1// SPDX-License-Identifier: GPL-2.0
2/*
3 *  linux/fs/ext4/symlink.c
4 *
5 * Only fast symlinks left here - the rest is done by generic code. AV, 1999
6 *
7 * Copyright (C) 1992, 1993, 1994, 1995
8 * Remy Card (card@masi.ibp.fr)
9 * Laboratoire MASI - Institut Blaise Pascal
10 * Universite Pierre et Marie Curie (Paris VI)
11 *
12 *  from
13 *
14 *  linux/fs/minix/symlink.c
15 *
16 *  Copyright (C) 1991, 1992  Linus Torvalds
17 *
18 *  ext4 symlink handling code
19 */
20
21#include <linux/fs.h>
22#include <linux/namei.h>
23#include "ext4.h"
24#include "xattr.h"
25
26static const char *ext4_encrypted_get_link(struct dentry *dentry,
27					   struct inode *inode,
28					   struct delayed_call *done)
29{
30	struct buffer_head *bh = NULL;
31	const void *caddr;
32	unsigned int max_size;
33	const char *paddr;
34
35	if (!dentry)
36		return ERR_PTR(-ECHILD);
37
38	if (ext4_inode_is_fast_symlink(inode)) {
39		caddr = EXT4_I(inode)->i_data;
40		max_size = sizeof(EXT4_I(inode)->i_data);
41	} else {
42		bh = ext4_bread(NULL, inode, 0, 0);
43		if (IS_ERR(bh))
44			return ERR_CAST(bh);
45		if (!bh) {
46			EXT4_ERROR_INODE(inode, "bad symlink.");
47			return ERR_PTR(-EFSCORRUPTED);
48		}
49		caddr = bh->b_data;
50		max_size = inode->i_sb->s_blocksize;
51	}
52
53	paddr = fscrypt_get_symlink(inode, caddr, max_size, done);
54	brelse(bh);
55	return paddr;
56}
57
58static int ext4_encrypted_symlink_getattr(struct mnt_idmap *idmap,
59					  const struct path *path,
60					  struct kstat *stat, u32 request_mask,
61					  unsigned int query_flags)
62{
63	ext4_getattr(idmap, path, stat, request_mask, query_flags);
64
65	return fscrypt_symlink_getattr(path, stat);
66}
67
68static void ext4_free_link(void *bh)
69{
70	brelse(bh);
71}
72
73static const char *ext4_get_link(struct dentry *dentry, struct inode *inode,
74				 struct delayed_call *callback)
75{
76	struct buffer_head *bh;
77	char *inline_link;
78
79	/*
80	 * Create a new inlined symlink is not supported, just provide a
81	 * method to read the leftovers.
82	 */
83	if (ext4_has_inline_data(inode)) {
84		if (!dentry)
85			return ERR_PTR(-ECHILD);
86
87		inline_link = ext4_read_inline_link(inode);
88		if (!IS_ERR(inline_link))
89			set_delayed_call(callback, kfree_link, inline_link);
90		return inline_link;
91	}
92
93	if (!dentry) {
94		bh = ext4_getblk(NULL, inode, 0, EXT4_GET_BLOCKS_CACHED_NOWAIT);
95		if (IS_ERR(bh) || !bh)
96			return ERR_PTR(-ECHILD);
97		if (!ext4_buffer_uptodate(bh)) {
98			brelse(bh);
99			return ERR_PTR(-ECHILD);
100		}
101	} else {
102		bh = ext4_bread(NULL, inode, 0, 0);
103		if (IS_ERR(bh))
104			return ERR_CAST(bh);
105		if (!bh) {
106			EXT4_ERROR_INODE(inode, "bad symlink.");
107			return ERR_PTR(-EFSCORRUPTED);
108		}
109	}
110
111	set_delayed_call(callback, ext4_free_link, bh);
112	nd_terminate_link(bh->b_data, inode->i_size,
113			  inode->i_sb->s_blocksize - 1);
114	return bh->b_data;
115}
116
117const struct inode_operations ext4_encrypted_symlink_inode_operations = {
118	.get_link	= ext4_encrypted_get_link,
119	.setattr	= ext4_setattr,
120	.getattr	= ext4_encrypted_symlink_getattr,
121	.listxattr	= ext4_listxattr,
122};
123
124const struct inode_operations ext4_symlink_inode_operations = {
125	.get_link	= ext4_get_link,
126	.setattr	= ext4_setattr,
127	.getattr	= ext4_getattr,
128	.listxattr	= ext4_listxattr,
129};
130
131const struct inode_operations ext4_fast_symlink_inode_operations = {
132	.get_link	= simple_get_link,
133	.setattr	= ext4_setattr,
134	.getattr	= ext4_getattr,
135	.listxattr	= ext4_listxattr,
136};
137