pending fix:
>
> https://lore.kernel.org/r/ff7a28cddfc28e7a3fb8292c680510f35ec54391.1728898147.git.lukas@wunner.de/
>
> Would you mind testing this combination? It did work in my own
> testing, but if you could test it as well that would raise the
> confidence.
>
> I've looked at the source code of wpa_supplicant as well as
> various IKEv1 daemons (strongswan, libreswan, isakmpd, raccoon)
> and none of them seems to use the kernel's Key Retention Service,
> so iwd is the only known user space application affected so far.
>
> Thanks,
>
> Lukas
This patch also fixes the issue for me (on top of next-20241028).
Thanks,
Tested-by: Klara Modin <klarasmodin at gmail.com>
>
> -- >8 --
>
> diff --git a/crypto/asymmetric_keys/public_key.c b/crypto/asymmetric_keys/public_key.c
> index c98c158..bbd07a9 100644
> --- a/crypto/asymmetric_keys/public_key.c
> +++ b/crypto/asymmetric_keys/public_key.c
> @@ -93,7 +93,7 @@ static void public_key_destroy(void *payload0, void *payload3)
> pkey->pkey_algo);
> } else {
> if (!hash_algo)
> - return -EINVAL;
> + hash_algo = "none";
> n = snprintf(alg_name, CRYPTO_MAX_ALG_NAME,
> "pkcs1(%s,%s)",
> pkey->pkey_algo, hash_algo);
> diff --git a/crypto/rsassa-pkcs1.c b/crypto/rsassa-pkcs1.c
> index 9c28f1c..4d077fc9 100644
> --- a/crypto/rsassa-pkcs1.c
> +++ b/crypto/rsassa-pkcs1.c
> @@ -27,6 +27,8 @@
> * https://www.rfc-editor.org/rfc/rfc9580#table-24
> */
>
> +static const u8 hash_prefix_none[] = { };
> +
> static const u8 hash_prefix_md5[] = {
> 0x30, 0x20, 0x30, 0x0c, 0x06, 0x08, /* SEQUENCE (SEQUENCE (OID */
> 0x2a, 0x86, 0x48, 0x86, 0xf7, 0x0d, 0x02, 0x05, /* <algorithm>, */
> @@ -93,6 +95,7 @@
> size_t size;
> } hash_prefixes[] = {
> #define _(X) { #X, hash_prefix_##X, sizeof(hash_prefix_##X) }
> + _(none),
> _(md5),
> _(sha1),
> _(rmd160),
> @@ -119,9 +122,18 @@ static const struct hash_prefix *rsassa_pkcs1_find_hash_prefix(const char *name)
> return NULL;
> }
>
> -static unsigned int rsassa_pkcs1_hash_len(const struct hash_prefix *p)
> +static bool rsassa_pkcs1_invalid_hash_len(unsigned int len,
> + const struct hash_prefix *p)
> {
> /*
> + * Legacy protocols such as TLS 1.1 or earlier and IKE version 1
> + * do not prepend a Full Hash Prefix to the hash. In that case,
> + * the size of the Full Hash Prefix is zero.
> + */
> + if (p->data == hash_prefix_none)
> + return false;
> +
> + /*
> * The final byte of the Full Hash Prefix encodes the hash length.
