libbpf: move libbpf_sha256() implementation into libbpf_utils.c

Move sha256 implementation out of already large and unwieldy libbpf.c
into libbpf_utils.c where we'll keep reusable helpers.

Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20251001171326.3883055-5-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Eduard Zingerman <eddyz87@gmail.com>

1 files changed, 95 insertions, 0 deletions

diff --git a/tools/lib/bpf/libbpf_utils.c b/tools/lib/bpf/libbpf_utils.c
index ee3013e9b77c..f8290a0b3aaf 100644
--- a/tools/lib/bpf/libbpf_utils.c
+++ b/tools/lib/bpf/libbpf_utils.c
@@ -11,6 +11,9 @@
 #include <stdio.h>
 #include <string.h>
 #include <errno.h>
+#include <inttypes.h>
+#include <linux/kernel.h>
+#include <linux/unaligned.h>
 
 #include "libbpf.h"
 #include "libbpf_internal.h"
@@ -145,3 +148,95 @@ const char *libbpf_errstr(int err)
 		return buf;
 	}
 }
+
+#define SHA256_BLOCK_LENGTH 64
+#define Ch(x, y, z) (((x) & (y)) ^ (~(x) & (z)))
+#define Maj(x, y, z) (((x) & (y)) ^ ((x) & (z)) ^ ((y) & (z)))
+#define Sigma_0(x) (ror32((x), 2) ^ ror32((x), 13) ^ ror32((x), 22))
+#define Sigma_1(x) (ror32((x), 6) ^ ror32((x), 11) ^ ror32((x), 25))
+#define sigma_0(x) (ror32((x), 7) ^ ror32((x), 18) ^ ((x) >> 3))
+#define sigma_1(x) (ror32((x), 17) ^ ror32((x), 19) ^ ((x) >> 10))
+
+static const __u32 sha256_K[64] = {
+	0x428a2f98, 0x71374491, 0xb5c0fbcf, 0xe9b5dba5, 0x3956c25b, 0x59f111f1,
+	0x923f82a4, 0xab1c5ed5, 0xd807aa98, 0x12835b01, 0x243185be, 0x550c7dc3,
+	0x72be5d74, 0x80deb1fe, 0x9bdc06a7, 0xc19bf174, 0xe49b69c1, 0xefbe4786,
+	0x0fc19dc6, 0x240ca1cc, 0x2de92c6f, 0x4a7484aa, 0x5cb0a9dc, 0x76f988da,
+	0x983e5152, 0xa831c66d, 0xb00327c8, 0xbf597fc7, 0xc6e00bf3, 0xd5a79147,
+	0x06ca6351, 0x14292967, 0x27b70a85, 0x2e1b2138, 0x4d2c6dfc, 0x53380d13,
+	0x650a7354, 0x766a0abb, 0x81c2c92e, 0x92722c85, 0xa2bfe8a1, 0xa81a664b,
+	0xc24b8b70, 0xc76c51a3, 0xd192e819, 0xd6990624, 0xf40e3585, 0x106aa070,
+	0x19a4c116, 0x1e376c08, 0x2748774c, 0x34b0bcb5, 0x391c0cb3, 0x4ed8aa4a,
+	0x5b9cca4f, 0x682e6ff3, 0x748f82ee, 0x78a5636f, 0x84c87814, 0x8cc70208,
+	0x90befffa, 0xa4506ceb, 0xbef9a3f7, 0xc67178f2,
+};
+
+#define SHA256_ROUND(i, a, b, c, d, e, f, g, h)                                \
+	{                                                                      \
+		__u32 tmp = h + Sigma_1(e) + Ch(e, f, g) + sha256_K[i] + w[i]; \
+		d += tmp;                                                      \
+		h = tmp + Sigma_0(a) + Maj(a, b, c);                           \
+	}
+
+static void sha256_blocks(__u32 state[8], const __u8 *data, size_t nblocks)
+{
+	while (nblocks--) {
+		__u32 a = state[0];
+		__u32 b = state[1];
+		__u32 c = state[2];
+		__u32 d = state[3];
+		__u32 e = state[4];
+		__u32 f = state[5];
+		__u32 g = state[6];
+		__u32 h = state[7];
+		__u32 w[64];
+		int i;
+
+		for (i = 0; i < 16; i++)
+			w[i] = get_unaligned_be32(&data[4 * i]);
+		for (; i < ARRAY_SIZE(w); i++)
+			w[i] = sigma_1(w[i - 2]) + w[i - 7] +
+			       sigma_0(w[i - 15]) + w[i - 16];
+		for (i = 0; i < ARRAY_SIZE(w); i += 8) {
+			SHA256_ROUND(i + 0, a, b, c, d, e, f, g, h);
+			SHA256_ROUND(i + 1, h, a, b, c, d, e, f, g);
+			SHA256_ROUND(i + 2, g, h, a, b, c, d, e, f);
+			SHA256_ROUND(i + 3, f, g, h, a, b, c, d, e);
+			SHA256_ROUND(i + 4, e, f, g, h, a, b, c, d);
+			SHA256_ROUND(i + 5, d, e, f, g, h, a, b, c);
+			SHA256_ROUND(i + 6, c, d, e, f, g, h, a, b);
+			SHA256_ROUND(i + 7, b, c, d, e, f, g, h, a);
+		}
+		state[0] += a;
+		state[1] += b;
+		state[2] += c;
+		state[3] += d;
+		state[4] += e;
+		state[5] += f;
+		state[6] += g;
+		state[7] += h;
+		data += SHA256_BLOCK_LENGTH;
+	}
+}
+
+void libbpf_sha256(const void *data, size_t len, __u8 out[SHA256_DIGEST_LENGTH])
+{
+	__u32 state[8] = { 0x6a09e667, 0xbb67ae85, 0x3c6ef372, 0xa54ff53a,
+			   0x510e527f, 0x9b05688c, 0x1f83d9ab, 0x5be0cd19 };
+	const __be64 bitcount = cpu_to_be64((__u64)len * 8);
+	__u8 final_data[2 * SHA256_BLOCK_LENGTH] = { 0 };
+	size_t final_len = len % SHA256_BLOCK_LENGTH;
+	int i;
+
+	sha256_blocks(state, data, len / SHA256_BLOCK_LENGTH);
+
+	memcpy(final_data, data + len - final_len, final_len);
+	final_data[final_len] = 0x80;
+	final_len = round_up(final_len + 9, SHA256_BLOCK_LENGTH);
+	memcpy(&final_data[final_len - 8], &bitcount, 8);
+
+	sha256_blocks(state, final_data, final_len / SHA256_BLOCK_LENGTH);
+
+	for (i = 0; i < ARRAY_SIZE(state); i++)
+		put_unaligned_be32(state[i], &out[4 * i]);
+}