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printk: add print_hex_dump_devel()

PATCH In review Thorsten Blum 3 participants 5 messages Mar 19 – Mar 27

Subsystems (4)
Stable branch Crypto API Printk Freescale CAAM (Cryptographic Acceleration and Assurance Module) driver
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Thorsten Blum

author
#0 lore raw

PATCH v3 1/2 printk: add print_hex_dump_devel()

Add print_hex_dump_devel() as the hex dump equivalent of pr_devel(), which emits output only when DEBUG is enabled, but keeps call sites compiled otherwise.

Suggested-by Herbert Xu <[email protected]>
Signed-off-by Thorsten Blum <[email protected]>
---
 include/linux/printk.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)
include/linux/printk.h +13 -0
index 63d516c873b4..54e3c621fec3 100644
@@ -801,6 +801,19 @@ static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type,
 }
 #endif
 
+#if defined(DEBUG)
+#define print_hex_dump_devel(prefix_str, prefix_type, rowsize,		\
+			     groupsize, buf, len, ascii)		\
+	print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, rowsize,	\
+		       groupsize, buf, len, ascii)
+#else
+static inline void print_hex_dump_devel(const char *prefix_str, int prefix_type,
+					int rowsize, int groupsize,
+					const void *buf, size_t len, bool ascii)
+{
+}
+#endif
+
 /**
  * print_hex_dump_bytes - shorthand form of print_hex_dump() with default params
  * @prefix_str: string to prefix each line with;
author
#1 lore raw

PATCH v3 2/2 crypto: caam - guard HMAC key hex dumps in hash_digest_key

Use print_hex_dump_devel() for dumping sensitive HMAC key bytes in hash_digest_key() to avoid leaking secrets at runtime when CONFIG_DYNAMIC_DEBUG is enabled.

Fixes 045e36780f11 ("crypto: caam - ahash hmac support")
Fixes 3f16f6c9d632 ("crypto: caam/qi2 - add support for ahash algorithms")
Cc [email protected]
Signed-off-by Thorsten Blum <[email protected]>

---
This patch now depends on patch 1 in the series.

Changes in v3:
- Convert single CAAM patch into a 2-patch series
- Use print_hex_dump_devel() helper from patch 1/2 to keep call sites compiled (Herbert)
- Link to v2: https://lore.kernel.org/lkml/[email protected]/

Changes in v2:
- Debug-guard key hex dumps instead of removing them entirely (Herbert)
- Use print_hex_dump() instead of print_hex_dump_debug() since the dumps
are already guarded by DEBUG
- Link to v1: https://lore.kernel.org/lkml/[email protected]/

---
 drivers/crypto/caam/caamalg_qi2.c | 4 ++--
 drivers/crypto/caam/caamhash.c    | 4 ++--
 2 files changed, 4 insertions(+), 4 deletions(-)
drivers/crypto/caam/caamalg_qi2.c +2 -2
index 167372936ca7..ec40d8ada4a9 100644
@@ -3269,7 +3269,7 @@ static int hash_digest_key(struct caam_hash_ctx *ctx, u32 *keylen, u8 *key,
 	dpaa2_fl_set_addr(out_fle, key_dma);
 	dpaa2_fl_set_len(out_fle, digestsize);
 
-	print_hex_dump_debug("key_in@" __stringify(__LINE__)": ",
+	print_hex_dump_devel("key_in@" __stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, key, *keylen, 1);
 	print_hex_dump_debug("shdesc@" __stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),

@@ -3289,7 +3289,7 @@ static int hash_digest_key(struct caam_hash_ctx *ctx, u32 *keylen, u8 *key,
 		/* in progress */
 		wait_for_completion(&result.completion);
 		ret = result.err;
-		print_hex_dump_debug("digested key@" __stringify(__LINE__)": ",
+		print_hex_dump_devel("digested key@" __stringify(__LINE__)": ",
 				     DUMP_PREFIX_ADDRESS, 16, 4, key,
 				     digestsize, 1);
 	}
drivers/crypto/caam/caamhash.c +2 -2
index 628c43a7efc4..b8e6cc382d93 100644
@@ -393,7 +393,7 @@ static int hash_digest_key(struct caam_hash_ctx *ctx, u32 *keylen, u8 *key,
 	append_seq_store(desc, digestsize, LDST_CLASS_2_CCB |
 			 LDST_SRCDST_BYTE_CONTEXT);
 