> *
> * This needs to be revisited should hash algorithms with more than
> @@ -130,7 +142,7 @@ static unsigned int rsassa_pkcs1_hash_len(const struct hash_prefix *p)
> */
> static_assert(HASH_MAX_DIGESTSIZE <= 127);
>
> - return p->data[p->size - 1];
> + return len != p->data[p->size - 1];
> }
>
> struct rsassa_pkcs1_ctx {
> @@ -167,7 +179,7 @@ static int rsassa_pkcs1_sign(struct crypto_sig *tfm,
> if (dlen < ctx->key_size)
> return -EOVERFLOW;
>
> - if (slen != rsassa_pkcs1_hash_len(hash_prefix))
> + if (rsassa_pkcs1_invalid_hash_len(slen, hash_prefix))
> return -EINVAL;
>
> if (slen + hash_prefix->size > ctx->key_size - 11)
> @@ -237,7 +249,7 @@ static int rsassa_pkcs1_verify(struct crypto_sig *tfm,
> /* RFC 8017 sec 8.2.2 step 1 - length checking */
> if (!ctx->key_size ||
> slen != ctx->key_size ||
> - dlen != rsassa_pkcs1_hash_len(hash_prefix))
> + rsassa_pkcs1_invalid_hash_len(dlen, hash_prefix))
> return -EINVAL;
>
> /* RFC 8017 sec 8.2.2 step 2 - RSA verification */
> diff --git a/crypto/testmgr.c b/crypto/testmgr.c
> index 7d768f0..86126be 100644
> --- a/crypto/testmgr.c
> +++ b/crypto/testmgr.c
> @@ -5540,6 +5540,12 @@ static int alg_test_null(const struct alg_test_desc *desc,
> .cipher = __VECS(fcrypt_pcbc_tv_template)
> }
> }, {
> + .alg = "pkcs1(rsa,none)",
> + .test = alg_test_sig,
> + .suite = {
> + .sig = __VECS(pkcs1_rsa_none_tv_template)
> + }
> + }, {
> .alg = "pkcs1(rsa,sha224)",
> .test = alg_test_null,
> .fips_allowed = 1,
> diff --git a/crypto/testmgr.h b/crypto/testmgr.h
> index 55aae18..d4c232a 100644
> --- a/crypto/testmgr.h
> +++ b/crypto/testmgr.h
> @@ -1983,6 +1983,61 @@ struct kpp_testvec {
> };
>
> /*
> + * PKCS#1 RSA test vectors for hash algorithm "none"
> + * (i.e. the hash in "m" is not prepended by a Full Hash Prefix)
> + *
> + * Obtained from:
> + * https://vcsjones.dev/sometimes-valid-rsa-dotnet/
> + * https://gist.github.com/vcsjones/ab4c2327b53ed018eada76b75ef4fd99
> + */
> +static const struct sig_testvec pkcs1_rsa_none_tv_template[] = {
> + {
> + .key =
> + "\x30\x82\x01\x0a\x02\x82\x01\x01\x00\xa2\x63\x0b\x39\x44\xb8\xbb"
> + "\x23\xa7\x44\x49\xbb\x0e\xff\xa1\xf0\x61\x0a\x53\x93\xb0\x98\xdb"
> + "\xad\x2c\x0f\x4a\xc5\x6e\xff\x86\x3c\x53\x55\x0f\x15\xce\x04\x3f"
> + "\x2b\xfd\xa9\x96\x96\xd9\xbe\x61\x79\x0b\x5b\xc9\x4c\x86\x76\xe5"
> + "\xe0\x43\x4b\x22\x95\xee\xc2\x2b\x43\xc1\x9f\xd8\x68\xb4\x8e\x40"
