[PATCH v3 8/9] ima: define a canonical binary_runtime_measurements list format
Mimi Zohar
zohar at linux.vnet.ibm.com
Tue Sep 6 07:03:03 PDT 2016
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.
Changelog v3:
- restore PCR value properly
Signed-off-by: Mimi Zohar <zohar at linux.vnet.ibm.com>
---
Documentation/kernel-parameters.txt | 4 ++++
security/integrity/ima/ima.h | 6 ++++++
security/integrity/ima/ima_fs.c | 28 +++++++++++++++++++++-------
security/integrity/ima/ima_kexec.c | 11 +++++++++--
security/integrity/ima/ima_template.c | 24 ++++++++++++++++++++++--
security/integrity/ima/ima_template_lib.c | 7 +++++--
6 files changed, 67 insertions(+), 13 deletions(-)
diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 46c030a..5e8037fc 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1580,6 +1580,10 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
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 | ... }
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index e8303c9..eb0f4dd 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -112,6 +112,12 @@ struct ima_kexec_hdr {
u64 count;
};
+/*
+ * 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);
diff --git a/security/integrity/ima/ima_fs.c b/security/integrity/ima/ima_fs.c
index 66e5dd5..2bcad99 100644
--- a/security/integrity/ima/ima_fs.c
+++ b/security/integrity/ima/ima_fs.c
@@ -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++) {
diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c
index 04a2e71..a76647e 100644
--- a/security/integrity/ima/ima_kexec.c
+++ b/security/integrity/ima/ima_kexec.c
@@ -33,8 +33,7 @@ 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 */
@@ -48,6 +47,8 @@ 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++;
@@ -66,7 +67,13 @@ 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);
diff --git a/security/integrity/ima/ima_template.c b/security/integrity/ima/ima_template.c
index e689b572f..9d6faac 100644
--- a/security/integrity/ima/ima_template.c
+++ b/security/integrity/ima/ima_template.c
@@ -304,6 +304,9 @@ static int ima_restore_template_data(struct ima_template_desc *template_desc,
}
offset += sizeof(field_data->len);
+ 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;
@@ -354,7 +357,7 @@ 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;
@@ -363,6 +366,12 @@ 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 0;
@@ -373,6 +382,7 @@ 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)) {
if (count > ULONG_MAX - 1) {
pr_err("attempting to restore too many measurements");
@@ -380,6 +390,11 @@ int ima_restore_measurement_list(loff_t size, void *buf)
}
hdr_v1 = bufp;
+
+ 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 + hdr_v1->template_name_len) > bufendp)) {
pr_err("attempting to restore a template name \
@@ -429,6 +444,10 @@ 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;
@@ -443,7 +462,8 @@ 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;
diff --git a/security/integrity/ima/ima_template_lib.c b/security/integrity/ima/ima_template_lib.c
index f9bae04..f9ba37b 100644
--- a/security/integrity/ima/ima_template_lib.c
+++ b/security/integrity/ima/ima_template_lib.c
@@ -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;
--
2.1.0
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