Merge branch 'siphash'

Jason A. Donenfeld says:

====================
Introduce The SipHash PRF

This patch series introduces SipHash into the kernel. SipHash is a
cryptographically secure PRF, which serves a variety of functions, and is
introduced in patch #1. The following patch #2 introduces HalfSipHash,
an optimization suitable for hash tables only. Finally, the last two patches
in this series show two usages of the introduced siphash function family.
It is expected that after this initial introduction, other usages will follow.

Please read the extensive descriptions in patch #1 and patch #2 of what these
functions do and the various levels of assurances. They're products of intense
cryptographic research, and I believe they're suitable for the uses outlined
herein.

The use of SipHash is not limited to the networking subsystem -- indeed I
would like to use it in other places too in the kernel. But after discussing
with a few on this list and at Linus' suggestion, the initial import of these
functions is coming through the networking tree. After these are merged, it
will then be easier to expand use elsewhere.

Changes v2->v3:
  - hsiphash keys now simply use an unsigned long, in order to avoid
    a cluttered ifdef and make it a bit more clear what's happening.
  - A typo in the documentation has been fixed.
  - The documentation has been augmented with an example relating to struct
    packing and passing.
  - The net_secret variable is now __read_mostly.

Hopefully this is the last of the required revisions, and v3 can be merged
into net-next.
====================

Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 140 insertions, 0 deletions

diff --git a/include/linux/siphash.h b/include/linux/siphash.h
new file mode 100644
index 000000000000..fa7a6b9cedbf
--- /dev/null
+++ b/include/linux/siphash.h
@@ -0,0 +1,140 @@
+/* Copyright (C) 2016 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
+ *
+ * This file is provided under a dual BSD/GPLv2 license.
+ *
+ * SipHash: a fast short-input PRF
+ * https://131002.net/siphash/
+ *
+ * This implementation is specifically for SipHash2-4 for a secure PRF
+ * and HalfSipHash1-3/SipHash1-3 for an insecure PRF only suitable for
+ * hashtables.
+ */
+
+#ifndef _LINUX_SIPHASH_H
+#define _LINUX_SIPHASH_H
+
+#include <linux/types.h>
+#include <linux/kernel.h>
+
+#define SIPHASH_ALIGNMENT __alignof__(u64)
+typedef struct {
+	u64 key[2];
+} siphash_key_t;
+
+u64 __siphash_aligned(const void *data, size_t len, const siphash_key_t *key);
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+u64 __siphash_unaligned(const void *data, size_t len, const siphash_key_t *key);
+#endif
+
+u64 siphash_1u64(const u64 a, const siphash_key_t *key);
+u64 siphash_2u64(const u64 a, const u64 b, const siphash_key_t *key);
+u64 siphash_3u64(const u64 a, const u64 b, const u64 c,
+		 const siphash_key_t *key);
+u64 siphash_4u64(const u64 a, const u64 b, const u64 c, const u64 d,
+		 const siphash_key_t *key);
+u64 siphash_1u32(const u32 a, const siphash_key_t *key);
+u64 siphash_3u32(const u32 a, const u32 b, const u32 c,
+		 const siphash_key_t *key);
+
+static inline u64 siphash_2u32(const u32 a, const u32 b,
+			       const siphash_key_t *key)
+{
+	return siphash_1u64((u64)b << 32 | a, key);
+}
+static inline u64 siphash_4u32(const u32 a, const u32 b, const u32 c,
+			       const u32 d, const siphash_key_t *key)
+{
+	return siphash_2u64((u64)b << 32 | a, (u64)d << 32 | c, key);
+}
+
+
+static inline u64 ___siphash_aligned(const __le64 *data, size_t len,
+				     const siphash_key_t *key)
+{
+	if (__builtin_constant_p(len) && len == 4)
+		return siphash_1u32(le32_to_cpup((const __le32 *)data), key);
+	if (__builtin_constant_p(len) && len == 8)
+		return siphash_1u64(le64_to_cpu(data[0]), key);
+	if (__builtin_constant_p(len) && len == 16)
+		return siphash_2u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
+				    key);
+	if (__builtin_constant_p(len) && len == 24)
+		return siphash_3u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
+				    le64_to_cpu(data[2]), key);
+	if (__builtin_constant_p(len) && len == 32)
+		return siphash_4u64(le64_to_cpu(data[0]), le64_to_cpu(data[1]),
+				    le64_to_cpu(data[2]), le64_to_cpu(data[3]),
+				    key);
+	return __siphash_aligned(data, len, key);
+}
+
+/**
+ * siphash - compute 64-bit siphash PRF value
+ * @data: buffer to hash
+ * @size: size of @data
+ * @key: the siphash key
+ */
+static inline u64 siphash(const void *data, size_t len,
+			  const siphash_key_t *key)
+{
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (!IS_ALIGNED((unsigned long)data, SIPHASH_ALIGNMENT))
+		return __siphash_unaligned(data, len, key);
+#endif
+	return ___siphash_aligned(data, len, key);
+}
+
+#define HSIPHASH_ALIGNMENT __alignof__(unsigned long)
+typedef struct {
+	unsigned long key[2];
+} hsiphash_key_t;
+
+u32 __hsiphash_aligned(const void *data, size_t len,
+		       const hsiphash_key_t *key);
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+u32 __hsiphash_unaligned(const void *data, size_t len,
+			 const hsiphash_key_t *key);
+#endif
+
+u32 hsiphash_1u32(const u32 a, const hsiphash_key_t *key);
+u32 hsiphash_2u32(const u32 a, const u32 b, const hsiphash_key_t *key);
+u32 hsiphash_3u32(const u32 a, const u32 b, const u32 c,
+		  const hsiphash_key_t *key);
+u32 hsiphash_4u32(const u32 a, const u32 b, const u32 c, const u32 d,
+		  const hsiphash_key_t *key);
+
+static inline u32 ___hsiphash_aligned(const __le32 *data, size_t len,
+				      const hsiphash_key_t *key)
+{
+	if (__builtin_constant_p(len) && len == 4)
+		return hsiphash_1u32(le32_to_cpu(data[0]), key);
+	if (__builtin_constant_p(len) && len == 8)
+		return hsiphash_2u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
+				     key);
+	if (__builtin_constant_p(len) && len == 12)
+		return hsiphash_3u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
+				     le32_to_cpu(data[2]), key);
+	if (__builtin_constant_p(len) && len == 16)
+		return hsiphash_4u32(le32_to_cpu(data[0]), le32_to_cpu(data[1]),
+				     le32_to_cpu(data[2]), le32_to_cpu(data[3]),
+				     key);
+	return __hsiphash_aligned(data, len, key);
+}
+
+/**
+ * hsiphash - compute 32-bit hsiphash PRF value
+ * @data: buffer to hash
+ * @size: size of @data
+ * @key: the hsiphash key
+ */
+static inline u32 hsiphash(const void *data, size_t len,
+			   const hsiphash_key_t *key)
+{
+#ifndef CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS
+	if (!IS_ALIGNED((unsigned long)data, HSIPHASH_ALIGNMENT))
+		return __hsiphash_unaligned(data, len, key);
+#endif
+	return ___hsiphash_aligned(data, len, key);
+}
+
+#endif /* _LINUX_SIPHASH_H */