Subject: [PATCH 16/26] bpf: Use sha1() instead of sha1_transform() in bpf_prog_calc_tag()

From: Eric Biggers <[email-masked]>
Date: Sat, 12 Jul 2025 16:23:07 -0700

Now that there's a proper SHA-1 library API, just use that instead of
the low-level SHA-1 compression function.  This eliminates the need for
bpf_prog_calc_tag() to implement the SHA-1 padding itself.  No
functional change.

Signed-off-by: Eric Biggers <[email-masked]>
---
 include/linux/filter.h |  6 ------
 kernel/bpf/core.c      | 49 +++++++-----------------------------------
 2 files changed, 8 insertions(+), 47 deletions(-)

diff --git a/include/linux/filter.h b/include/linux/filter.h
index f5cf4d35d83e9..3aa33e904a4ed 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -995,16 +995,10 @@ void bpf_prog_change_xdp(struct bpf_prog *prev_prog, struct bpf_prog *prog);
 static inline u32 bpf_prog_insn_size(const struct bpf_prog *prog)
 {
 	return prog->len * sizeof(struct bpf_insn);
 }
 
-static inline u32 bpf_prog_tag_scratch_size(const struct bpf_prog *prog)
-{
-	return round_up(bpf_prog_insn_size(prog) +
-			sizeof(__be64) + 1, SHA1_BLOCK_SIZE);
-}
-
 static inline unsigned int bpf_prog_size(unsigned int proglen)
 {
 	return max(sizeof(struct bpf_prog),
 		   offsetof(struct bpf_prog, insns[proglen]));
 }
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index dae281a1286d5..a1b727ffa4548 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -287,32 +287,23 @@ void __bpf_prog_free(struct bpf_prog *fp)
 	vfree(fp);
 }
 
 int bpf_prog_calc_tag(struct bpf_prog *fp)
 {
-	const u32 bits_offset = SHA1_BLOCK_SIZE - sizeof(__be64);
-	u32 raw_size = bpf_prog_tag_scratch_size(fp);
-	u32 digest[SHA1_DIGEST_WORDS];
-	u32 ws[SHA1_WORKSPACE_WORDS];
-	u32 i, bsize, psize, blocks;
+	size_t size = bpf_prog_insn_size(fp);
+	u8 digest[SHA1_DIGEST_SIZE];
 	struct bpf_insn *dst;
 	bool was_ld_map;
-	u8 *raw, *todo;
-	__be32 *result;
-	__be64 *bits;
+	u32 i;
 
-	raw = vmalloc(raw_size);
-	if (!raw)
+	dst = vmalloc(size);
+	if (!dst)
 		return -ENOMEM;
 
-	sha1_init_raw(digest);
-	memset(ws, 0, sizeof(ws));
-
 	/* We need to take out the map fd for the digest calculation
 	 * since they are unstable from user space side.
 	 */
-	dst = (void *)raw;
 	for (i = 0, was_ld_map = false; i < fp->len; i++) {
 		dst[i] = fp->insnsi[i];
 		if (!was_ld_map &&
 		    dst[i].code == (BPF_LD | BPF_IMM | BPF_DW) &&
 		    (dst[i].src_reg == BPF_PSEUDO_MAP_FD ||
@@ -328,37 +319,13 @@ int bpf_prog_calc_tag(struct bpf_prog *fp)
 			dst[i].imm = 0;
 		} else {
 			was_ld_map = false;
 		}
 	}
-
-	psize = bpf_prog_insn_size(fp);
-	memset(&raw[psize], 0, raw_size - psize);
-	raw[psize++] = 0x80;
-
-	bsize  = round_up(psize, SHA1_BLOCK_SIZE);
-	blocks = bsize / SHA1_BLOCK_SIZE;
-	todo   = raw;
-	if (bsize - psize >= sizeof(__be64)) {
-		bits = (__be64 *)(todo + bsize - sizeof(__be64));
-	} else {
-		bits = (__be64 *)(todo + bsize + bits_offset);
-		blocks++;
-	}
-	*bits = cpu_to_be64((psize - 1) << 3);
-
-	while (blocks--) {
-		sha1_transform(digest, todo, ws);
-		todo += SHA1_BLOCK_SIZE;
-	}
-
-	result = (__force __be32 *)digest;
-	for (i = 0; i < SHA1_DIGEST_WORDS; i++)
-		result[i] = cpu_to_be32(digest[i]);
-	memcpy(fp->tag, result, sizeof(fp->tag));
-
-	vfree(raw);
+	sha1((const u8 *)dst, size, digest);
+	memcpy(fp->tag, digest, sizeof(fp->tag));
+	vfree(dst);
 	return 0;
 }
 
 static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, s32 end_old,
 				s32 end_new, s32 curr, const bool probe_pass)
-- 
2.50.1