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ima: define a canonical binary_runtime_measurements list format

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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: Mimi Zohar <zohar@linux.vnet.ibm.com>
Acked-by: Dmitry 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: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Mimi Zohar 2016-12-19 16:22:57 -08:00 committed by Linus Torvalds
parent c7d0936770
commit d68a6fe9fc
6 changed files with 66 additions and 13 deletions
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4
Documentation/admin-guide/kernel-parameters.txt
View File

@ -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 | ... }

6
security/integrity/ima/ima.h
View File

@ -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);

28
security/integrity/ima/ima_fs.c
View File

@ -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++) {

11
security/integrity/ima/ima_kexec.c
View File

@ -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);

23
security/integrity/ima/ima_template.c
View File

@ -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;

7
security/integrity/ima/ima_template_lib.c
View File

@ -103,8 +103,11 @@ static void ima_show_template_data_binary(struct seq_file *m,
u32 len = (show == IMA_SHOW_BINARY_OLD_STRING_FMT) ?
strlen(field_data->data) : field_data->len;
if (show != IMA_SHOW_BINARY_NO_FIELD_LEN)
ima_putc(m, &len, sizeof(len));
if (show != IMA_SHOW_BINARY_NO_FIELD_LEN) {
u32 field_len = !ima_canonical_fmt ? len : cpu_to_le32(len);
ima_putc(m, &field_len, sizeof(field_len));
}
if (!len)
return;