Merge tag 'integrity-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity

Pull integrity updates from Mimi Zohar:
 "The main changes are extending the TPM 2.0 PCR banks with bank
  specific file hashes, calculating the "boot_aggregate" based on other
  TPM PCR banks, using the default IMA hash algorithm, instead of SHA1,
  as the basis for the cache hash table key, and preventing the mprotect
  syscall to circumvent an IMA mmap appraise policy rule.

   - In preparation for extending TPM 2.0 PCR banks with bank specific
     digests, commit 0b6cf6b97b7e ("tpm: pass an array of
     tpm_extend_digest structures to tpm_pcr_extend()") modified
     tpm_pcr_extend(). The original SHA1 file digests were
     padded/truncated, before being extended into the other TPM PCR
     banks. This pull request calculates and extends the TPM PCR banks
     with bank specific file hashes completing the above change.

   - The "boot_aggregate", the first IMA measurement list record, is the
     "trusted boot" link between the pre-boot environment and the
     running OS. With TPM 2.0, the "boot_aggregate" record is not
     limited to being based on the SHA1 TPM PCR bank, but can be
     calculated based on any enabled bank, assuming the hash algorithm
     is also enabled in the kernel.

  Other changes include the following and five other bug fixes/code
  clean up:

   - supporting both a SHA1 and a larger "boot_aggregate" digest in a
     custom template format containing both the the SHA1 ('d') and
     larger digests ('d-ng') fields.

   - Initial hash table key fix, but additional changes would be good"

* tag 'integrity-v5.8' of git://git.kernel.org/pub/scm/linux/kernel/git/zohar/linux-integrity:
  ima: Directly free *entry in ima_alloc_init_template() if digests is NULL
  ima: Call ima_calc_boot_aggregate() in ima_eventdigest_init()
  ima: Directly assign the ima_default_policy pointer to ima_rules
  ima: verify mprotect change is consistent with mmap policy
  evm: Fix possible memory leak in evm_calc_hmac_or_hash()
  ima: Set again build_ima_appraise variable
  ima: Remove redundant policy rule set in add_rules()
  ima: Fix ima digest hash table key calculation
  ima: Use ima_hash_algo for collision detection in the measurement list
  ima: Calculate and extend PCR with digests in ima_template_entry
  ima: Allocate and initialize tfm for each PCR bank
  ima: Switch to dynamically allocated buffer for template digests
  ima: Store template digest directly in ima_template_entry
  ima: Evaluate error in init_ima()
  ima: Switch to ima_hash_algo for boot aggregate

1 files changed, 214 insertions, 38 deletions

diff --git a/security/integrity/ima/ima_crypto.c b/security/integrity/ima/ima_crypto.c
index 88b5e288f241..ba5cc3264240 100644
--- a/security/integrity/ima/ima_crypto.c
+++ b/security/integrity/ima/ima_crypto.c
@@ -57,7 +57,22 @@ 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;
+};
+
+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.
+ */
+int ima_extra_slots __ro_after_init;
+
+static struct ima_algo_desc *ima_algo_array;
+
+static int __init ima_init_ima_crypto(void)
 {
 	long rc;
 
@@ -76,26 +91,137 @@ 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 < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++)
+		if (ima_algo_array[i].tfm && ima_algo_array[i].algo == algo)
+			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_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) {
+		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);
+	if (!ima_algo_array) {
+		rc = -ENOMEM;
+		goto out;
+	}
+
+	for (i = 0; i < NR_BANKS(ima_tpm_chip); 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 == 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 >= NR_BANKS(ima_tpm_chip)) {
+		if (ima_hash_algo == HASH_ALGO_SHA1) {
+			ima_algo_array[ima_sha1_idx].tfm = ima_shash_tfm;
+		} else {
+			ima_algo_array[ima_sha1_idx].tfm =
+						ima_alloc_tfm(HASH_ALGO_SHA1);
+			if (IS_ERR(ima_algo_array[ima_sha1_idx].tfm)) {
+				rc = PTR_ERR(ima_algo_array[ima_sha1_idx].tfm);
+				goto out_array;
+			}
+		}
+
+		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++) {
+		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 < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++)
+		if (ima_algo_array[i].tfm == tfm)
+			return;
+
+	crypto_free_shash(tfm);
 }
 
 /**
@@ -464,17 +590,15 @@ out:
  * Calculate the hash of template data
  */
 static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
-					 struct ima_template_desc *td,
-					 int num_fields,
-					 struct ima_digest_data *hash,
-					 struct crypto_shash *tfm)
+					 struct ima_template_entry *entry,
+					 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;
-
-	hash->length = crypto_shash_digestsize(tfm);
+	shash->tfm = ima_algo_array[tfm_idx].tfm;
 
 	rc = crypto_shash_init(shash);
 	if (rc != 0)
@@ -504,27 +628,44 @@ static int ima_calc_field_array_hash_tfm(struct ima_field_data *field_data,
 	}
 
 	if (!rc)
-		rc = crypto_shash_final(shash, hash->digest);
+		rc = crypto_shash_final(shash, entry->digests[tfm_idx].digest);
 
 	return rc;
 }
 
 int ima_calc_field_array_hash(struct ima_field_data *field_data,
-			      struct ima_template_desc *desc, int num_fields,
-			      struct ima_digest_data *hash)
+			      struct ima_template_entry *entry)
 {
-	struct crypto_shash *tfm;
-	int rc;
+	u16 alg_id;
+	int rc, i;
 
