Subject: [PATCH RFC v1 2/3] ipv6: move from sha1 to blake2s in address calculation

From: "Jason A. Donenfeld" <[email-masked]>
Date: Wed, 12 Jan 2022 14:12:03 +0100

BLAKE2s is faster and more secure. SHA-1 has been broken for a long time
now. This also removes some code complexity, and lets us potentially
remove sha1 from lib, which would further reduce vmlinux size.

Cc: Geert Uytterhoeven <[email-masked]>
Cc: Herbert Xu <[email-masked]>
Cc: Ard Biesheuvel <[email-masked]>
Cc: Jean-Philippe Aumasson <[email-masked]>
Cc: [email-masked]
Signed-off-by: Jason A. Donenfeld <[email-masked]>
---
 net/ipv6/addrconf.c | 31 +++++++++----------------------
 1 file changed, 9 insertions(+), 22 deletions(-)

diff --git a/net/ipv6/addrconf.c b/net/ipv6/addrconf.c
index 3445f8017430..f5cb534aa261 100644
--- a/net/ipv6/addrconf.c
+++ b/net/ipv6/addrconf.c
@@ -61,7 +61,7 @@
 #include <linux/delay.h>
 #include <linux/notifier.h>
 #include <linux/string.h>
-#include <linux/hash.h>
+#include <crypto/blake2s.h>
 
 #include <net/net_namespace.h>
 #include <net/sock.h>
@@ -3225,25 +3225,16 @@ 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 union {
-		char __data[SHA1_BLOCK_SIZE];
-		struct {
-			struct in6_addr secret;
-			__be32 prefix[2];
-			unsigned char hwaddr[MAX_ADDR_LEN];
-			u8 dad_count;
-		} __packed;
-	} data;
-
+	struct {
+		struct in6_addr secret;
+		__be32 prefix[2];
+		unsigned char hwaddr[MAX_ADDR_LEN];
+		u8 dad_count;
+	} __packed data;
 	struct in6_addr secret;
 	struct in6_addr temp;
 	struct net *net = dev_net(idev->dev);
 
-	BUILD_BUG_ON(sizeof(data.__data) != sizeof(data));
-
 	if (idev->cnf.stable_secret.initialized)
 		secret = idev->cnf.stable_secret.secret;
 	else if (net->ipv6.devconf_dflt->stable_secret.initialized)
@@ -3254,20 +3245,16 @@ static int ipv6_generate_stable_address(struct in6_addr *address,
 retry:
 	spin_lock_bh(&lock);
 
-	sha1_init(digest);
 	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);
-
 	temp = *address;
-	temp.s6_addr32[2] = (__force __be32)digest[0];
-	temp.s6_addr32[3] = (__force __be32)digest[1];
+	blake2s((u8 *)&temp.s6_addr32[2], (u8 *)&data, NULL,
+		sizeof(temp.s6_addr32[2]) * 2, sizeof(data), 0);
 
 	spin_unlock_bh(&lock);
 
-- 
2.34.1