[PATCH v1 net-next] net: Use sockaddr_storage for getsockopt(SO_PEERNAME).

[PATCH v1 net-next] net: Use sockaddr_storage for getsockopt(SO_PEERNAME).

[Kuniyuki Iwashima]

Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") started
applying strict rules to standard string functions.

It does not work well with conventional socket code around each protocol-
specific struct sockaddr_XXX, which is cast from sockaddr_storage and has
a bigger size than fortified functions expect.  (See Link)

We must cast the protocol-specific address back to sockaddr_storage
to call such functions.

However, in the case of getsockaddr(SO_PEERNAME), the rationale is a bit
unclear as the buffer is defined by char[128] which is the same size as
sockaddr_storage.

Let's use sockaddr_storage implicitly.

Link: https://lore.kernel.org/netdev/20230720004410.87588-1-kuniyu@amazon.com/
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
---
 net/core/sock.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/net/core/sock.c b/net/core/sock.c
index ab1e8d1bd5a1..4ad267ba0099 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -1806,14 +1806,14 @@ int sk_getsockopt(struct sock *sk, int level, int optname,
 
 	case SO_PEERNAME:
 	{
-		char address[128];
+		struct sockaddr_storage address;
 
-		lv = sock->ops->getname(sock, (struct sockaddr *)address, 2);
+		lv = sock->ops->getname(sock, (struct sockaddr *)&address, 2);
 		if (lv < 0)
 			return -ENOTCONN;
 		if (lv < len)
 			return -EINVAL;
-		if (copy_to_sockptr(optval, address, len))
+		if (copy_to_sockptr(optval, &address, len))
 			return -EFAULT;
 		goto lenout;
 	}
-- 
2.30.2

Re: [PATCH v1 net-next] net: Use sockaddr_storage for getsockopt(SO_PEERNAME).

[Eric Dumazet]

On Thu, Jul 20, 2023 at 2:55 AM Kuniyuki Iwashima <kuniyu@amazon.com> wrote:
>
> Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") started
> applying strict rules to standard string functions.
>
> It does not work well with conventional socket code around each protocol-
> specific struct sockaddr_XXX, which is cast from sockaddr_storage and has
> a bigger size than fortified functions expect.  (See Link)
>
> We must cast the protocol-specific address back to sockaddr_storage
> to call such functions.
>
> However, in the case of getsockaddr(SO_PEERNAME), the rationale is a bit
> unclear as the buffer is defined by char[128] which is the same size as
> sockaddr_storage.
>
> Let's use sockaddr_storage implicitly.
>
> Link: https://lore.kernel.org/netdev/20230720004410.87588-1-kuniyu@amazon.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Reviewed-by: Eric Dumazet <edumazet@google.com>

Thanks.

RE: [PATCH v1 net-next] net: Use sockaddr_storage for getsockopt(SO_PEERNAME).

[Willem de Bruijn]

Kuniyuki Iwashima wrote:
> Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") started
> applying strict rules to standard string functions.
> 
> It does not work well with conventional socket code around each protocol-
> specific struct sockaddr_XXX, which is cast from sockaddr_storage and has
> a bigger size than fortified functions expect.  (See Link)
> 
> We must cast the protocol-specific address back to sockaddr_storage
> to call such functions.
> 
> However, in the case of getsockaddr(SO_PEERNAME), the rationale is a bit
> unclear as the buffer is defined by char[128] which is the same size as
> sockaddr_storage.
> 
> Let's use sockaddr_storage implicitly.

explicitly
 
> Link: https://lore.kernel.org/netdev/20230720004410.87588-1-kuniyu@amazon.com/
> Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>

Reviewed-by: Willem de Bruijn <willemb@google.com>

Re: [PATCH v1 net-next] net: Use sockaddr_storage for getsockopt(SO_PEERNAME).

[Kuniyuki Iwashima]

From: Willem de Bruijn <willemdebruijn.kernel@gmail.com>
Date: Thu, 20 Jul 2023 09:50:46 -0400
> Kuniyuki Iwashima wrote:
> > Commit df8fc4e934c1 ("kbuild: Enable -fstrict-flex-arrays=3") started
> > applying strict rules to standard string functions.
> > 
> > It does not work well with conventional socket code around each protocol-
> > specific struct sockaddr_XXX, which is cast from sockaddr_storage and has
> > a bigger size than fortified functions expect.  (See Link)
> > 
> > We must cast the protocol-specific address back to sockaddr_storage
> > to call such functions.
> > 
> > However, in the case of getsockaddr(SO_PEERNAME), the rationale is a bit
> > unclear as the buffer is defined by char[128] which is the same size as
> > sockaddr_storage.
> > 
> > Let's use sockaddr_storage implicitly.
> 
> explicitly

Will fix in v2, thanks!


>  
> > Link: https://lore.kernel.org/netdev/20230720004410.87588-1-kuniyu@amazon.com/
> > Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
> 
> Reviewed-by: Willem de Bruijn <willemb@google.com>