Quoting Daniel Lezcano (daniel.lezcano@xxxxxxx):
> From: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
>
> Reorganize proc_get_sb so it can be called before the struct pid
> of the first process is allocated.
>
> Signed-off-by: Eric W. Biederman <ebiederm@xxxxxxxxxxxx>
> Signed-off-by: Daniel Lezcano <daniel.lezcano@xxxxxxx>
Acked-by: Serge E. Hallyn <serge@xxxxxxxxxx>
> ---
> fs/proc/root.c | 25 +++++++------------------
> kernel/fork.c | 6 ------
> kernel/pid_namespace.c | 11 +++++++++--
> 3 files changed, 16 insertions(+), 26 deletions(-)
>
> diff --git a/fs/proc/root.c b/fs/proc/root.c
> index ef9fa8e..e5e2bfa 100644
> --- a/fs/proc/root.c
> +++ b/fs/proc/root.c
> @@ -43,17 +43,6 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
> struct pid_namespace *ns;
> struct proc_inode *ei;
>
> - if (proc_mnt) {
> - /* Seed the root directory with a pid so it doesn't need
> - * to be special in base.c. I would do this earlier but
> - * the only task alive when /proc is mounted the first time
> - * is the init_task and it doesn't have any pids.
> - */
> - ei = PROC_I(proc_mnt->mnt_sb->s_root->d_inode);
> - if (!ei->pid)
> - ei->pid = find_get_pid(1);
> - }
> -
> if (flags & MS_KERNMOUNT)
> ns = (struct pid_namespace *)data;
> else
> @@ -71,16 +60,16 @@ static struct dentry *proc_mount(struct file_system_type *fs_type,
> return ERR_PTR(err);
> }
>
> - ei = PROC_I(sb->s_root->d_inode);
> - if (!ei->pid) {
> - rcu_read_lock();
> - ei->pid = get_pid(find_pid_ns(1, ns));
> - rcu_read_unlock();
> - }
> -
> sb->s_flags |= MS_ACTIVE;
> }
>
> + ei = PROC_I(sb->s_root->d_inode);
> + if (!ei->pid) {
> + rcu_read_lock();
> + ei->pid = get_pid(find_pid_ns(1, ns));
> + rcu_read_unlock();
> + }
> +
> return dget(sb->s_root);
> }
>
> diff --git a/kernel/fork.c b/kernel/fork.c
> index c9f0784..e7a5907 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -1180,12 +1180,6 @@ static struct task_struct *copy_process(unsigned long clone_flags,
> pid = alloc_pid(p->nsproxy->pid_ns);
> if (!pid)
> goto bad_fork_cleanup_io;
> -
> - if (clone_flags & CLONE_NEWPID) {
> - retval = pid_ns_prepare_proc(p->nsproxy->pid_ns);
> - if (retval < 0)
> - goto bad_fork_free_pid;
> - }
> }
>
> p->pid = pid_nr(pid);
> diff --git a/kernel/pid_namespace.c b/kernel/pid_namespace.c
> index a5aff94..e9c9adc 100644
> --- a/kernel/pid_namespace.c
> +++ b/kernel/pid_namespace.c
> @@ -14,6 +14,7 @@
> #include <linux/err.h>
> #include <linux/acct.h>
> #include <linux/slab.h>
> +#include <linux/proc_fs.h>
>
> #define BITS_PER_PAGE (PAGE_SIZE*8)
>
> @@ -72,7 +73,7 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
> {
> struct pid_namespace *ns;
> unsigned int level = parent_pid_ns->level + 1;
> - int i;
> + int i, err = -ENOMEM;
>
> ns = kmem_cache_zalloc(pid_ns_cachep, GFP_KERNEL);
> if (ns == NULL)
> @@ -96,14 +97,20 @@ static struct pid_namespace *create_pid_namespace(struct pid_namespace *parent_p
> for (i = 1; i < PIDMAP_ENTRIES; i++)
> atomic_set(&ns->pidmap[i].nr_free, BITS_PER_PAGE);
>
> + err = pid_ns_prepare_proc(ns);
> + if (err)
> + goto out_put_parent_pid_ns;
> +
> return ns;
>
> +out_put_parent_pid_ns:
> + put_pid_ns(parent_pid_ns);
> out_free_map:
> kfree(ns->pidmap[0].page);
> out_free:
> kmem_cache_free(pid_ns_cachep, ns);
> out:
> - return ERR_PTR(-ENOMEM);
> + return ERR_PTR(err);
> }
>
> static void destroy_pid_namespace(struct pid_namespace *ns)
> --
> 1.7.1
>
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