linux-kernel - Re: [PATCH net-next v3 02/10] udp/ipv6: move pending section of udpv6

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Date:   Mon, 16 May 2022 15:11:07 +0200
From:   Paolo Abeni <pabeni@...hat.com>
To:     Pavel Begunkov <asml.silence@...il.com>, netdev@...r.kernel.org,
        "David S . Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>
Cc:     David Ahern <dsahern@...nel.org>,
        Eric Dumazet <edumazet@...gle.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH net-next v3 02/10] udp/ipv6: move pending section of
 udpv6_sendmsg

On Fri, 2022-05-13 at 16:26 +0100, Pavel Begunkov wrote:
> Move up->pending section of udpv6_sendmsg() to the beginning of the
> function. Even though it require some code duplication for sin6 parsing,
> it clearly localises the pending handling in one place, removes an extra
> if and more importantly will prepare the code for further patches.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
> ---
>  net/ipv6/udp.c | 70 ++++++++++++++++++++++++++++++--------------------
>  1 file changed, 42 insertions(+), 28 deletions(-)
> 
> diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
> index 11d44ed46953..85bff1252f5c 100644
> --- a/net/ipv6/udp.c
> +++ b/net/ipv6/udp.c
> @@ -1318,6 +1318,46 @@ int udpv6_sendmsg(struct sock *sk, struct msghdr *msg, size_t len)
>  	ipc6.sockc.tsflags = sk->sk_tsflags;
>  	ipc6.sockc.mark = sk->sk_mark;
>  
> +	/* Rough check on arithmetic overflow,
> +	   better check is made in ip6_append_data().
> +	   */
> +	if (unlikely(len > INT_MAX - sizeof(struct udphdr)))
> +		return -EMSGSIZE;
> +
> +	getfrag  =  is_udplite ?  udplite_getfrag : ip_generic_getfrag;
> +
> +	/* There are pending frames. */
> +	if (up->pending) {
> +		if (up->pending == AF_INET)
> +			return udp_sendmsg(sk, msg, len);
> +
> +		/* Do a quick destination sanity check before corking. */
> +		if (sin6) {
> +			if (msg->msg_namelen < offsetof(struct sockaddr, sa_data))
> +				return -EINVAL;
> +			if (sin6->sin6_family == AF_INET6) {
> +				if (msg->msg_namelen < SIN6_LEN_RFC2133)
> +					return -EINVAL;
> +				if (ipv6_addr_any(&sin6->sin6_addr) &&
> +				    ipv6_addr_v4mapped(&np->saddr))
> +					return -EINVAL;

It looks like 'any' destination with ipv4 mapped source is now
rejected, while the existing code accept it.

/P