[CRIU] [PATCH v5 16/21] unix: Add support of ghost sockets
Cyrill Gorcunov
gorcunov at gmail.com
Thu May 10 17:57:56 MSK 2018
Unix sockets may be connected via deleted socket name,
moreover the name may be reused (ie same sun_addr but
different inodes).
To be able to handle them we do a few tricks:
- when collecting sockets we figure out if "deleted"
mark is present on the socket and if such we rename
it to a new unique name (~criu-%u format)
- to not deal with deleted subdirectories and such we put
this socket inside a current working directory then
save the descriptor in fdstore engine
- on restore we connect via procfs/fd/X as suggested by
Andrew Vagin
Signed-off-by: Cyrill Gorcunov <gorcunov at gmail.com>
---
criu/cr-restore.c | 4 +
criu/include/sockets.h | 1 +
criu/sk-unix.c | 238 +++++++++++++++++++++++++++++++++++++------------
3 files changed, 187 insertions(+), 56 deletions(-)
diff --git a/criu/cr-restore.c b/criu/cr-restore.c
index 54216b8ea359..2c947f3ffcef 100644
--- a/criu/cr-restore.c
+++ b/criu/cr-restore.c
@@ -388,6 +388,10 @@ static int root_prepare_shared(void)
if (ret)
goto err;
+ ret = unix_resolve_ghost_addr();
+ if (ret)
+ goto err;
+
show_saved_files();
err:
return ret;
diff --git a/criu/include/sockets.h b/criu/include/sockets.h
index db330428850c..23f5b11c1b58 100644
--- a/criu/include/sockets.h
+++ b/criu/include/sockets.h
@@ -60,6 +60,7 @@ extern int netlink_receive_one(struct nlmsghdr *hdr, struct ns_id *ns, void *arg
extern int unix_sk_id_add(unsigned int ino);
extern int unix_sk_ids_parse(char *optarg);
+extern int unix_resolve_ghost_addr(void);
extern int do_dump_opt(int sk, int level, int name, void *val, int len);
#define dump_opt(s, l, n, f) do_dump_opt(s, l, n, f, sizeof(*f))
diff --git a/criu/sk-unix.c b/criu/sk-unix.c
index f6d3500df4a1..03aca89eee18 100644
--- a/criu/sk-unix.c
+++ b/criu/sk-unix.c
@@ -31,6 +31,7 @@
#include "fdstore.h"
#include "fdinfo.h"
#include "kerndat.h"
+#include "rst-malloc.h"
#include "protobuf.h"
#include "images/sk-unix.pb-c.h"
@@ -90,10 +91,14 @@ struct unix_sk_desc {
};
static LIST_HEAD(unix_sockets);
+static LIST_HEAD(unix_ghost_addr);
static int unix_resolve_name(int lfd, uint32_t id, struct unix_sk_desc *d,
UnixSkEntry *ue, const struct fd_parms *p);
+struct unix_sk_info;
+static void unlink_sk(struct unix_sk_info *ui);
+
struct unix_sk_listen_icon {
unsigned int peer_ino;
struct unix_sk_desc *sk_desc;
@@ -886,12 +891,14 @@ struct unix_sk_info {
char *name;
char *name_dir;
unsigned flags;
+ int fdstore_id;
struct unix_sk_info *peer;
struct pprep_head peer_resolve; /* XXX : union with the above? */
struct file_desc d;
struct list_head connected; /* List of sockets, connected to me */
struct list_head node; /* To link in peer's connected list */
struct list_head scm_fles;
+ struct list_head ghost_node;
/*
* For DGRAM sockets with queues, we should only restore the queue
@@ -916,6 +923,7 @@ struct scm_fle {
#define USK_PAIR_MASTER 0x1
#define USK_PAIR_SLAVE 0x2
+#define USK_GHOST_FDSTORE 0x4
static struct unix_sk_info *find_unix_sk_by_ino(int ino)
{
@@ -1241,6 +1249,7 @@ static int prep_unix_sk_cwd(struct unix_sk_info *ui, int *prev_cwd_fd,
static int post_open_standalone(struct file_desc *d, int fd)
{
+ int fdstore_fd = -1, procfs_self_dir = -1, len;
struct unix_sk_info *ui;
