net: Create child with CLONE_VM in prepare_net_namespaces()

Submitted by Kirill Tkhai on March 15, 2017, 2:41 p.m.

Details

Message ID 148958882927.8293.16835009880572289679.stgit@localhost.localdomain
State New
Series "net: Create child with CLONE_VM in prepare_net_namespaces()"
Headers show

Commit Message

Kirill Tkhai March 15, 2017, 2:41 p.m.
Some functions in prepare_net_ns() use vmalloc(), and this
memory should be visible to our children.

https://travis-ci.org/tkhai/criu/builds/211359724

Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
 criu/net.c |   14 +++++++++++---
 1 file changed, 11 insertions(+), 3 deletions(-)

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diff --git a/criu/net.c b/criu/net.c
index 309e2bd66..89082f2ef 100644
--- a/criu/net.c
+++ b/criu/net.c
@@ -1756,20 +1756,27 @@  static int create_net_ns(void *arg)
 
 int prepare_net_namespaces()
 {
-	char stack[128] __stack_aligned__;
+	int status, stack_size;
 	struct ns_id *nsid;
-	int status;
+	char *stack;
 	pid_t pid;
 
 	if (!(root_ns_mask & CLONE_NEWNET))
 		return 0;
 
+	stack_size = 2 * 1024 * 1024;
+	stack = mmap(NULL, stack_size, PROT_WRITE | PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
+	if (stack == MAP_FAILED) {
+		pr_perror("Can't allocate stack");
+		return -1;
+	}
+
 	for (nsid = ns_ids; nsid != NULL; nsid = nsid->next) {
 		if (nsid->nd != &net_ns_desc)
 			continue;
 
 		if (root_user_ns && nsid->user_ns != root_user_ns) {
-			pid = clone(create_net_ns, stack + 128, SIGCHLD, nsid);
+			pid = clone(create_net_ns, stack + stack_size, CLONE_VM | SIGCHLD, nsid);
 			if (pid < 0) {
 				pr_perror("Can't clone");
 				goto err;
@@ -1785,6 +1792,7 @@  int prepare_net_namespaces()
 			goto err;
 	}
 
+	munmap(stack, stack_size);
 	close_service_fd(NS_FD_OFF);
 
 	return 0;

Comments

Kirill Tkhai March 15, 2017, 3:36 p.m.
Ignore this one

On 15.03.2017 17:41, Kirill Tkhai wrote:
> Some functions in prepare_net_ns() use vmalloc(), and this
> memory should be visible to our children.
> 
> https://travis-ci.org/tkhai/criu/builds/211359724
> 
> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> ---
>  criu/net.c |   14 +++++++++++---
>  1 file changed, 11 insertions(+), 3 deletions(-)
> 
> diff --git a/criu/net.c b/criu/net.c
> index 309e2bd66..89082f2ef 100644
> --- a/criu/net.c
> +++ b/criu/net.c
> @@ -1756,20 +1756,27 @@ static int create_net_ns(void *arg)
>  
>  int prepare_net_namespaces()
>  {
> -	char stack[128] __stack_aligned__;
> +	int status, stack_size;
>  	struct ns_id *nsid;
> -	int status;
> +	char *stack;
>  	pid_t pid;
>  
>  	if (!(root_ns_mask & CLONE_NEWNET))
>  		return 0;
>  
> +	stack_size = 2 * 1024 * 1024;
> +	stack = mmap(NULL, stack_size, PROT_WRITE | PROT_READ, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
> +	if (stack == MAP_FAILED) {
> +		pr_perror("Can't allocate stack");
> +		return -1;
> +	}
> +
>  	for (nsid = ns_ids; nsid != NULL; nsid = nsid->next) {
>  		if (nsid->nd != &net_ns_desc)
>  			continue;
>  
>  		if (root_user_ns && nsid->user_ns != root_user_ns) {
> -			pid = clone(create_net_ns, stack + 128, SIGCHLD, nsid);
> +			pid = clone(create_net_ns, stack + stack_size, CLONE_VM | SIGCHLD, nsid);
>  			if (pid < 0) {
>  				pr_perror("Can't clone");
>  				goto err;
> @@ -1785,6 +1792,7 @@ int prepare_net_namespaces()
>  			goto err;
>  	}
>  
> +	munmap(stack, stack_size);
>  	close_service_fd(NS_FD_OFF);
>  
>  	return 0;
>