[CRIU] [PATCH 3/5] unix: add ability to set callbacks for external sockets (v2)
Andrey Vagin
avagin at openvz.org
Thu Dec 5 09:58:57 PST 2013
We don't know a state behind an external socket. It depends on logic
of the program, which handles this socket.
This patch adds ability to load a library with callbacks for dumping
and restoring external sockets.
This patch introduces two callbacks cr_plugin_dump_unix_sk and
cr_plugin_restore_unix_sk. If a callback can not handle a socket, it
must return CRIU_CB_SKIP.
The main questions, what kind of information should be tranfered in
these callbacks. Pls, think a few minutes about that and send me
your opinion.
v2: Use uflags instread of adding a new field
Signed-off-by: Andrey Vagin <avagin at openvz.org>
---
include/criu-plugin.h | 12 ++++++++++
include/image.h | 1 +
include/plugin.h | 9 ++++++++
lib.c | 56 +++++++++++++++++++++++++++++++++++++++++++++
sk-unix.c | 63 +++++++++++++++++++++++++++++++++++++++++++--------
5 files changed, 131 insertions(+), 10 deletions(-)
diff --git a/include/criu-plugin.h b/include/criu-plugin.h
index 44abb2a..963d1d0 100644
--- a/include/criu-plugin.h
+++ b/include/criu-plugin.h
@@ -20,7 +20,19 @@
#ifndef __CRIU_PLUGIN_H__
#define __CRIU_PLUGIN_H__
+#include <limits.h>
+
typedef int (cr_plugin_init_t)(void);
typedef void (cr_plugin_fini_t)(void);
+#define CRIU_CB_SKIP INT_MIN
+/*
+ * The callbacks for unix sockets resturn:
+ * - CR_CB_SKIP if this callback is not suitable for this socket
+ * - negative values, if something failed
+ * - zero, if the socket was dumped or restored
+ */
+typedef int (cr_plugin_dump_unix_sk_t)(int fd, int ino, int peer_ino);
+typedef int (cr_plugin_restore_unix_sk_t)(int ino, char *name, int len);
+
#endif
diff --git a/include/image.h b/include/image.h
index 099f510..32ee0af 100644
--- a/include/image.h
+++ b/include/image.h
@@ -33,6 +33,7 @@
#define USK_EXTERN (1 << 0)
#define USK_SERVICE (1 << 1)
+#define USK_CALLBACK (1 << 2)
#define VMA_AREA_NONE (0 << 0)
#define VMA_AREA_REGULAR (1 << 0) /* Dumpable area */
diff --git a/include/plugin.h b/include/plugin.h
index 8653a5b..8538a1b 100644
--- a/include/plugin.h
+++ b/include/plugin.h
@@ -2,10 +2,13 @@
#define __CR_PLUGIN_H__
#include "criu-plugin.h"
+#include <limits.h>
struct cr_plugin_entry {
union {
cr_plugin_fini_t *cr_fini;
+ cr_plugin_dump_unix_sk_t *cr_plugin_dump_unix_sk;
+ cr_plugin_restore_unix_sk_t *cr_plugin_restore_unix_sk;
};
struct cr_plugin_entry *next;
@@ -13,10 +16,16 @@ struct cr_plugin_entry {
struct cr_plugins {
struct cr_plugin_entry *cr_fini;
+ struct cr_plugin_entry *cr_plugin_dump_unix_sk;
+ struct cr_plugin_entry *cr_plugin_restore_unix_sk;
};
extern struct cr_plugins cr_plugins;
void cr_lib_fini(void);
int cr_lib_init(void);
+
+int cr_plugin_dump_unix_sk(int fd, int ino, int peer_ino);
+int cr_plugin_restore_unix_sk(int ino, char *name, int len);
+
#endif
diff --git a/lib.c b/lib.c
index 387bb84..28ab101 100644
--- a/lib.c
+++ b/lib.c
@@ -12,6 +12,48 @@
struct cr_plugins cr_plugins;
+#define add_plugin_func(name) \
+ do { \
+ name ## _t *name; \
+ name = dlsym(h, #name); \
+ if (name) { \
+ struct cr_plugin_entry *__ce; \
+ __ce = xmalloc(sizeof(struct cr_plugin_entry)); \
+ if (__ce == NULL) \
+ return -1; \
+ __ce->name = name; \
+ __ce->next = cr_plugins.name; \
+ cr_plugins.name = __ce; \
+ } \
+ } while (0); \
+
+
+#define run_plugin_funcs(name, ...) ({ \
+ struct cr_plugin_entry *__ce = cr_plugins.name; \
+ int __ret = CRIU_CB_SKIP; \
+ \
+ while (__ce) { \
+ __ret = __ce->name(__VA_ARGS__); \
+ if (__ret == CRIU_CB_SKIP) { \
+ __ce = __ce->next; \
+ continue; \
+ } \
+ break; \
+ } \
+ \
+ __ret; \
+ }) \
+
+int cr_plugin_dump_unix_sk(int fd, int ino, int peer_ino)
+{
+ return run_plugin_funcs(cr_plugin_dump_unix_sk, fd, ino, peer_ino);
+}
+
+int cr_plugin_restore_unix_sk(int ino, char *name, int len)
+{
+ return run_plugin_funcs(cr_plugin_restore_unix_sk, ino, name, len);
+}
+
static int cr_lib_load(char *path)
{
struct cr_plugin_entry *ce;
@@ -25,6 +67,9 @@ static int cr_lib_load(char *path)
return -1;
}
