Hi Eric,
A few comments on your patch set.
On Fri, 2011-05-06 at 19:24 -0700, Eric W. Biederman wrote:
> diff --git a/fs/proc/inode.c b/fs/proc/inode.c
> index d15aa1b..74b48cf 100644
> --- a/fs/proc/inode.c
> +++ b/fs/proc/inode.c
> @@ -28,6 +28,7 @@ static void proc_evict_inode(struct inode *inode)
> {
> struct proc_dir_entry *de;
> struct ctl_table_header *head;
> + const struct proc_ns_operations *ns_ops;
>
> truncate_inode_pages(&inode->i_data, 0);
> end_writeback(inode);
> @@ -44,6 +45,10 @@ static void proc_evict_inode(struct inode *inode)
> rcu_assign_pointer(PROC_I(inode)->sysctl, NULL);
> sysctl_head_put(head);
> }
> + /* Release any associated namespace */
> + ns_ops = PROC_I(inode)->ns_ops;
> + if (ns_ops && ns_ops->put)
> + ns_ops->put(PROC_I(inode)->ns);
Is it ever valid for ns_ops->put to be null? If not, I suggest removing
the check.
> diff --git a/fs/proc/namespaces.c b/fs/proc/namespaces.c
> new file mode 100644
> index 0000000..6ae9f07
> --- /dev/null
> +++ b/fs/proc/namespaces.c
...
> +static struct dentry *proc_ns_dir_lookup(struct inode *dir,
> + struct dentry *dentry, struct nameidata *nd)
> +{
> + struct dentry *error;
> + struct task_struct *task = get_proc_task(dir);
> + const struct proc_ns_operations **entry, **last;
> + unsigned int len = dentry->d_name.len;
> +
> + error = ERR_PTR(-ENOENT);
> +
> + if (!task)
> + goto out_no_task;
> +
> + error = ERR_PTR(-EPERM);
> + if (!ptrace_may_access(task, PTRACE_MODE_READ))
> + goto out;
> +
> + last = &ns_entries[ARRAY_SIZE(ns_entries) - 1];
> + for (entry = ns_entries; entry <= last; entry++) {
> + if (strlen((*entry)->name) != len)
> + continue;
> + if (!memcmp(dentry->d_name.name, (*entry)->name, len))
> + break;
> + }
> + if (entry > last)
> + goto out;
This returns EPERM when it should return ENOENT?
> +
> + error = proc_ns_instantiate(dir, dentry, task, *entry);
> +out:
> + put_task_struct(task);
> +out_no_task:
> + return error;
> +}
...
> --- a/include/linux/proc_fs.h
> +++ b/include/linux/proc_fs.h
> @@ -250,6 +257,15 @@ kclist_add(struct kcore_list *new, void *addr, size_t size, int type)
> extern void kclist_add(struct kcore_list *, void *, size_t, int type);
> #endif
>
> +struct nsproxy;
> +struct proc_ns_operations {
> + const char *name;
> + int type;
> + void *(*get)(struct task_struct *task);
> + void (*put)(void *ns);
> + int (*install)(struct nsproxy *nsproxy, void *ns);
> +};
> +
> union proc_op {
> int (*proc_get_link)(struct inode *, struct path *);
> int (*proc_read)(struct task_struct *task, char *page);
> @@ -268,6 +284,8 @@ struct proc_inode {
> struct proc_dir_entry *pde;
> struct ctl_table_header *sysctl;
> struct ctl_table *sysctl_entry;
> + void *ns;
> + const struct proc_ns_operations *ns_ops;
> struct inode vfs_inode;
> };
Not that I have any better ideas, but it seems a bit undesirable to
increase the size of proc_inode for this one purpose.
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