enter container namespace with opened ns fd

After process exit,the path of pid ns will disappear,
open it first to prohibit ns being released.

Signed-off-by: Gao feng <omarapazanadi@gmail.com>

src/container.c

@@ -430,11 +430,13 @@ int hyper_start_container(struct hyper_container *container,
 {
 	int stacksize = getpagesize() * 4;
 	struct hyper_container_arg arg = {
-		.c = container,
-		.utsns = utsns,
-		.ipcns = ipcns,
+		.c	= container,
+		.utsns	= utsns,
+		.ipcns	= ipcns,
+		.pipe	= {-1, -1},
 	};
 	int flags = CLONE_NEWNS | SIGCHLD;
+	char path[128];
 	uint32_t type;
 	void *stack;
 	int pid;
@@ -467,7 +469,13 @@ int hyper_start_container(struct hyper_container *container,
 		perror("create child process failed");
 		goto fail;
 	}
+	sprintf(path, "/proc/%d/ns/mnt", pid);
 	container->exec.pid = pid;
+	container->ns = open(path, O_RDONLY | O_CLOEXEC);
+	if (container->ns < 0) {
+		perror("open container mount ns failed");
+		goto fail;
+	}
 
 	/* wait for ready message */
 	if (hyper_get_type_block(arg.pipe[0], &type) < 0 || type != READY) {
@@ -484,6 +492,10 @@ int hyper_start_container(struct hyper_container *container,
 	fprintf(stdout, "container %s init pid is %d\n", container->id, pid);
 	return 0;
 fail:
+	close(arg.pipe[0]);
+	close(arg.pipe[1]);
+	close(container->ns);
+	container->ns = -1;
 	fprintf(stdout, "container %s init exit code %d\n", container->id, -1);
 	container->exec.code = -1;
 	return -1;
@@ -552,6 +564,7 @@ void hyper_cleanup_container(struct hyper_pod *pod)
 			free(map->path);
 		}
 		free(c->maps);
+		close(c->ns);
 	}
 
 	free(pod->c);

src/container.h

@@ -33,6 +33,7 @@ struct hyper_container {
 	int			vols_num;
 	int			envs_num;
 	int			maps_num;
+	int			ns;
 	uint32_t		code;
 	struct hyper_exec	exec;
 };

src/exec.c

@@ -204,22 +204,21 @@ int hyper_enter_container(struct hyper_pod *pod,
 		return -1;
 	}
 
-	sprintf(path, "/proc/%d/ns/uts", c->exec.pid);
+	sprintf(path, "/proc/%d/ns/uts", pod->init_pid);
 	utsns = open(path, O_RDONLY| O_CLOEXEC);
 	if (utsns < 0) {
 		perror("fail to open utsns of pod init");
 		goto out;
 	}
 
-	sprintf(path, "/proc/%d/ns/ipc", c->exec.pid);
+	sprintf(path, "/proc/%d/ns/ipc", pod->init_pid);
 	ipcns = open(path, O_RDONLY| O_CLOEXEC);
 	if (ipcns < 0) {
 		perror("fail to open ipcns of pod init");
 		goto out;
 	}
 
-	sprintf(path, "/proc/%d/ns/mnt", c->exec.pid);
-	mntns = open(path, O_RDONLY| O_CLOEXEC);
+	mntns = c->ns;
 	if (mntns < 0) {
 		perror("fail to open mntns of pod init");
 		goto out;
@@ -248,7 +247,6 @@ int hyper_enter_container(struct hyper_pod *pod,
 out:
 	close(ipcns);
 	close(utsns);
-	close(mntns);
 
 	return ret;
 }

src/init.c

@@ -752,8 +752,7 @@ static int hyper_cmd_write_file(char *json, int length)
 		goto out;
 	}
 
-	sprintf(path, "/proc/%d/ns/mnt", c->exec.pid);
-	mntns = open(path, O_RDONLY);
+	mntns = c->ns;
 	if (mntns < 0) {
 		perror("fail to open mnt ns");
 		goto out;
@@ -813,7 +812,6 @@ static int hyper_cmd_write_file(char *json, int length)
 out:
 	close(pipe[0]);
 	close(pipe[1]);
-	close(mntns);
 	free(writter.id);
 	free(writter.file);
 	free(writter.data);
@@ -901,7 +899,6 @@ static int hyper_cmd_read_file(char *json, int length, uint32_t *datalen, uint8_
 	int stacksize = getpagesize() * 4;
 	void *stack = malloc(stacksize);
 	int pid, ret = -1;
-	char path[128];
 	uint32_t type;
 
 	if (stack == NULL) {
@@ -927,8 +924,7 @@ static int hyper_cmd_read_file(char *json, int length, uint32_t *datalen, uint8_
 		goto out;
 	}
 
-	sprintf(path, "/proc/%d/ns/mnt", c->exec.pid);
-	arg.mntns = open(path, O_RDONLY);
+	arg.mntns = c->ns;
 	if (arg.mntns < 0) {
 		perror("fail to open mnt ns");
 		goto out;
@@ -955,7 +951,6 @@ static int hyper_cmd_read_file(char *json, int length, uint32_t *datalen, uint8_
 out:
 	close(arg.pipe[0]);
 	close(arg.pipe[1]);
-	close(arg.mntns);
 	free(reader.id);
 	free(reader.file);
 

src/parse.c

@@ -199,6 +199,7 @@ static int hyper_parse_container(struct hyper_pod *pod, struct hyper_container *
 
 	c->exec.init = 1;
 	c->exec.code = -1;
+	c->ns = -1;
 
 	next_container = toks[i].size;
 	fprintf(stdout, "next container %d\n", next_container);