[CRIU] [PATCH 17/18] sk-unix: Add ability to restore sockets with deleted vfs addresses
Cyrill Gorcunov
gorcunov at openvz.org
Sun Apr 9 15:28:49 PDT 2017
If dgram sockets are bound with vfs name and the name removed
from the file system we can't bind/connect to such name. To
resolve it we do the following
- all ghost names previously gathered into chains are
changed to have more-less unique names adding postfixes
- opon socket opening it's binding/connection is delayed
until previous copy is removed
Signed-off-by: Cyrill Gorcunov <gorcunov at openvz.org>
---
criu/sk-unix.c | 247 ++++++++++++++++++++++++++++++++++++++++++++++++++++-----
1 file changed, 227 insertions(+), 20 deletions(-)
diff --git a/criu/sk-unix.c b/criu/sk-unix.c
index cdad971e3dea..d2808631e144 100644
--- a/criu/sk-unix.c
+++ b/criu/sk-unix.c
@@ -9,6 +9,7 @@
#include <sys/un.h>
#include <stdlib.h>
#include <dlfcn.h>
+#include <libgen.h>
#include "libnetlink.h"
#include "cr_options.h"
@@ -812,6 +813,9 @@ struct unix_sk_info {
struct list_head node; /* To link in peer's connected list */
struct list_head ghost_addr_node;
+ struct unix_sk_info *ghost_master;
+ atomic_t ghost_counter;
+ size_t ghost_keep;
/*
* For DGRAM sockets with queues, we should only restore the queue
@@ -823,6 +827,8 @@ struct unix_sk_info {
bool listen;
};
+static int bind_unix_sk(int sk, struct unix_sk_info *ui);
+
#define USK_PAIR_MASTER (1 << 0)
#define USK_PAIR_SLAVE (1 << 1)
#define USK_GHOST_NAME (1 << 2)
@@ -961,10 +967,27 @@ static int post_open_unix_sk(struct file_desc *d, int fd)
{
struct unix_sk_info *ui;
struct unix_sk_info *peer;
+ struct unix_sk_info *gm;
struct sockaddr_un addr;
int cwd_fd = -1, root_fd = -1;
ui = container_of(d, struct unix_sk_info, d);
+ gm = ui->ghost_master;
+
+ if (ui->flags & USK_GHOST_WAIT) {
+ if (!(gm->flags & USK_ADDR_RDY))
+ return 1;
+ if (ui->flags & (USK_PAIR_MASTER | USK_PAIR_SLAVE)) {
+ if (bind_unix_sk(fd, ui))
+ return -1;
+ return 0;
+ }
+ } else if (ui->flags & USK_GHOST_NAME) {
+ if (bind_unix_sk(fd, ui))
+ return -1;
+ return 0;
+ }
+
BUG_ON((ui->flags & (USK_PAIR_MASTER | USK_PAIR_SLAVE)) ||
(ui->ue->uflags & (USK_CALLBACK | USK_INHERIT)));
@@ -993,6 +1016,13 @@ static int post_open_unix_sk(struct file_desc *d, int fd)
return -1;
}
+ if (gm) {
+ if (!atomic_dec_and_test(&gm->ghost_counter)) {
+ if (unlink((char *)gm->ue->name.data) < 0)
+ pr_perror("failed to unlink %s", gm->ue->name.data);
+ }
+ }
+
revert_unix_sk_cwd(peer, &cwd_fd, &root_fd);
if (peer->queuer == ui->ue->ino && restore_sk_queue(fd, peer->ue->id))
@@ -1001,6 +1031,71 @@ static int post_open_unix_sk(struct file_desc *d, int fd)
return restore_sk_common(fd, ui);
}
+/*
+ * When path where socket lives is deleted, we need to reconstruct
+ * it back up but allow caller to remove it after.
