[PATCH net] ipv4: ping: fix bind address validity check

[Carlos Llamas]

Commit 8ff978b8b222 ("ipv4/raw: support binding to nonlocal addresses")
introduced a helper function to fold duplicated validity checks of bind
addresses into inet_addr_valid_or_nonlocal(). However, this caused an
unintended regression in ping_check_bind_addr(), which previously would
reject binding to multicast and broadcast addresses, but now these are
both incorrectly allowed as reported in [1].

This patch restores the original check. A simple reordering is done to
improve readability and make it evident that multicast and broadcast
addresses should not be allowed. Also, add an early exit for INADDR_ANY
which replaces lost behavior added by commit 0ce779a9f501 ("net: Avoid
unnecessary inet_addr_type() call when addr is INADDR_ANY").

[1] https://lore.kernel.org/netdev/CANP3RGdkAcDyAZoT1h8Gtuu0saq+eOrrTiWbxnOs+5zn+cpyKg@xxxxxxxxxxxxxx/

Fixes: 8ff978b8b222 ("ipv4/raw: support binding to nonlocal addresses")
Cc: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Cc: Riccardo Paolo Bestetti <pbl@xxxxxxxxx>
Reported-by: Maciej Żenczykowski <maze@xxxxxxxxxx>
Signed-off-by: Carlos Llamas <cmllamas@xxxxxxxxxx>
---
 net/ipv4/ping.c | 10 +++++++---
 1 file changed, 7 insertions(+), 3 deletions(-)

diff --git a/net/ipv4/ping.c b/net/ipv4/ping.c
index 1a43ca73f94d..3c6101def7d6 100644
--- a/net/ipv4/ping.c
+++ b/net/ipv4/ping.c
@@ -319,12 +319,16 @@ static int ping_check_bind_addr(struct sock *sk, struct inet_sock *isk,
 		pr_debug("ping_check_bind_addr(sk=%p,addr=%pI4,port=%d)\n",
 			 sk, &addr->sin_addr.s_addr, ntohs(addr->sin_port));
 
+		if (addr->sin_addr.s_addr == htonl(INADDR_ANY))
+			return 0;
+
 		tb_id = l3mdev_fib_table_by_index(net, sk->sk_bound_dev_if) ? : tb_id;
 		chk_addr_ret = inet_addr_type_table(net, addr->sin_addr.s_addr, tb_id);
 
-		if (!inet_addr_valid_or_nonlocal(net, inet_sk(sk),
-					         addr->sin_addr.s_addr,
-	                                         chk_addr_ret))
+		if (chk_addr_ret == RTN_MULTICAST ||
+		    chk_addr_ret == RTN_BROADCAST ||
+		    (chk_addr_ret != RTN_LOCAL &&
+		     !inet_can_nonlocal_bind(net, isk)))
 			return -EADDRNOTAVAIL;
 
 #if IS_ENABLED(CONFIG_IPV6)
-- 
2.36.1.476.g0c4daa206d-goog