3d3ed3c38f5644a0e872b1474cf90bf2afd70219
[releases.git] / symlink.c
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 user_namespace *mnt_userns,
59                                           const struct path *path,
60                                           struct kstat *stat, u32 request_mask,
61                                           unsigned int query_flags)
62 {
63         ext4_getattr(mnt_userns, 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))
96                         return ERR_CAST(bh);
97                 if (!bh || !ext4_buffer_uptodate(bh))
98                         return ERR_PTR(-ECHILD);
99         } else {
100                 bh = ext4_bread(NULL, inode, 0, 0);
101                 if (IS_ERR(bh))
102                         return ERR_CAST(bh);
103                 if (!bh) {
104                         EXT4_ERROR_INODE(inode, "bad symlink.");
105                         return ERR_PTR(-EFSCORRUPTED);
106                 }
107         }
108
109         set_delayed_call(callback, ext4_free_link, bh);
110         nd_terminate_link(bh->b_data, inode->i_size,
111                           inode->i_sb->s_blocksize - 1);
112         return bh->b_data;
113 }
114
115 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
116         .get_link       = ext4_encrypted_get_link,
117         .setattr        = ext4_setattr,
118         .getattr        = ext4_encrypted_symlink_getattr,
119         .listxattr      = ext4_listxattr,
120 };
121
122 const struct inode_operations ext4_symlink_inode_operations = {
123         .get_link       = ext4_get_link,
124         .setattr        = ext4_setattr,
125         .getattr        = ext4_getattr,
126         .listxattr      = ext4_listxattr,
127 };
128
129 const struct inode_operations ext4_fast_symlink_inode_operations = {
130         .get_link       = simple_get_link,
131         .setattr        = ext4_setattr,
132         .getattr        = ext4_getattr,
133         .listxattr      = ext4_listxattr,
134 };