[PATCH v2] KEYS: trusted: Debugging as a feature

[Jarkko Sakkinen <jarkko@kernel.org>]

TPM_DEBUG, and other similar flags, are a non-standard way to specify a
feature in Linux kernel.  Introduce CONFIG_TRUSTED_KEYS_DEBUG for
trusted keys, and use it to replace these ad-hoc feature flags.

Given that trusted keys debug dumps can contain sensitive data, harden
the feature as follows:

1. In the Kconfig description postulate that pr_debug() statements must be
   used.
2. Use pr_debug() statements in TPM 1.x driver to print the protocol dump.

Traces, when actually needed, can be easily enabled by providing
trusted.dyndbg='+p' in the kernel command-line.

Cc: Srish Srinivasan <ssrish@linux.ibm.com>
Reported-by: Nayna Jain <nayna@linux.ibm.com>
Closes: https://lore.kernel.org/all/7f8b8478-5cd8-4d97-bfd0-341fd5cf10f9@linux.ibm.com/
Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org>
---
v2:
- Implement for all trusted keys backends.
- Add HAVE_TRUSTED_KEYS_DEBUG as it is a good practice despite full
  coverage.
---
 include/keys/trusted-type.h               | 18 +++++-------
 security/keys/trusted-keys/Kconfig        | 19 ++++++++++++
 security/keys/trusted-keys/trusted_caam.c |  4 +--
 security/keys/trusted-keys/trusted_tpm1.c | 36 +++++++++++------------
 4 files changed, 46 insertions(+), 31 deletions(-)

diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
index 03527162613f..620a1f890b6b 100644
--- a/include/keys/trusted-type.h
+++ b/include/keys/trusted-type.h
@@ -83,18 +83,16 @@ struct trusted_key_source {
 
 extern struct key_type key_type_trusted;
 
-#define TRUSTED_DEBUG 0
-
-#if TRUSTED_DEBUG
+#ifdef CONFIG_TRUSTED_KEYS_DEBUG
 static inline void dump_payload(struct trusted_key_payload *p)
 {
-	pr_info("key_len %d\n", p->key_len);
-	print_hex_dump(KERN_INFO, "key ", DUMP_PREFIX_NONE,
-		       16, 1, p->key, p->key_len, 0);
-	pr_info("bloblen %d\n", p->blob_len);
-	print_hex_dump(KERN_INFO, "blob ", DUMP_PREFIX_NONE,
-		       16, 1, p->blob, p->blob_len, 0);
-	pr_info("migratable %d\n", p->migratable);
+	pr_debug("key_len %d\n", p->key_len);
+	print_hex_dump_debug("key ", DUMP_PREFIX_NONE,
+			     16, 1, p->key, p->key_len, 0);
+	pr_debug("bloblen %d\n", p->blob_len);
+	print_hex_dump_debug("blob ", DUMP_PREFIX_NONE,
+			     16, 1, p->blob, p->blob_len, 0);
+	pr_debug("migratable %d\n", p->migratable);
 }
 #else
 static inline void dump_payload(struct trusted_key_payload *p)
diff --git a/security/keys/trusted-keys/Kconfig b/security/keys/trusted-keys/Kconfig
index 9e00482d886a..2ad9ba0e03f1 100644
--- a/security/keys/trusted-keys/Kconfig
+++ b/security/keys/trusted-keys/Kconfig
@@ -1,10 +1,25 @@
 config HAVE_TRUSTED_KEYS
 	bool
 
+config HAVE_TRUSTED_KEYS_DEBUG
+	bool
+
+config TRUSTED_KEYS_DEBUG
+	bool "Debug trusted keys"
+	depends on HAVE_TRUSTED_KEYS_DEBUG
+	default n
+	help
+	  Trusted keys backends and core code that support debug dumps
+	  can opt-in that feature here. Dumps must only use DEBUG
+	  level output, as sensitive data may pass by. In the
+	  kernel-command line traces can be enabled via
+	  trusted.dyndbg='+p'.
+
 config TRUSTED_KEYS_TPM
 	bool "TPM-based trusted keys"
 	depends on TCG_TPM >= TRUSTED_KEYS
 	default y
+	select HAVE_TRUSTED_KEYS_DEBUG
 	select CRYPTO_HASH_INFO
 	select CRYPTO_LIB_SHA1
 	select CRYPTO_LIB_UTILS
@@ -23,6 +38,7 @@ config TRUSTED_KEYS_TEE
 	bool "TEE-based trusted keys"
 	depends on TEE >= TRUSTED_KEYS
 	default y
+	select HAVE_TRUSTED_KEYS_DEBUG
 	select HAVE_TRUSTED_KEYS
 	help
 	  Enable use of the Trusted Execution Environment (TEE) as trusted
@@ -33,6 +49,7 @@ config TRUSTED_KEYS_CAAM
 	depends on CRYPTO_DEV_FSL_CAAM_JR >= TRUSTED_KEYS
 	select CRYPTO_DEV_FSL_CAAM_BLOB_GEN
 	default y
+	select HAVE_TRUSTED_KEYS_DEBUG
 	select HAVE_TRUSTED_KEYS
 	help
 	  Enable use of NXP's Cryptographic Accelerator and Assurance Module
@@ -42,6 +59,7 @@ config TRUSTED_KEYS_DCP
 	bool "DCP-based trusted keys"
 	depends on CRYPTO_DEV_MXS_DCP >= TRUSTED_KEYS
 	default y
+	select HAVE_TRUSTED_KEYS_DEBUG
 	select HAVE_TRUSTED_KEYS
 	help
 	  Enable use of NXP's DCP (Data Co-Processor) as trusted key backend.
@@ -50,6 +68,7 @@ config TRUSTED_KEYS_PKWM
 	bool "PKWM-based trusted keys"
 	depends on PSERIES_PLPKS >= TRUSTED_KEYS
 	default y
+	select HAVE_TRUSTED_KEYS_DEBUG
 	select HAVE_TRUSTED_KEYS
 	help
 	  Enable use of IBM PowerVM Key Wrapping Module (PKWM) as a trusted key backend.
diff --git a/security/keys/trusted-keys/trusted_caam.c b/security/keys/trusted-keys/trusted_caam.c
index 601943ce0d60..015cddc6b53c 100644
--- a/security/keys/trusted-keys/trusted_caam.c
+++ b/security/keys/trusted-keys/trusted_caam.c
@@ -28,10 +28,10 @@ static const match_table_t key_tokens = {
 	{opt_err, NULL}
 };
 
