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Date: Tue, 14 Apr 2020 00:02:54 +0300
From: Leşe Doru Călin <lesedorucalin01@...il.com>
To: David Miller <davem@...emloft.net>, netdev@...r.kernel.org
Cc: Alexey Kuznetsov <kuznet@....inr.ac.ru>,
Hideaki YOSHIFUJI <yoshfuji@...ux-ipv6.org>
Subject: [PATCH v2] net: UDP repair mode for retrieving the send queue of
corked UDP socket
Hello everyone!
In this year's edition of GSoC, there is a project idea for CRIU to add support
for checkpoint/restore of cork-ed UDP sockets. But to add it, the kernel API needs
to be extended.
This is what this patch does. It adds UDP "repair mode" for UDP sockets in a similar
approach to the TCP "repair mode", but only the send queue is necessary to be retrieved.
So the patch extends the recv and setsockopt syscalls. Using UDP_REPAIR option in
setsockopt, caller can set the socket in repair mode. If it is setted, the
recv/recvfrom/recvmsg will receive the write queue and the destination of the data.
As in the TCP mode, to change the repair mode requires the CAP_NET_ADMIN capability
and to receive data the caller is obliged to use the MSG_PEEK flag.
Best regards,
Lese Doru
Signed-off-by: Lese Doru Calin <lesedorucalin01@...il.com>
---
include/linux/udp.h | 3 +-
include/uapi/linux/udp.h | 1
net/ipv4/udp.c | 60 +++++++++++++++++++++++++++++++++++++++++++++++
net/ipv6/udp.c | 45 +++++++++++++++++++++++++++++++++++
4 files changed, 108 insertions(+), 1 deletion(-)
diff --git a/include/linux/udp.h b/include/linux/udp.h
index aa84597bdc33..b22bd70118ce 100644
--- a/include/linux/udp.h
+++ b/include/linux/udp.h
@@ -51,7 +51,8 @@ struct udp_sock {
* different encapsulation layer set
* this
*/
- gro_enabled:1; /* Can accept GRO packets */
+ gro_enabled:1, /* Can accept GRO packets */
+ repair:1;/* Receive the send queue */
/*
* Following member retains the information to create a UDP header
* when the socket is uncorked.
diff --git a/include/uapi/linux/udp.h b/include/uapi/linux/udp.h
index 4828794efcf8..2fe78329d6da 100644
--- a/include/uapi/linux/udp.h
+++ b/include/uapi/linux/udp.h
@@ -29,6 +29,7 @@ struct udphdr {
/* UDP socket options */
#define UDP_CORK 1 /* Never send partially complete segments */
+#define UDP_REPAIR 19 /* Receive the send queue */
#define UDP_ENCAP 100 /* Set the socket to accept encapsulated packets */
#define UDP_NO_CHECK6_TX 101 /* Disable sending checksum for UDP6X */
#define UDP_NO_CHECK6_RX 102 /* Disable accpeting checksum for UDP6 */
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index 32564b350823..306cd70e40cb 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -1720,6 +1720,28 @@ struct sk_buff *__skb_recv_udp(struct sock *sk, unsigned int flags,
}
EXPORT_SYMBOL(__skb_recv_udp);
+static int udp_peek_sndq(struct sock *sk, struct msghdr *msg, int off, int len)
+{
+ int copy, copied = 0, err = 0;
+ struct sk_buff *skb;
+
+ skb_queue_walk(&sk->sk_write_queue, skb) {
+ copy = len - copied;
+ if (copy > skb->len - off)
+ copy = skb->len - off;
+
+ err = skb_copy_datagram_msg(skb, off, msg, copy);
+ if (err)
+ break;
+
+ copied += copy;
+
+ if (len <= copied)
+ break;
+ }
+ return err ?: copied;
+}
+
/*
* This should be easy, if there is something there we
* return it, otherwise we block.
