On Tue, Apr 19, 2016 at 10:04:20PM -0500, Eric W. Biederman wrote:
> +#ifdef CONFIG_UNIX98_PTYS
> +int path_pts(struct path *path)
> +{
> + /* Find "pts" in the same directory as the input path */
> + struct dentry *child, *parent;
> + struct qstr this;
> + int ret;
> +
> + ret = path_parent_directory(path);
> + if (ret)
> + return ret;
> +
> + parent = path->dentry;
> + if (!d_can_lookup(parent))
> + return -ENOENT;
And how, pray tell, would a parent of anything fail to be a directory?
> + this.name = "pts";
> + this.len = 3;
> + this.hash = full_name_hash(this.name, this.len);
> + if (parent->d_flags & DCACHE_OP_HASH) {
> + int err = parent->d_op->d_hash(parent, &this);
> + if (err < 0)
> + return err;
> + }
> + inode_lock(parent->d_inode);
What the hell for? What does that lock on parent change for the
dcache lookup you are doing here?
> + child = d_lookup(parent, &this);
> + inode_unlock(parent->d_inode);
> + if (!child)
> + return -ENOENT;
Take a look at d_hash_and_lookup(), BTW...
> + path->dentry = child;
> + dput(parent);
> + follow_mount(path);
> + return 0;
> +}
> +#endif
> +
> int user_path_at_empty(int dfd, const char __user *name, unsigned flags,
> struct path *path, int *empty)
> {
> diff --git a/include/linux/devpts_fs.h b/include/linux/devpts_fs.h
> index e0ee0b3000b2..486f6282b0c6 100644
> --- a/include/linux/devpts_fs.h
> +++ b/include/linux/devpts_fs.h
> @@ -17,36 +17,21 @@
>
> #ifdef CONFIG_UNIX98_PTYS
>
> -int devpts_new_index(struct inode *ptmx_inode);
> -void devpts_kill_index(struct inode *ptmx_inode, int idx);
> -void devpts_add_ref(struct inode *ptmx_inode);
> -void devpts_del_ref(struct inode *ptmx_inode);
> +struct pts_fs_info;
> +
> +struct pts_fs_info *devpts_acquire(struct file *filp);
> +void devpts_release(struct pts_fs_info *fsi);
> +
> +int devpts_new_index(struct pts_fs_info *fsi);
> +void devpts_kill_index(struct pts_fs_info *fsi, int idx);
> /* mknod in devpts */
> -struct inode *devpts_pty_new(struct inode *ptmx_inode, dev_t device, int
> index,
> +struct inode *devpts_pty_new(struct pts_fs_info *fsi, dev_t device, int
> index,
> void *priv);
> /* get private structure */
> void *devpts_get_priv(struct inode *pts_inode);
> /* unlink */
> void devpts_pty_kill(struct inode *inode);
>
> -#else
> -
> -/* Dummy stubs in the no-pty case */
> -static inline int devpts_new_index(struct inode *ptmx_inode) { return
> -EINVAL; }
> -static inline void devpts_kill_index(struct inode *ptmx_inode, int idx) { }
> -static inline void devpts_add_ref(struct inode *ptmx_inode) { }
> -static inline void devpts_del_ref(struct inode *ptmx_inode) { }
> -static inline struct inode *devpts_pty_new(struct inode *ptmx_inode,
> - dev_t device, int index, void *priv)
> -{
> - return ERR_PTR(-EINVAL);
> -}
> -static inline void *devpts_get_priv(struct inode *pts_inode)
> -{
> - return NULL;
> -}
> -static inline void devpts_pty_kill(struct inode *inode) { }
> -
> #endif
>
>
> diff --git a/include/linux/namei.h b/include/linux/namei.h
> index 77d01700daf7..f29abda31e6d 100644
> --- a/include/linux/namei.h
> +++ b/include/linux/namei.h
> @@ -45,6 +45,8 @@ enum {LAST_NORM, LAST_ROOT, LAST_DOT, LAST_DOTDOT,
> LAST_BIND};
> #define LOOKUP_ROOT 0x2000
> #define LOOKUP_EMPTY 0x4000
>
> +extern int path_pts(struct path *path);
> +
> extern int user_path_at_empty(int, const char __user *, unsigned, struct
> path *, int *empty);
>
> static inline int user_path_at(int dfd, const char __user *name, unsigned
> flags,
> --
> 2.8.1
>
