[PATCH 5/8] ima: allocate and initialize tfm for each PCR bank

Roberto Sassu
2020-01-27T17:06:56Z

This patch creates a crypto_shash structure for each allocated PCR bank and
for SHA1 if a bank with that algorithm is not currently allocated.

Signed-off-by: Roberto Sassu <roberto.sassu@huawei.com>
---
security/integrity/ima/ima_crypto.c | 137 +++++++++++++++++++++++-----
1 file changed, 113 insertions(+), 24 deletions(-)

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 57b06321d5c8..63fb4bdf80b0 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -59,7 +59,14 @@ MODULE_PARM_DESC(ahash_bufsize, "Maximum ahash buffer size");
static struct crypto_shash *ima_shash_tfm;
static struct crypto_ahash *ima_ahash_tfm;

-int __init ima_init_crypto(void)
+struct ima_algo_desc {
+ struct crypto_shash *tfm;
+ enum hash_algo algo;
+};
+
+static struct ima_algo_desc *ima_algo_array;
+
+int __init ima_init_ima_crypto(void)
{
long rc;

@@ -78,26 +85,116 @@ int __init ima_init_crypto(void)
static struct crypto_shash *ima_alloc_tfm(enum hash_algo algo)
{
struct crypto_shash *tfm = ima_shash_tfm;
- int rc;
+ int rc, i;

if (algo < 0 || algo >= HASH_ALGO__LAST)
algo = ima_hash_algo;

- if (algo != ima_hash_algo) {
- tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
- if (IS_ERR(tfm)) {
- rc = PTR_ERR(tfm);
- pr_err("Can not allocate %s (reason: %d)\n",
- hash_algo_name[algo], rc);
- }
+ if (algo == ima_hash_algo)
+ return tfm;
+
+ for (i = 0; i < ima_tpm_chip->nr_allocated_banks + 1; i++)
+ if (ima_algo_array[i].algo == algo && ima_algo_array[i].tfm)
+ return ima_algo_array[i].tfm;
+
+ tfm = crypto_alloc_shash(hash_algo_name[algo], 0, 0);
+ if (IS_ERR(tfm)) {
+ rc = PTR_ERR(tfm);
+ pr_err("Can not allocate %s (reason: %d)\n",
+ hash_algo_name[algo], rc);
}
return tfm;
}

+int __init ima_init_crypto(void)
+{
+ enum hash_algo algo;
+ long rc;
+ int i;
+
+ rc = ima_init_ima_crypto();
+ if (rc)
+ return rc;
+
+ ima_algo_array = kmalloc_array(ima_tpm_chip->nr_allocated_banks + 1,
+ sizeof(*ima_algo_array), GFP_KERNEL);
+ if (!ima_algo_array) {
+ rc = -ENOMEM;
+ goto out;
+ }
+
+ for (i = 0; i < ima_tpm_chip->nr_allocated_banks + 1; i++) {
+ ima_algo_array[i].tfm = NULL;
+ ima_algo_array[i].algo = HASH_ALGO__LAST;
+ }
+
+ ima_sha1_idx = -1;
+
+ for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
+ algo = ima_tpm_chip->allocated_banks[i].crypto_id;
+ ima_algo_array[i].algo = algo;
+
+ /* unknown TPM algorithm */
+ if (algo == HASH_ALGO__LAST)
+ continue;
+
+ if (algo == HASH_ALGO_SHA1)
+ ima_sha1_idx = i;
+
+ if (algo == ima_hash_algo) {
+ ima_algo_array[i].tfm = ima_shash_tfm;
+ continue;
+ }
+
+ ima_algo_array[i].tfm = ima_alloc_tfm(algo);
+ if (IS_ERR(ima_algo_array[i].tfm)) {
+ if (algo == HASH_ALGO_SHA1) {
+ rc = PTR_ERR(ima_algo_array[i].tfm);
+ ima_algo_array[i].tfm = NULL;
+ goto out_array;
+ }
+
+ ima_algo_array[i].tfm = NULL;
+ }
+ }
+
+ if (ima_sha1_idx < 0) {
+ ima_algo_array[i].tfm = ima_alloc_tfm(HASH_ALGO_SHA1);
+ if (IS_ERR(ima_algo_array[i].tfm)) {
+ rc = PTR_ERR(ima_algo_array[i].tfm);
+ goto out_array;
+ }
+
+ ima_sha1_idx = i;
+ ima_algo_array[i].algo = HASH_ALGO_SHA1;
+ }
+
+ return 0;
+out_array:
+ for (i = 0; i < ima_tpm_chip->nr_allocated_banks + 1; i++) {
+ if (!ima_algo_array[i].tfm ||
+ ima_algo_array[i].tfm == ima_shash_tfm)
+ continue;
+
+ crypto_free_shash(ima_algo_array[i].tfm);
+ }
+out:
+ crypto_free_shash(ima_shash_tfm);
+ return rc;
+}
+
static void ima_free_tfm(struct crypto_shash *tfm)
{
- if (tfm != ima_shash_tfm)
- crypto_free_shash(tfm);
+ int i;
+
+ if (tfm == ima_shash_tfm)
+ return;
+
+ for (i = 0; i < ima_tpm_chip->nr_allocated_banks + 1; i++)
+ if (ima_algo_array[i].tfm == tfm)
+ return;
+
+ crypto_free_shash(tfm);
}

/**
@@ -467,14 +564,14 @@ int ima_calc_file_hash(struct file *file, struct ima_digest_data *hash)
*/
static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
struct ima_template_entry *entry,
- struct crypto_shash *tfm)
+ int tfm_idx)
{
- SHASH_DESC_ON_STACK(shash, tfm);
+ SHASH_DESC_ON_STACK(shash, ima_algo_array[tfm_idx].tfm);
struct ima_template_desc *td = entry->template_desc;
int num_fields = entry->template_desc->num_fields;
int rc, i;

- shash->tfm = tfm;
+ shash->tfm = ima_algo_array[tfm_idx].tfm;

rc = crypto_shash_init(shash);
if (rc != 0)
@@ -505,7 +602,7 @@ static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,

if (!rc)
rc = crypto_shash_final(shash,
- entry->digests[ima_sha1_idx].digest);
+ entry->digests[tfm_idx].digest);

return rc;
}
@@ -513,17 +610,9 @@ static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
int ima_calc_field_array_hash(struct ima_field_data *field_data,
struct ima_template_entry *entry)
{
- struct crypto_shash *tfm;
int rc;

- tfm = ima_alloc_tfm(HASH_ALGO_SHA1);
- if (IS_ERR(tfm))
- return PTR_ERR(tfm);
-
- rc = ima_calc_field_array_hash_tfm(field_data, entry, tfm);
-
- ima_free_tfm(tfm);
-
+ rc = ima_calc_field_array_hash_tfm(field_data, entry, ima_sha1_idx);
return rc;
}

--
2.17.1