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From:   Riccardo Paolo Bestetti <pbl@bestov.io>
Cc:     Riccardo Paolo Bestetti <pbl@bestov.io>,
        "David S. Miller" <davem@davemloft.net>,
        Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>,
        David Ahern <dsahern@kernel.org>,
        Jakub Kicinski <kuba@kernel.org>, netdev@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: [PATCH] ipv4/raw: support binding to nonlocal addresses
Date:   Sun, 21 Mar 2021 01:20:45 +0100
Message-Id: <20210321002045.23700-1-pbl@bestov.io>
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Add support to inet raw sockets for binding to nonlocal addresses
through the IP_FREEBIND and IP_TRANSPARENT socket options, as well as
the ipv4.ip_nonlocal_bind kernel parameter.

Signed-off-by: Riccardo Paolo Bestetti <pbl@bestov.io>
---
 net/ipv4/raw.c | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/net/ipv4/raw.c b/net/ipv4/raw.c
index 50a73178d63a..734c0332b54b 100644
--- a/net/ipv4/raw.c
+++ b/net/ipv4/raw.c
@@ -717,6 +717,7 @@ static int raw_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 {
 	struct inet_sock *inet = inet_sk(sk);
 	struct sockaddr_in *addr = (struct sockaddr_in *) uaddr;
+	struct net *net = sock_net(sk);
 	u32 tb_id = RT_TABLE_LOCAL;
 	int ret = -EINVAL;
 	int chk_addr_ret;
@@ -732,7 +733,8 @@ static int raw_bind(struct sock *sk, struct sockaddr *uaddr, int addr_len)
 					    tb_id);
 
 	ret = -EADDRNOTAVAIL;
-	if (addr->sin_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
+	if (!inet_can_nonlocal_bind(net, inet) &&
+	    addr->sin_addr.s_addr && chk_addr_ret != RTN_LOCAL &&
 	    chk_addr_ret != RTN_MULTICAST && chk_addr_ret != RTN_BROADCAST)
 		goto out;
 	inet->inet_rcv_saddr = inet->inet_saddr = addr->sin_addr.s_addr;
-- 
2.31.0