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Subject[C/R v20][PATCH 77/96] c/r: add support for listening INET sockets (v2)
Date
From: Dan Smith <danms@us.ibm.com>

This is an incremental step towards supporting checkpoint/restart on
AF_INET sockets. In this scenario, any sockets that were in TCP_LISTEN
state are restored as they were. Any that were connected are forced to
TCP_CLOSE. This should cover a range of use cases that involve
applications that are tolerant of such an interruption.

Changelog [v19-rc1]:
- [Matt Helsley] Add cpp definitions for enums

Changes in v2:
- Fix whitespace
- Fix return in inet_checkpoint() on failed ckpt_hdr_get_type()
- Fix garbage free on error path of inet_read_buffer()
- Fix unnecessary ret=0 in inet_read_buffers()
- Add inet_precheck() (like unix) to validate the address lengths (and
more later)

Cc: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Dan Smith <danms@us.ibm.com>
Acked-by: Oren Laadan <orenl@librato.com>
Acked-by: Serge E. Hallyn <serue@us.ibm.com>
Tested-by: Serge E. Hallyn <serue@us.ibm.com>
---
Documentation/checkpoint/readme.txt | 21 ++++
include/linux/checkpoint_hdr.h | 12 ++
include/net/inet_common.h | 13 +++
net/checkpoint.c | 9 ++
net/ipv4/Makefile | 1 +
net/ipv4/af_inet.c | 6 +
net/ipv4/checkpoint.c | 190 +++++++++++++++++++++++++++++++++++
7 files changed, 252 insertions(+), 0 deletions(-)
create mode 100644 net/ipv4/checkpoint.c

diff --git a/Documentation/checkpoint/readme.txt b/Documentation/checkpoint/readme.txt
index 4fa5560..2548bb4 100644
--- a/Documentation/checkpoint/readme.txt
+++ b/Documentation/checkpoint/readme.txt
@@ -344,6 +344,27 @@ we will be forced to more carefully review each of those features.
However, this can be controlled with a sysctl-variable.


+Sockets
+=======
+
+For AF_UNIX sockets, both endpoints must be within the checkpointed
+task set to maintain a connected state after restart. UNIX sockets
+that are in the process of passing a descriptor will cause the
+checkpoint to fail with -EBUSY indicating a transient state that
+cannot be checkpointed. Listening sockets with an unaccepted peer
+will also cause an -EBUSY result.
+
+AF_INET sockets with endpoints outside the checkpointed task set may
+remain open if care is taken to avoid TCP timeouts and resets.
+Careful use of a virtual IP address can help avoid emission of an RST
+to the non-checkpointed endpoint. If desired, the
+RESTART_SOCK_LISTENONLY flag may be passed to the restart syscall
+which will cause all connected AF_INET sockets to be closed during the
+restore process. Listening sockets will still be restored to their
+original state, which makes this mode a candidate for something like
+an HTTP server.
+
+
Kernel interfaces
=================

diff --git a/include/linux/checkpoint_hdr.h b/include/linux/checkpoint_hdr.h
index ad2f0f2..cf36fe1 100644
--- a/include/linux/checkpoint_hdr.h
+++ b/include/linux/checkpoint_hdr.h
@@ -14,11 +14,13 @@
#include <linux/types.h>
#include <linux/socket.h>
#include <linux/un.h>
+#include <linux/in.h>
#else
#include <sys/types.h>
#include <linux/types.h>
#include <sys/socket.h>
#include <sys/un.h>
+#include <netinet/in.h>
#endif

/*
@@ -152,6 +154,8 @@ enum {
#define CKPT_HDR_SOCKET_FRAG CKPT_HDR_SOCKET_FRAG
CKPT_HDR_SOCKET_UNIX,
#define CKPT_HDR_SOCKET_UNIX CKPT_HDR_SOCKET_UNIX
+ CKPT_HDR_SOCKET_INET,
+#define CKPT_HDR_SOCKET_INET CKPT_HDR_SOCKET_INET

CKPT_HDR_TAIL = 9001,
#define CKPT_HDR_TAIL CKPT_HDR_TAIL
@@ -570,6 +574,14 @@ struct ckpt_hdr_socket_unix {
struct sockaddr_un raddr;
} __attribute__ ((aligned(8)));

+struct ckpt_hdr_socket_inet {
+ struct ckpt_hdr h;
+ __u32 laddr_len;
+ __u32 raddr_len;
+ struct sockaddr_in laddr;
+ struct sockaddr_in raddr;
+} __attribute__((aligned(8)));
+
struct ckpt_hdr_file_socket {
struct ckpt_hdr_file common;
__s32 sock_objref;
diff --git a/include/net/inet_common.h b/include/net/inet_common.h
index 18c7732..bf04e6e 100644
--- a/include/net/inet_common.h
+++ b/include/net/inet_common.h
@@ -45,6 +45,19 @@ extern int inet_ctl_sock_create(struct sock **sk,
unsigned char protocol,
struct net *net);

