Commit 8df9d1a4 authored by Miklos Szeredi's avatar Miklos Szeredi Committed by Al Viro
Browse files

vfs: show unreachable paths in getcwd and proc 



Prepend "(unreachable)" to path strings if the path is not reachable
from the current root.

Two places updated are
 - the return string from getcwd()
 - and symlinks under /proc/$PID.

Other uses of d_path() are left unchanged (we know that some old
software crashes if /proc/mounts is changed).

Signed-off-by: default avatarMiklos Szeredi <mszeredi@suse.cz>
Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent ffd1f4ed

fs/dcache.c

+50 −4
Original line number Diff line number Diff line
@@ -2019,6 +2019,11 @@ static int path_with_deleted(const struct path *path, struct path *root, 
	return prepend_path(path, root, buf, buflen);

}



static int prepend_unreachable(char **buffer, int *buflen)

{

	return prepend(buffer, buflen, "(unreachable)", 13);

}



/**

 * d_path - return the path of a dentry

 * @path: path to report
@@ -2064,6 +2069,39 @@ char *d_path(const struct path *path, char *buf, int buflen) 
}

EXPORT_SYMBOL(d_path);



/**

 * d_path_with_unreachable - return the path of a dentry

 * @path: path to report

 * @buf: buffer to return value in

 * @buflen: buffer length

 *

 * The difference from d_path() is that this prepends "(unreachable)"

 * to paths which are unreachable from the current process' root.

 */

char *d_path_with_unreachable(const struct path *path, char *buf, int buflen)

{

	char *res = buf + buflen;

	struct path root;

	struct path tmp;

	int error;



	if (path->dentry->d_op && path->dentry->d_op->d_dname)

		return path->dentry->d_op->d_dname(path->dentry, buf, buflen);



	get_fs_root(current->fs, &root);

	spin_lock(&dcache_lock);

	tmp = root;

	error = path_with_deleted(path, &tmp, &res, &buflen);

	if (!error && !path_equal(&tmp, &root))

		error = prepend_unreachable(&res, &buflen);

	spin_unlock(&dcache_lock);

	path_put(&root);

	if (error)

		res =  ERR_PTR(error);



	return res;

}



/*

 * Helper function for dentry_operations.d_dname() members

 */
@@ -2173,14 +2211,22 @@ SYSCALL_DEFINE2(getcwd, char __user *, buf, unsigned long, size) 
	if (!d_unlinked(pwd.dentry)) {

		unsigned long len;

		struct path tmp = root;

		char * cwd;

		char *cwd = page + PAGE_SIZE;

		int buflen = PAGE_SIZE;



		cwd = __d_path(&pwd, &tmp, page, PAGE_SIZE);

		prepend(&cwd, &buflen, "\0", 1);

		error = prepend_path(&pwd, &tmp, &cwd, &buflen);

		spin_unlock(&dcache_lock);



		error = PTR_ERR(cwd);

		if (IS_ERR(cwd))

		if (error)

			goto out;



		/* Unreachable from current root */

		if (!path_equal(&tmp, &root)) {

			error = prepend_unreachable(&cwd, &buflen);

			if (error)

				goto out;

		}



		error = -ERANGE;

		len = PAGE_SIZE + page - cwd;

fs/proc/base.c

+1 −1
Original line number Diff line number Diff line
@@ -1526,7 +1526,7 @@ static int do_proc_readlink(struct path *path, char __user *buffer, int buflen) 
	if (!tmp)

		return -ENOMEM;



	pathname = d_path(path, tmp, PAGE_SIZE);

	pathname = d_path_with_unreachable(path, tmp, PAGE_SIZE);

	len = PTR_ERR(pathname);

	if (IS_ERR(pathname))

		goto out;

include/linux/dcache.h

+1 −0
Original line number Diff line number Diff line
@@ -315,6 +315,7 @@ extern char *dynamic_dname(struct dentry *, char *, int, const char *, ...); 


extern char *__d_path(const struct path *path, struct path *root, char *, int);

extern char *d_path(const struct path *, char *, int);

extern char *d_path_with_unreachable(const struct path *, char *, int);

extern char *__dentry_path(struct dentry *, char *, int);

extern char *dentry_path(struct dentry *, char *, int);

include/linux/path.h

+5 −0
Original line number Diff line number Diff line
@@ -12,4 +12,9 @@ struct path { 
extern void path_get(struct path *);

extern void path_put(struct path *);



static inline int path_equal(const struct path *path1, const struct path *path2)

{

	return path1->mnt == path2->mnt && path1->dentry == path2->dentry;

}



#endif  /* _LINUX_PATH_H */

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