[CRIU] [PATCH v6 7/9] unix: Add support of ghost sockets
Andrey Vagin
avagin at virtuozzo.com
Tue May 22 21:36:49 MSK 2018
On Mon, May 21, 2018 at 11:05:59PM +0300, Cyrill Gorcunov wrote:
> 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 order
> this sockets creation and deletion with mutex, together
> with adding missing directories, and save this descriptors
> in fdstore if there are peers connected to
>
> - 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 | 357 +++++++++++++++++++++++++++++++++++++++++--------
> 3 files changed, 309 insertions(+), 53 deletions(-)
>
> diff --git a/criu/cr-restore.c b/criu/cr-restore.c
> index e969c24cd1d8..645a0e724970 100644
> --- a/criu/cr-restore.c
> +++ b/criu/cr-restore.c
> @@ -384,6 +384,10 @@ static int root_prepare_shared(void)
> if (ret)
> goto err;
>
> + ret = unix_prepare_root_shared();
> + if (ret)
> + goto err;
> +
> ret = add_fake_unix_queuers();
> if (ret)
> goto err;
> diff --git a/criu/include/sockets.h b/criu/include/sockets.h
> index 1d0e1f29304c..f2085ace70b2 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_prepare_root_shared(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 88859da02f35..c0b607d3a1d0 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"
> @@ -31,6 +32,7 @@
> #include "fdstore.h"
> #include "fdinfo.h"
> #include "kerndat.h"
> +#include "rst-malloc.h"
>
> #include "protobuf.h"
> #include "images/sk-unix.pb-c.h"
> @@ -89,11 +91,21 @@ struct unix_sk_desc {
> UnixSkEntry *ue;
> };
>
> +/*
> + * The mutex_ghost is accessed from different tasks,
> + * so make sure it is in shared memory.
> + */
> +static mutex_t *mutex_ghost;
> +
> 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 int unlink_sk(struct unix_sk_info *ui);
> +
> struct unix_sk_listen_icon {
> unsigned int peer_ino;
> struct unix_sk_desc *sk_desc;
> @@ -886,12 +898,15 @@ 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;
> + size_t ghost_dir_pos;
>
> /*
> * For DGRAM sockets with queues, we should only restore the queue
> @@ -916,6 +931,8 @@ struct scm_fle {
>
> #define USK_PAIR_MASTER 0x1
> #define USK_PAIR_SLAVE 0x2
> +#define USK_GHOST_FDSTORE 0x4
pls add a comment what USK_GHOST_FDSTORE means
> +#define USK_GHOST_RENAMED 0x8
>
> static struct unix_sk_info *find_unix_sk_by_ino(int ino)
> {
> @@ -1241,6 +1258,7 @@ 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;
........
> static void try_resolve_unix_peer(struct unix_sk_info *ui);
> @@ -1812,6 +2007,8 @@ 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->ghost_dir_pos = 0;
> ui->peer = NULL;
> ui->queuer = NULL;
> ui->bound = 0;
> @@ -1826,6 +2023,51 @@ 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;
> +}
> +
> +int unix_prepare_root_shared(void)
> +{
> + struct unix_sk_info *ui, *t;
> +
> + mutex_ghost = shmalloc(sizeof(*mutex_ghost));
> + if (!mutex_ghost) {
> + pr_err("ghost: Can't allocate mutex\n");
> + return -ENOMEM;
> + }
> + mutex_init(mutex_ghost);
> +
> + pr_debug("ghost: Resolving addresses\n");
> +
> + list_for_each_entry(ui, &unix_ghost_addr, ghost_node) {
> + pr_debug("ghost: id %#x type %s state %s ino %d peer %d address %s\n",
> + ui->ue->id, socket_type_name(ui->ue->type),
> + tcp_state_name(ui->ue->state),
> + ui->ue->ino, ui->peer ? ui->peer->ue->ino : 0,
> + ui->name);
> +
> + 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.
is it an old comment?
> + */
> + list_for_each_entry(t, &unix_sockets, list) {
Why do we need this loop
> + if (t->flags & USK_GHOST_FDSTORE)
> + continue;
> + if (ui == t || t->peer != ui)
> + continue;
> +
> + pr_debug("\t\tghost: id %#x type %s state %s connected to us %d -> %d\n",
> + t->ue->id, socket_type_name(t->ue->type),
> + tcp_state_name(t->ue->state),
> + t->ue->ino, ui->ue->ino);
> + }
> + ui->flags |= USK_GHOST_FDSTORE;
> + }
>
> return 0;
> }
> @@ -1873,6 +2115,15 @@ 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 %d\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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