Andrew Geissler | c926e17 | 2021-05-07 16:11:35 -0500 | [diff] [blame^] | 1 | From a0541334a6394f8237a4393b7372693cd7e96f15 Mon Sep 17 00:00:00 2001 |
| 2 | From: Jouni Malinen <j@w1.fi> |
| 3 | Date: Sat, 13 Mar 2021 18:19:31 +0200 |
| 4 | Subject: [PATCH] ASN.1: Validate DigestAlgorithmIdentifier parameters |
| 5 | |
| 6 | The supported hash algorithms do not use AlgorithmIdentifier parameters. |
| 7 | However, there are implementations that include NULL parameters in |
| 8 | addition to ones that omit the parameters. Previous implementation did |
| 9 | not check the parameters value at all which supported both these cases, |
| 10 | but did not reject any other unexpected information. |
| 11 | |
| 12 | Use strict validation of digest algorithm parameters and reject any |
| 13 | unexpected value when validating a signature. This is needed to prevent |
| 14 | potential forging attacks. |
| 15 | |
| 16 | Signed-off-by: Jouni Malinen <j@w1.fi> |
| 17 | |
| 18 | Upstream-Status: Backport |
| 19 | CVE: CVE-2021-30004 |
| 20 | |
| 21 | Reference to upstream patch: |
| 22 | [https://w1.fi/cgit/hostap/commit/?id=a0541334a6394f8237a4393b7372693cd7e96f15] |
| 23 | |
| 24 | Signed-off-by: Stefan Ghinea <stefan.ghinea@windriver.com> |
| 25 | --- |
| 26 | src/tls/pkcs1.c | 21 +++++++++++++++++++++ |
| 27 | src/tls/x509v3.c | 20 ++++++++++++++++++++ |
| 28 | 2 files changed, 41 insertions(+) |
| 29 | |
| 30 | diff --git a/src/tls/pkcs1.c b/src/tls/pkcs1.c |
| 31 | index 141ac50..e09db07 100644 |
| 32 | --- a/src/tls/pkcs1.c |
| 33 | +++ b/src/tls/pkcs1.c |
| 34 | @@ -240,6 +240,8 @@ int pkcs1_v15_sig_ver(struct crypto_public_key *pk, |
| 35 | os_free(decrypted); |
| 36 | return -1; |
| 37 | } |
| 38 | + wpa_hexdump(MSG_MSGDUMP, "PKCS #1: DigestInfo", |
| 39 | + hdr.payload, hdr.length); |
| 40 | |
| 41 | pos = hdr.payload; |
| 42 | end = pos + hdr.length; |
| 43 | @@ -261,6 +263,8 @@ int pkcs1_v15_sig_ver(struct crypto_public_key *pk, |
| 44 | os_free(decrypted); |
| 45 | return -1; |
| 46 | } |
| 47 | + wpa_hexdump(MSG_MSGDUMP, "PKCS #1: DigestAlgorithmIdentifier", |
| 48 | + hdr.payload, hdr.length); |
| 49 | da_end = hdr.payload + hdr.length; |
| 50 | |
| 51 | if (asn1_get_oid(hdr.payload, hdr.length, &oid, &next)) { |
| 52 | @@ -269,6 +273,23 @@ int pkcs1_v15_sig_ver(struct crypto_public_key *pk, |
| 53 | os_free(decrypted); |
| 54 | return -1; |
| 55 | } |
| 56 | + wpa_hexdump(MSG_MSGDUMP, "PKCS #1: Digest algorithm parameters", |
| 57 | + next, da_end - next); |
| 58 | + |
| 59 | + /* |
| 60 | + * RFC 5754: The correct encoding for the SHA2 algorithms would be to |
| 61 | + * omit the parameters, but there are implementation that encode these |
| 62 | + * as a NULL element. Allow these two cases and reject anything else. |
| 63 | + */ |
| 64 | + if (da_end > next && |
| 65 | + (asn1_get_next(next, da_end - next, &hdr) < 0 || |
| 66 | + !asn1_is_null(&hdr) || |
| 67 | + hdr.payload + hdr.length != da_end)) { |
| 68 | + wpa_printf(MSG_DEBUG, |
| 69 | + "PKCS #1: Unexpected digest algorithm parameters"); |
| 70 | + os_free(decrypted); |
| 71 | + return -1; |
| 72 | + } |
| 73 | |
| 74 | if (!asn1_oid_equal(&oid, hash_alg)) { |
| 75 | char txt[100], txt2[100]; |
| 76 | diff --git a/src/tls/x509v3.c b/src/tls/x509v3.c |
| 77 | index 1bd5aa0..bf2289f 100644 |
| 78 | --- a/src/tls/x509v3.c |
| 79 | +++ b/src/tls/x509v3.c |
| 80 | @@ -1834,6 +1834,7 @@ int x509_check_signature(struct x509_certificate *issuer, |
| 81 | os_free(data); |
| 82 | return -1; |
| 83 | } |
| 84 | + wpa_hexdump(MSG_MSGDUMP, "X509: DigestInfo", hdr.payload, hdr.length); |
| 85 | |
| 86 | pos = hdr.payload; |
| 87 | end = pos + hdr.length; |
| 88 | @@ -1855,6 +1856,8 @@ int x509_check_signature(struct x509_certificate *issuer, |
| 89 | os_free(data); |
| 90 | return -1; |
| 91 | } |
| 92 | + wpa_hexdump(MSG_MSGDUMP, "X509: DigestAlgorithmIdentifier", |
| 93 | + hdr.payload, hdr.length); |
| 94 | da_end = hdr.payload + hdr.length; |
| 95 | |
| 96 | if (asn1_get_oid(hdr.payload, hdr.length, &oid, &next)) { |
| 97 | @@ -1862,6 +1865,23 @@ int x509_check_signature(struct x509_certificate *issuer, |
| 98 | os_free(data); |
| 99 | return -1; |
| 100 | } |
| 101 | + wpa_hexdump(MSG_MSGDUMP, "X509: Digest algorithm parameters", |
| 102 | + next, da_end - next); |
| 103 | + |
| 104 | + /* |
| 105 | + * RFC 5754: The correct encoding for the SHA2 algorithms would be to |
| 106 | + * omit the parameters, but there are implementation that encode these |
| 107 | + * as a NULL element. Allow these two cases and reject anything else. |
| 108 | + */ |
| 109 | + if (da_end > next && |
| 110 | + (asn1_get_next(next, da_end - next, &hdr) < 0 || |
| 111 | + !asn1_is_null(&hdr) || |
| 112 | + hdr.payload + hdr.length != da_end)) { |
| 113 | + wpa_printf(MSG_DEBUG, |
| 114 | + "X509: Unexpected digest algorithm parameters"); |
| 115 | + os_free(data); |
| 116 | + return -1; |
| 117 | + } |
| 118 | |
| 119 | if (x509_sha1_oid(&oid)) { |
| 120 | if (signature->oid.oid[6] != 5 /* sha-1WithRSAEncryption */) { |
| 121 | -- |
| 122 | 2.17.1 |
| 123 | |