ipv6: Switch to higher-level SHA-1 functions

There's now a proper SHA-1 API that follows the usual conventions for
hash function APIs: sha1_init(), sha1_update(), sha1_final(), sha1().
The only remaining user of the older low-level SHA-1 API,
sha1_init_raw() and sha1_transform(), is ipv6_generate_stable_address().
I'd like to remove this older API, which is too low-level.

Unfortunately, ipv6_generate_stable_address() does in fact skip the
SHA-1 finalization for some reason.  So the values it computes are not
standard SHA-1 values, and it sort of does want the low-level API.

Still, it's still possible to use the higher-level functions sha1_init()
and sha1_update() to get the same result, provided that the resulting
state is used directly, skipping sha1_final().

So, let's do that instead.  This will allow removing the low-level API.

Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Acked-by: David Ahern <dsahern@kernel.org>
Link: https://patch.msgid.link/20260123051656.396371-2-ebiggers@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 7138e0e67991987b52f83c0c456e299af2a77804..6db9cf9e2a509730c74a4183b43ba1f76cfeea3f 100644 (file)
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -3339,11 +3339,10 @@ static int ipv6_generate_stable_address(struct in6_addr *address,
                                        const struct inet6_dev *idev)
 {
        static DEFINE_SPINLOCK(lock);
-       static __u32 digest[SHA1_DIGEST_WORDS];
-       static __u32 workspace[SHA1_WORKSPACE_WORDS];
+       static struct sha1_ctx sha_ctx;
 
        static union {
-               char __data[SHA1_BLOCK_SIZE];
+               u8 __data[SHA1_BLOCK_SIZE];
                struct {
                        struct in6_addr secret;
                        __be32 prefix[2];
@@ -3368,20 +3367,26 @@ static int ipv6_generate_stable_address(struct in6_addr *address,
 retry:
        spin_lock_bh(&lock);
 
-       sha1_init_raw(digest);
+       sha1_init(&sha_ctx);
+
        memset(&data, 0, sizeof(data));
-       memset(workspace, 0, sizeof(workspace));
        memcpy(data.hwaddr, idev->dev->perm_addr, idev->dev->addr_len);
        data.prefix[0] = address->s6_addr32[0];
        data.prefix[1] = address->s6_addr32[1];
        data.secret = secret;
        data.dad_count = dad_count;
 
-       sha1_transform(digest, data.__data, workspace);
+       sha1_update(&sha_ctx, data.__data, sizeof(data));
 
+       /*
+        * Note that the SHA-1 finalization is omitted here, and the digest is
+        * pulled directly from the internal SHA-1 state (making it incompatible
+        * with standard SHA-1).  Unusual, but technically okay since the data
+        * length is fixed and is a multiple of the SHA-1 block size.
+        */
        temp = *address;
-       temp.s6_addr32[2] = (__force __be32)digest[0];
-       temp.s6_addr32[3] = (__force __be32)digest[1];
+       temp.s6_addr32[2] = (__force __be32)sha_ctx.state.h[0];
+       temp.s6_addr32[3] = (__force __be32)sha_ctx.state.h[1];
 
        spin_unlock_bh(&lock);