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Thu, 10 Sep 2026 14:19:41 -0700 (PDT) Date: Thu, 10 Sep 2026 14:19:35 -0700 From: Stanislav Fomichev To: Fernando Fernandez Mancera Cc: netdev@vger.kernel.org, horms@kernel.org, kuba@kernel.org, pabeni@redhat.com, edumazet@google.com, davem@davemloft.net, David Ahern , Ido Schimmel , Willem de Bruijn , Kees Cook , Kuniyuki Iwashima , Richard Gobert , Marc Kleine-Budde , Jeff Layton , Qi Tang , linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/13 net-next] net: inet: relocate ip_generic_getfrag and guard IPv4 socket logic Message-ID: References: <20260910144914.8025-1-fmancera@suse.de> <20260910144914.8025-4-fmancera@suse.de> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20260910144914.8025-4-fmancera@suse.de> On 09/10, Fernando Fernandez Mancera wrote: > To enable compiling the INET subsystem without IPv4, shared generic > utilities must be relocated and IPv4 socket logic must be guarded for > CONFIG_IPV4. > > This patch moves the generic ip_generec_getfrag() from ip_output.c to > af_inet.c. It also introduces CONFIG_IPV4 guards around af_inet.c to > reject IPv4-specific ioctls, protocol registrations and bind requests. > The same guard is added to reject IPv4-mapped IPv6. > > Signed-off-by: Fernando Fernandez Mancera > --- > net/ipv4/af_inet.c | 96 +++++++++++++++++++++++++++++++++++++------- > net/ipv4/ip_output.c | 18 --------- > net/ipv6/af_inet6.c | 5 +++ > net/ipv6/datagram.c | 12 ++++++ > 4 files changed, 99 insertions(+), 32 deletions(-) > > diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c > index d9421ac38d78..b0c48ba544bf 100644 > --- a/net/ipv4/af_inet.c > +++ b/net/ipv4/af_inet.c > @@ -129,6 +129,28 @@ > int disable_ipv6_mod; > EXPORT_SYMBOL(disable_ipv6_mod); > > +/* Keep the function here for now as it is generic, it should be moved > + * to a common L3 place > + */ > +int > +ip_generic_getfrag(void *from, char *to, int offset, int len, int odd, struct sk_buff *skb) > +{ > + struct msghdr *msg = from; > + > + if (skb->ip_summed == CHECKSUM_PARTIAL) { > + if (!copy_from_iter_full(to, len, &msg->msg_iter)) > + return -EFAULT; > + } else { > + __wsum csum = 0; > + > + if (!csum_and_copy_from_iter_full(to, len, &csum, &msg->msg_iter)) > + return -EFAULT; > + skb->csum = csum_block_add(skb->csum, csum, odd); > + } > + return 0; > +} > +EXPORT_SYMBOL(ip_generic_getfrag); > + > /* The inetsw table contains everything that inet_create needs to > * build a new socket. > */ > @@ -425,8 +447,10 @@ int inet_release(struct socket *sock) > if (!sk->sk_kern_sock) > BPF_CGROUP_RUN_PROG_INET_SOCK_RELEASE(sk); > > +#if IS_ENABLED(CONFIG_IPV4) > /* Applications forget to leave groups before exiting */ > ip_mc_drop_socket(sk); > +#endif > > /* If linger is set, we don't return until the close > * is complete. Otherwise we return immediately. The > @@ -478,6 +502,7 @@ EXPORT_SYMBOL(inet_bind); > int __inet_bind(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len, > u32 flags) > { > +#if IS_ENABLED(CONFIG_IPV4) > struct sockaddr_in *addr = (struct sockaddr_in *)uaddr; > struct inet_sock *inet = inet_sk(sk); > struct net *net = sock_net(sk); > @@ -570,6 +595,9 @@ int __inet_bind(struct sock *sk, struct sockaddr_unsized *uaddr, int addr_len, > release_sock(sk); > out: > return err; > +#else > + return -EAFNOSUPPORT; > +#endif > } > > int inet_dgram_connect(struct socket *sock, struct sockaddr_unsized *uaddr, > @@ -962,18 +990,24 @@ EXPORT_SYMBOL(inet_shutdown); > int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) > { > struct sock *sk = sock->sk; > - int err = 0; > - struct net *net = sock_net(sk); > +#if IS_ENABLED(CONFIG_IPV4) > void __user *p = (void __user *)arg; > - struct ifreq ifr; > + struct net *net = sock_net(sk); > struct rtentry rt; > + struct ifreq ifr; > +#endif > + int err = 0; > > switch (cmd) { > case SIOCADDRT: > case SIOCDELRT: > +#if IS_ENABLED(CONFIG_IPV4) > if (copy_from_user(&rt, p, sizeof(struct rtentry))) > return -EFAULT; > err = ip_rt_ioctl(net, cmd, &rt); > +#else > + err = -EOPNOTSUPP; > +#endif > break; > case SIOCRTMSG: > err = -EINVAL; > @@ -981,18 +1015,26 @@ int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) > case SIOCDARP: > case SIOCGARP: > case SIOCSARP: > +#if IS_ENABLED(CONFIG_IPV4) > err = arp_ioctl(net, cmd, (void __user *)arg); > +#else > + err = -EOPNOTSUPP; > +#endif > break; > case SIOCGIFADDR: > case SIOCGIFBRDADDR: > case SIOCGIFNETMASK: > case SIOCGIFDSTADDR: > case SIOCGIFPFLAGS: > +#if IS_ENABLED(CONFIG_IPV4) > if (get_user_ifreq(&ifr, NULL, p)) > return -EFAULT; > err = devinet_ioctl(net, cmd, &ifr); > if (!err && put_user_ifreq(&ifr, p)) > err = -EFAULT; > +#else > + err = -EOPNOTSUPP; > +#endif > break; > > case SIOCSIFADDR: > @@ -1001,9 +1043,13 @@ int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg) > case SIOCSIFDSTADDR: > case SIOCSIFPFLAGS: > case SIOCSIFFLAGS: > +#if IS_ENABLED(CONFIG_IPV4) > if (get_user_ifreq(&ifr, NULL, p)) > return -EFAULT; > err = devinet_ioctl(net, cmd, &ifr); > +#else > + err = -EOPNOTSUPP; > +#endif (passing by comment) Don't we have a coding style rule to avoid ifdef conditional in C code? Should we add some new devinet4_ioctl/etc wrappers that we can conditionally compile out in the headers?