[PATCH v2 03/23] ima: provide support for arbitrary hash algorithms

From: Mimi Zohar
Date: Mon Oct 21 2013 - 18:52:01 EST

From: Dmitry Kasatkin <d.kasatkin@xxxxxxxxxxx>

In preparation of supporting more hash algorithms with larger hash sizes
needed for signature verification, this patch replaces the 20 byte sized
digest, with a more flexible structure. The new structure includes the
hash algorithm, digest size, and digest.

Changelog:
- recalculate filedata hash for the measurement list, if the signature
hash digest size is greater than 20 bytes.
- use generic HASH_ALGO_
- make ima_calc_file_hash static
- scripts lindent and checkpatch fixes

Signed-off-by: Dmitry Kasatkin <d.kasatkin@xxxxxxxxxxx>
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
---
crypto/asymmetric_keys/x509_parser.h | 2 --
crypto/asymmetric_keys/x509_public_key.c | 3 +-
security/integrity/ima/Kconfig | 1 +
security/integrity/ima/ima.h | 7 +++--
security/integrity/ima/ima_api.c | 32 +++++++++++++++------
security/integrity/ima/ima_appraise.c | 20 +++++++------
security/integrity/ima/ima_crypto.c | 49 ++++++++++++++++++++++++++------
security/integrity/ima/ima_main.c | 6 ++--
security/integrity/integrity.h | 15 ++++++++--
9 files changed, 100 insertions(+), 35 deletions(-)

diff --git a/crypto/asymmetric_keys/x509_parser.h b/crypto/asymmetric_keys/x509_parser.h
index 04c81bd..87d9cc2 100644
--- a/crypto/asymmetric_keys/x509_parser.h
+++ b/crypto/asymmetric_keys/x509_parser.h
@@ -21,8 +21,6 @@ struct x509_certificate {
char *authority; /* Authority key fingerprint as hex */
struct tm valid_from;
struct tm valid_to;
- enum pkey_algo pkey_algo : 8; /* Public key algorithm */
- enum hash_algo sig_hash_algo : 8; /* Signature hash algorithm */
const void *tbs; /* Signed data */
unsigned tbs_size; /* Size of signed data */
unsigned raw_sig_size; /* Size of sigature */
diff --git a/crypto/asymmetric_keys/x509_public_key.c b/crypto/asymmetric_keys/x509_public_key.c
index 0a6bfad..f83300b 100644
--- a/crypto/asymmetric_keys/x509_public_key.c
+++ b/crypto/asymmetric_keys/x509_public_key.c
@@ -213,7 +213,8 @@ static int x509_key_preparse(struct key_preparsed_payload *prep)
cert->valid_to.tm_year + 1900, cert->valid_to.tm_mon + 1,
cert->valid_to.tm_mday, cert->valid_to.tm_hour,
cert->valid_to.tm_min, cert->valid_to.tm_sec);
- pr_devel("Cert Signature: %s\n",
+ pr_devel("Cert Signature: %s + %s\n",
+ pkey_algo_name[cert->sig.pkey_algo],
hash_algo_name[cert->sig.pkey_hash_algo]);

if (!cert->fingerprint) {
diff --git a/security/integrity/ima/Kconfig b/security/integrity/ima/Kconfig
index 39196ab..e6628e7 100644
--- a/security/integrity/ima/Kconfig
+++ b/security/integrity/ima/Kconfig
@@ -9,6 +9,7 @@ config IMA
select CRYPTO_HMAC
select CRYPTO_MD5
select CRYPTO_SHA1
+ select CRYPTO_HASH_INFO
select TCG_TPM if HAS_IOMEM && !UML
select TCG_TIS if TCG_TPM && X86
select TCG_IBMVTPM if TCG_TPM && PPC64
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index b3dd616..eb86032 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -39,7 +39,7 @@ enum tpm_pcrs { TPM_PCR0 = 0, TPM_PCR8 = 8 };
/* set during initialization */
extern int ima_initialized;
extern int ima_used_chip;
-extern char *ima_hash;
+extern int ima_hash_algo;
extern int ima_appraise;

