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authorRoberto Sassu <roberto.sassu@huawei.com>2020-03-25 11:54:24 +0100
committerMimi Zohar <zohar@linux.ibm.com>2020-04-19 22:03:39 -0400
commit2592677c0486e64a08e0b930a7dfa6fbf77e6fc1 (patch)
treec4cd48197855b2fea5f3c1e0ee86edf6a759d84c
parent1ea973df6e2166d1a576cabe5d08925d3261ff9d (diff)
downloadlinux-2592677c0486e64a08e0b930a7dfa6fbf77e6fc1.tar.gz
ima: Use ima_hash_algo for collision detection in the measurement list
Before calculating a digest for each PCR bank, collisions were detected with a SHA1 digest. This patch includes ima_hash_algo among the algorithms used to calculate the template digest and checks collisions on that digest. The position in the measurement entry array of the template digest calculated with the IMA default hash algorithm is stored in the ima_hash_algo_idx global variable and is determined at IMA initialization time. Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com> Signed-off-by: Mimi Zohar <zohar@linux.ibm.com>
-rw-r--r--security/integrity/ima/ima.h1
-rw-r--r--security/integrity/ima/ima_crypto.c19
-rw-r--r--security/integrity/ima/ima_queue.c8
3 files changed, 23 insertions, 5 deletions
diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
index 2a7ed68e6414..467dfdbea25c 100644
--- a/security/integrity/ima/ima.h
+++ b/security/integrity/ima/ima.h
@@ -53,6 +53,7 @@ extern int ima_policy_flag;
/* set during initialization */
extern int ima_hash_algo;
extern int ima_sha1_idx __ro_after_init;
+extern int ima_hash_algo_idx __ro_after_init;
extern int ima_extra_slots __ro_after_init;
extern int ima_appraise;
extern struct tpm_chip *ima_tpm_chip;
diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index a94972d3f929..5201f5ec2ce4 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -63,6 +63,7 @@ struct ima_algo_desc {
};
int ima_sha1_idx __ro_after_init;
+int ima_hash_algo_idx __ro_after_init;
/*
* Additional number of slots reserved, as needed, for SHA1
* and IMA default algo.
@@ -122,15 +123,25 @@ int __init ima_init_crypto(void)
return rc;
ima_sha1_idx = -1;
+ ima_hash_algo_idx = -1;
for (i = 0; i < NR_BANKS(ima_tpm_chip); i++) {
algo = ima_tpm_chip->allocated_banks[i].crypto_id;
if (algo == HASH_ALGO_SHA1)
ima_sha1_idx = i;
+
+ if (algo == ima_hash_algo)
+ ima_hash_algo_idx = i;
}
- if (ima_sha1_idx < 0)
+ if (ima_sha1_idx < 0) {
ima_sha1_idx = NR_BANKS(ima_tpm_chip) + ima_extra_slots++;
+ if (ima_hash_algo == HASH_ALGO_SHA1)
+ ima_hash_algo_idx = ima_sha1_idx;
+ }
+
+ if (ima_hash_algo_idx < 0)
+ ima_hash_algo_idx = NR_BANKS(ima_tpm_chip) + ima_extra_slots++;
ima_algo_array = kcalloc(NR_BANKS(ima_tpm_chip) + ima_extra_slots,
sizeof(*ima_algo_array), GFP_KERNEL);
@@ -179,6 +190,12 @@ int __init ima_init_crypto(void)
ima_algo_array[ima_sha1_idx].algo = HASH_ALGO_SHA1;
}
+ if (ima_hash_algo_idx >= NR_BANKS(ima_tpm_chip) &&
+ ima_hash_algo_idx != ima_sha1_idx) {
+ ima_algo_array[ima_hash_algo_idx].tfm = ima_shash_tfm;
+ ima_algo_array[ima_hash_algo_idx].algo = ima_hash_algo;
+ }
+
return 0;
out_array:
for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++) {
diff --git a/security/integrity/ima/ima_queue.c b/security/integrity/ima/ima_queue.c
index 82a9ca43b989..fb4ec270f620 100644
--- a/security/integrity/ima/ima_queue.c
+++ b/security/integrity/ima/ima_queue.c
@@ -55,8 +55,8 @@ static struct ima_queue_entry *ima_lookup_digest_entry(u8 *digest_value,
key = ima_hash_key(digest_value);
rcu_read_lock();
hlist_for_each_entry_rcu(qe, &ima_htable.queue[key], hnext) {
- rc = memcmp(qe->entry->digests[ima_sha1_idx].digest,
- digest_value, TPM_DIGEST_SIZE);
+ rc = memcmp(qe->entry->digests[ima_hash_algo_idx].digest,
+ digest_value, hash_digest_size[ima_hash_algo]);
if ((rc == 0) && (qe->entry->pcr == pcr)) {
ret = qe;
break;
@@ -108,7 +108,7 @@ static int ima_add_digest_entry(struct ima_template_entry *entry,
atomic_long_inc(&ima_htable.len);
if (update_htable) {
- key = ima_hash_key(entry->digests[ima_sha1_idx].digest);
+ key = ima_hash_key(entry->digests[ima_hash_algo_idx].digest);
hlist_add_head_rcu(&qe->hnext, &ima_htable.queue[key]);
}
@@ -160,7 +160,7 @@ int ima_add_template_entry(struct ima_template_entry *entry, int violation,
const char *op, struct inode *inode,
const unsigned char *filename)
{
- u8 *digest = entry->digests[ima_sha1_idx].digest;
+ u8 *digest = entry->digests[ima_hash_algo_idx].digest;
struct tpm_digest *digests_arg = entry->digests;
const char *audit_cause = "hash_added";
char tpm_audit_cause[AUDIT_CAUSE_LEN_MAX];