-	tfm = ima_alloc_tfm(hash->algo);
-	if (IS_ERR(tfm))
-		return PTR_ERR(tfm);
+	rc = ima_calc_field_array_hash_tfm(field_data, entry, ima_sha1_idx);
+	if (rc)
+		return rc;
 
-	rc = ima_calc_field_array_hash_tfm(field_data, desc, num_fields,
-					   hash, tfm);
+	entry->digests[ima_sha1_idx].alg_id = TPM_ALG_SHA1;
 
-	ima_free_tfm(tfm);
+	for (i = 0; i < NR_BANKS(ima_tpm_chip) + ima_extra_slots; i++) {
+		if (i == ima_sha1_idx)
+			continue;
+
+		if (i < NR_BANKS(ima_tpm_chip)) {
+			alg_id = ima_tpm_chip->allocated_banks[i].alg_id;
+			entry->digests[i].alg_id = alg_id;
+		}
+
+		/* for unmapped TPM algorithms digest is still a padded SHA1 */
+		if (!ima_algo_array[i].tfm) {
+			memcpy(entry->digests[i].digest,
+			       entry->digests[ima_sha1_idx].digest,
+			       TPM_DIGEST_SIZE);
+			continue;
+		}
 
+		rc = ima_calc_field_array_hash_tfm(field_data, entry, i);
+		if (rc)
+			return rc;
+	}
 	return rc;
 }
 
@@ -655,18 +796,29 @@ static void __init ima_pcrread(u32 idx, struct tpm_digest *d)
 }
 
 /*
- * Calculate the boot aggregate hash
+ * The boot_aggregate is a cumulative hash over TPM registers 0 - 7.  With
+ * TPM 1.2 the boot_aggregate was based on reading the SHA1 PCRs, but with
+ * TPM 2.0 hash agility, TPM chips could support multiple TPM PCR banks,
+ * allowing firmware to configure and enable different banks.
+ *
+ * Knowing which TPM bank is read to calculate the boot_aggregate digest
+ * needs to be conveyed to a verifier.  For this reason, use the same
+ * hash algorithm for reading the TPM PCRs as for calculating the boot
+ * aggregate digest as stored in the measurement list.
  */
-static int __init ima_calc_boot_aggregate_tfm(char *digest,
-					      struct crypto_shash *tfm)
+static int ima_calc_boot_aggregate_tfm(char *digest, u16 alg_id,
+				       struct crypto_shash *tfm)
 {
-	struct tpm_digest d = { .alg_id = TPM_ALG_SHA1, .digest = {0} };
+	struct tpm_digest d = { .alg_id = alg_id, .digest = {0} };
 	int rc;
 	u32 i;
 	SHASH_DESC_ON_STACK(shash, tfm);
 
 	shash->tfm = tfm;
 
+	pr_devel("calculating the boot-aggregate based on TPM bank: %04x\n",
+		 d.alg_id);
+
 	rc = crypto_shash_init(shash);
 	if (rc != 0)
 		return rc;
@@ -675,24 +827,48 @@ static int __init ima_calc_boot_aggregate_tfm(char *digest,
 	for (i = TPM_PCR0; i < TPM_PCR8; i++) {
 		ima_pcrread(i, &d);
 		/* now accumulate with current aggregate */
-		rc = crypto_shash_update(shash, d.digest, TPM_DIGEST_SIZE);
+		rc = crypto_shash_update(shash, d.digest,
+					 crypto_shash_digestsize(tfm));
 	}
 	if (!rc)
 		crypto_shash_final(shash, digest);
 	return rc;
 }
 
-int __init ima_calc_boot_aggregate(struct ima_digest_data *hash)
+int ima_calc_boot_aggregate(struct ima_digest_data *hash)
 {
 	struct crypto_shash *tfm;
-	int rc;
+	u16 crypto_id, alg_id;
+	int rc, i, bank_idx = -1;
+
+	for (i = 0; i < ima_tpm_chip->nr_allocated_banks; i++) {
+		crypto_id = ima_tpm_chip->allocated_banks[i].crypto_id;
+		if (crypto_id == hash->algo) {
+			bank_idx = i;
+			break;
+		}
+
+		if (crypto_id == HASH_ALGO_SHA256)
+			bank_idx = i;
+
+		if (bank_idx == -1 && crypto_id == HASH_ALGO_SHA1)
+			bank_idx = i;
+	}
+
+	if (bank_idx == -1) {
+		pr_err("No suitable TPM algorithm for boot aggregate\n");
+		return 0;
+	}
+
+	hash->algo = ima_tpm_chip->allocated_banks[bank_idx].crypto_id;
 
 	tfm = ima_alloc_tfm(hash->algo);
 	if (IS_ERR(tfm))
 		return PTR_ERR(tfm);
 
 	hash->length = crypto_shash_digestsize(tfm);
-	rc = ima_calc_boot_aggregate_tfm(hash->digest, tfm);
+	alg_id = ima_tpm_chip->allocated_banks[bank_idx].alg_id;
+	rc = ima_calc_boot_aggregate_tfm(hash->digest, alg_id, tfm);
 
 	ima_free_tfm(tfm);