Re: [PATCH v2 05/10] pidns: Add a limit on the number of pid namespaces

[Serge E. Hallyn]

Quoting Eric W. Biederman (ebied...@xmission.com):
> Signed-off-by: "Eric W. Biederman" 

Acked-by: Serge Hallyn 

> ---
>  include/linux/user_namespace.h |  1 +
>  kernel/pid_namespace.c | 22 ++
>  kernel/user_namespace.c|  1 +
>  3 files changed, 20 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
> index f74a0facc696..47733637741a 100644
> --- a/include/linux/user_namespace.h
> +++ b/include/linux/user_namespace.h
> @@ -24,6 +24,7 @@ struct uid_gid_map {/* 64 bytes -- 1 cache line */
>  
>  enum ucounts {
>   UCOUNT_USER_NAMESPACES,
> + UCOUNT_PID_NAMESPACES,
>   UCOUNT_COUNTS,
>  };
>  
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index a65ba137fd15..049cc14ae37a 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -79,6 +79,16 @@ static void proc_cleanup_work(struct work_struct *work)
>  /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
>  #define MAX_PID_NS_LEVEL 32
>  
> +static bool inc_pid_namespaces(struct user_namespace *ns)
> +{
> + return inc_ucount(ns, UCOUNT_PID_NAMESPACES);
> +}
> +
> +static void dec_pid_namespaces(struct user_namespace *ns)
> +{
> + dec_ucount(ns, UCOUNT_PID_NAMESPACES);
> +}
> +
>  static struct pid_namespace *create_pid_namespace(struct user_namespace 
> *user_ns,
>   struct pid_namespace *parent_pid_ns)
>  {
> @@ -87,15 +97,16 @@ static struct pid_namespace *create_pid_namespace(struct 
> user_namespace *user_ns
>   int i;
>   int err;
>  
> - if (level > MAX_PID_NS_LEVEL) {
> - err = -EINVAL;
> + err = -EINVAL;
> + if (level > MAX_PID_NS_LEVEL)
> + goto out;
> + if (!inc_pid_namespaces(user_ns))
>   goto out;
> - }
>  
>   err = -ENOMEM;
>   ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
>   if (ns == NULL)
> - goto out;
> + goto out_dec;
>  
>   ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
>   if (!ns->pidmap[0].page)
> @@ -129,6 +140,8 @@ out_free_map:
>   kfree(ns->pidmap[0].page);
>  out_free:
>   kmem_cache_free(pid_ns_cachep, ns);
> +out_dec:
> + dec_pid_namespaces(user_ns);
>  out:
>   return ERR_PTR(err);
>  }
> @@ -146,6 +159,7 @@ static void destroy_pid_namespace(struct pid_namespace 
> *ns)
>   ns_free_inum(>ns);
>   for (i = 0; i < PIDMAP_ENTRIES; i++)
>   kfree(ns->pidmap[i].page);
> + dec_pid_namespaces(ns->user_ns);
>   put_user_ns(ns->user_ns);
>   call_rcu(>rcu, delayed_free_pidns);
>  }
> diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
> index 728d7e4995ff..02a03ead7afc 100644
> --- a/kernel/user_namespace.c
> +++ b/kernel/user_namespace.c
> @@ -77,6 +77,7 @@ static int count_max = COUNT_MAX;
>   }
>  static struct ctl_table userns_table[] = {
>   UCOUNT_ENTRY("max_user_namespaces"),
> + UCOUNT_ENTRY("max_pid_namespaces"),
>   { }
>  };
>  #endif /* CONFIG_SYSCTL */
> -- 
> 2.8.3

[PATCH v2 05/10] pidns: Add a limit on the number of pid namespaces

[Eric W. Biederman]

Signed-off-by: "Eric W. Biederman" 
---
 include/linux/user_namespace.h |  1 +
 kernel/pid_namespace.c | 22 ++
 kernel/user_namespace.c|  1 +
 3 files changed, 20 insertions(+), 4 deletions(-)

diff --git a/include/linux/user_namespace.h b/include/linux/user_namespace.h
index f74a0facc696..47733637741a 100644
--- a/include/linux/user_namespace.h
+++ b/include/linux/user_namespace.h
@@ -24,6 +24,7 @@ struct uid_gid_map {  /* 64 bytes -- 1 cache line */
 
 enum ucounts {
UCOUNT_USER_NAMESPACES,
+   UCOUNT_PID_NAMESPACES,
UCOUNT_COUNTS,
 };
 
diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
index a65ba137fd15..049cc14ae37a 100644
--- a/kernel/pid_namespace.c
+++ b/kernel/pid_namespace.c
@@ -79,6 +79,16 @@ static void proc_cleanup_work(struct work_struct *work)
 /* MAX_PID_NS_LEVEL is needed for limiting size of 'struct pid' */
 #define MAX_PID_NS_LEVEL 32
 
+static bool inc_pid_namespaces(struct user_namespace *ns)
+{
+   return inc_ucount(ns, UCOUNT_PID_NAMESPACES);
+}
+
+static void dec_pid_namespaces(struct user_namespace *ns)
+{
+   dec_ucount(ns, UCOUNT_PID_NAMESPACES);
+}
+
 static struct pid_namespace *create_pid_namespace(struct user_namespace 
*user_ns,
struct pid_namespace *parent_pid_ns)
 {
@@ -87,15 +97,16 @@ static struct pid_namespace *create_pid_namespace(struct 
user_namespace *user_ns
int i;
int err;
 
-   if (level > MAX_PID_NS_LEVEL) {
-   err = -EINVAL;
+   err = -EINVAL;
+   if (level > MAX_PID_NS_LEVEL)
+   goto out;
+   if (!inc_pid_namespaces(user_ns))
goto out;
-   }
 
err = -ENOMEM;
ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
if (ns == NULL)
-   goto out;
+   goto out_dec;
 
ns->pidmap[0].page = kzalloc(PAGE_SIZE, GFP_KERNEL);
if (!ns->pidmap[0].page)
@@ -129,6 +140,8 @@ out_free_map:
kfree(ns->pidmap[0].page);
 out_free:
kmem_cache_free(pid_ns_cachep, ns);
+out_dec:
+   dec_pid_namespaces(user_ns);
 out:
return ERR_PTR(err);
 }
@@ -146,6 +159,7 @@ static void destroy_pid_namespace(struct pid_namespace *ns)
ns_free_inum(>ns);
for (i = 0; i < PIDMAP_ENTRIES; i++)
kfree(ns->pidmap[i].page);
+   dec_pid_namespaces(ns->user_ns);
put_user_ns(ns->user_ns);
call_rcu(>rcu, delayed_free_pidns);
 }
diff --git a/kernel/user_namespace.c b/kernel/user_namespace.c
index 728d7e4995ff..02a03ead7afc 100644
--- a/kernel/user_namespace.c
+++ b/kernel/user_namespace.c
@@ -77,6 +77,7 @@ static int count_max = COUNT_MAX;
}
 static struct ctl_table userns_table[] = {
UCOUNT_ENTRY("max_user_namespaces"),
+   UCOUNT_ENTRY("max_pid_namespaces"),
{ }
 };
 #endif /* CONFIG_SYSCTL */
-- 
2.8.3