/* IMA inode template definition */
@@ -70,8 +70,9 @@ void ima_fs_cleanup(void);
int ima_inode_alloc(struct inode *inode);
int ima_add_template_entry(struct ima_template_entry *entry, int violation,
const char *op, struct inode *inode);
-int ima_calc_file_hash(struct file *file, char *digest);
-int ima_calc_buffer_hash(const void *data, int len, char *digest);
+int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash);
+int ima_calc_buffer_hash(const void *data, int len,
+ struct ima_digest_data *hash);
int ima_calc_boot_aggregate(char *digest);
void ima_add_violation(struct inode *inode, const unsigned char *filename,
const char *op, const char *cause);
diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
index 1c03e8f1..e531fe2 100644
--- a/security/integrity/ima/ima_api.c
+++ b/security/integrity/ima/ima_api.c
@@ -44,6 +44,7 @@ int ima_store_template(struct ima_template_entry *entry,
const char *op = "add_template_measure";
const char *audit_cause = "hashing_error";
int result;
+ struct ima_digest_data hash;

memset(entry->digest, 0, sizeof(entry->digest));
entry->template_name = IMA_TEMPLATE_NAME;
@@ -51,14 +52,14 @@ int ima_store_template(struct ima_template_entry *entry,

if (!violation) {
result = ima_calc_buffer_hash(&entry->template,
- entry->template_len,
- entry->digest);
+ entry->template_len, &hash);
if (result < 0) {
integrity_audit_msg(AUDIT_INTEGRITY_PCR, inode,
entry->template_name, op,
audit_cause, result, 0);
return result;
}
+ memcpy(entry->digest, hash.digest, hash.length);
}
result = ima_add_template_entry(entry, violation, op, inode);
return result;
@@ -147,8 +148,9 @@ int ima_collect_measurement(struct integrity_iint_cache *iint,
if (!(iint->flags & IMA_COLLECTED)) {
u64 i_version = file_inode(file)->i_version;

- iint->ima_xattr.type = IMA_XATTR_DIGEST;
- result = ima_calc_file_hash(file, iint->ima_xattr.digest);
+ /* use default hash algorithm */
+ iint->ima_hash.algo = ima_hash_algo;
+ result = ima_calc_file_hash(file, &iint->ima_hash);
if (!result) {
iint->version = i_version;
iint->flags |= IMA_COLLECTED;
@@ -196,7 +198,21 @@ void ima_store_measurement(struct integrity_iint_cache *iint,
return;
}
memset(&entry->template, 0, sizeof(entry->template));
- memcpy(entry->template.digest, iint->ima_xattr.digest, IMA_DIGEST_SIZE);
+ if (iint->ima_hash.algo != ima_hash_algo) {
+ struct ima_digest_data hash;
+
+ hash.algo = ima_hash_algo;
+ result = ima_calc_file_hash(file, &hash);
+ if (result)
+ integrity_audit_msg(AUDIT_INTEGRITY_DATA, inode,
+ filename, "collect_data", "failed",
+ result, 0);
+ else
+ memcpy(entry->template.digest, hash.digest,
+ hash.length);
+ } else
+ memcpy(entry->template.digest, iint->ima_hash.digest,
+ iint->ima_hash.length);
strcpy(entry->template.file_name,
(strlen(filename) > IMA_EVENT_NAME_LEN_MAX) ?
file->f_dentry->d_name.name : filename);
@@ -212,14 +228,14 @@ void ima_audit_measurement(struct integrity_iint_cache *iint,
const unsigned char *filename)
{
struct audit_buffer *ab;
- char hash[(IMA_DIGEST_SIZE * 2) + 1];
+ char hash[(iint->ima_hash.length * 2) + 1];
int i;

if (iint->flags & IMA_AUDITED)
return;

