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Commit d68a6fe9 authored by Mimi Zohar's avatar Mimi Zohar Committed by Linus Torvalds
Browse files

ima: define a canonical binary_runtime_measurements list format 

The IMA binary_runtime_measurements list is currently in platform native
format.

To allow restoring a measurement list carried across kexec with a
different endianness than the targeted kernel, this patch defines
little-endian as the canonical format.  For big endian systems wanting
to save/restore the measurement list from a system with a different
endianness, a new boot command line parameter named "ima_canonical_fmt"
is defined.

Considerations: use of the "ima_canonical_fmt" boot command line option
will break existing userspace applications on big endian systems
expecting the binary_runtime_measurements list to be in platform native
format.

Link: http://lkml.kernel.org/r/1480554346-29071-10-git-send-email-zohar@linux.vnet.ibm.com


Signed-off-by: default avatarMimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: default avatarDmitry Kasatkin <dmitry.kasatkin@gmail.com>
Cc: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andreas Steffen <andreas.steffen@strongswan.org>
Cc: Josh Sklar <sklar@linux.vnet.ibm.com>
Cc: Dave Young <dyoung@redhat.com>
Cc: Vivek Goyal <vgoyal@redhat.com>
Cc: Baoquan He <bhe@redhat.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Stewart Smith <stewart@linux.vnet.ibm.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent c7d09367

Documentation/admin-guide/kernel-parameters.txt

+4 −0
Original line number Diff line number Diff line
@@ -1441,6 +1441,10 @@ 
			The builtin appraise policy appraises all files

			owned by uid=0.



	ima_canonical_fmt [IMA]

			Use the canonical format for the binary runtime

			measurements, instead of host native format.



	ima_hash=	[IMA]

			Format: { md5 | sha1 | rmd160 | sha256 | sha384

				   | sha512 | ... }

security/integrity/ima/ima.h

+6 −0
Original line number Diff line number Diff line
@@ -122,6 +122,12 @@ void ima_load_kexec_buffer(void); 
static inline void ima_load_kexec_buffer(void) {}

#endif /* CONFIG_HAVE_IMA_KEXEC */



/*

 * The default binary_runtime_measurements list format is defined as the

 * platform native format.  The canonical format is defined as little-endian.

 */

extern bool ima_canonical_fmt;



/* Internal IMA function definitions */

int ima_init(void);

int ima_fs_init(void);

security/integrity/ima/ima_fs.c

+21 −7
Original line number Diff line number Diff line
@@ -28,6 +28,16 @@ 


static DEFINE_MUTEX(ima_write_mutex);



bool ima_canonical_fmt;

static int __init default_canonical_fmt_setup(char *str)

{

#ifdef __BIG_ENDIAN

	ima_canonical_fmt = 1;

#endif

	return 1;

}

__setup("ima_canonical_fmt", default_canonical_fmt_setup);



static int valid_policy = 1;

#define TMPBUFLEN 12

static ssize_t ima_show_htable_value(char __user *buf, size_t count,
@@ -122,7 +132,7 @@ int ima_measurements_show(struct seq_file *m, void *v) 
	struct ima_queue_entry *qe = v;

	struct ima_template_entry *e;

	char *template_name;

	int namelen;

	u32 pcr, namelen, template_data_len; /* temporary fields */

	bool is_ima_template = false;

	int i;
@@ -139,25 +149,29 @@ int ima_measurements_show(struct seq_file *m, void *v) 
	 * PCR used defaults to the same (config option) in

	 * little-endian format, unless set in policy

	 */

	ima_putc(m, &e->pcr, sizeof(e->pcr));

	pcr = !ima_canonical_fmt ? e->pcr : cpu_to_le32(e->pcr);

	ima_putc(m, &pcr, sizeof(e->pcr));



	/* 2nd: template digest */

	ima_putc(m, e->digest, TPM_DIGEST_SIZE);



	/* 3rd: template name size */

	namelen = strlen(template_name);

	namelen = !ima_canonical_fmt ? strlen(template_name) :

		cpu_to_le32(strlen(template_name));

	ima_putc(m, &namelen, sizeof(namelen));



	/* 4th:  template name */

	ima_putc(m, template_name, namelen);

	ima_putc(m, template_name, strlen(template_name));



	/* 5th:  template length (except for 'ima' template) */

	if (strcmp(template_name, IMA_TEMPLATE_IMA_NAME) == 0)

		is_ima_template = true;



	if (!is_ima_template)

		ima_putc(m, &e->template_data_len,

			 sizeof(e->template_data_len));

	if (!is_ima_template) {

		template_data_len = !ima_canonical_fmt ? e->template_data_len :

			cpu_to_le32(e->template_data_len);

		ima_putc(m, &template_data_len, sizeof(e->template_data_len));