@@ -1729,8 +1751,10 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
int flags, int *addr_len)
{
struct inet_sock *inet = inet_sk(sk);
+ struct udp_sock *up = udp_sk(sk);
DECLARE_SOCKADDR(struct sockaddr_in *, sin, msg->msg_name);
struct sk_buff *skb;
+ struct flowi4 *fl4;
unsigned int ulen, copied;
int off, err, peeking = flags & MSG_PEEK;
int is_udplite = IS_UDPLITE(sk);
@@ -1739,6 +1763,12 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
if (flags & MSG_ERRQUEUE)
return ip_recv_error(sk, msg, len, addr_len);
+ if (unlikely(up->repair)) {
+ if (!peeking)
+ return -EPERM;
+ goto recv_sndq;
+ }
+
try_again:
off = sk_peek_offset(sk, flags);
skb = __skb_recv_udp(sk, flags, noblock, &off, &err);
@@ -1832,6 +1862,18 @@ int udp_recvmsg(struct sock *sk, struct msghdr *msg, size_t len, int noblock,
cond_resched();
msg->msg_flags &= ~MSG_TRUNC;
goto try_again;
+
+recv_sndq:
+ off = sizeof(struct iphdr) + sizeof(struct udphdr);
+ if (sin) {
+ fl4 = &inet->cork.fl.u.ip4;
+ sin->sin_family = AF_INET;
+ sin->sin_port = fl4->fl4_dport;
+ sin->sin_addr.s_addr = fl4->daddr;
+ memset(sin->sin_zero, 0, sizeof(sin->sin_zero));
+ *addr_len = sizeof(*sin);
+ }
+ return udp_peek_sndq(sk, msg, off, len);
}
int udp_pre_connect(struct sock *sk, struct sockaddr *uaddr, int addr_len)
@@ -2525,6 +2567,11 @@ void udp_destroy_sock(struct sock *sk)
}
}
+static inline bool udp_can_repair_sock(const struct sock *sk)
+{
+ return ns_capable(sock_net(sk)->user_ns, CAP_NET_ADMIN);
+}
+
/*
* Socket option code for UDP
*/
@@ -2557,6 +2604,15 @@ int udp_lib_setsockopt(struct sock *sk, int level, int optname,
}
break;
+ case UDP_REPAIR:
+ if (!udp_can_repair_sock(sk))
+ err = -EPERM;
+ else if (val != 0)
+ up->repair = 1;
+ else
+ up->repair = 0;
+ break;
+
case UDP_ENCAP:
switch (val) {
case 0:
@@ -2678,6 +2734,10 @@ int udp_lib_getsockopt(struct sock *sk, int level, int optname,
val = up->corkflag;
break;
+ case UDP_REPAIR:
+ val = up->repair;
+ break;
+
case UDP_ENCAP:
val = up->encap_type;
break;
diff --git a/net/ipv6/udp.c b/net/ipv6/udp.c
index 7d4151747340..ec653f9fce2d 100644
--- a/net/ipv6/udp.c
+++ b/net/ipv6/udp.c
@@ -250,6 +250,28 @@ struct sock *udp6_lib_lookup(struct net *net, const struct in6_addr *saddr, __be
EXPORT_SYMBOL_GPL(udp6_lib_lookup);
#endif
+static int udp6_peek_sndq(struct sock *sk, struct msghdr *msg, int off, int len)
+{
+ int copy, copied = 0, err = 0;
+ struct sk_buff *skb;
+
+ skb_queue_walk(&sk->sk_write_queue, skb) {
+ copy = len - copied;
+ if (copy > skb->len - off)
+ copy = skb->len - off;
+
+ err = skb_copy_datagram_msg(skb, off, msg, copy);
+ if (err)
+ break;
+
+ copied += copy;
+
+ if (len <= copied)
+ break;
+ }
+ return err ?: copied;
+}
+
/* do not use the scratch area len for jumbogram: their length execeeds the
* scratch area space; note that the IP6CB flags is still in the first
* cacheline, so checking for jumbograms is cheap
@@ -269,7 +291,9 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
{
struct ipv6_pinfo *np = inet6_sk(sk);
struct inet_sock *inet = inet_sk(sk);
+ struct udp_sock *up = udp_sk(sk);
struct sk_buff *skb;
+ struct flowi6 *fl6;
unsigned int ulen, copied;
int off, err, peeking = flags & MSG_PEEK;
int is_udplite = IS_UDPLITE(sk);
@@ -283,6 +307,12 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
if (np->rxpmtu && np->rxopt.bits.rxpmtu)
return ipv6_recv_rxpmtu(sk, msg, len, addr_len);
+ if (unlikely(up->repair)) {
+ if (!peeking)
+ return -EPERM;
+ goto recv_sndq;
+ }
+
try_again:
off = sk_peek_offset(sk, flags);
skb = __skb_recv_udp(sk, flags, noblock, &off, &err);
@@ -394,6 +424,21 @@ int udpv6_recvmsg(struct sock *sk, struct msghdr *msg, size_t len,
cond_resched();
msg->msg_flags &= ~MSG_TRUNC;
goto try_again;
+
+recv_sndq:
+ off = sizeof(struct ipv6hdr) + sizeof(struct udphdr);
+ if (msg->msg_name) {
+ DECLARE_SOCKADDR(struct sockaddr_in6 *, sin6, msg->msg_name);
+
+ fl6 = &inet->cork.fl.u.ip6;
+ sin6->sin6_family = AF_INET6;
+ sin6->sin6_port = fl6->fl6_dport;
+ sin6->sin6_flowinfo = 0;
+ sin6->sin6_addr = fl6->daddr;
+ sin6->sin6_scope_id = fl6->flowi6_oif;
+ *addr_len = sizeof(*sin6);
+ }
+ return udp6_peek_sndq(sk, msg, off, len);
}
DEFINE_STATIC_KEY_FALSE(udpv6_encap_needed_key);
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