diff mbox series

[2/5] pstore: Allow for arbitrary compression algorithm

Message ID 20221018020815.2872331-2-keescook@chromium.org (mailing list archive)
State Changes Requested
Headers show
Series pstore: Use zstd directly by default for compression | expand

Commit Message

Kees Cook Oct. 18, 2022, 2:08 a.m. UTC 
Since there is no longer a need for figuring out worst-case compression
size, there is no reason to limit the compression algorithm choice.
Greatly simplifies Kconfig.

Cc: Tony Luck <tony.luck@intel.com>
Cc: "Guilherme G. Piccoli" <gpiccoli@igalia.com>
Cc: Nick Terrell <terrelln@fb.com>
Cc: linux-hardening@vger.kernel.org
Signed-off-by: Kees Cook <keescook@chromium.org>
---
 fs/pstore/Kconfig    | 122 ++++++++++++-------------------------------
 fs/pstore/platform.c |  39 ++++++--------
 2 files changed, 47 insertions(+), 114 deletions(-)
diff mbox series

Patch

diff --git a/fs/pstore/Kconfig b/fs/pstore/Kconfig
index 8adabde685f1..a95b3981cb0e 100644
--- a/fs/pstore/Kconfig
+++ b/fs/pstore/Kconfig
@@ -22,99 +22,41 @@  config PSTORE_DEFAULT_KMSG_BYTES
 	  Defines default size of pstore kernel log storage.
 	  Can be enlarged if needed, not recommended to shrink it.
 
-config PSTORE_DEFLATE_COMPRESS
-	tristate "DEFLATE (ZLIB) compression"
-	default y
-	depends on PSTORE
-	select CRYPTO_DEFLATE
-	help
-	  This option enables DEFLATE (also known as ZLIB) compression
-	  algorithm support.
-
-config PSTORE_LZO_COMPRESS
-	tristate "LZO compression"
-	depends on PSTORE
-	select CRYPTO_LZO
-	help
-	  This option enables LZO compression algorithm support.
-
-config PSTORE_LZ4_COMPRESS
-	tristate "LZ4 compression"
-	depends on PSTORE
-	select CRYPTO_LZ4
-	help
-	  This option enables LZ4 compression algorithm support.
-
-config PSTORE_LZ4HC_COMPRESS
-	tristate "LZ4HC compression"
-	depends on PSTORE
-	select CRYPTO_LZ4HC
-	help
-	  This option enables LZ4HC (high compression) mode algorithm.
-
-config PSTORE_842_COMPRESS
-	bool "842 compression"
-	depends on PSTORE
-	select CRYPTO_842
-	help
-	  This option enables 842 compression algorithm support.
-
-config PSTORE_ZSTD_COMPRESS
-	bool "zstd compression"
-	depends on PSTORE
-	select CRYPTO_ZSTD
-	help
-	  This option enables zstd compression algorithm support.
-
-config PSTORE_COMPRESS
-	def_bool y
-	depends on PSTORE
-	depends on PSTORE_DEFLATE_COMPRESS || PSTORE_LZO_COMPRESS ||	\
-		   PSTORE_LZ4_COMPRESS || PSTORE_LZ4HC_COMPRESS ||	\
-		   PSTORE_842_COMPRESS || PSTORE_ZSTD_COMPRESS
-
 choice
-	prompt "Default pstore compression algorithm"
-	depends on PSTORE_COMPRESS
-	help
-	  This option chooses the default active compression algorithm.
-	  This change be changed at boot with "pstore.compress=..." on
-	  the kernel command line.
-
-	  Currently, pstore has support for 6 compression algorithms:
-	  deflate, lzo, lz4, lz4hc, 842 and zstd.
-
-	  The default compression algorithm is deflate.
-
-	config PSTORE_DEFLATE_COMPRESS_DEFAULT
-		bool "deflate" if PSTORE_DEFLATE_COMPRESS
-
-	config PSTORE_LZO_COMPRESS_DEFAULT
-		bool "lzo" if PSTORE_LZO_COMPRESS
-
-	config PSTORE_LZ4_COMPRESS_DEFAULT
-		bool "lz4" if PSTORE_LZ4_COMPRESS
-
-	config PSTORE_LZ4HC_COMPRESS_DEFAULT
-		bool "lz4hc" if PSTORE_LZ4HC_COMPRESS
-
-	config PSTORE_842_COMPRESS_DEFAULT
-		bool "842" if PSTORE_842_COMPRESS
-
-	config PSTORE_ZSTD_COMPRESS_DEFAULT
-		bool "zstd" if PSTORE_ZSTD_COMPRESS
-
+	prompt "Panic dump compression"
+	depends on PSTORE
+	default PSTORE_COMPRESS_CRYPTO
+	help
+	  Choose whether and how to compress the panic dump output. This
+	  is usually only needed for very storage-constrained backends.
+
+	config PSTORE_COMPRESS_CRYPTO
+		bool "Use an arbitrary compression algorithm via the Crypto API"
+		help
+		  If the default compression algorithm from PSTORE_COMPRESS
+		  is not desired, an arbitrary one can be chosen if it is
+		  available to from the Crypto API. Note that this may reserve
+		  non-trivial amounts of per-CPU memory.
+
+	config PSTORE_COMPRESS_NONE
+		bool "Do not compress panic dumps"
+		help
+		  Do not compress the panic dump output. This leave the
+		  output easily readable in memory, if non-pstore forensics
+		  tools want to examine the contents easily.
 endchoice
 
