1 /*
2 * linux/fs/ext4/symlink.c
3 *
4 * Only fast symlinks left here - the rest is done by generic code. AV, 1999
5 *
6 * Copyright (C) 1992, 1993, 1994, 1995
7 * Remy Card (card@masi.ibp.fr)
8 * Laboratoire MASI - Institut Blaise Pascal
9 * Universite Pierre et Marie Curie (Paris VI)
10 *
11 * from
12 *
13 * linux/fs/minix/symlink.c
14 *
15 * Copyright (C) 1991, 1992 Linus Torvalds
16 *
17 * ext4 symlink handling code
18 */
19
20 #include <linux/fs.h>
21 #include <linux/namei.h>
22 #include "ext4.h"
23 #include "xattr.h"
24
25 #ifdef CONFIG_EXT4_FS_ENCRYPTION
ext4_encrypted_follow_link(struct dentry * dentry,void ** cookie)26 static const char *ext4_encrypted_follow_link(struct dentry *dentry, void **cookie)
27 {
28 struct page *cpage = NULL;
29 char *caddr, *paddr = NULL;
30 struct ext4_str cstr, pstr;
31 struct inode *inode = d_inode(dentry);
32 struct ext4_encrypted_symlink_data *sd;
33 loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
34 int res;
35 u32 plen, max_size = inode->i_sb->s_blocksize;
36
37 res = ext4_get_encryption_info(inode);
38 if (res)
39 return ERR_PTR(res);
40
41 if (ext4_inode_is_fast_symlink(inode)) {
42 caddr = (char *) EXT4_I(inode)->i_data;
43 max_size = sizeof(EXT4_I(inode)->i_data);
44 } else {
45 cpage = read_mapping_page(inode->i_mapping, 0, NULL);
46 if (IS_ERR(cpage))
47 return ERR_CAST(cpage);
48 caddr = page_address(cpage);
49 caddr[size] = 0;
50 }
51
52 /* Symlink is encrypted */
53 sd = (struct ext4_encrypted_symlink_data *)caddr;
54 cstr.name = sd->encrypted_path;
55 cstr.len = le16_to_cpu(sd->len);
56 if ((cstr.len +
57 sizeof(struct ext4_encrypted_symlink_data) - 1) >
58 max_size) {
59 /* Symlink data on the disk is corrupted */
60 res = -EFSCORRUPTED;
61 goto errout;
62 }
63 plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
64 EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
65 paddr = kmalloc(plen + 1, GFP_NOFS);
66 if (!paddr) {
67 res = -ENOMEM;
68 goto errout;
69 }
70 pstr.name = paddr;
71 pstr.len = plen;
72 res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
73 if (res < 0)
74 goto errout;
75 /* Null-terminate the name */
76 if (res <= plen)
77 paddr[res] = '\0';
78 if (cpage)
79 page_cache_release(cpage);
80 return *cookie = paddr;
81 errout:
82 if (cpage)
83 page_cache_release(cpage);
84 kfree(paddr);
85 return ERR_PTR(res);
86 }
87
88 const struct inode_operations ext4_encrypted_symlink_inode_operations = {
89 .readlink = generic_readlink,
90 .follow_link = ext4_encrypted_follow_link,
91 .put_link = kfree_put_link,
92 .setattr = ext4_setattr,
93 .setxattr = generic_setxattr,
94 .getxattr = generic_getxattr,
95 .listxattr = ext4_listxattr,
96 .removexattr = generic_removexattr,
97 };
98 #endif
99
100 const struct inode_operations ext4_symlink_inode_operations = {
101 .readlink = generic_readlink,
102 .follow_link = page_follow_link_light,
103 .put_link = page_put_link,
104 .setattr = ext4_setattr,
105 .setxattr = generic_setxattr,
106 .getxattr = generic_getxattr,
107 .listxattr = ext4_listxattr,
108 .removexattr = generic_removexattr,
109 };
110
111 const struct inode_operations ext4_fast_symlink_inode_operations = {
112 .readlink = generic_readlink,
113 .follow_link = simple_follow_link,
114 .setattr = ext4_setattr,
115 .setxattr = generic_setxattr,
116 .getxattr = generic_getxattr,
117 .listxattr = ext4_listxattr,
118 .removexattr = generic_removexattr,
119 };
120