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>

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/842/842_decompress.c b/lib/842/842_decompress.c
index 5446ff0c9ba0..8881dad2a6a0 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;