-	print_hex_dump_debug("key_in@"__stringify(__LINE__)": ",
+	print_hex_dump_devel("key_in@"__stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, key, *keylen, 1);
 	print_hex_dump_debug("jobdesc@"__stringify(__LINE__)": ",
 			     DUMP_PREFIX_ADDRESS, 16, 4, desc, desc_bytes(desc),

@@ -408,7 +408,7 @@ static int hash_digest_key(struct caam_hash_ctx *ctx, u32 *keylen, u8 *key,
 		wait_for_completion(&result.completion);
 		ret = result.err;
 
-		print_hex_dump_debug("digested key@"__stringify(__LINE__)": ",
+		print_hex_dump_devel("digested key@"__stringify(__LINE__)": ",
 				     DUMP_PREFIX_ADDRESS, 16, 4, key,
 				     digestsize, 1);
 	}
maintainer
#2 lore raw
In reply to Thorsten Blum
Quoted 19 lines · Thorsten Blum

Add print_hex_dump_devel() as the hex dump equivalent of pr_devel(), which emits output only when DEBUG is enabled, but keeps call sites compiled otherwise.

Suggested-by Herbert Xu <[email protected]>
Signed-off-by Thorsten Blum <[email protected]>
---
 include/linux/printk.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)
include/linux/printk.h +1 -0
index 63d516c873b4..54e3c621fec3 100644
@@ -801,6 +801,19 @@ static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type,
 }
 #endif
 
+#if defined(DEBUG)

include/linux/printk.h static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type, · line 814

Quoted 10 lines
include/linux/printk.h +10 -0
+#define print_hex_dump_devel(prefix_str, prefix_type, rowsize,		\
+			     groupsize, buf, len, ascii)		\
+	print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, rowsize,	\
+		       groupsize, buf, len, ascii)
+#else
+static inline void print_hex_dump_devel(const char *prefix_str, int prefix_type,
+					int rowsize, int groupsize,
+					const void *buf, size_t len, bool ascii)
+{
+}

If you look at the implementation of pr_devel(), it is using no_printk() in the !DEBUG case. I believe this is to validate correct arg formatting, even if the code will optimized out.

John Ogness

maintainer Reviewed-by
#3 lore raw
Quoted 6 lines · John Ogness
Quoted 6 lines
include/linux/printk.h +6 -0
+#define print_hex_dump_devel(prefix_str, prefix_type, rowsize,		\
+			     groupsize, buf, len, ascii)		\
+	print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, rowsize,	\
+		       groupsize, buf, len, ascii)
+#else
+static inline void print_hex_dump_devel(const char *prefix_str, int prefix_type,
Quoted 8 lines

include/linux/printk.h static inline void print_hex_dump_debug(const char *prefix_str, int prefix_type, · line 814

Quoted 4 lines
include/linux/printk.h +4 -0
+					int rowsize, int groupsize,
+					const void *buf, size_t len, bool ascii)
+{
+}

If you look at the implementation of pr_devel(), it is using no_printk() in the !DEBUG case. I believe this is to validate correct arg formatting, even if the code will optimized out.

Sorry, print_hex_dump() has no printf formatting.

Reviewed-by John Ogness <[email protected]>
maintainer
#4 lore raw
In reply to Thorsten Blum
Quoted 9 lines · Thorsten Blum

Add print_hex_dump_devel() as the hex dump equivalent of pr_devel(), which emits output only when DEBUG is enabled, but keeps call sites compiled otherwise.

Suggested-by Herbert Xu <[email protected]>
Signed-off-by Thorsten Blum <[email protected]>
---
 include/linux/printk.h | 13 +++++++++++++
 1 file changed, 13 insertions(+)

All applied. Thanks.

Signature · 3 lines
Email: Herbert Xu <[email protected]>
Home Page: http://gondor.apana.org.au/~herbert/
PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt