move the SIOCDELRT and SIOCADDRT compat_ioctl handlers v3

move the SIOCDELRT and SIOCADDRT compat_ioctl handlers v3

[Christoph Hellwig]

Hi Dave,

this series moves the compat_ioctl handlers into the protocol handlers,
avoiding the need to override the address space limited as in the current
handler.

Changes since v3:
 - moar variable reordering

Changes since v1:
 - reorder a bunch of variable declarations

[PATCH 1/4] ipv6: lift copy_from_user out of ipv6_route_ioctl

[Christoph Hellwig]

Prepare for better compat ioctl handling by moving the user copy out
of ipv6_route_ioctl.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/net/ip6_route.h |  3 ++-
 net/ipv6/af_inet6.c     | 16 +++++++++------
 net/ipv6/route.c        | 44 +++++++++++++++--------------------------
 3 files changed, 28 insertions(+), 35 deletions(-)

diff --git a/include/net/ip6_route.h b/include/net/ip6_route.h
index e525f003e6197..2a5277758379e 100644
--- a/include/net/ip6_route.h
+++ b/include/net/ip6_route.h
@@ -118,7 +118,8 @@ void ip6_route_init_special_entries(void);
 int ip6_route_init(void);
 void ip6_route_cleanup(void);
 
-int ipv6_route_ioctl(struct net *net, unsigned int cmd, void __user *arg);
+int ipv6_route_ioctl(struct net *net, unsigned int cmd,
+		struct in6_rtmsg *rtmsg);
 
 int ip6_route_add(struct fib6_config *cfg, gfp_t gfp_flags,
 		  struct netlink_ext_ack *extack);
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index 771a462a8322b..a618beb9b6d54 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -542,21 +542,25 @@ EXPORT_SYMBOL(inet6_getname);
 
 int inet6_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
+	void __user *argp = (void __user *)arg;
 	struct sock *sk = sock->sk;
 	struct net *net = sock_net(sk);
 
 	switch (cmd) {
 	case SIOCADDRT:
-	case SIOCDELRT:
-
-		return ipv6_route_ioctl(net, cmd, (void __user *)arg);
+	case SIOCDELRT: {
+		struct in6_rtmsg rtmsg;
 
+		if (copy_from_user(&rtmsg, argp, sizeof(rtmsg)))
+			return -EFAULT;
+		return ipv6_route_ioctl(net, cmd, &rtmsg);
+	}
 	case SIOCSIFADDR:
-		return addrconf_add_ifaddr(net, (void __user *) arg);
+		return addrconf_add_ifaddr(net, argp);
 	case SIOCDIFADDR:
-		return addrconf_del_ifaddr(net, (void __user *) arg);
+		return addrconf_del_ifaddr(net, argp);
 	case SIOCSIFDSTADDR:
-		return addrconf_set_dstaddr(net, (void __user *) arg);
+		return addrconf_set_dstaddr(net, argp);
 	default:
 		if (!sk->sk_prot->ioctl)
 			return -ENOIOCTLCMD;
diff --git a/net/ipv6/route.c b/net/ipv6/route.c
index a8b4add0b5454..a52ec1b86432b 100644
--- a/net/ipv6/route.c
+++ b/net/ipv6/route.c
@@ -4336,41 +4336,29 @@ static void rtmsg_to_fib6_config(struct net *net,
 	};
 }
 
-int ipv6_route_ioctl(struct net *net, unsigned int cmd, void __user *arg)
+int ipv6_route_ioctl(struct net *net, unsigned int cmd, struct in6_rtmsg *rtmsg)
 {
 	struct fib6_config cfg;
-	struct in6_rtmsg rtmsg;
 	int err;
 
-	switch (cmd) {
-	case SIOCADDRT:		/* Add a route */
-	case SIOCDELRT:		/* Delete a route */
-		if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
-			return -EPERM;
-		err = copy_from_user(&rtmsg, arg,
-				     sizeof(struct in6_rtmsg));
-		if (err)
-			return -EFAULT;
+	if (cmd != SIOCADDRT && cmd != SIOCDELRT)
+		return -EINVAL;
+	if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
+		return -EPERM;
 
-		rtmsg_to_fib6_config(net, &rtmsg, &cfg);
+	rtmsg_to_fib6_config(net, rtmsg, &cfg);
 
