Commit 1bc82070 authored by Aleksa Sarai's avatar Aleksa Sarai Committed by Al Viro
Browse files

namei: allow nd_jump_link() to produce errors 



In preparation for LOOKUP_NO_MAGICLINKS, it's necessary to add the
ability for nd_jump_link() to return an error which the corresponding
get_link() caller must propogate back up to the VFS.

Suggested-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
Signed-off-by: default avatarAleksa Sarai <cyphar@cyphar.com>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent ce623f89

fs/namei.c

+2 −1
Original line number Diff line number Diff line
@@ -859,7 +859,7 @@ static int nd_jump_root(struct nameidata *nd) 
 * Helper to directly jump to a known parsed path from ->get_link,

 * caller must have taken a reference to path beforehand.

 */

void nd_jump_link(struct path *path)

int nd_jump_link(struct path *path)

{

	struct nameidata *nd = current->nameidata;

	path_put(&nd->path);
@@ -867,6 +867,7 @@ void nd_jump_link(struct path *path) 
	nd->path = *path;

	nd->inode = nd->path.dentry->d_inode;

	nd->flags |= LOOKUP_JUMPED;

	return 0;

}



static inline void put_link(struct nameidata *nd)

fs/proc/base.c

+1 −2
Original line number Diff line number Diff line
@@ -1626,8 +1626,7 @@ static const char *proc_pid_get_link(struct dentry *dentry, 
	if (error)

		goto out;



	nd_jump_link(&path);

	return NULL;

	error = nd_jump_link(&path);

out:

	return ERR_PTR(error);

}

fs/proc/namespaces.c

+9 −5
Original line number Diff line number Diff line
@@ -51,11 +51,15 @@ static const char *proc_ns_get_link(struct dentry *dentry, 
	if (!task)

		return ERR_PTR(-EACCES);



	if (ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS)) {

	if (!ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS))

		goto out;



	error = ns_get_path(&ns_path, task, ns_ops);

		if (!error)

			nd_jump_link(&ns_path);

	}

	if (error)

		goto out;



	error = nd_jump_link(&ns_path);

out:

	put_task_struct(task);

	return ERR_PTR(error);

}

include/linux/namei.h

+1 −1
Original line number Diff line number Diff line
@@ -69,7 +69,7 @@ extern int follow_up(struct path *); 
extern struct dentry *lock_rename(struct dentry *, struct dentry *);

extern void unlock_rename(struct dentry *, struct dentry *);



extern void nd_jump_link(struct path *path);

extern int __must_check nd_jump_link(struct path *path);



static inline void nd_terminate_link(void *name, size_t len, size_t maxlen)

{

security/apparmor/apparmorfs.c

+4 −2
Original line number Diff line number Diff line
@@ -2573,16 +2573,18 @@ static const char *policy_get_link(struct dentry *dentry, 
{

	struct aa_ns *ns;

	struct path path;

	int error;



	if (!dentry)

		return ERR_PTR(-ECHILD);



	ns = aa_get_current_ns();

	path.mnt = mntget(aafs_mnt);

	path.dentry = dget(ns_dir(ns));

	nd_jump_link(&path);

	error = nd_jump_link(&path);

	aa_put_ns(ns);



	return NULL;

	return ERR_PTR(error);

}



static int policy_readlink(struct dentry *dentry, char __user *buffer,