[PATCH v9 3/8] KEYS: trusted: Replace a redundant instance of tpm2_hash_map

[Jarkko Sakkinen <jarkko@kernel.org>]

'trusted_tpm2' duplicates 'tpm2_hash_map' originally part of the TPN
driver, which is suboptimal.

Implement and export `tpm2_find_hash_alg()` in the driver, and substitute
the redundant code in 'trusted_tpm2' with a call to the new function.

Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v9:
- Improved the commit message a bit.
v8:
- Remove spurious tpm2_alg_to_crypto_id.
- Check return value of tpm2_find_hash_alg correctly in trusted_tpm2.c
  i.e, fail on "hash_alg < 0". Trusted keys were tested but I had my
  test harness misconfigured. I bisected the failure to this patch.
- The diff was not exactly minimal. Further optimize it.
v7:
- A new patch.
---
 drivers/char/tpm/tpm2-cmd.c               | 14 +++++++++++++-
 include/linux/tpm.h                       |  1 +
 security/keys/trusted-keys/trusted_tpm2.c | 23 ++++-------------------
 3 files changed, 18 insertions(+), 20 deletions(-)

diff --git a/drivers/char/tpm/tpm2-cmd.c b/drivers/char/tpm/tpm2-cmd.c
index e298194883e8..a121c518ff6f 100644
--- a/drivers/char/tpm/tpm2-cmd.c
+++ b/drivers/char/tpm/tpm2-cmd.c
@@ -18,7 +18,7 @@ static bool disable_pcr_integrity;
 module_param(disable_pcr_integrity, bool, 0444);
 MODULE_PARM_DESC(disable_pcr_integrity, "Disable integrity protection of TPM2_PCR_Extend");
 
-static struct tpm2_hash tpm2_hash_map[] = {
+struct tpm2_hash tpm2_hash_map[] = {
 	{HASH_ALGO_SHA1, TPM_ALG_SHA1},
 	{HASH_ALGO_SHA256, TPM_ALG_SHA256},
 	{HASH_ALGO_SHA384, TPM_ALG_SHA384},
@@ -26,6 +26,18 @@ static struct tpm2_hash tpm2_hash_map[] = {
 	{HASH_ALGO_SM3_256, TPM_ALG_SM3_256},
 };
 
+int tpm2_find_hash_alg(unsigned int crypto_id)
+{
+	int i;
+
+	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++)
+		if (crypto_id == tpm2_hash_map[i].crypto_id)
+			return tpm2_hash_map[i].tpm_id;
+
+	return -EINVAL;
+}
+EXPORT_SYMBOL_GPL(tpm2_find_hash_alg);
+
 int tpm2_get_timeouts(struct tpm_chip *chip)
 {
 	chip->timeout_a = msecs_to_jiffies(TPM2_TIMEOUT_A);
diff --git a/include/linux/tpm.h b/include/linux/tpm.h
index 973458a38250..cbd3a70c0378 100644
--- a/include/linux/tpm.h
+++ b/include/linux/tpm.h
@@ -477,6 +477,7 @@ extern int tpm_pcr_extend(struct tpm_chip *chip, u32 pcr_idx,
 extern int tpm_get_random(struct tpm_chip *chip, u8 *data, size_t max);
 extern struct tpm_chip *tpm_default_chip(void);
 void tpm2_flush_context(struct tpm_chip *chip, u32 handle);
+int tpm2_find_hash_alg(unsigned int crypto_id);
 
 static inline void tpm_buf_append_empty_auth(struct tpm_buf *buf, u32 handle)
 {
diff --git a/security/keys/trusted-keys/trusted_tpm2.c b/security/keys/trusted-keys/trusted_tpm2.c
index c414a7006d78..4467e880ebd5 100644
--- a/security/keys/trusted-keys/trusted_tpm2.c
+++ b/security/keys/trusted-keys/trusted_tpm2.c
@@ -18,14 +18,6 @@
 
 #include "tpm2key.asn1.h"
 
-static struct tpm2_hash tpm2_hash_map[] = {
-	{HASH_ALGO_SHA1, TPM_ALG_SHA1},
-	{HASH_ALGO_SHA256, TPM_ALG_SHA256},
-	{HASH_ALGO_SHA384, TPM_ALG_SHA384},
-	{HASH_ALGO_SHA512, TPM_ALG_SHA512},
-	{HASH_ALGO_SM3_256, TPM_ALG_SM3_256},
-};
-
 static u32 tpm2key_oid[] = { 2, 23, 133, 10, 1, 5 };
 
 static int tpm2_key_encode(struct trusted_key_payload *payload,
@@ -244,20 +236,13 @@ int tpm2_seal_trusted(struct tpm_chip *chip,
 	off_t offset = TPM_HEADER_SIZE;
 	struct tpm_buf buf, sized;
 	int blob_len = 0;
-	u32 hash;
+	int hash;
 	u32 flags;
-	int i;
 	int rc;
 
-	for (i = 0; i < ARRAY_SIZE(tpm2_hash_map); i++) {
-		if (options->hash == tpm2_hash_map[i].crypto_id) {
-			hash = tpm2_hash_map[i].tpm_id;
-			break;
-		}
-	}
-
-	if (i == ARRAY_SIZE(tpm2_hash_map))
-		return -EINVAL;
+	hash = tpm2_find_hash_alg(options->hash);
+	if (hash < 0)
+		return hash;
 
 	if (!options->keyhandle)
 		return -EINVAL;
-- 
2.52.0