struct unix_sk_info *peer;
struct sockaddr_un addr;
@@ -1269,22 +1278,43 @@ static int post_open_standalone(struct file_desc *d, int fd)
memset(&addr, 0, sizeof(addr));
addr.sun_family = AF_UNIX;
- memcpy(&addr.sun_path, peer->name, peer->ue->name.len);
pr_info("\tConnect %#x to %#x\n", ui->ue->ino, peer->ue->ino);
if (prep_unix_sk_cwd(peer, &cwd_fd, NULL, &ns_fd))
return -1;
- if (connect(fd, (struct sockaddr *)&addr,
- sizeof(addr.sun_family) +
- peer->ue->name.len) < 0) {
+ if (peer->flags & USK_GHOST_FDSTORE) {
+ procfs_self_dir = open_proc(PROC_SELF, "fd");
+ fdstore_fd = fdstore_get(peer->fdstore_id);
+
+ if (fdstore_fd < 0 || procfs_self_dir < 0)
+ goto err_revert_and_exit;
+
+
+ /*
+ * WARNING: After this call we rely on revert_unix_sk_cwd
+ * to restore the former directories so that connect
+ * will operate inside proc/self/fd/X.
+ */
+ if (fchdir(procfs_self_dir)) {
+ pr_perror("Can't change to procfs/self");
+ goto err_revert_and_exit;
+ }
+ len = snprintf(addr.sun_path, UNIX_PATH_MAX, "%d", fdstore_fd);
+ } else {
+ memcpy(&addr.sun_path, peer->name, peer->ue->name.len);
+ len = peer->ue->name.len;
+ }
+
+ if (connect(fd, (struct sockaddr *)&addr, sizeof(addr.sun_family) + len) < 0) {
pr_perror("Can't connect %#x socket", ui->ue->ino);
- revert_unix_sk_cwd(peer, &cwd_fd, &root_fd, &ns_fd);
- return -1;
+ goto err_revert_and_exit;
}
ui->is_connected = true;
+ close_safe(&procfs_self_dir);
+ close_safe(&fdstore_fd);
revert_unix_sk_cwd(peer, &cwd_fd, &root_fd, &ns_fd);
restore_queue:
@@ -1296,51 +1326,37 @@ static int post_open_standalone(struct file_desc *d, int fd)
if (ui->queuer && !ui->queuer->peer_queue_restored)
return 1;
return restore_sk_common(fd, ui);
+
+err_revert_and_exit:
+ close_safe(&procfs_self_dir);
+ close_safe(&fdstore_fd);
+ revert_unix_sk_cwd(peer, &cwd_fd, &root_fd, &ns_fd);
+ return -1;
}
-static int bind_deleted_unix_sk(int sk, struct unix_sk_info *ui,
- struct sockaddr_un *addr)
+static int keep_deleted(struct unix_sk_info *ui, struct sockaddr_un *addr)
{
- char temp[PATH_MAX];
- int ret;
-
- pr_info("found duplicate unix socket bound at %s\n", addr->sun_path);
-
- ret = snprintf(temp, sizeof(temp),
- "%s-%s-%d", addr->sun_path, "criu-temp", getpid());
- /* this shouldn't happen, since sun_addr is only 108 chars long */
- if (ret < 0 || ret >= sizeof(temp)) {
- pr_err("snprintf of %s failed?\n", addr->sun_path);
- return -1;
- }
-
- ret = rename(addr->sun_path, temp);
- if (ret < 0) {
- pr_perror("couldn't move socket for binding");
- return -1;
- }
-
- ret = bind(sk, (struct sockaddr *)addr,
- sizeof(addr->sun_family) + ui->ue->name.len);
- if (ret < 0) {
- pr_perror("Can't bind socket after move");
- return -1;
- }
-
- ret = rename(temp, addr->sun_path);
- if (ret < 0) {
- pr_perror("couldn't move socket back");
- return -1;
+ if (ui->ue->deleted && (ui->flags & USK_GHOST_FDSTORE)) {
+ int fd = open(addr->sun_path, O_PATH);
+ if (fd < 0) {
+ pr_perror("ghost: Can't open %s", addr->sun_path);
+ return -1;
+ }
+ ui->fdstore_id = fdstore_add(fd);
+ pr_debug("ghost: %#x fdstore_id %d %s\n",
+ ui->ue->ino, ui->fdstore_id, ui->ue->name.data);
+ close(fd);
+ return ui->fdstore_id;
}
-
- /* we've handled the deleted-ness of this
- * socket and we don't want to delete it later
- * since it's not /this/ socket.