> + "\x4f\xee\x85\x38\xb9\x11\xc5\x23\xf2\x64\x58\xf0\x15\x32\x6f\x4e"
> + "\x57\xa1\xae\x88\xa4\x02\xd7\x2a\x1e\xcd\x4b\xe1\xdd\x63\xd5\x17"
> + "\x89\x32\x5b\xb0\x5e\x99\x5a\xa8\x9d\x28\x50\x0e\x17\xee\x96\xdb"
> + "\x61\x3b\x45\x51\x1d\xcf\x12\x56\x0b\x92\x47\xfc\xab\xae\xf6\x66"
> + "\x3d\x47\xac\x70\x72\xe7\x92\xe7\x5f\xcd\x10\xb9\xc4\x83\x64\x94"
> + "\x19\xbd\x25\x80\xe1\xe8\xd2\x22\xa5\xd0\xba\x02\x7a\xa1\x77\x93"
> + "\x5b\x65\xc3\xee\x17\x74\xbc\x41\x86\x2a\xdc\x08\x4c\x8c\x92\x8c"
> + "\x91\x2d\x9e\x77\x44\x1f\x68\xd6\xa8\x74\x77\xdb\x0e\x5b\x32\x8b"
> + "\x56\x8b\x33\xbd\xd9\x63\xc8\x49\x9d\x3a\xc5\xc5\xea\x33\x0b\xd2"
> + "\xf1\xa3\x1b\xf4\x8b\xbe\xd9\xb3\x57\x8b\x3b\xde\x04\xa7\x7a\x22"
> + "\xb2\x24\xae\x2e\xc7\x70\xc5\xbe\x4e\x83\x26\x08\xfb\x0b\xbd\xa9"
> + "\x4f\x99\x08\xe1\x10\x28\x72\xaa\xcd\x02\x03\x01\x00\x01",
> + .key_len = 294,
> + .m =
> + "\x68\xb4\xf9\x26\x34\x31\x25\xdd\x26\x50\x13\x68\xc1\x99\x26\x71"
> + "\x19\xa2\xde\x81",
> + .m_size = 20,
> + .c =
> + "\x6a\xdb\x39\xe5\x63\xb3\x25\xde\x58\xca\xc3\xf1\x36\x9c\x0b\x36"
> + "\xb7\xd6\x69\xf9\xba\xa6\x68\x14\x8c\x24\x52\xd3\x25\xa5\xf3\xad"
> + "\xc9\x47\x44\xde\x06\xd8\x0f\x56\xca\x2d\xfb\x0f\xe9\x99\xe2\x9d"
> + "\x8a\xe8\x7f\xfb\x9a\x99\x96\xf1\x2c\x4a\xe4\xc0\xae\x4d\x29\x47"
> + "\x38\x96\x51\x2f\x6d\x8e\xb8\x88\xbd\x1a\x0a\x70\xbc\x23\x38\x67"
> + "\x62\x22\x01\x23\x71\xe5\xbb\x95\xea\x6b\x8d\x31\x62\xbf\xf0\xc4"
> + "\xb9\x46\xd6\x67\xfc\x4c\xe6\x1f\xd6\x5d\xf7\xa9\xad\x3a\xf1\xbf"
> + "\xa2\xf9\x66\xde\xb6\x8e\xec\x8f\x81\x8d\x1e\x3a\x12\x27\x6a\xfc"
> + "\xae\x92\x9f\xc3\x87\xc3\xba\x8d\x04\xb8\x8f\x0f\x61\x68\x9a\x96"
> + "\x2c\x80\x2c\x32\x40\xde\x9d\xb9\x9b\xe2\xe4\x45\x2e\x91\x47\x5c"
> + "\x47\xa4\x9d\x02\x57\x59\xf7\x75\x5d\x5f\x32\x82\x75\x5d\xe5\x78"
> + "\xc9\x19\x61\x46\x06\x9d\xa5\x1d\xd6\x32\x48\x9a\xdb\x09\x29\x81"
> + "\x14\x2e\xf0\x27\xe9\x37\x13\x74\xec\xa5\xcd\x67\x6b\x19\xf6\x88"
> + "\xf0\xc2\x8b\xa8\x7f\x2f\x76\x5a\x3e\x0c\x47\x5d\xe8\x82\x50\x27"
> + "\x40\xce\x27\x41\x45\xa0\xcf\xaa\x2f\xd3\xad\x3c\xbf\x73\xff\x93"
> + "\xe3\x78\x49\xd9\xa9\x78\x22\x81\x9a\xe5\xe2\x94\xe9\x40\xab\xf1",
> + .c_size = 256,
> + .public_key_vec = true,
> + },
> +};
> +
> +/*
> * PKCS#1 RSA test vectors. Obtained from CAVS testing.
> */
> static const struct sig_testvec pkcs1_rsa_tv_template[] = {
>
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