From: Roberto Sassu <roberto.sassu@huawei.com> To: Ken Goldman <kgold@linux.vnet.ibm.com>, <linux-ima-devel@lists.sourceforge.net> Cc: <linux-security-module@vger.kernel.org>, <linux-kernel@vger.kernel.org> Subject: Re: [Linux-ima-devel] [PATCH 0/7] IMA: new parser for ima_restore_measurement_list() Date: Wed, 17 May 2017 09:25:05 +0200 [thread overview] Message-ID: <42b629dd-0d1f-b066-03e4-c013d0891ba7@huawei.com> (raw) In-Reply-To: <4f5bc289-92cb-1ce2-4496-387efbb11769@linux.vnet.ibm.com> On 5/16/2017 9:00 PM, Ken Goldman wrote: > On 5/16/2017 8:53 AM, Roberto Sassu wrote: >> A new IMA measurement list format, called Crypto Agile, will be introduced >> shortly to take full advantage of the algorithm flexibility of TPM 2.0. >> With the new format, it will be possible to provide for each list entry >> multiple digests, each calculated with an algorithm supported by the TPM. >> Those digests will be used by remote entities to verify the integrity of >> the measurements list. >> >> The current (SHA1) and the new (Crypto Agile) format definitions are: >> >> SHA1: pcr[4] digest[20] >> template_name_len[4] template_name[template_name_len] >> template_data_len[4] template_data[template_data_len] >> >> Crypto Agile: pcr[4] total_digest_len[4] >> digest1_len[4] digest1[digest1_len] ... >> digestN_len[4] digestN[digestN_len] >> template_name_len[4] template_name[template_name_len] >> template_data_len[4] template_data[template_data_len] > > 1 - In this proposed format, how does the parser or consumer of the log > know what algorithm is used for digestN. The format of digestN is: <algo name>:\0<digest value>, the same used for the file digest. > For example, the TCG standard format uses TPML_DIGEST_VALUES > uint32_t count - the number of digests TPMT_HA > TPMT_HA digests[] > > where a TPMT_HA is > algorithm identifier > digest byte array > > 2 - Not a criticism, just a question for understanding ... Would it be > true that the total_digest_length == the sum of all the digestN_len > values plus 4 bytes for each length. Yes. > Does it determine how many digests there are by when the total length is > consumed? Yes. Since the number of digests is unknown until the buffer is parsed, the parser consumes the data until the buffer end is reached. Then, it returns the number of digests to the caller. Roberto
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From: roberto.sassu@huawei.com (Roberto Sassu) To: linux-security-module@vger.kernel.org Subject: [Linux-ima-devel] [PATCH 0/7] IMA: new parser for ima_restore_measurement_list() Date: Wed, 17 May 2017 09:25:05 +0200 [thread overview] Message-ID: <42b629dd-0d1f-b066-03e4-c013d0891ba7@huawei.com> (raw) In-Reply-To: <4f5bc289-92cb-1ce2-4496-387efbb11769@linux.vnet.ibm.com> On 5/16/2017 9:00 PM, Ken Goldman wrote: > On 5/16/2017 8:53 AM, Roberto Sassu wrote: >> A new IMA measurement list format, called Crypto Agile, will be introduced >> shortly to take full advantage of the algorithm flexibility of TPM 2.0. >> With the new format, it will be possible to provide for each list entry >> multiple digests, each calculated with an algorithm supported by the TPM. >> Those digests will be used by remote entities to verify the integrity of >> the measurements list. >> >> The current (SHA1) and the new (Crypto Agile) format definitions are: >> >> SHA1: pcr[4] digest[20] >> template_name_len[4] template_name[template_name_len] >> template_data_len[4] template_data[template_data_len] >> >> Crypto Agile: pcr[4] total_digest_len[4] >> digest1_len[4] digest1[digest1_len] ... >> digestN_len[4] digestN[digestN_len] >> template_name_len[4] template_name[template_name_len] >> template_data_len[4] template_data[template_data_len] > > 