- */
- ui->ue->deleted = false;
return 0;
}
+static void drop_deleted(struct unix_sk_info *ui)
+{
+ if (ui->ue->deleted)
+ unlink_sk(ui);
+}
+
static int bind_unix_sk(int sk, struct unix_sk_info *ui)
{
struct sockaddr_un addr;
@@ -1368,19 +1384,14 @@ static int bind_unix_sk(int sk, struct unix_sk_info *ui)
if (ui->name[0] && prep_unix_sk_cwd(ui, &cwd_fd, NULL, &ns_fd))
return -1;
+ pr_debug("bind_unix_sk: id %#x ino %#x addr %s\n",
+ ui->ue->id, ui->ue->ino, ui->name);
ret = bind(sk, (struct sockaddr *)&addr,
sizeof(addr.sun_family) + ui->ue->name.len);
- if (ret < 0) {
- if (ui->ue->has_deleted && ui->ue->deleted && errno == EADDRINUSE) {
- if (bind_deleted_unix_sk(sk, ui, &addr))
- goto done;
- } else {
- pr_perror("Can't bind socket");
- goto done;
- }
- }
+ if (ret < 0)
+ goto done;
- if (*ui->name && ui->ue->file_perms) {
+ if (ui->ue->file_perms) {
FilePermsEntry *perms = ui->ue->file_perms;
char fname[PATH_MAX];
@@ -1403,8 +1414,8 @@ static int bind_unix_sk(int sk, struct unix_sk_info *ui)
}
}
- if (ui->ue->deleted && unlink((char *)ui->ue->name.data) < 0) {
- pr_perror("failed to unlink %s", ui->ue->name.data);
+ if (keep_deleted(ui, &addr) < 0) {
+ pr_err("Can't save socket in fdstore\n");
goto done;
}
@@ -1416,6 +1427,7 @@ static int bind_unix_sk(int sk, struct unix_sk_info *ui)
exit_code = 0;
done:
revert_unix_sk_cwd(ui, &cwd_fd, &root_fd, &ns_fd);
+ drop_deleted(ui);
return exit_code;
}
@@ -1556,6 +1568,7 @@ static int open_unixsk_standalone(struct unix_sk_info *ui, int *new_fd)
fle = file_master(&ui->d);
pr_info_opening("standalone", ui, fle);
+
if (fle->stage == FLE_OPEN)
return post_open_standalone(&ui->d, fle->fe->fd);
@@ -1812,6 +1825,7 @@ static int init_unix_sk_info(struct unix_sk_info *ui, UnixSkEntry *ue)
ui->name_dir = (void *)ue->name_dir;
ui->flags = 0;
+ ui->fdstore_id = -1;
ui->peer = NULL;
ui->queuer = NULL;
ui->bound = 0;
@@ -1826,6 +1840,109 @@ static int init_unix_sk_info(struct unix_sk_info *ui, UnixSkEntry *ue)
INIT_LIST_HEAD(&ui->connected);
INIT_LIST_HEAD(&ui->node);
INIT_LIST_HEAD(&ui->scm_fles);
+ INIT_LIST_HEAD(&ui->ghost_node);
+
+ return 0;
+}
+
+#define GHOST_NAME_FMT "~criu-%u"
+#define GHOST_NAME_FMT_PREFIX 6 /* num of chars before counter */
+
+static int ghost_new_name(char *name, size_t namelen,
+ char **name_new, size_t *namelen_new)
+{
+ char sname[64], *pos, *oldname = name;
+ static unsigned int unix_name_cnt = 0;
+ size_t k;
+
+ pr_debug("\tghost: handling name %s namelen %zu\n", name, namelen);
+
+ for (pos = &name[namelen - 1]; pos > name; pos--) {
