netdev - [PATCH net v3 3/4] rxrpc: Improve setsockopt() handling of malformed user input

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Message-Id: <20241119-sockptr-copy-fixes-v3-3-d752cac4be8e@rbox.co>
Date: Tue, 19 Nov 2024 14:31:42 +0100
From: Michal Luczaj <mhal@...x.co>
To: Marcel Holtmann <marcel@...tmann.org>, 
 Johan Hedberg <johan.hedberg@...il.com>, 
 Luiz Augusto von Dentz <luiz.dentz@...il.com>, 
 "David S. Miller" <davem@...emloft.net>, Eric Dumazet <edumazet@...gle.com>, 
 Paolo Abeni <pabeni@...hat.com>, Simon Horman <horms@...nel.org>, 
 David Howells <dhowells@...hat.com>, Marc Dionne <marc.dionne@...istor.com>
Cc: Luiz Augusto von Dentz <luiz.von.dentz@...el.com>, 
 linux-bluetooth@...r.kernel.org, netdev@...r.kernel.org, 
 linux-afs@...ts.infradead.org, Jakub Kicinski <kuba@...nel.org>, 
 Michal Luczaj <mhal@...x.co>
Subject: [PATCH net v3 3/4] rxrpc: Improve setsockopt() handling of
 malformed user input

copy_from_sockptr() does not return negative value on error; instead, it
reports the number of bytes that failed to copy. Since it's deprecated,
switch to copy_safe_from_sockptr().

Note: Keeping the `optlen != sizeof(unsigned int)` check as
copy_safe_from_sockptr() by itself would also accept
optlen > sizeof(unsigned int). Which would allow a more lenient handling
of inputs.

Fixes: 17926a79320a ("[AF_RXRPC]: Provide secure RxRPC sockets for use by userspace and kernel both")
Signed-off-by: Michal Luczaj <mhal@...x.co>
---
 net/rxrpc/af_rxrpc.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/net/rxrpc/af_rxrpc.c b/net/rxrpc/af_rxrpc.c
index f4844683e12039d636253cb06f622468593487eb..9d8bd0b37e41da9f99e2661ae4a29569f5eab650 100644
--- a/net/rxrpc/af_rxrpc.c
+++ b/net/rxrpc/af_rxrpc.c
@@ -707,9 +707,10 @@ static int rxrpc_setsockopt(struct socket *sock, int level, int optname,
 			ret = -EISCONN;
 			if (rx->sk.sk_state != RXRPC_UNBOUND)
 				goto error;
-			ret = copy_from_sockptr(&min_sec_level, optval,
-				       sizeof(unsigned int));
-			if (ret < 0)
+			ret = copy_safe_from_sockptr(&min_sec_level,
+						     sizeof(min_sec_level),
+						     optval, optlen);
+			if (ret)
 				goto error;
 			ret = -EINVAL;
 			if (min_sec_level > RXRPC_SECURITY_MAX)

-- 
2.46.2