-#ifdef CAAM_DEBUG
+#ifdef CONFIG_TRUSTED_KEYS_DEBUG
 static inline void dump_options(const struct caam_pkey_info *pkey_info)
 {
-	pr_info("key encryption algo %d\n", pkey_info->key_enc_algo);
+	pr_debug("key encryption algo %d\n", pkey_info->key_enc_algo);
 }
 #else
 static inline void dump_options(const struct caam_pkey_info *pkey_info)
diff --git a/security/keys/trusted-keys/trusted_tpm1.c b/security/keys/trusted-keys/trusted_tpm1.c
index c865c97aa1b4..8fe889c7cdd1 100644
--- a/security/keys/trusted-keys/trusted_tpm1.c
+++ b/security/keys/trusted-keys/trusted_tpm1.c
@@ -46,38 +46,36 @@ enum {
 	SRK_keytype = 4
 };
 
-#define TPM_DEBUG 0
-
-#if TPM_DEBUG
+#ifdef CONFIG_TRUSTED_KEYS_DEBUG
 static inline void dump_options(struct trusted_key_options *o)
 {
-	pr_info("sealing key type %d\n", o->keytype);
-	pr_info("sealing key handle %0X\n", o->keyhandle);
-	pr_info("pcrlock %d\n", o->pcrlock);
-	pr_info("pcrinfo %d\n", o->pcrinfo_len);
-	print_hex_dump(KERN_INFO, "pcrinfo ", DUMP_PREFIX_NONE,
-		       16, 1, o->pcrinfo, o->pcrinfo_len, 0);
+	pr_debug("sealing key type %d\n", o->keytype);
+	pr_debug("sealing key handle %0X\n", o->keyhandle);
+	pr_debug("pcrlock %d\n", o->pcrlock);
+	pr_debug("pcrinfo %d\n", o->pcrinfo_len);
+	print_hex_dump_debug("pcrinfo ", DUMP_PREFIX_NONE,
+			     16, 1, o->pcrinfo, o->pcrinfo_len, 0);
 }
 
 static inline void dump_sess(struct osapsess *s)
 {
-	print_hex_dump(KERN_INFO, "trusted-key: handle ", DUMP_PREFIX_NONE,
-		       16, 1, &s->handle, 4, 0);
-	pr_info("secret:\n");
-	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE,
-		       16, 1, &s->secret, SHA1_DIGEST_SIZE, 0);
-	pr_info("trusted-key: enonce:\n");
-	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE,
-		       16, 1, &s->enonce, SHA1_DIGEST_SIZE, 0);
+	print_hex_dump_debug("trusted-key: handle ", DUMP_PREFIX_NONE,
+			     16, 1, &s->handle, 4, 0);
+	pr_debug("secret:\n");
+	print_hex_dump_debug("", DUMP_PREFIX_NONE,
+			     16, 1, &s->secret, SHA1_DIGEST_SIZE, 0);
+	pr_debug("trusted-key: enonce:\n");
+	print_hex_dump_debug("", DUMP_PREFIX_NONE,
+			     16, 1, &s->enonce, SHA1_DIGEST_SIZE, 0);
 }
 
 static inline void dump_tpm_buf(unsigned char *buf)
 {
 	int len;
 
-	pr_info("\ntpm buffer\n");
+	pr_debug("\ntpm buffer\n");
 	len = LOAD32(buf, TPM_SIZE_OFFSET);
-	print_hex_dump(KERN_INFO, "", DUMP_PREFIX_NONE, 16, 1, buf, len, 0);
+	print_hex_dump_debug("", DUMP_PREFIX_NONE, 16, 1, buf, len, 0);
 }
 #else
 static inline void dump_options(struct trusted_key_options *o)
-- 
2.47.3