selftests/bpf: Test packet range of pointers sharing an idgrafted

Add tests where two packet pointers share an id and tightening one
pointer's umax from its var_off would put it less than their constant
distance from the other's umax: with an index & 0x38 capped at 50, the
base pointer keeps umax 50, so the pointer 8 bytes further on must keep
umax 58, even though its known bits allow at most 56.

These refused a valid program or accepted an out-of-bounds access before
the fix:

- check the advanced copy, load through the base: valid, was refused;
- check the base, load the byte at base + 1 through a copy advanced by
  8: was accepted;
- check base + 4, load 4 bytes at base + 2 through base + 8: reads two
  bytes past the checked range, was accepted;
- the same as the second with data_meta pointers checked against data:
  was accepted.

These pass with and without the fix and cover nearby paths:

- subtract an unknown scalar from a checked pointer and load below it
  (the range is kept across a new id);
- reach a load through two paths whose checks cover 8 and 7 bytes after
  the loaded pointer; the second path must not be pruned by the first;
- spill a copy of a pointer, check the pointer, fill the copy and load
  one byte past the checked range: the load is refused, and the copy
  has the range of the check.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 52 insertions, 0 deletions

diff --git a/include/crypto/nh.h b/include/crypto/nh.h
new file mode 100644
index 000000000..465e85bf2
--- /dev/null
+++ b/include/crypto/nh.h
@@ -0,0 +1,52 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * NH hash function for Adiantum
+ */
+
+#ifndef _CRYPTO_NH_H
+#define _CRYPTO_NH_H
+
+#include <linux/types.h>
+
+/* NH parameterization: */
+
+/* Endianness: little */
+/* Word size: 32 bits (works well on NEON, SSE2, AVX2) */
+
+/* Stride: 2 words (optimal on ARM32 NEON; works okay on other CPUs too) */
+#define NH_PAIR_STRIDE		2
+#define NH_MESSAGE_UNIT		(NH_PAIR_STRIDE * 2 * sizeof(u32))
+
+/* Num passes (Toeplitz iteration count): 4, to give ε = 2^{-128} */
+#define NH_NUM_PASSES		4
+#define NH_HASH_BYTES		(NH_NUM_PASSES * sizeof(u64))
+
+/* Max message size: 1024 bytes (32x compression factor) */
+#define NH_NUM_STRIDES		64
+#define NH_MESSAGE_WORDS	(NH_PAIR_STRIDE * 2 * NH_NUM_STRIDES)
+#define NH_MESSAGE_BYTES	(NH_MESSAGE_WORDS * sizeof(u32))
+#define NH_KEY_WORDS		(NH_MESSAGE_WORDS + \
+				 NH_PAIR_STRIDE * 2 * (NH_NUM_PASSES - 1))
+#define NH_KEY_BYTES		(NH_KEY_WORDS * sizeof(u32))
+
+/**
+ * nh() - NH hash function for Adiantum
+ * @key: The key.  @message_len + 48 bytes of it are used.  This is NH_KEY_BYTES
+ *	 if @message_len has its maximum length of NH_MESSAGE_BYTES.
+ * @message: The message
+ * @message_len: The message length in bytes.  Must be a multiple of 16
+ *		 (NH_MESSAGE_UNIT) and at most 1024 (NH_MESSAGE_BYTES).
+ * @hash: (output) The resulting hash value
+ *
+ * Note: the pseudocode for NH in the Adiantum paper iterates over 1024-byte
+ * segments of the message, computes a 32-byte hash for each, and returns all
+ * the hashes concatenated together.  In contrast, this function just hashes one
+ * segment and returns one hash.  It's the caller's responsibility to call this
+ * function for each 1024-byte segment and collect all the hashes.
+ *
+ * Context: Any context.
+ */
+void nh(const u32 *key, const u8 *message, size_t message_len,
+	__le64 hash[NH_NUM_PASSES]);
+
+#endif /* _CRYPTO_NH_H */