From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
To: Mimi Zohar <zohar@linux.vnet.ibm.com>
Cc: linux-integrity@vger.kernel.org,
linux-security-module@vger.kernel.org, keyrings@vger.kernel.org,
linux-crypto@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
linux-kernel@vger.kernel.org,
Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
James Morris <james.l.morris@oracle.com>,
"Serge E. Hallyn" <serge@hallyn.com>,
David Howells <dhowells@redhat.com>,
David Woodhouse <dwmw2@infradead.org>,
Jessica Yu <jeyu@redhat.com>,
Rusty Russell <rusty@rustcorp.com.au>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>, "AKASHI\,
Takahiro" <takahiro.akashi@linaro.org>
Subject: Re: [PATCH v5 12/18] MODSIGN: Export module signature definitions
Date: Thu, 26 Oct 2017 20:47:29 -0200 [thread overview]
Message-ID: <87po99wmpq.fsf@linux.vnet.ibm.com> (raw)
In-Reply-To: <1509048728.5886.112.camel@linux.vnet.ibm.com>
Mimi Zohar <zohar@linux.vnet.ibm.com> writes:
> On Tue, 2017-10-17 at 22:53 -0200, Thiago Jung Bauermann wrote:
>> IMA will use the module_signature format for append signatures, so export
>> the relevant definitions and factor out the code which verifies that the
>> appended signature trailer is valid.
>>
>> Also, create a CONFIG_MODULE_SIG_FORMAT option so that IMA can select it
>> and be able to use validate_module_signature without having to depend on
>> CONFIG_MODULE_SIG.
>>
>> Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
>
> Reviewed-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
>
> One minor comment below...
Thanks!
>> diff --git a/kernel/module_signing.c b/kernel/module_signing.c
>> index 937c844bee4a..204c60d4cc9f 100644
>> --- a/kernel/module_signing.c
>> +++ b/kernel/module_signing.c
>> @@ -11,36 +11,38 @@
>>
>> #include <linux/kernel.h>
>> #include <linux/errno.h>
>> +#include <linux/module_signature.h>
>> #include <linux/string.h>
>> #include <linux/verification.h>
>> #include <crypto/public_key.h>
>> #include "module-internal.h"
>>
>> -enum pkey_id_type {
>> - PKEY_ID_PGP, /* OpenPGP generated key ID */
>> - PKEY_ID_X509, /* X.509 arbitrary subjectKeyIdentifier */
>> - PKEY_ID_PKCS7, /* Signature in PKCS#7 message */
>> -};
>> -
>> -/*
>> - * Module signature information block.
>> - *
>> - * The constituents of the signature section are, in order:
>> +/**
>> + * validate_module_sig - validate that the given signature is sane
>> *
>> - * - Signer's name
>> - * - Key identifier
>> - * - Signature data
>> - * - Information block
>> + * @ms: Signature to validate.
>> + * @file_len: Size of the file to which @ms is appended.
>> */
>> -struct module_signature {
>> - u8 algo; /* Public-key crypto algorithm [0] */
>> - u8 hash; /* Digest algorithm [0] */
>> - u8 id_type; /* Key identifier type [PKEY_ID_PKCS7] */
>> - u8 signer_len; /* Length of signer's name [0] */
>> - u8 key_id_len; /* Length of key identifier [0] */
>> - u8 __pad[3];
>> - __be32 sig_len; /* Length of signature data */
>> -};
>> +int validate_module_sig(const struct module_signature *ms, size_t file_len)
>> +{
>> + if (be32_to_cpu(ms->sig_len) >= file_len - sizeof(*ms))
>> + return -EBADMSG;
>> + else if (ms->id_type != PKEY_ID_PKCS7) {
>> + pr_err("Module is not signed with expected PKCS#7 message\n");
>> + return -ENOPKG;
>> + } else if (ms->algo != 0 ||
>> + ms->hash != 0 ||
>> + ms->signer_len != 0 ||
>> + ms->key_id_len != 0 ||
>> + ms->__pad[0] != 0 ||
>> + ms->__pad[1] != 0 ||
>> + ms->__pad[2] != 0) {
>> + pr_err("PKCS#7 signature info has unexpected non-zero params\n");
>> + return -EBADMSG;
>> + }
>> +
>
> When moving code from one place to another, it's easier to review when
> there aren't code changes as well. In this case, the original code
> doesn't have "else clauses".
Indeed. I changed the code back to using separate if clauses, making
only the changes that are required for the refactoring.
> Here some of the if/then/else clauses
> have braces others don't. There shouldn't be a mixture.
Does this still apply when the if clauses are separate as in the
original code? Should the first if still have braces?
--
Thiago Jung Bauermann
IBM Linux Technology Center
next prev parent reply other threads:[~2017-10-26 22:47 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-10-18 0:53 [PATCH v5 00/18] Appended signatures support for IMA appraisal Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 01/18] ima: Remove redundant conditional operator Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 02/18] ima: Remove some superfluous parentheses Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 03/18] evm, ima: Remove " Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 04/18] evm, ima: Remove more " Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 05/18] ima: Simplify ima_eventsig_init Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 06/18] ima: Improvements in ima_appraise_measurement Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 07/18] integrity: Introduce struct evm_xattr Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 08/18] integrity: Select CONFIG_KEYS instead of depending on it Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 09/18] ima: Don't pass xattr value to EVM xattr verification Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 10/18] ima: Store measurement after appraisal Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 11/18] ima: Export func_tokens Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 12/18] MODSIGN: Export module signature definitions Thiago Jung Bauermann
2017-10-26 20:12 ` Mimi Zohar
2017-10-26 22:47 ` Thiago Jung Bauermann [this message]
2017-10-26 23:13 ` Mimi Zohar
2017-10-18 0:53 ` [PATCH v5 13/18] PKCS#7: Introduce pkcs7_get_message_sig and verify_pkcs7_message_sig Thiago Jung Bauermann
2017-10-26 20:12 ` Mimi Zohar
2017-10-18 0:53 ` [PATCH v5 14/18] integrity: Introduce integrity_keyring_from_id Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 15/18] ima: Add modsig appraise_type option for module-style appended signatures Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 16/18] ima: Add functions to read and verify a modsig signature Thiago Jung Bauermann
2017-10-18 0:53 ` [PATCH v5 17/18] ima: Implement support for module-style appended signatures Thiago Jung Bauermann
2017-10-31 13:31 ` Mimi Zohar
2017-10-18 0:53 ` [PATCH v5 18/18] ima: Write modsig to the measurement list Thiago Jung Bauermann
2017-10-26 20:07 ` Mimi Zohar
2017-10-26 22:02 ` Thiago Jung Bauermann
2017-10-26 20:53 ` [PATCH v5 00/18] Appended signatures support for IMA appraisal Mimi Zohar
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