+ */
+static int bind_on_deleted(int sk, struct unix_sk_info *ui, size_t *keep)
+{
+ char path[PATH_MAX], *pos;
+ struct sockaddr_un addr;
+ int ret, _keep;
+
+ if (ui->ue->name.len >= sizeof(path)) {
+ pr_err("Too long name for socket\n");
+ return -ENOSPC;
+ }
+
+ memcpy(path, ui->name, ui->ue->name.len);
+ path[ui->ue->name.len] = '\0';
+
+ for (pos = strrchr(path, '/'); pos;
+ pos = strrchr(path, '/')) {
+ *pos = '\0';
+
+ ret = access(path, R_OK | W_OK | X_OK);
+ if (ret == 0)
+ break;
+
+ if (errno != ENOENT) {
+ ret = -errno;
+ pr_perror("Can't access %s\n", path);
+ return ret;
+ }
+ }
+
+ _keep = pos ? pos - path : ui->ue->name.len;
+
+ memcpy(path, ui->name, ui->ue->name.len);
+ path[ui->ue->name.len] = '\0';
+
+ pos = dirname(path);
+ ret = mkdirpat(AT_FDCWD, pos, 0755);
+ if (ret) {
+ pr_err("Can't create %s\n", pos);
+ return ret;
+ }
+
+ memset(&addr, 0, sizeof(addr));
+ addr.sun_family = AF_UNIX;
+ memcpy(&addr.sun_path, ui->name, ui->ue->name.len);
+
+ ret = bind(sk, (struct sockaddr *)&addr,
+ sizeof(addr.sun_family) + ui->ue->name.len);
+ if (ret < 0) {
+ pr_perror("Can't bind on socket %s", (char *)ui->ue->name.data);
+ goto out;
+ }
+
+ *keep = _keep;
+ return 0;
+
+out:
+ if (rmdirp(pos, _keep))
+ pr_err("Can't cleanup %s\n", pos);
+ return ret;
+}
+
static int bind_unix_sk(int sk, struct unix_sk_info *ui)
{
struct sockaddr_un addr;
@@ -1071,10 +1166,14 @@ static int bind_unix_sk(int sk, struct unix_sk_info *ui)
ui->ue->deleted = false;
} else {
- pr_perror("Can't bind socket");
- goto done;
+ if (bind_on_deleted(sk, ui, &ui->ghost_keep)) {
+ pr_err("Can't bind socket\n");
+ goto done;
+ }
+ ui->flags |= USK_ADDR_RDY;
}
}
+ ui->flags |= USK_ADDR_RDY;
if (*ui->name && ui->ue->file_perms) {
FilePermsEntry *perms = ui->ue->file_perms;
@@ -1099,9 +1198,24 @@ 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);
- goto done;
+ if (ui->ue->deleted) {
+ struct unix_sk_info *gm = ui->ghost_master;
+ bool do_unlink = true;
+
+ if (gm) {
+ if (!atomic_dec_and_test(&gm->ghost_counter))
+ do_unlink = false;
+ }
+
+ if (!atomic_dec_and_test(&ui->ghost_counter))
+ do_unlink = false;
+
+ if (do_unlink) {
+ if (unlink((char *)ui->ue->name.data) < 0) {
+ pr_perror("failed to unlink %s", ui->ue->name.data);
+ goto done;
+ }
+ }
}
}
@@ -1118,7 +1232,7 @@ done:
static int open_unixsk_pair_master(struct unix_sk_info *ui, int *new_fd)
{
- int sk[2];
+ int sk[2], ret = 0;
struct unix_sk_info *peer = ui->peer;
pr_info("Opening pair master (id %#x ino %#x peer %#x)\n",
@@ -1137,8 +1251,11 @@ static int open_unixsk_pair_master(struct unix_sk_info *ui, int *new_fd)
if (restore_sk_queue(sk[1], ui->ue->id))
return -1;
- if (bind_unix_sk(sk[0], ui))
- return -1;
+ if (!(ui->flags & USK_GHOST_WAIT)) {
+ if (bind_unix_sk(sk[0], ui))
+ return -1;
+ } else
+ ret = 1;
if (restore_sk_common(sk[0], ui))
return -1;
@@ -1151,12 +1268,12 @@ static int open_unixsk_pair_master(struct unix_sk_info *ui, int *new_fd)
close(sk[1]);
*new_fd = sk[0];
- return 0;
+ return ret;
}
static int open_unixsk_pair_slave(struct unix_sk_info *ui, int *new_fd)
{
- int sk, ret;
+ int sk, ret = 0;
ret = recv_desc_from_peer(&ui->d, &sk);
if (ret != 0) {
@@ -1165,19 +1282,22 @@ static int open_unixsk_pair_slave(struct unix_sk_info *ui, int *new_fd)
return ret;
}
- if (bind_unix_sk(sk, ui))
- return -1;
+ if (!(ui->flags & USK_GHOST_WAIT)) {
+ if (bind_unix_sk(sk, ui))
+ return -1;
+ } else
+ ret = 1;
if (restore_sk_common(sk, ui))
return -1;
*new_fd = sk;
- return 0;
+ return ret;
}
static int open_unixsk_standalone(struct unix_sk_info *ui, int *new_fd)
{
- int sk;