+#ifdef CONFIG_CHECKPOINT
+struct ckpt_ctx;
+struct ckpt_hdr_socket;
+extern int inet_checkpoint(struct ckpt_ctx *ctx, struct socket *sock);
+extern int inet_collect(struct ckpt_ctx *ctx, struct socket *sock);
+extern int inet_restore(struct ckpt_ctx *cftx, struct socket *sock,
+ struct ckpt_hdr_socket *h);
+#else
+#define inet_checkpoint NULL
+#define inet_collect NULL
+#define inet_restore NULL
+#endif /* CONFIG_CHECKPOINT */
+
static inline void inet_ctl_sock_destroy(struct sock *sk)
{
sk_release_kernel(sk);
diff --git a/net/checkpoint.c b/net/checkpoint.c
index 386a0c6..6fe7aa2 100644
--- a/net/checkpoint.c
+++ b/net/checkpoint.c
@@ -935,6 +935,15 @@ struct sock *do_sock_restore(struct ckpt_ctx *ctx)
if (ret < 0)
goto err;

+ if ((h->sock_common.family == AF_INET) &&
+ (h->sock.state != TCP_LISTEN)) {
+ /* Temporary hack to enable restore of TCP_LISTEN sockets
+ * while forcing anything else to a closed state
+ */
+ sock->sk->sk_state = TCP_CLOSE;
+ sock->state = SS_UNCONNECTED;
+ }
+
ckpt_hdr_put(ctx, h);
return sock->sk;
err:
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 80ff87c..c00d8ce 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -49,6 +49,7 @@ obj-$(CONFIG_TCP_CONG_LP) += tcp_lp.o
obj-$(CONFIG_TCP_CONG_YEAH) += tcp_yeah.o
obj-$(CONFIG_TCP_CONG_ILLINOIS) += tcp_illinois.o
obj-$(CONFIG_NETLABEL) += cipso_ipv4.o
+obj-$(CONFIG_CHECKPOINT) += checkpoint.o

