crypto: 842 - Add CRC and validation support

This patch adds CRC generation and validation support for nx-842.
Add CRC flag so that nx842 coprocessor includes CRC during compression
and validates during decompression.

Also changes in 842 SW compression to append CRC value at the end
of template and checks during decompression.

Signed-off-by: Haren Myneni <haren@us.ibm.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

3 files changed, 32 insertions, 0 deletions

diff --git a/lib/842/842.h b/lib/842/842.h
index 7c20003..e0a122bc 100644
--- a/lib/842/842.h
+++ b/lib/842/842.h
@@ -76,6 +76,7 @@
 #include <linux/module.h>
 #include <linux/kernel.h>
 #include <linux/bitops.h>
+#include <linux/crc32.h>
 #include <asm/unaligned.h>
 
 #include <linux/sw842.h>
@@ -98,6 +99,7 @@
 #define I2_BITS		(8)
 #define I4_BITS		(9)
 #define I8_BITS		(8)
+#define CRC_BITS	(32)
 
 #define REPEAT_BITS_MAX		(0x3f)
 #define SHORT_DATA_BITS_MAX	(0x7)
diff --git a/lib/842/842_compress.c b/lib/842/842_compress.c
index 7ce6894..4051339 100644
--- a/lib/842/842_compress.c
+++ b/lib/842/842_compress.c
@@ -490,6 +490,7 @@ int sw842_compress(const u8 *in, unsigned int ilen,
 	int ret;
 	u64 last, next, pad, total;
 	u8 repeat_count = 0;
+	u32 crc;
 
 	BUILD_BUG_ON(sizeof(*p) > SW842_MEM_COMPRESS);
 
@@ -580,6 +581,18 @@ skip_comp:
 	if (ret)
 		return ret;
 
+	/*
+	 * crc(0:31) is appended to target data starting with the next
+	 * bit after End of stream template.
+	 * nx842 calculates CRC for data in big-endian format. So doing
+	 * same here so that sw842 decompression can be used for both
+	 * compressed data.
+	 */
+	crc = crc32_be(0, in, ilen);
+	ret = add_bits(p, crc, CRC_BITS);
+	if (ret)
+		return ret;
+
 	if (p->bit) {
 		p->out++;
 		p->olen--;
diff --git a/lib/842/842_decompress.c b/lib/842/842_decompress.c
index 5446ff0..8881dad 100644
--- a/lib/842/842_decompress.c
+++ b/lib/842/842_decompress.c
@@ -285,6 +285,7 @@ int sw842_decompress(const u8 *in, unsigned int ilen,
 	struct sw842_param p;
 	int ret;
 	u64 op, rep, tmp, bytes, total;
+	u64 crc;
 
 	p.in = (u8 *)in;
 	p.bit = 0;
@@ -375,6 +376,22 @@ int sw842_decompress(const u8 *in, unsigned int ilen,
 		}
 	} while (op != OP_END);
 
+	/*
+	 * crc(0:31) is saved in compressed data starting with the
+	 * next bit after End of stream template.
+	 */
+	ret = next_bits(&p, &crc, CRC_BITS);
+	if (ret)
+		return ret;
+
+	/*
+	 * Validate CRC saved in compressed data.
+	 */
+	if (crc != (u64)crc32_be(0, out, total - p.olen)) {
+		pr_debug("CRC mismatch for decompression\n");
+		return -EINVAL;
+	}
+
 	if (unlikely((total - p.olen) > UINT_MAX))
 		return -ENOSPC;