On 3/24/26 4:30 PM, Jarkko Sakkinen wrote:
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 <[email protected]>
Reported-by: Nayna Jain <[email protected]>
Closes: 
https://lore.kernel.org/all/[email protected]/
Signed-off-by: Jarkko Sakkinen <[email protected]>


Tested on PKWM and emulated TPM backends.

Tested-by: Srish Srinivasan <[email protected]>


---
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)

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