-		rtnl_lock();
-		switch (cmd) {
-		case SIOCADDRT:
-			err = ip6_route_add(&cfg, GFP_KERNEL, NULL);
-			break;
-		case SIOCDELRT:
-			err = ip6_route_del(&cfg, NULL);
-			break;
-		default:
-			err = -EINVAL;
-		}
-		rtnl_unlock();
-
-		return err;
+	rtnl_lock();
+	switch (cmd) {
+	case SIOCADDRT:
+		err = ip6_route_add(&cfg, GFP_KERNEL, NULL);
+		break;
+	case SIOCDELRT:
+		err = ip6_route_del(&cfg, NULL);
+		break;
 	}
-
-	return -EINVAL;
+	rtnl_unlock();
+	return err;
 }
 
 /*
-- 
2.26.2

[PATCH 2/4] ipv6: move SIOCADDRT and SIOCDELRT handling into ->compat_ioctl

[Christoph Hellwig]

To prepare removing the global routing_ioctl hack start lifting the code
into a newly added ipv6 ->compat_ioctl handler.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/net/ipv6.h   |  2 ++
 net/dccp/ipv6.c      |  1 +
 net/ipv6/af_inet6.c  | 53 +++++++++++++++++++++++++++++++++++++
 net/ipv6/raw.c       |  1 +
 net/l2tp/l2tp_ip6.c  |  1 +
 net/mptcp/protocol.c |  1 +
 net/sctp/ipv6.c      |  1 +
 net/socket.c         | 63 ++++++++++++--------------------------------
 8 files changed, 77 insertions(+), 46 deletions(-)

diff --git a/include/net/ipv6.h b/include/net/ipv6.h
index 955badd1e8ffc..5fc3a9d7b053e 100644
--- a/include/net/ipv6.h
+++ b/include/net/ipv6.h
@@ -1115,6 +1115,8 @@ int inet6_bind(struct socket *sock, struct sockaddr *uaddr, int addr_len);
 int inet6_getname(struct socket *sock, struct sockaddr *uaddr,
 		  int peer);
 int inet6_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg);
+int inet6_compat_ioctl(struct socket *sock, unsigned int cmd,
+		unsigned long arg);
 
 int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 			      struct sock *sk);
diff --git a/net/dccp/ipv6.c b/net/dccp/ipv6.c
index 1e5e08cc0bfc3..650187d688519 100644
--- a/net/dccp/ipv6.c
+++ b/net/dccp/ipv6.c
@@ -1082,6 +1082,7 @@ static const struct proto_ops inet6_dccp_ops = {
 	.mmap		   = sock_no_mmap,
 	.sendpage	   = sock_no_sendpage,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
diff --git a/net/ipv6/af_inet6.c b/net/ipv6/af_inet6.c
index a618beb9b6d54..b69496eaf9226 100644
--- a/net/ipv6/af_inet6.c
+++ b/net/ipv6/af_inet6.c
@@ -60,6 +60,7 @@
 #include <net/calipso.h>
 #include <net/seg6.h>
 #include <net/rpl.h>
+#include <net/compat.h>
 
 #include <linux/uaccess.h>
 #include <linux/mroute6.h>
@@ -571,6 +572,56 @@ int inet6_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 }
 EXPORT_SYMBOL(inet6_ioctl);
 
+#ifdef CONFIG_COMPAT
+struct compat_in6_rtmsg {
+	struct in6_addr		rtmsg_dst;
+	struct in6_addr		rtmsg_src;
+	struct in6_addr		rtmsg_gateway;
+	u32			rtmsg_type;
+	u16			rtmsg_dst_len;
+	u16			rtmsg_src_len;
+	u32			rtmsg_metric;
+	u32			rtmsg_info;
+	u32			rtmsg_flags;
+	s32			rtmsg_ifindex;
+};
+
+static int inet6_compat_routing_ioctl(struct sock *sk, unsigned int cmd,
+		struct compat_in6_rtmsg __user *ur)
+{
+	struct in6_rtmsg rt;
+
+	if (copy_from_user(&rt.rtmsg_dst, &ur->rtmsg_dst,
+			3 * sizeof(struct in6_addr)) ||
+	    get_user(rt.rtmsg_type, &ur->rtmsg_type) ||
+	    get_user(rt.rtmsg_dst_len, &ur->rtmsg_dst_len) ||
+	    get_user(rt.rtmsg_src_len, &ur->rtmsg_src_len) ||
+	    get_user(rt.rtmsg_metric, &ur->rtmsg_metric) ||
+	    get_user(rt.rtmsg_info, &ur->rtmsg_info) ||
+	    get_user(rt.rtmsg_flags, &ur->rtmsg_flags) ||
+	    get_user(rt.rtmsg_ifindex, &ur->rtmsg_ifindex))
+		return -EFAULT;
+
+
+	return ipv6_route_ioctl(sock_net(sk), cmd, &rt);
+}
+
+int inet6_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
+{
+	void __user *argp = compat_ptr(arg);
+	struct sock *sk = sock->sk;
+
+	switch (cmd) {
+	case SIOCADDRT:
+	case SIOCDELRT:
+		return inet6_compat_routing_ioctl(sk, cmd, argp);
+	default:
+		return -ENOIOCTLCMD;
+	}
+}
+EXPORT_SYMBOL_GPL(inet6_compat_ioctl);
+#endif /* CONFIG_COMPAT */
+
 INDIRECT_CALLABLE_DECLARE(int udpv6_sendmsg(struct sock *, struct msghdr *,
 					    size_t));
 int inet6_sendmsg(struct socket *sock, struct msghdr *msg, size_t size)
@@ -632,6 +683,7 @@ const struct proto_ops inet6_stream_ops = {
 	.read_sock	   = tcp_read_sock,
 	.peek_len	   = tcp_peek_len,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
@@ -660,6 +712,7 @@ const struct proto_ops inet6_dgram_ops = {
 	.sendpage	   = sock_no_sendpage,
 	.set_peek_off	   = sk_set_peek_off,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
diff --git a/net/ipv6/raw.c b/net/ipv6/raw.c
index 0028aa1d78691..8ef5a7b30524f 100644
--- a/net/ipv6/raw.c
+++ b/net/ipv6/raw.c
@@ -1377,6 +1377,7 @@ const struct proto_ops inet6_sockraw_ops = {
 	.mmap		   = sock_no_mmap,
 	.sendpage	   = sock_no_sendpage,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
diff --git a/net/l2tp/l2tp_ip6.c b/net/l2tp/l2tp_ip6.c
index d148766f40d11..fdfef926c5916 100644
--- a/net/l2tp/l2tp_ip6.c
+++ b/net/l2tp/l2tp_ip6.c
@@ -758,6 +758,7 @@ static const struct proto_ops l2tp_ip6_ops = {
 	.mmap		   = sock_no_mmap,
 	.sendpage	   = sock_no_sendpage,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
diff --git a/net/mptcp/protocol.c b/net/mptcp/protocol.c
index e3a628bea2b81..ba9d3d5c625f7 100644
--- a/net/mptcp/protocol.c
+++ b/net/mptcp/protocol.c
@@ -2068,6 +2068,7 @@ static const struct proto_ops mptcp_v6_stream_ops = {
 	.mmap		   = sock_no_mmap,
 	.sendpage	   = inet_sendpage,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
diff --git a/net/sctp/ipv6.c b/net/sctp/ipv6.c
index c87af430107ae..ccfa0ab3e7f48 100644
--- a/net/sctp/ipv6.c
+++ b/net/sctp/ipv6.c
@@ -1032,6 +1032,7 @@ static const struct proto_ops inet6_seqpacket_ops = {
 	.recvmsg	   = inet_recvmsg,
 	.mmap		   = sock_no_mmap,
 #ifdef CONFIG_COMPAT
+	.compat_ioctl	   = inet6_compat_ioctl,
 	.compat_setsockopt = compat_sock_common_setsockopt,
 	.compat_getsockopt = compat_sock_common_getsockopt,
 #endif
diff --git a/net/socket.c b/net/socket.c
index 1c9a7260a41de..6824470757753 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -3384,62 +3384,33 @@ struct rtentry32 {
 	unsigned short  rt_irtt;        /* Initial RTT                  */
 };
 
-struct in6_rtmsg32 {
-	struct in6_addr		rtmsg_dst;
-	struct in6_addr		rtmsg_src;
-	struct in6_addr		rtmsg_gateway;
-	u32			rtmsg_type;
-	u16			rtmsg_dst_len;
-	u16			rtmsg_src_len;
-	u32			rtmsg_metric;
-	u32			rtmsg_info;
-	u32			rtmsg_flags;
-	s32			rtmsg_ifindex;
-};
-
 static int routing_ioctl(struct net *net, struct socket *sock,
 			 unsigned int cmd, void __user *argp)
 {
+	struct rtentry32 __user *ur4 = argp;
 	int ret;
 	void *r = NULL;
-	struct in6_rtmsg r6;
 	struct rtentry r4;
 	char devname[16];
 	u32 rtdev;
 	mm_segment_t old_fs = get_fs();
 
-	if (sock && sock->sk && sock->sk->sk_family == AF_INET6) { /* ipv6 */
-		struct in6_rtmsg32 __user *ur6 = argp;
-		ret = copy_from_user(&r6.rtmsg_dst, &(ur6->rtmsg_dst),
-			3 * sizeof(struct in6_addr));
-		ret |= get_user(r6.rtmsg_type, &(ur6->rtmsg_type));
-		ret |= get_user(r6.rtmsg_dst_len, &(ur6->rtmsg_dst_len));
-		ret |= get_user(r6.rtmsg_src_len, &(ur6->rtmsg_src_len));
-		ret |= get_user(r6.rtmsg_metric, &(ur6->rtmsg_metric));
-		ret |= get_user(r6.rtmsg_info, &(ur6->rtmsg_info));
-		ret |= get_user(r6.rtmsg_flags, &(ur6->rtmsg_flags));
-		ret |= get_user(r6.rtmsg_ifindex, &(ur6->rtmsg_ifindex));
-
-		r = (void *) &r6;
-	} else { /* ipv4 */
-		struct rtentry32 __user *ur4 = argp;
-		ret = copy_from_user(&r4.rt_dst, &(ur4->rt_dst),
-					3 * sizeof(struct sockaddr));
-		ret |= get_user(r4.rt_flags, &(ur4->rt_flags));
-		ret |= get_user(r4.rt_metric, &(ur4->rt_metric));
-		ret |= get_user(r4.rt_mtu, &(ur4->rt_mtu));
-		ret |= get_user(r4.rt_window, &(ur4->rt_window));
-		ret |= get_user(r4.rt_irtt, &(ur4->rt_irtt));
-		ret |= get_user(rtdev, &(ur4->rt_dev));
-		if (rtdev) {
-			ret |= copy_from_user(devname, compat_ptr(rtdev), 15);
-			r4.rt_dev = (char __user __force *)devname;
-			devname[15] = 0;
-		} else
-			r4.rt_dev = NULL;
-
-		r = (void *) &r4;
-	}
+	ret = copy_from_user(&r4.rt_dst, &(ur4->rt_dst),
+				3 * sizeof(struct sockaddr));
+	ret |= get_user(r4.rt_flags, &(ur4->rt_flags));
+	ret |= get_user(r4.rt_metric, &(ur4->rt_metric));
+	ret |= get_user(r4.rt_mtu, &(ur4->rt_mtu));
+	ret |= get_user(r4.rt_window, &(ur4->rt_window));
+	ret |= get_user(r4.rt_irtt, &(ur4->rt_irtt));
+	ret |= get_user(rtdev, &(ur4->rt_dev));
+	if (rtdev) {
+		ret |= copy_from_user(devname, compat_ptr(rtdev), 15);
+		r4.rt_dev = (char __user __force *)devname;
+		devname[15] = 0;
+	} else
+		r4.rt_dev = NULL;
+
+	r = (void *) &r4;
 
 	if (ret) {
 		ret = -EFAULT;
-- 
2.26.2

[PATCH 3/4] appletalk: factor out a atrtr_ioctl_addrt helper

[Christoph Hellwig]

Add a helper than can be shared with the upcoming compat ioctl handler.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 net/appletalk/ddp.c | 33 ++++++++++++++++++++-------------
 1 file changed, 20 insertions(+), 13 deletions(-)

diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index b41375d4d295d..4177a74f65436 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -867,6 +867,24 @@ static int atif_ioctl(int cmd, void __user *arg)
 	return copy_to_user(arg, &atreq, sizeof(atreq)) ? -EFAULT : 0;
 }
 
+static int atrtr_ioctl_addrt(struct rtentry *rt)
+{
+	struct net_device *dev = NULL;
+
+	if (rt->rt_dev) {
+		char name[IFNAMSIZ];
+
+		if (copy_from_user(name, rt->rt_dev, IFNAMSIZ-1))
+			return -EFAULT;
+		name[IFNAMSIZ-1] = '\0';
+
+		dev = __dev_get_by_name(&init_net, name);
+		if (!dev)
+			return -ENODEV;
+	}
+	return atrtr_create(rt, dev);
+}
+
 /* Routing ioctl() calls */
 static int atrtr_ioctl(unsigned int cmd, void __user *arg)
 {
@@ -882,19 +900,8 @@ static int atrtr_ioctl(unsigned int cmd, void __user *arg)
 		return atrtr_delete(&((struct sockaddr_at *)
 				      &rt.rt_dst)->sat_addr);
 
-	case SIOCADDRT: {
-		struct net_device *dev = NULL;
-		if (rt.rt_dev) {
-			char name[IFNAMSIZ];
-			if (copy_from_user(name, rt.rt_dev, IFNAMSIZ-1))
-				return -EFAULT;
-			name[IFNAMSIZ-1] = '\0';
-			dev = __dev_get_by_name(&init_net, name);
-			if (!dev)
-				return -ENODEV;
-		}
-		return atrtr_create(&rt, dev);
-	}
+	case SIOCADDRT:
+		return atrtr_ioctl_addrt(&rt);
 	}
 	return -EINVAL;
 }
-- 
2.26.2

[PATCH 4/4] ipv4,appletalk: move SIOCADDRT and SIOCDELRT handling into ->compat_ioctl

[Christoph Hellwig]

To prepare removing the global routing_ioctl hack start lifting the code
into the ipv4 and appletalk ->compat_ioctl handlers.  Unlike the existing
handler we don't bother copying in the name - there are no compat issues for
char arrays.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/net/compat.h | 18 +++++++++++++
 net/appletalk/ddp.c  | 49 ++++++++++++++++++++++++++++++----
 net/ipv4/af_inet.c   | 38 ++++++++++++++++++++++-----
 net/socket.c         | 62 --------------------------------------------
 4 files changed, 94 insertions(+), 73 deletions(-)

diff --git a/include/net/compat.h b/include/net/compat.h
index e341260642fee..2b5e1f7ba1533 100644
--- a/include/net/compat.h
+++ b/include/net/compat.h
@@ -30,6 +30,24 @@ struct compat_cmsghdr {
 	compat_int_t	cmsg_type;
 };
 
+struct compat_rtentry {
+	u32		rt_pad1;
+	struct sockaddr rt_dst;         /* target address               */
+	struct sockaddr rt_gateway;     /* gateway addr (RTF_GATEWAY)   */
+	struct sockaddr rt_genmask;     /* target network mask (IP)     */
+	unsigned short	rt_flags;
+	short		rt_pad2;
+	u32		rt_pad3;
+	unsigned char	rt_tos;
+	unsigned char	rt_class;
+	short		rt_pad4;
+	short		rt_metric;      /* +1 for binary compatibility! */
+	compat_uptr_t	rt_dev;         /* forcing the device at add    */
+	u32		rt_mtu;         /* per route MTU/Window         */
+	u32		rt_window;      /* Window clamping              */
+	unsigned short  rt_irtt;        /* Initial RTT                  */
+};
+
 #else /* defined(CONFIG_COMPAT) */
 /*
  * To avoid compiler warnings:
diff --git a/net/appletalk/ddp.c b/net/appletalk/ddp.c
index 4177a74f65436..15787e8c0629a 100644
--- a/net/appletalk/ddp.c
+++ b/net/appletalk/ddp.c
@@ -57,6 +57,7 @@
 #include <net/sock.h>
 #include <net/tcp_states.h>
 #include <net/route.h>
+#include <net/compat.h>
 #include <linux/atalk.h>
 #include <linux/highmem.h>
 
@@ -1839,20 +1840,58 @@ static int atalk_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 
 
 #ifdef CONFIG_COMPAT
+static int atalk_compat_routing_ioctl(struct sock *sk, unsigned int cmd,
+		struct compat_rtentry __user *ur)
+{
+	compat_uptr_t rtdev;
+	struct rtentry rt;
+
+	if (copy_from_user(&rt.rt_dst, &ur->rt_dst,
+			3 * sizeof(struct sockaddr)) ||
+	    get_user(rt.rt_flags, &ur->rt_flags) ||
+	    get_user(rt.rt_metric, &ur->rt_metric) ||
+	    get_user(rt.rt_mtu, &ur->rt_mtu) ||
+	    get_user(rt.rt_window, &ur->rt_window) ||
+	    get_user(rt.rt_irtt, &ur->rt_irtt) ||
+	    get_user(rtdev, &ur->rt_dev))
+		return -EFAULT;
+
+	switch (cmd) {
+	case SIOCDELRT:
+		if (rt.rt_dst.sa_family != AF_APPLETALK)
+			return -EINVAL;
+		return atrtr_delete(&((struct sockaddr_at *)
+				      &rt.rt_dst)->sat_addr);
+
+	case SIOCADDRT:
+		rt.rt_dev = compat_ptr(rtdev);
+		return atrtr_ioctl_addrt(&rt);
+	default:
+		return -EINVAL;
+	}
+}
 static int atalk_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
+	void __user *argp = compat_ptr(arg);
+	struct sock *sk = sock->sk;
+
+	switch (cmd) {
+	case SIOCADDRT:
+	case SIOCDELRT:
+		return atalk_compat_routing_ioctl(sk, cmd, argp);
 	/*
 	 * SIOCATALKDIFADDR is a SIOCPROTOPRIVATE ioctl number, so we
 	 * cannot handle it in common code. The data we access if ifreq
 	 * here is compatible, so we can simply call the native
 	 * handler.
 	 */
-	if (cmd == SIOCATALKDIFADDR)
-		return atalk_ioctl(sock, cmd, (unsigned long)compat_ptr(arg));
-
-	return -ENOIOCTLCMD;
+	case SIOCATALKDIFADDR:
+		return atalk_ioctl(sock, cmd, (unsigned long)argp);
+	default:
+		return -ENOIOCTLCMD;
+	}
 }
-#endif
+#endif /* CONFIG_COMPAT */
 
 
 static const struct net_proto_family atalk_family_ops = {
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index fcf0d12a407a9..c35a8b2e0499e 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -116,6 +116,7 @@
 #include <linux/mroute.h>
 #endif
 #include <net/l3mdev.h>
+#include <net/compat.h>
 
 #include <trace/events/sock.h>
 
@@ -970,17 +971,42 @@ int inet_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 EXPORT_SYMBOL(inet_ioctl);
 
 #ifdef CONFIG_COMPAT
+static int inet_compat_routing_ioctl(struct sock *sk, unsigned int cmd,
+		struct compat_rtentry __user *ur)
+{
+	compat_uptr_t rtdev;
+	struct rtentry rt;
+
+	if (copy_from_user(&rt.rt_dst, &ur->rt_dst,
+			3 * sizeof(struct sockaddr)) ||
+	    get_user(rt.rt_flags, &ur->rt_flags) ||
+	    get_user(rt.rt_metric, &ur->rt_metric) ||
+	    get_user(rt.rt_mtu, &ur->rt_mtu) ||
+	    get_user(rt.rt_window, &ur->rt_window) ||
+	    get_user(rt.rt_irtt, &ur->rt_irtt) ||
+	    get_user(rtdev, &ur->rt_dev))
+		return -EFAULT;
+
+	rt.rt_dev = compat_ptr(rtdev);
+	return ip_rt_ioctl(sock_net(sk), cmd, &rt);
+}
+
 static int inet_compat_ioctl(struct socket *sock, unsigned int cmd, unsigned long arg)
 {
+	void __user *argp = compat_ptr(arg);
 	struct sock *sk = sock->sk;
-	int err = -ENOIOCTLCMD;
-
-	if (sk->sk_prot->compat_ioctl)
-		err = sk->sk_prot->compat_ioctl(sk, cmd, arg);
 
-	return err;
+	switch (cmd) {
+	case SIOCADDRT:
+	case SIOCDELRT:
+		return inet_compat_routing_ioctl(sk, cmd, argp);
+	default:
+		if (!sk->sk_prot->compat_ioctl)
+			return -ENOIOCTLCMD;
+		return sk->sk_prot->compat_ioctl(sk, cmd, arg);
+	}
 }
-#endif
+#endif /* CONFIG_COMPAT */
 
 const struct proto_ops inet_stream_ops = {
 	.family		   = PF_INET,
diff --git a/net/socket.c b/net/socket.c
index 6824470757753..80422fc3c836e 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -3366,65 +3366,6 @@ static int compat_sioc_ifmap(struct net *net, unsigned int cmd,
 	return err;
 }
 
-struct rtentry32 {
-	u32		rt_pad1;
-	struct sockaddr rt_dst;         /* target address               */
-	struct sockaddr rt_gateway;     /* gateway addr (RTF_GATEWAY)   */
-	struct sockaddr rt_genmask;     /* target network mask (IP)     */
-	unsigned short	rt_flags;
-	short		rt_pad2;
-	u32		rt_pad3;
-	unsigned char	rt_tos;
-	unsigned char	rt_class;
-	short		rt_pad4;
-	short		rt_metric;      /* +1 for binary compatibility! */
-	/* char * */ u32 rt_dev;        /* forcing the device at add    */
-	u32		rt_mtu;         /* per route MTU/Window         */
-	u32		rt_window;      /* Window clamping              */
-	unsigned short  rt_irtt;        /* Initial RTT                  */
-};
-
-static int routing_ioctl(struct net *net, struct socket *sock,
-			 unsigned int cmd, void __user *argp)
-{
-	struct rtentry32 __user *ur4 = argp;
-	int ret;
-	void *r = NULL;
-	struct rtentry r4;
-	char devname[16];
-	u32 rtdev;
-	mm_segment_t old_fs = get_fs();
-
-	ret = copy_from_user(&r4.rt_dst, &(ur4->rt_dst),
-				3 * sizeof(struct sockaddr));
-	ret |= get_user(r4.rt_flags, &(ur4->rt_flags));
-	ret |= get_user(r4.rt_metric, &(ur4->rt_metric));
-	ret |= get_user(r4.rt_mtu, &(ur4->rt_mtu));
-	ret |= get_user(r4.rt_window, &(ur4->rt_window));
-	ret |= get_user(r4.rt_irtt, &(ur4->rt_irtt));
-	ret |= get_user(rtdev, &(ur4->rt_dev));
-	if (rtdev) {
-		ret |= copy_from_user(devname, compat_ptr(rtdev), 15);
-		r4.rt_dev = (char __user __force *)devname;
-		devname[15] = 0;
-	} else
-		r4.rt_dev = NULL;
-
-	r = (void *) &r4;
-
-	if (ret) {
-		ret = -EFAULT;
-		goto out;
-	}
-
-	set_fs(KERNEL_DS);
-	ret = sock_do_ioctl(net, sock, cmd, (unsigned long) r);
-	set_fs(old_fs);
-
-out:
-	return ret;
-}
-
 /* Since old style bridge ioctl's endup using SIOCDEVPRIVATE
  * for some operations; this forces use of the newer bridge-utils that
  * use compatible ioctls
@@ -3463,9 +3404,6 @@ static int compat_sock_ioctl_trans(struct file *file, struct socket *sock,
 	case SIOCGIFMAP:
 	case SIOCSIFMAP:
 		return compat_sioc_ifmap(net, cmd, argp);
-	case SIOCADDRT:
-	case SIOCDELRT:
-		return routing_ioctl(net, sock, cmd, argp);
 	case SIOCGSTAMP_OLD:
 	case SIOCGSTAMPNS_OLD:
 		if (!sock->ops->gettstamp)
-- 
2.26.2

Re: move the SIOCDELRT and SIOCADDRT compat_ioctl handlers v3

[David Miller]

From: Christoph Hellwig <hch@lst.de>
Date: Mon, 18 May 2020 08:28:04 +0200

> this series moves the compat_ioctl handlers into the protocol handlers,
> avoiding the need to override the address space limited as in the current
> handler.
> 
> Changes since v3:
>  - moar variable reordering
> 
> Changes since v1:
>  - reorder a bunch of variable declarations

Series applied to net-next, thank you.