+ add_plugin_func(cr_plugin_dump_unix_sk);
+ add_plugin_func(cr_plugin_restore_unix_sk);
+
ce = NULL;
f_fini = dlsym(h, "cr_plugin_fini");
if (f_fini) {
@@ -48,10 +93,21 @@ static int cr_lib_load(char *path)
return 0;
}
+#define cr_plugin_free(name) do { \
+ while (cr_plugins.name) { \
+ ce = cr_plugins.name; \
+ cr_plugins.name = cr_plugins.name->next; \
+ xfree(ce); \
+ } \
+} while (0) \
+
void cr_lib_fini(void)
{
struct cr_plugin_entry *ce;
+ cr_plugin_free(cr_plugin_dump_unix_sk);
+ cr_plugin_free(cr_plugin_restore_unix_sk);
+
while (cr_plugins.cr_fini) {
ce = cr_plugins.cr_fini;
cr_plugins.cr_fini = cr_plugins.cr_fini->next;
diff --git a/sk-unix.c b/sk-unix.c
index 8980efd..9dd8280 100644
--- a/sk-unix.c
+++ b/sk-unix.c
@@ -7,6 +7,7 @@
#include <fcntl.h>
#include <sys/un.h>
#include <stdlib.h>
+#include <dlfcn.h>
#include "asm/types.h"
#include "libnetlink.h"
@@ -23,6 +24,7 @@
#include "sk-queue.h"
#include "mount.h"
#include "cr-service.h"
+#include "plugin.h"
#include "protobuf.h"
#include "protobuf/sk-unix.pb-c.h"
@@ -469,6 +471,30 @@ int unix_receive_one(struct nlmsghdr *h, void *arg)
return unix_collect_one(m, tb);
}
+static int try_to_dump_with_callback(struct unix_sk_desc *peer, bool *need_callback)
+{
+ struct unix_sk_desc *sk;
+ int ret = -1;
+
+ *need_callback = false;
+ list_for_each_entry(sk, &peer->peer_list, peer_node) {
+ ret = cr_plugin_dump_unix_sk(sk->fd, sk->sd.ino, sk->peer_ino);
+ if (ret == CRIU_CB_SKIP) {
+ if (!*need_callback)
+ return 0;
+
+ pr_err("The callback is not suitable for all peer sockets\n");
+ return -1;
+ }
+ if (ret < 0)
+ return -1;
+
+ *need_callback = true;
+ }
+
+ return ret;
+}
+
int fix_external_unix_sockets(void)
{
struct unix_sk_desc *sk;
@@ -479,22 +505,28 @@ int fix_external_unix_sockets(void)
UnixSkEntry e = UNIX_SK_ENTRY__INIT;
FownEntry fown = FOWN_ENTRY__INIT;
SkOptsEntry skopts = SK_OPTS_ENTRY__INIT;
+ bool need_callback;
show_one_unix("Dumping extern", sk);
BUG_ON(sk->sd.already_dumped);
- if (!opts.ext_unix_sk) {
- show_one_unix("Runaway socket", sk);
- pr_err("External socket is used. "
- "Consider using --" USK_EXT_PARAM " option.\n");
+ if (try_to_dump_with_callback(sk, &need_callback))
goto err;
- }
- if (sk->type != SOCK_DGRAM) {
- show_one_unix("Ext stream not supported", sk);
- pr_err("Can't dump half of stream unix connection.\n");
- goto err;
+ if (!need_callback) {
+ if (!opts.ext_unix_sk) {
+ show_one_unix("Runaway socket", sk);
+ pr_err("External socket is used. "
+ "Consider using --" USK_EXT_PARAM " option.\n");
+ goto err;
+ }
+
+ if (sk->type != SOCK_DGRAM) {
+ show_one_unix("Ext stream not supported", sk);
+ pr_err("Can't dump half of stream unix connection.\n");
+ goto err;
+ }
}
e.id = fd_id_generate_special();
@@ -507,6 +539,8 @@ int fix_external_unix_sockets(void)
e.peer = 0;
e.fown = &fown;
e.opts = &skopts;
+ if (need_callback)
+ e.uflags |= USK_CALLBACK;
if (pb_write_one(fdset_fd(glob_fdset, CR_FD_UNIXSK), &e, PB_UNIX_SK))
goto err;
@@ -576,6 +610,8 @@ static int post_open_unix_sk(struct file_desc *d, int fd)
if (peer == NULL)
return 0;
+ if (peer->ue->uflags & USK_CALLBACK)
+ return 0;
pr_info("\tConnect %#x to %#x\n", ui->ue->ino, peer->ue->ino);
@@ -781,6 +817,12 @@ static int open_unixsk_standalone(struct unix_sk_info *ui)
close(sks[1]);
sk = sks[0];
+ } else if (ui->peer && ui->peer->ue->uflags & USK_CALLBACK) {
+ sk = cr_plugin_restore_unix_sk(ui->ue->ino, ui->name, ui->ue->name.len);
+ if (sk < 0)
+ return -1;
+
+ goto out;
} else if ((ui->ue->state == TCP_ESTABLISHED) && !ui->ue->peer) {
int ret, sks[2];
@@ -831,7 +873,7 @@ static int open_unixsk_standalone(struct unix_sk_info *ui)
return -1;
}
}
-
+out:
if (rst_file_params(sk, ui->ue->fown, ui->ue->flags))
return -1;
@@ -932,6 +974,7 @@ int resolve_unix_peers(void)
* special option to be passed.
*/
if ((peer->ue->uflags & USK_EXTERN) &&
+ !(peer->ue->uflags & USK_CALLBACK) &&
!(opts.ext_unix_sk)) {
pr_err("External socket found in image. "
"Consider using the --" USK_EXT_PARAM " option "
--
1.8.3.1
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