+ int sk, ret = 0;
pr_info("Opening standalone socket (id %#x ino %#x peer %#x)\n",
ui->ue->id, ui->ue->ino, ui->ue->peer);
@@ -1295,8 +1415,11 @@ static int open_unixsk_standalone(struct unix_sk_info *ui, int *new_fd)
}
}
- if (bind_unix_sk(sk, ui))
- return -1;
+ if (!(ui->flags & USK_GHOST_WAIT)) {
+ if (bind_unix_sk(sk, ui))
+ return -1;
+ } else
+ ret = 1;
if (ui->ue->state == TCP_LISTEN) {
pr_info("\tPutting %#x into listen state\n", ui->ue->ino);
@@ -1323,7 +1446,7 @@ out:
return -1;
*new_fd = sk;
- return 0;
+ return ret;
}
static int open_unix_sk(struct file_desc *d, int *new_fd)
@@ -1332,12 +1455,12 @@ static int open_unix_sk(struct file_desc *d, int *new_fd)
struct unix_sk_info *ui;
int ret;
+ ui = container_of(d, struct unix_sk_info, d);
+
fle = file_master(d);
if (fle->stage >= FLE_OPEN)
return post_open_unix_sk(d, fle->fe->fd);
- ui = container_of(d, struct unix_sk_info, d);
-
if (inherited_fd(d, new_fd)) {
ui->ue->uflags |= USK_INHERIT;
ret = *new_fd >= 0 ? 0 : -1;
@@ -1408,6 +1531,9 @@ static int collect_one_unixsk(void *o, ProtobufCMessage *base, struct cr_img *i)
ui->name_dir = (void *)ui->ue->name_dir;
INIT_LIST_HEAD(&ui->ghost_addr_node);
+ ui->ghost_master = NULL;
+ atomic_set(&ui->ghost_counter, 1);
+ ui->ghost_keep = 0;
if (add_post_prepare_cb_once(resolve_unix_peers, NULL))
return -1;
@@ -1515,6 +1641,87 @@ static void interconnected_pair(struct unix_sk_info *ui, struct unix_sk_info *pe
}
}
+static int ghost_new_name(char *name, size_t namelen,
+ char **name_new, size_t *namelen_new)
+{
+ static unsigned int cnt = 0;
+ char sname[64];
+ size_t k;
+
+ k = snprintf(sname, sizeof(sname), "criu-%u", cnt++);
+ *namelen_new = namelen + k + 1;
+ if (*namelen_new > UNIX_PATH_MAX) {
+ pr_err("ghost: New name for socket is too long\n");
+ return -1;
+ }
+
+ *name_new = shmalloc(*namelen_new);
+ if (!*name_new) {
+ pr_err("ghost: Can't allocate new name for socket\n");
+ return -ENOMEM;
+ }
+
+ k = snprintf(*name_new, *namelen_new, "%s-%s", name, sname) + 1;
+ if (k != *namelen_new) {
+ pr_err("ghost: Name stripped\n");
+ return -1;
+ }
+
+ return 0;
+}
+
+static int resolve_unix_ghosts(void)
+{
+ struct unix_sk_info *ui, *t;
+ ghost_addr_t *ga;
+
+ pr_debug("ghost: Resolving addresses\n");
+
+ list_for_each_entry(ga, &unix_ghost_addr, list) {
+ pr_debug("ghost: address %s\n", ga->name);
+
+ list_for_each_entry(ui, &ga->children, ghost_addr_node) {
+ size_t newnamelen;
+ char *newname;
+
+ if (ui->flags & USK_GHOST_NAME)
+ continue;
+
+ pr_debug("\tghost: ino %#x peer %#x\n", ui->ue->ino,
+ ui->peer ? ui->peer->ue->ino : 0);
+
+ if (ghost_new_name(ga->name, ga->namelen,
+ &newname, &newnamelen))
+ return -1;
+
+ pr_debug("\tghost: name transition %s -> %s\n",
+ ui->name, newname);
+ ui->name = newname;
+ ui->ue->name.len = newnamelen;
+ ui->ue->name.data = (void *)newname;
+ ui->flags |= USK_GHOST_NAME;
+ atomic_inc(&ui->ghost_counter);
+
+ unlink_stale(ui);
+
+ list_for_each_entry(t, &unix_sockets, list) {
+ if (t->flags & (USK_GHOST_NAME | USK_GHOST_WAIT))
+ continue;
+ if (t->peer != ui)
+ continue;
+ pr_debug("\t\tghost: connected to us %#x -> %#x\n",
+ t->ue->ino, ui->ue->ino);
+
+ t->flags |= USK_GHOST_NAME | USK_GHOST_WAIT;
+ t->ghost_master = ui;
+ atomic_inc(&ui->ghost_counter);
+ }
+ }
+ }
+
+ return 0;
+}
+
static int resolve_unix_peers(void *unused)
{
struct unix_sk_info *ui, *peer;
@@ -1559,7 +1766,7 @@ static int resolve_unix_peers(void *unused)
}
- return 0;
+ return resolve_unix_ghosts();
}
int unix_sk_id_add(unsigned int ino)
--
2.7.4
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