+ if (*pos == GHOST_NAME_FMT[0])
+ break;
+ }
+
+ if (strncmp(pos, GHOST_NAME_FMT, GHOST_NAME_FMT_PREFIX) == 0) {
+ unsigned int __cnt;
+
+ if (sscanf(pos, GHOST_NAME_FMT, &__cnt) == 1) {
+ pr_debug("\tghost: unix_name_cnt %d detected\n", __cnt);
+ if (__cnt != unix_name_cnt)
+ unix_name_cnt += __cnt;
+ }
+ }
+
+ memzero(sname, sizeof(sname));
+ k = snprintf(sname, sizeof(sname), GHOST_NAME_FMT, unix_name_cnt++) + 1;
+ if (k > sizeof(sname) || k > UNIX_PATH_MAX) {
+ pr_err("\tghost: New name for socket is too long\n");
+ return -1;
+ }
+ *namelen_new = k;
+
+ *name_new = shmalloc(*namelen_new);
+ if (!*name_new) {
+ pr_err("\tghost: Can't allocate new name for socket\n");
+ return -ENOMEM;
+ }
+
+ memcpy(*name_new, sname, k);
+
+ pr_debug("\tghost: name transition %s -> %s\n", oldname, *name_new);
+ return 0;
+}
+
+int unix_resolve_ghost_addr(void)
+{
+ struct unix_sk_info *ui, *t;
+
+ pr_debug("ghost: Resolving addresses\n");
+
+ /*
+ * Walk over ghost unix entries and find one
+ * which gonna be a master and won't unlink
+ * the name until all peers are connected to
+ * this designation.
+ */
+
+ list_for_each_entry(ui, &unix_ghost_addr, ghost_node) {
+ size_t newnamelen;
+ char *newname;
+
+ pr_debug("ghost: ino %#x peer %#x address %s\n",
+ ui->ue->ino, ui->peer ? ui->peer->ue->ino : 0,
+ ui->name);
+
+ unlink_sk(ui);
+
+ if (ghost_new_name(ui->name, ui->ue->name.len,
+ &newname, &newnamelen))
+ return -1;
+
+ ui->name = newname;
+ ui->ue->name.len = newnamelen;
+ ui->ue->name.data = (void *)newname;
+
+ unlink_sk(ui);
+
+ /*
+ * Figure out who is connected to this peer,
+ * so the name will be removed from FS only
+ * when last one is connected.
+ */
+ list_for_each_entry(t, &unix_sockets, list) {
+ if (t->flags & USK_GHOST_FDSTORE)
+ continue;
+ if (ui == t || t->peer != ui)
+ continue;
+
+ pr_debug("\t\tghost: connected to us %#x -> %#x\n",
+ t->ue->ino, ui->ue->ino);
+
+ if (!(ui->flags & USK_GHOST_FDSTORE))
+ ui->flags |= USK_GHOST_FDSTORE;
+ }
+ }
return 0;
}
@@ -1873,6 +1990,15 @@ static int collect_one_unixsk(void *o, ProtobufCMessage *base, struct cr_img *i)
add_post_prepare_cb(&ui->peer_resolve);
}
+ if (ui->ue->deleted) {
+ if (!ui->name || !ui->ue->name.len || !ui->name[0]) {
+ pr_err("No name present, ino %#x\n", ui->ue->ino);
+ return -1;
+ }
+
+ list_add_tail(&ui->ghost_node, &unix_ghost_addr);
+ }
+
list_add_tail(&ui->list, &unix_sockets);
return file_desc_add(&ui->d, ui->ue->id, &unix_desc_ops);
}
--
2.14.3
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