Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752684AbaDXUHj (ORCPT ); Thu, 24 Apr 2014 16:07:39 -0400 Received: from mail-wi0-f174.google.com ([209.85.212.174]:53047 "EHLO mail-wi0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751754AbaDXUHh (ORCPT ); Thu, 24 Apr 2014 16:07:37 -0400 MIME-Version: 1.0 In-Reply-To: <1398358432.2293.17.camel@dhcp-9-2-203-236.watson.ibm.com> References: <0f7915604c69374f15cbaf36c499a5d88264e89d.1398259638.git.d.kasatkin@samsung.com> <1398358432.2293.17.camel@dhcp-9-2-203-236.watson.ibm.com> Date: Thu, 24 Apr 2014 23:07:35 +0300 Message-ID: Subject: Re: [PATCH 01/20] KEYS: verify a certificate is signed by a 'trusted' key From: Dmitry Kasatkin To: Mimi Zohar Cc: Dmitry Kasatkin , David Howells , James Morris , Roberto Sassu , linux-security-module@vger.kernel.org, "linux-kernel@vger.kernel.org" Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 24 April 2014 19:53, Mimi Zohar wrote: > On Wed, 2014-04-23 at 16:30 +0300, Dmitry Kasatkin wrote: >> From: Mimi Zohar >> >> Only public keys, with certificates signed by an existing >> 'trusted' key on the system trusted keyring, should be added >> to a trusted keyring. This patch adds support for verifying >> a certificate's signature. >> >> This is derived from David Howells pkcs7_request_asymmetric_key() patch. >> >> Changes: >> - Flaged out the code to prevent build break if system keyring >> is not enabled (Dmitry). > > An updated version of this patch was posted, which resolves the Kconfig > issues. There are a number of other issues which need to be addressed, > before this patch can be upstreamed. Please refer to the patch > description for more details - > http://marc.info/?l=linux-security-module&m=138672063109662&w=2 > Oh. I was using this patch from your public tree.. Updated version is missing there and I missed it out. Will rebase on the top of it as soon as it is available. > Reminder, as per Documentation/SubmittingPatches: "#ifdefs are ugly", > please no ifdefs in C code. > Right, we know it. Making separate C file for one function isn't ugly? - Dmitry > thanks, > > Mimi > >> >> Signed-off-by: Mimi Zohar >> Signed-off-by: David Howells >> Signed-off-by: Dmitry Kasatkin >> --- >> crypto/asymmetric_keys/x509_public_key.c | 85 +++++++++++++++++++++++++++++++- >> 1 file changed, 84 insertions(+), 1 deletion(-) >> >> diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c >> index 382ef0d..d279f43 100644 >> --- a/crypto/asymmetric_keys/x509_public_key.c >> +++ b/crypto/asymmetric_keys/x509_public_key.c >> @@ -18,6 +18,7 @@ >> #include >> #include >> #include >> +#include >> #include >> #include "asymmetric_keys.h" >> #include "public_key.h" >> @@ -102,6 +103,82 @@ int x509_check_signature(const struct public_key *pub, >> } >> EXPORT_SYMBOL_GPL(x509_check_signature); >> >> +#ifdef CONFIG_SYSTEM_TRUSTED_KEYRING >> +/* >> + * Find a key in the given keyring by issuer and authority. >> + */ >> +static struct key *x509_request_asymmetric_key( >> + struct key *keyring, >> + const char *signer, size_t signer_len, >> + const char *authority, size_t auth_len) >> +{ >> + key_ref_t key; >> + char *id; >> + >> + /* Construct an identifier. */ >> + id = kmalloc(signer_len + 2 + auth_len + 1, GFP_KERNEL); >> + if (!id) >> + return ERR_PTR(-ENOMEM); >> + >> + memcpy(id, signer, signer_len); >> + id[signer_len + 0] = ':'; >> + id[signer_len + 1] = ' '; >> + memcpy(id + signer_len + 2, authority, auth_len); >> + id[signer_len + 2 + auth_len] = 0; >> + >> + pr_debug("Look up: \"%s\"\n", id); >> + >> + key = keyring_search(make_key_ref(keyring, 1), >> + &key_type_asymmetric, id); >> + if (IS_ERR(key)) >> + pr_debug("Request for module key '%s' err %ld\n", >> + id, PTR_ERR(key)); >> + kfree(id); >> + >> + if (IS_ERR(key)) { >> + switch (PTR_ERR(key)) { >> + /* Hide some search errors */ >> + case -EACCES: >> + case -ENOTDIR: >> + case -EAGAIN: >> + return ERR_PTR(-ENOKEY); >> + default: >> + return ERR_CAST(key); >> + } >> + } >> + >> + pr_devel("<==%s() = 0 [%x]\n", __func__, key_serial(key_ref_to_ptr(key))); >> + return key_ref_to_ptr(key); >> +} >> + >> +/* >> + * Check the new certificate against the ones in the trust keyring. If one of >> + * those is the signing key and validates the new certificate, then mark the >> + * new certificate as being trusted. >> + * >> + * Return 0 if the new certificate was successfully validated, 1 if we couldn't >> + * find a matching parent certificate in the trusted list and an error if there >> + * is a matching certificate but the signature check fails. >> + */ >> +static int x509_validate_trust(struct x509_certificate *cert, >> + struct key *trust_keyring) >> +{ >> + const struct public_key *pk; >> + struct key *key; >> + int ret = 1; >> + >> + key = x509_request_asymmetric_key(trust_keyring, >> + cert->issuer, strlen(cert->issuer), >> + cert->authority, >> + strlen(cert->authority)); >> + if (!IS_ERR(key)) { >> + pk = key->payload.data; >> + ret = x509_check_signature(pk, cert); >> + } >> + return ret; >> +} >> +#endif >> + >> /* >> * Attempt to parse a data blob for a key as an X509 certificate. >> */ >> @@ -155,9 +232,15 @@ static int x509_key_preparse(struct key_preparsed_payload *prep) >> /* Check the signature on the key if it appears to be self-signed */ >> if (!cert->authority || >> strcmp(cert->fingerprint, cert->authority) == 0) { >> - ret = x509_check_signature(cert->pub, cert); >> + ret = x509_check_signature(cert->pub, cert); /* self-signed */ >> if (ret < 0) >> goto error_free_cert; >> + } else { >> +#ifdef CONFIG_SYSTEM_TRUSTED_KEYRING >> + ret = x509_validate_trust(cert, system_trusted_keyring); >> + if (!ret) >> + prep->trusted = 1; >> +#endif >> } >> >> /* Propose a description */ > > > -- > To unsubscribe from this list: send the line "unsubscribe linux-security-module" in > the body of a message to majordomo@vger.kernel.org > More majordomo info at http://vger.kernel.org/majordomo-info.html -- Thanks, Dmitry -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/