diff options
| -rw-r--r-- | crypto/asymmetric_keys/pkcs7_verify.c | 88 |
1 files changed, 87 insertions, 1 deletions
diff --git a/crypto/asymmetric_keys/pkcs7_verify.c b/crypto/asymmetric_keys/pkcs7_verify.c index 745e5c86a35e..51ff36f3a913 100644 --- a/crypto/asymmetric_keys/pkcs7_verify.c +++ b/crypto/asymmetric_keys/pkcs7_verify.c @@ -170,6 +170,91 @@ static int pkcs7_find_key(struct pkcs7_message *pkcs7, } /* + * Verify the internal certificate chain as best we can. + */ +static int pkcs7_verify_sig_chain(struct pkcs7_message *pkcs7, + struct pkcs7_signed_info *sinfo) +{ + struct x509_certificate *x509 = sinfo->signer, *p; + int ret; + + kenter(""); + + for (p = pkcs7->certs; p; p = p->next) + p->seen = false; + + for (;;) { + pr_debug("verify %s: %s\n", x509->subject, x509->fingerprint); + x509->seen = true; + ret = x509_get_sig_params(x509); + if (ret < 0) + return ret; + + if (x509->issuer) + pr_debug("- issuer %s\n", x509->issuer); + if (x509->authority) + pr_debug("- authkeyid %s\n", x509->authority); + + if (!x509->authority || + (x509->subject && + strcmp(x509->subject, x509->issuer) == 0)) { + /* If there's no authority certificate specified, then + * the certificate must be self-signed and is the root + * of the chain. Likewise if the cert is its own + * authority. + */ + pr_debug("- no auth?\n"); + if (x509->raw_subject_size != x509->raw_issuer_size || + memcmp(x509->raw_subject, x509->raw_issuer, + x509->raw_issuer_size) != 0) + return 0; + + ret = x509_check_signature(x509->pub, x509); + if (ret < 0) + return ret; + x509->signer = x509; + pr_debug("- self-signed\n"); + return 0; + } + + /* Look through the X.509 certificates in the PKCS#7 message's + * list to see if the next one is there. + */ + pr_debug("- want %s\n", x509->authority); + for (p = pkcs7->certs; p; p = p->next) { + pr_debug("- cmp [%u] %s\n", p->index, p->fingerprint); + if (p->raw_subject_size == x509->raw_issuer_size && + strcmp(p->fingerprint, x509->authority) == 0 && + memcmp(p->raw_subject, x509->raw_issuer, + x509->raw_issuer_size) == 0) + goto found_issuer; + } + + /* We didn't find the root of this chain */ + pr_debug("- top\n"); + return 0; + + found_issuer: + pr_debug("- issuer %s\n", p->subject); + if (p->seen) { + pr_warn("Sig %u: X.509 chain contains loop\n", + sinfo->index); + return 0; + } + ret = x509_check_signature(p->pub, x509); + if (ret < 0) + return ret; + x509->signer = p; + if (x509 == p) { + pr_debug("- self-signed\n"); + return 0; + } + x509 = p; + might_sleep(); + } +} + +/* * Verify one signed information block from a PKCS#7 message. */ static int pkcs7_verify_one(struct pkcs7_message *pkcs7, @@ -201,7 +286,8 @@ static int pkcs7_verify_one(struct pkcs7_message *pkcs7, pr_devel("Verified signature %u\n", sinfo->index); - return 0; + /* Verify the internal certificate chain */ + return pkcs7_verify_sig_chain(pkcs7, sinfo); } /** |