	}



	/* 6th:  template specific data */

	for (i = 0; i < e->template_desc->num_fields; i++) {

security/integrity/ima/ima_kexec.c

+9 −2
Original line number Diff line number Diff line
@@ -21,8 +21,7 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, 
{

	struct ima_queue_entry *qe;

	struct seq_file file;

	struct ima_kexec_hdr khdr = {

		.version = 1, .buffer_size = 0, .count = 0};

	struct ima_kexec_hdr khdr;

	int ret = 0;



	/* segment size can't change between kexec load and execute */
@@ -36,6 +35,8 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, 
	file.read_pos = 0;

	file.count = sizeof(khdr);	/* reserved space */



	memset(&khdr, 0, sizeof(khdr));

	khdr.version = 1;

	list_for_each_entry_rcu(qe, &ima_measurements, later) {

		if (file.count < file.size) {

			khdr.count++;
@@ -54,7 +55,13 @@ static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, 
	 * (eg. version, buffer size, number of measurements)

	 */

	khdr.buffer_size = file.count;

	if (ima_canonical_fmt) {

		khdr.version = cpu_to_le16(khdr.version);

		khdr.count = cpu_to_le64(khdr.count);

		khdr.buffer_size = cpu_to_le64(khdr.buffer_size);

	}

	memcpy(file.buf, &khdr, sizeof(khdr));



	print_hex_dump(KERN_DEBUG, "ima dump: ", DUMP_PREFIX_NONE,

			16, 1, file.buf,

			file.count < 100 ? file.count : 100, true);

security/integrity/ima/ima_template.c

+21 −2
Original line number Diff line number Diff line
@@ -302,6 +302,9 @@ static int ima_restore_template_data(struct ima_template_desc *template_desc, 
		}

		offset += sizeof(*field_data);



		if (ima_canonical_fmt)

			field_data->len = le32_to_cpu(field_data->len);



		if (offset > (template_data_size - field_data->len)) {

			pr_err("Restoring the template field data failed\n");

			ret = -EINVAL;
@@ -352,7 +355,7 @@ int ima_restore_measurement_list(loff_t size, void *buf) 
	struct binary_data_v1 *data_v1;



	void *bufp = buf + sizeof(*khdr);

	void *bufendp = buf + khdr->buffer_size;

	void *bufendp;

	struct ima_template_entry *entry;

	struct ima_template_desc *template_desc;

	unsigned long count = 0;
@@ -361,6 +364,12 @@ int ima_restore_measurement_list(loff_t size, void *buf) 
	if (!buf || size < sizeof(*khdr))

		return 0;



	if (ima_canonical_fmt) {

		khdr->version = le16_to_cpu(khdr->version);

		khdr->count = le64_to_cpu(khdr->count);

		khdr->buffer_size = le64_to_cpu(khdr->buffer_size);

	}



	if (khdr->version != 1) {

		pr_err("attempting to restore a incompatible measurement list");

		return -EINVAL;
@@ -376,6 +385,7 @@ int ima_restore_measurement_list(loff_t size, void *buf) 
	 * v1 format: pcr, digest, template-name-len, template-name,

	 *	      template-data-size, template-data

	 */

	bufendp = buf + khdr->buffer_size;

	while ((bufp < bufendp) && (count++ < khdr->count)) {

		hdr_v1 = bufp;

		if (bufp > (bufendp - sizeof(*hdr_v1))) {
@@ -385,6 +395,10 @@ int ima_restore_measurement_list(loff_t size, void *buf) 
		}

		bufp += sizeof(*hdr_v1);



		if (ima_canonical_fmt)

			hdr_v1->template_name_len =

			    le32_to_cpu(hdr_v1->template_name_len);



		if ((hdr_v1->template_name_len >= MAX_TEMPLATE_NAME_LEN) ||

		    (bufp > (bufendp - hdr_v1->template_name_len))) {

			pr_err("attempting to restore a template name \
@@ -434,6 +448,10 @@ int ima_restore_measurement_list(loff_t size, void *buf) 
		}

		bufp += (u_int8_t) sizeof(data_v1->template_data_size);



		if (ima_canonical_fmt)

			data_v1->template_data_size =

			    le32_to_cpu(data_v1->template_data_size);



		if (bufp > (bufendp - data_v1->template_data_size)) {

			pr_err("restoring the template data failed\n");

			ret = -EINVAL;
@@ -449,7 +467,8 @@ int ima_restore_measurement_list(loff_t size, void *buf) 
			break;



		memcpy(entry->digest, hdr_v1->digest, TPM_DIGEST_SIZE);

		entry->pcr = hdr_v1->pcr;

		entry->pcr =

		    !ima_canonical_fmt ? hdr_v1->pcr : le32_to_cpu(hdr_v1->pcr);

		ret = ima_restore_measurement_entry(entry);

		if (ret < 0)

			break;