1 - In this proposed format, how does the parser or consumer of the log > know what algorithm is used for digestN. The format of digestN is: <algo name>:\0<digest value>, the same used for the file digest. > For example, the TCG standard format uses TPML_DIGEST_VALUES > uint32_t count - the number of digests TPMT_HA > TPMT_HA digests[] > > where a TPMT_HA is > algorithm identifier > digest byte array > > 2 - Not a criticism, just a question for understanding ... Would it be > true that the total_digest_length == the sum of all the digestN_len > values plus 4 bytes for each length. Yes. > Does it determine how many digests there are by when the total length is > consumed? Yes. Since the number of digests is unknown until the buffer is parsed, the parser consumes the data until the buffer end is reached. Then, it returns the number of digests to the caller. Roberto -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo at vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
next prev parent reply other threads:[~2017-05-17 7:25 UTC|newest] Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top 2017-05-16 12:53 [PATCH 0/7] IMA: new parser for ima_restore_measurement_list() Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-05-16 12:53 ` [PATCH 1/7] ima: introduce ima_parse_buf() Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-06-05 5:54 ` [Linux-ima-devel] " Mimi Zohar 2017-06-05 5:54 ` Mimi Zohar 2017-05-16 12:53 ` [PATCH 2/7] ima: use ima_parse_buf() to parse measurements headers Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-05-16 12:53 ` [PATCH 3/7] ima: use ima_parse_buf() to parse template data Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-05-16 12:53 ` [PATCH 4/7] ima: declare get_binary_runtime_size() as non-static Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-05-16 12:53 ` [PATCH 5/7] ima: add securityfs interface to save a measurements list with kexec header Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-06-05 6:04 ` [Linux-ima-devel] " Mimi Zohar 2017-06-05 6:04 ` Mimi Zohar 2017-06-06 8:49 ` Roberto Sassu 2017-06-06 8:49 ` Roberto Sassu 2017-06-06 10:56 ` Mimi Zohar 2017-06-06 10:56 ` Mimi Zohar 2017-06-06 12:45 ` Roberto Sassu 2017-06-06 12:45 ` Roberto Sassu 2017-06-06 13:23 ` Mimi Zohar 2017-06-06 13:23 ` Mimi Zohar 2017-06-13 7:27 ` Roberto Sassu 2017-06-13 7:27 ` Roberto Sassu 2017-06-13 12:09 ` Mimi Zohar 2017-06-13 12:09 ` Mimi Zohar 2017-06-13 12:37 ` Roberto Sassu 2017-06-13 12:37 ` Roberto Sassu 2017-06-06 9:13 ` [Linux-ima-devel] " Roberto Sassu 2017-06-06 9:13 ` Roberto Sassu 2017-06-06 11:33 ` Mimi Zohar 2017-06-06 11:33 ` Mimi Zohar 2017-05-16 12:53 ` [PATCH 6/7] ima: add securityfs interface to restore a measurements list Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-06-05 5:56 ` [Linux-ima-devel] " Mimi Zohar 2017-06-05 5:56 ` Mimi Zohar 2017-05-16 12:53 ` [PATCH 7/7] ima: fix get_binary_runtime_size() Roberto Sassu 2017-05-16 12:53 ` Roberto Sassu 2017-05-16 19:00 ` [Linux-ima-devel] [PATCH 0/7] IMA: new parser for ima_restore_measurement_list() Ken Goldman 2017-05-16 19:00 ` Ken Goldman 2017-05-17 7:25 ` Roberto Sassu [this message] 2017-05-17 7:25 ` Roberto Sassu 2017-05-17 16:28 ` Ken Goldman 2017-05-17 16:28 ` Ken Goldman 2017-05-18 9:38 ` Roberto Sassu 2017-05-18 9:38 ` Roberto Sassu 2017-05-23 20:48 ` Ken Goldman 2017-05-23 20:48 ` Ken Goldman 2017-05-24 8:18 ` Roberto Sassu 2017-05-24 8:18 ` Roberto Sassu 2017-05-23 21:00 ` Ken Goldman 2017-05-23 21:00 ` Ken Goldman
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