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
26 static 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
58 static 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
68 static void ext4_free_link(void *bh)
69 {
70 brelse(bh);
71 }
72
73 static 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
117 const 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
124 const 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
131 const 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
Linux® is a registered trademark of Linus Torvalds in the United States and other countries.
TOMOYO® is a registered trademark of NTT DATA CORPORATION.