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From:   Thiago Jung Bauermann <bauerman@linux.ibm.com>
To:     Mimi Zohar <zohar@linux.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-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
        Dmitry Kasatkin <dmitry.kasatkin@gmail.com>,
        James Morris <jmorris@namei.org>,
        "Serge E. Hallyn" <serge@hallyn.com>,
        David Howells <dhowells@redhat.com>,
        David Woodhouse <dwmw2@infradead.org>,
        Jessica Yu <jeyu@kernel.org>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        "David S. Miller" <davem@davemloft.net>,
        Jonathan Corbet <corbet@lwn.net>,
        "AKASHI\, Takahiro" <takahiro.akashi@linaro.org>
Subject: Re: [PATCH v10 09/12] ima: Implement support for module-style appended signatures
In-reply-to: <1557442868.10635.87.camel@linux.ibm.com>
Date:   Tue, 28 May 2019 16:23:16 -0300
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Mimi Zohar <zohar@linux.ibm.com> writes:

> Hi Thiago,
>
>> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
>> index fca7a3f23321..a7a20a8c15c1 100644
>> --- a/security/integrity/ima/ima_policy.c
>> +++ b/security/integrity/ima/ima_policy.c
>> @@ -1144,6 +1144,12 @@ void ima_delete_rules(void)
>>  	}
>>  }
>>
>> +#define __ima_hook_stringify(str)	(#str),
>> +
>> +const char *const func_tokens[] = {
>> +	__ima_hooks(__ima_hook_stringify)
>> +};
>> +
>>  #ifdef	CONFIG_IMA_READ_POLICY
>>  enum {
>>  	mask_exec = 0, mask_write, mask_read, mask_append
>> @@ -1156,12 +1162,6 @@ static const char *const mask_tokens[] = {
>>  	"MAY_APPEND"
>>  };
>>
>> -#define __ima_hook_stringify(str)	(#str),
>> -
>> -static const char *const func_tokens[] = {
>> -	__ima_hooks(__ima_hook_stringify)
>> -};
>> -
>>  void *ima_policy_start(struct seq_file *m, loff_t *pos)
>>  {
>>  	loff_t l = *pos;
>
> Is moving this something left over from previous versions or there is
> a need for this change?

Well, it's not a strong need, but it's still relevant in the current
version. I use func_tokens in ima_read_modsig() in order to be able to
mention the hook name in mod_check_sig()'s error message:

In ima_read_modsig():

	rc = mod_check_sig(sig, buf_len, func_tokens[func]);

And in mod_check_sig():

		pr_err("%s: Module is not signed with expected PKCS#7 message\n",
		       name);

If you think it's not worth it to expose func_tokens, I can make
ima_read_modsig() pass a more generic const string such as "IMA modsig"
for example.

> Other than this, the patch looks good.

Nice!

--
Thiago Jung Bauermann
IBM Linux Technology Center