-config PSTORE_COMPRESS_DEFAULT
-	string
-	depends on PSTORE_COMPRESS
-	default "deflate" if PSTORE_DEFLATE_COMPRESS_DEFAULT
-	default "lzo" if PSTORE_LZO_COMPRESS_DEFAULT
-	default "lz4" if PSTORE_LZ4_COMPRESS_DEFAULT
-	default "lz4hc" if PSTORE_LZ4HC_COMPRESS_DEFAULT
-	default "842" if PSTORE_842_COMPRESS_DEFAULT
-	default "zstd" if PSTORE_ZSTD_COMPRESS_DEFAULT
+config PSTORE_COMPRESS_CRYPTO_DEFAULT
+	string "Crypto API compression algorithm"
+	depends on PSTORE_COMPRESS_CRYPTO
+	default "zstd"
+	help
+	  This option chooses the default active compression algorithm,
+	  and can be changed at boot with "pstore.compress=..." on the
+	  kernel command line. The chosen compression algorithm needs to
+	  be available to the crypto subsystem for it to be usable by
+	  pstore. For example, "zstd" needs CONFIG_CRYPTO_ZSTD, "deflate"
+	  needs CONFIG_CRYPTO_DEFLATE, etc.
 
 config PSTORE_CONSOLE
 	bool "Log kernel console messages"
diff --git a/fs/pstore/platform.c b/fs/pstore/platform.c
index ef0bc3ae161b..1f01c4b904fc 100644
--- a/fs/pstore/platform.c
+++ b/fs/pstore/platform.c
@@ -16,15 +16,6 @@ 
 #include <linux/console.h>
 #include <linux/module.h>
 #include <linux/pstore.h>
-#if IS_ENABLED(CONFIG_PSTORE_LZO_COMPRESS)
-#include <linux/lzo.h>
-#endif
-#if IS_ENABLED(CONFIG_PSTORE_LZ4_COMPRESS) || IS_ENABLED(CONFIG_PSTORE_LZ4HC_COMPRESS)
-#include <linux/lz4.h>
-#endif
-#if IS_ENABLED(CONFIG_PSTORE_ZSTD_COMPRESS)
-#include <linux/zstd.h>
-#endif
 #include <linux/crypto.h>
 #include <linux/string.h>
 #include <linux/timer.h>
@@ -80,9 +71,9 @@  static char *backend;
 module_param(backend, charp, 0444);
 MODULE_PARM_DESC(backend, "specific backend to use");
 
-static char *compress =
-#ifdef CONFIG_PSTORE_COMPRESS_DEFAULT
-		CONFIG_PSTORE_COMPRESS_DEFAULT;
+static char *compress __ro_after_init =
+#ifdef CONFIG_PSTORE_COMPRESS_CRYPTO_DEFAULT
+		CONFIG_PSTORE_COMPRESS_CRYPTO_DEFAULT;
 #else
 		NULL;
 #endif
@@ -166,18 +157,18 @@  static bool pstore_cannot_block_path(enum kmsg_dump_reason reason)
 static int pstore_compress(const void *in, void *out,
 			   unsigned int inlen, unsigned int outlen)
 {
-	int ret;
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS_CRYPTO)) {
+		int ret;
 
-	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS))
-		return -EINVAL;
-
-	ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
-	if (ret) {
-		pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
-		return ret;
+		ret = crypto_comp_compress(tfm, in, inlen, out, &outlen);
+		if (ret) {
+			pr_err("crypto_comp_compress failed, ret = %d!\n", ret);
+			return ret;
+		}
+		return outlen;
 	}
 
-	return outlen;
+	return -EINVAL;
 }
 
 static void allocate_buf_for_compression(void)
@@ -187,7 +178,7 @@  static void allocate_buf_for_compression(void)
 	char *buf;
 
 	/* Skip if not built-in or compression backend not selected yet. */
-	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !compress)
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS_NONE) || !compress)
 		return;
 
 	/* Skip if no pstore backend yet or compression init already done. */
@@ -226,7 +217,7 @@  static void allocate_buf_for_compression(void)
 
 static void free_buf_for_compression(void)
 {
-	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS) && tfm) {
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS_CRYPTO) && tfm) {
 		crypto_free_comp(tfm);
 		tfm = NULL;
 	}
@@ -578,7 +569,7 @@  static void decompress_record(struct pstore_record *record)
 	int unzipped_len;
 	char *unzipped, *workspace;
 
-	if (!IS_ENABLED(CONFIG_PSTORE_COMPRESS) || !record->compressed)
+	if (IS_ENABLED(CONFIG_PSTORE_COMPRESS_NONE) || !record->compressed)
 		return;
 
 	/* Only PSTORE_TYPE_DMESG support compression. */