- for (i = 0; i < IMA_DIGEST_SIZE; i++)
- hex_byte_pack(hash + (i * 2), iint->ima_xattr.digest[i]);
+ for (i = 0; i < iint->ima_hash.length; i++)
+ hex_byte_pack(hash + (i * 2), iint->ima_hash.digest[i]);
hash[i * 2] = '\0';

ab = audit_log_start(current->audit_context, GFP_KERNEL,
diff --git a/security/integrity/ima/ima_appraise.c b/security/integrity/ima/ima_appraise.c
index e3230d6..3833b0fa 100644
--- a/security/integrity/ima/ima_appraise.c
+++ b/security/integrity/ima/ima_appraise.c
@@ -43,12 +43,12 @@ int ima_must_appraise(struct inode *inode, int mask, enum ima_hooks func)
}

static int ima_fix_xattr(struct dentry *dentry,
- struct integrity_iint_cache *iint)
+ struct integrity_iint_cache *iint)
{
- iint->ima_xattr.type = IMA_XATTR_DIGEST;
+ iint->ima_hash.type = IMA_XATTR_DIGEST;
return __vfs_setxattr_noperm(dentry, XATTR_NAME_IMA,
- (u8 *)&iint->ima_xattr,
- sizeof(iint->ima_xattr), 0);
+ &iint->ima_hash.type,
+ 1 + iint->ima_hash.length, 0);
}

/* Return specific func appraised cached result */
@@ -159,8 +159,12 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
status = INTEGRITY_FAIL;
break;
}
- rc = memcmp(xattr_value->digest, iint->ima_xattr.digest,
- IMA_DIGEST_SIZE);
+ if (rc - 1 == iint->ima_hash.length)
+ rc = memcmp(xattr_value->digest,
+ iint->ima_hash.digest,
+ iint->ima_hash.length);
+ else
+ rc = -EINVAL;
if (rc) {
cause = "invalid-hash";
status = INTEGRITY_FAIL;
@@ -172,8 +176,8 @@ int ima_appraise_measurement(int func, struct integrity_iint_cache *iint,
iint->flags |= IMA_DIGSIG;
rc = integrity_digsig_verify(INTEGRITY_KEYRING_IMA,
xattr_value->digest, rc - 1,
- iint->ima_xattr.digest,
- IMA_DIGEST_SIZE);
+ iint->ima_hash.digest,
+ iint->ima_hash.length);
if (rc == -EOPNOTSUPP) {
status = INTEGRITY_UNKNOWN;
} else if (rc) {
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index a02e079..2fd1786 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -20,6 +20,7 @@
#include <linux/err.h>
#include <linux/slab.h>
#include <crypto/hash.h>
+#include <crypto/hash_info.h>
#include "ima.h"

static struct crypto_shash *ima_shash_tfm;
@@ -28,10 +29,11 @@ int ima_init_crypto(void)
{
long rc;

- ima_shash_tfm = crypto_alloc_shash(ima_hash, 0, 0);
+ ima_shash_tfm = crypto_alloc_shash(hash_algo_name[ima_hash_algo], 0, 0);
if (IS_ERR(ima_shash_tfm)) {
rc = PTR_ERR(ima_shash_tfm);
- pr_err("Can not allocate %s (reason: %ld)\n", ima_hash, rc);
+ pr_err("Can not allocate %s (reason: %ld)\n",
+ hash_algo_name[ima_hash_algo], rc);
return rc;
}
return 0;
@@ -40,17 +42,19 @@ int ima_init_crypto(void)
/*
* Calculate the MD5/SHA1 file digest
*/
-int ima_calc_file_hash(struct file *file, char *digest)
+static int ima_calc_file_hash_tfm(struct file *file,
+ struct ima_digest_data *hash,
+ struct crypto_shash *tfm)
{
loff_t i_size, offset = 0;
char *rbuf;
int rc, read = 0;
struct {
struct shash_desc shash;
- char ctx[crypto_shash_descsize(ima_shash_tfm)];
+ char ctx[crypto_shash_descsize(tfm)];
} desc;

- desc.shash.tfm = ima_shash_tfm;
+ desc.shash.tfm = tfm;
desc.shash.flags = 0;

rc = crypto_shash_init(&desc.shash);
@@ -85,17 +89,42 @@ int ima_calc_file_hash(struct file *file, char *digest)
}
kfree(rbuf);
if (!rc)
- rc = crypto_shash_final(&desc.shash, digest);
+ rc = crypto_shash_final(&desc.shash, hash->digest);
if (read)
file->f_mode &= ~FMODE_READ;
out:
return rc;
}

+int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
+{
+ struct crypto_shash *tfm = ima_shash_tfm;
+ int rc;
+
+ if (hash->algo != ima_hash_algo && hash->algo < HASH_ALGO__LAST) {
+ tfm = crypto_alloc_shash(hash_algo_name[hash->algo], 0, 0);
+ if (IS_ERR(tfm)) {
+ rc = PTR_ERR(tfm);
+ pr_err("Can not allocate %s (reason: %d)\n",
+ hash_algo_name[hash->algo], rc);
+ return rc;
+ }
+ }
+
+ hash->length = crypto_shash_digestsize(tfm);
+
+ rc = ima_calc_file_hash_tfm(file, hash, tfm);
+
+ if (tfm != ima_shash_tfm)
+ crypto_free_shash(tfm);
+
+ return rc;
+}
+
/*
* Calculate the hash of a given buffer
*/
-int ima_calc_buffer_hash(const void *data, int len, char *digest)
+int ima_calc_buffer_hash(const void *buf, int len, struct ima_digest_data *hash)
{
struct {
struct shash_desc shash;
@@ -105,7 +134,11 @@ int ima_calc_buffer_hash(const void *data, int len, char *digest)
desc.shash.tfm = ima_shash_tfm;
desc.shash.flags = 0;

- return crypto_shash_digest(&desc.shash, data, len, digest);
+ /* this function uses default algo */
+ hash->algo = ima_hash_algo;
+ hash->length = crypto_shash_digestsize(ima_shash_tfm);
+
+ return crypto_shash_digest(&desc.shash, buf, len, hash->digest);
}

static void __init ima_pcrread(int idx, u8 *pcr)
diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
index 0f359df..7708c21 100644
--- a/security/integrity/ima/ima_main.c
+++ b/security/integrity/ima/ima_main.c
@@ -24,6 +24,7 @@
#include <linux/slab.h>
#include <linux/xattr.h>
#include <linux/ima.h>
+#include <crypto/hash_info.h>

#include "ima.h"

@@ -35,11 +36,12 @@ int ima_appraise = IMA_APPRAISE_ENFORCE;
int ima_appraise;
#endif

-char *ima_hash = "sha1";
+int ima_hash_algo = HASH_ALGO_SHA1;
+
static int __init hash_setup(char *str)
{
if (strncmp(str, "md5", 3) == 0)
- ima_hash = "md5";
+ ima_hash_algo = HASH_ALGO_MD5;
return 1;
}
__setup("ima_hash=", hash_setup);
diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
index f867316..0b02ea8 100644
--- a/security/integrity/integrity.h
+++ b/security/integrity/integrity.h
@@ -59,20 +59,29 @@ enum evm_ima_xattr_type {
struct evm_ima_xattr_data {
u8 type;
u8 digest[SHA1_DIGEST_SIZE];
-} __attribute__((packed));
+} __packed;
+
+#define IMA_MAX_DIGEST_SIZE 64
+
+struct ima_digest_data {
+ u8 algo;
+ u8 length;
+ u8 type;
+ u8 digest[IMA_MAX_DIGEST_SIZE];
+} __packed;

/* integrity data associated with an inode */
struct integrity_iint_cache {
- struct rb_node rb_node; /* rooted in integrity_iint_tree */
+ struct rb_node rb_node; /* rooted in integrity_iint_tree */
struct inode *inode; /* back pointer to inode in question */
u64 version; /* track inode changes */
unsigned long flags;
- struct evm_ima_xattr_data ima_xattr;
enum integrity_status ima_file_status:4;
enum integrity_status ima_mmap_status:4;
enum integrity_status ima_bprm_status:4;
enum integrity_status ima_module_status:4;
enum integrity_status evm_status:4;
+ struct ima_digest_data ima_hash;
};

/* rbtree tree calls to lookup, insert, delete
--
1.8.1.4

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