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Dave Kleikampac27a0e2006-10-11 01:20:50 -07001/*
Mingming Cao617ba132006-10-11 01:20:53 -07002 * linux/fs/ext4/symlink.c
Dave Kleikampac27a0e2006-10-11 01:20:50 -07003 *
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 *
Mingming Cao617ba132006-10-11 01:20:53 -070017 * ext4 symlink handling code
Dave Kleikampac27a0e2006-10-11 01:20:50 -070018 */
19
20#include <linux/fs.h>
Dave Kleikampac27a0e2006-10-11 01:20:50 -070021#include <linux/namei.h>
Christoph Hellwig3dcf5452008-04-29 18:13:32 -040022#include "ext4.h"
Dave Kleikampac27a0e2006-10-11 01:20:50 -070023#include "xattr.h"
24
Theodore Ts'of348c252015-04-16 01:55:00 -040025#ifdef CONFIG_EXT4_FS_ENCRYPTION
Linus Torvaldsd857da72015-06-25 14:06:55 -070026static const char *ext4_encrypted_follow_link(struct dentry *dentry, void **cookie)
Dave Kleikampac27a0e2006-10-11 01:20:50 -070027{
Theodore Ts'of348c252015-04-16 01:55:00 -040028 struct page *cpage = NULL;
29 char *caddr, *paddr = NULL;
30 struct ext4_str cstr, pstr;
Linus Torvalds9ec3a642015-04-26 15:48:49 -070031 struct inode *inode = d_inode(dentry);
Theodore Ts'of348c252015-04-16 01:55:00 -040032 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
Theodore Ts'oc936e1e2015-05-31 13:34:22 -040037 res = ext4_get_encryption_info(inode);
Theodore Ts'ob7236e22015-05-18 13:17:47 -040038 if (res)
39 return ERR_PTR(res);
Theodore Ts'of348c252015-04-16 01:55:00 -040040
41 if (ext4_inode_is_fast_symlink(inode)) {
Linus Torvalds9ec3a642015-04-26 15:48:49 -070042 caddr = (char *) EXT4_I(inode)->i_data;
43 max_size = sizeof(EXT4_I(inode)->i_data);
Theodore Ts'of348c252015-04-16 01:55:00 -040044 } else {
45 cpage = read_mapping_page(inode->i_mapping, 0, NULL);
Theodore Ts'ob7236e22015-05-18 13:17:47 -040046 if (IS_ERR(cpage))
Al Viro680baac2015-05-02 13:32:22 -040047 return ERR_CAST(cpage);
Theodore Ts'of348c252015-04-16 01:55:00 -040048 caddr = kmap(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 = le32_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 = -EIO;
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;
Theodore Ts'od2299592015-05-18 13:15:47 -040071 pstr.len = plen;
Theodore Ts'ob7236e22015-05-18 13:17:47 -040072 res = _ext4_fname_disk_to_usr(inode, NULL, &cstr, &pstr);
Theodore Ts'of348c252015-04-16 01:55:00 -040073 if (res < 0)
74 goto errout;
75 /* Null-terminate the name */
76 if (res <= plen)
77 paddr[res] = '\0';
Theodore Ts'of348c252015-04-16 01:55:00 -040078 if (cpage) {
79 kunmap(cpage);
80 page_cache_release(cpage);
81 }
Al Viro680baac2015-05-02 13:32:22 -040082 return *cookie = paddr;
Theodore Ts'of348c252015-04-16 01:55:00 -040083errout:
Theodore Ts'of348c252015-04-16 01:55:00 -040084 if (cpage) {
85 kunmap(cpage);
86 page_cache_release(cpage);
87 }
88 kfree(paddr);
89 return ERR_PTR(res);
90}
91
Al Viroa7a67e82015-04-27 17:51:30 -040092const struct inode_operations ext4_encrypted_symlink_inode_operations = {
93 .readlink = generic_readlink,
Linus Torvaldsd857da72015-06-25 14:06:55 -070094 .follow_link = ext4_encrypted_follow_link,
Al Viroa7a67e82015-04-27 17:51:30 -040095 .put_link = kfree_put_link,
96 .setattr = ext4_setattr,
97 .setxattr = generic_setxattr,
98 .getxattr = generic_getxattr,
99 .listxattr = ext4_listxattr,
100 .removexattr = generic_removexattr,
101};
Theodore Ts'of348c252015-04-16 01:55:00 -0400102#endif
103
Arjan van de Ven754661f2007-02-12 00:55:38 -0800104const struct inode_operations ext4_symlink_inode_operations = {
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700105 .readlink = generic_readlink,
106 .follow_link = page_follow_link_light,
107 .put_link = page_put_link,
Dmitry Monakhov256a4532010-05-16 02:00:00 -0400108 .setattr = ext4_setattr,
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700109 .setxattr = generic_setxattr,
110 .getxattr = generic_getxattr,
Mingming Cao617ba132006-10-11 01:20:53 -0700111 .listxattr = ext4_listxattr,
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700112 .removexattr = generic_removexattr,
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700113};
114
Arjan van de Ven754661f2007-02-12 00:55:38 -0800115const struct inode_operations ext4_fast_symlink_inode_operations = {
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700116 .readlink = generic_readlink,
Al Viro75e75662015-05-02 10:13:58 -0400117 .follow_link = simple_follow_link,
Dmitry Monakhov256a4532010-05-16 02:00:00 -0400118 .setattr = ext4_setattr,
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700119 .setxattr = generic_setxattr,
120 .getxattr = generic_getxattr,
Mingming Cao617ba132006-10-11 01:20:53 -0700121 .listxattr = ext4_listxattr,
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700122 .removexattr = generic_removexattr,
Dave Kleikampac27a0e2006-10-11 01:20:50 -0700123};