obj-$(CONFIG_XFRM) += xfrm4_policy.o xfrm4_state.o xfrm4_input.o \
xfrm4_output.o
diff --git a/net/ipv4/af_inet.c b/net/ipv4/af_inet.c
index 7d12c6a..a56f21a 100644
--- a/net/ipv4/af_inet.c
+++ b/net/ipv4/af_inet.c
@@ -870,6 +870,9 @@ const struct proto_ops inet_stream_ops = {
.mmap = sock_no_mmap,
.sendpage = tcp_sendpage,
.splice_read = tcp_splice_read,
+ .checkpoint = inet_checkpoint,
+ .restore = inet_restore,
+ .collect = inet_collect,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_sock_common_setsockopt,
.compat_getsockopt = compat_sock_common_getsockopt,
@@ -896,6 +899,9 @@ const struct proto_ops inet_dgram_ops = {
.recvmsg = sock_common_recvmsg,
.mmap = sock_no_mmap,
.sendpage = inet_sendpage,
+ .checkpoint = inet_checkpoint,
+ .restore = inet_restore,
+ .collect = inet_collect,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_sock_common_setsockopt,
.compat_getsockopt = compat_sock_common_getsockopt,
diff --git a/net/ipv4/checkpoint.c b/net/ipv4/checkpoint.c
new file mode 100644
index 0000000..1982119
--- /dev/null
+++ b/net/ipv4/checkpoint.c
@@ -0,0 +1,190 @@
+/*
+ * Copyright 2009 IBM Corporation
+ *
+ * Author(s): Dan Smith <danms@us.ibm.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ */
+
+#include <linux/namei.h>
+#include <linux/checkpoint.h>
+#include <linux/checkpoint_hdr.h>
+#include <linux/tcp.h>
+#include <linux/in.h>
+#include <linux/deferqueue.h>
+#include <net/tcp_states.h>
+#include <net/tcp.h>
+
+struct dq_sock {
+ struct ckpt_ctx *ctx;
+ struct sock *sk;
+};
+
+struct dq_buffers {
+ struct ckpt_ctx *ctx;
+ struct sock *sk;
+};
+
+int inet_checkpoint(struct ckpt_ctx *ctx, struct socket *sock)
+{
+ struct ckpt_hdr_socket_inet *in;
+ int ret;
+
+ in = ckpt_hdr_get_type(ctx, sizeof(*in), CKPT_HDR_SOCKET_INET);
+ if (!in)
+ return -EINVAL;
+
+ ret = ckpt_sock_getnames(ctx, sock,
+ (struct sockaddr *)&in->laddr, &in->laddr_len,
+ (struct sockaddr *)&in->raddr, &in->raddr_len);
+ if (ret)
+ goto out;
+
+ ret = ckpt_write_obj(ctx, (struct ckpt_hdr *) in);
+ out:
+ ckpt_hdr_put(ctx, in);
+
+ return ret;
+}
+
+int inet_collect(struct ckpt_ctx *ctx, struct socket *sock)
+{
+ return ckpt_obj_collect(ctx, sock->sk, CKPT_OBJ_SOCK);
+}
+
+static int inet_read_buffer(struct ckpt_ctx *ctx, struct sk_buff_head *queue)
+{
+ struct sk_buff *skb = NULL;
+
+ skb = sock_restore_skb(ctx);
+ if (IS_ERR(skb))
+ return PTR_ERR(skb);
+
+ skb_queue_tail(queue, skb);
+ return skb->len;
+}
+
+static int inet_read_buffers(struct ckpt_ctx *ctx, struct sk_buff_head *queue)
+{
+ struct ckpt_hdr_socket_queue *h;
+ int ret = 0;
+ int i;
+
+ h = ckpt_read_obj_type(ctx, sizeof(*h), CKPT_HDR_SOCKET_QUEUE);
+ if (IS_ERR(h))
+ return PTR_ERR(h);
+
+ for (i = 0; i < h->skb_count; i++) {
+ ret = inet_read_buffer(ctx, queue);
+ ckpt_debug("read inet buffer %i: %i", i, ret);
+ if (ret < 0)
+ goto out;
+
+ if (ret > h->total_bytes) {
+ ret = -EINVAL;
+ ckpt_err(ctx, ret, "Buffers exceeded claim");
+ goto out;
+ }
+
+ h->total_bytes -= ret;
+ }
+
+ ret = h->skb_count;
+ out:
+ ckpt_hdr_put(ctx, h);
+
+ return ret;
+}
+
+static int inet_deferred_restore_buffers(void *data)
+{
+ struct dq_buffers *dq = (struct dq_buffers *)data;
+ struct ckpt_ctx *ctx = dq->ctx;
+ struct sock *sk = dq->sk;
+ int ret;
+
+ ret = inet_read_buffers(ctx, &sk->sk_receive_queue);
+ ckpt_debug("(R) inet_read_buffers: %i\n", ret);
+ if (ret < 0)
+ return ret;
+
+ ret = inet_read_buffers(ctx, &sk->sk_write_queue);
+ ckpt_debug("(W) inet_read_buffers: %i\n", ret);
+
+ return ret;
+}
+
+static int inet_defer_restore_buffers(struct ckpt_ctx *ctx, struct sock *sk)
+{
+ struct dq_buffers dq;
+
+ dq.ctx = ctx;
+ dq.sk = sk;
+
+ return deferqueue_add(ctx->files_deferq, &dq, sizeof(dq),
+ inet_deferred_restore_buffers, NULL);
+}
+
+static int inet_precheck(struct socket *sock, struct ckpt_hdr_socket_inet *in)
+{
+ if (in->laddr_len > sizeof(struct sockaddr_in)) {
+ ckpt_debug("laddr_len is too big\n");
+ return -EINVAL;
+ }
+
+ if (in->raddr_len > sizeof(struct sockaddr_in)) {
+ ckpt_debug("raddr_len is too big\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+int inet_restore(struct ckpt_ctx *ctx,
+ struct socket *sock,
+ struct ckpt_hdr_socket *h)
+{
+ struct ckpt_hdr_socket_inet *in;
+ int ret = 0;
+
+ in = ckpt_read_obj_type(ctx, sizeof(*in), CKPT_HDR_SOCKET_INET);
+ if (IS_ERR(in))
+ return PTR_ERR(in);
+
+ ret = inet_precheck(sock, in);
+ if (ret < 0)
+ goto out;
+
+ /* Listening sockets and those that are closed but have a local
+ * address need to call bind()
+ */
+ if ((h->sock.state == TCP_LISTEN) ||
+ ((h->sock.state == TCP_CLOSE) && (in->laddr_len > 0))) {
+ sock->sk->sk_reuse = 2;
+ inet_sk(sock->sk)->freebind = 1;
+ ret = sock->ops->bind(sock,
+ (struct sockaddr *)&in->laddr,
+ in->laddr_len);
+ ckpt_debug("inet bind: %i\n", ret);
+ if (ret < 0)
+ goto out;
+
+ if (h->sock.state == TCP_LISTEN) {
+ ret = sock->ops->listen(sock, h->sock.backlog);
+ ckpt_debug("inet listen: %i\n", ret);
+ if (ret < 0)
+ goto out;
+ }
+ } else {
+ if (!sock_flag(sock->sk, SOCK_DEAD))
+ ret = inet_defer_restore_buffers(ctx, sock->sk);
+ }
+ out:
+ ckpt_hdr_put(ctx, in);
+
+ return ret;
+}
+
--
1.6.3.3


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