summaryrefslogtreecommitdiff
path: root/fs/ext4/symlink.c
blob: 19f78f20975ea723f33e6488750f9645a7ea2d4a (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
/*
 *  linux/fs/ext4/symlink.c
 *
 * Only fast symlinks left here - the rest is done by generic code. AV, 1999
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/symlink.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext4 symlink handling code
 */

#include <linux/fs.h>
#include <linux/namei.h>
#include "ext4.h"
#include "xattr.h"

#ifdef CONFIG_EXT4_FS_ENCRYPTION
static void *ext4_follow_link(struct dentry *dentry, struct nameidata *nd)
{
	struct page *cpage = NULL;
	char *caddr, *paddr = NULL;
	struct ext4_str cstr, pstr;
	struct inode *inode = d_inode(dentry);
	struct ext4_fname_crypto_ctx *ctx = NULL;
	struct ext4_encrypted_symlink_data *sd;
	loff_t size = min_t(loff_t, i_size_read(inode), PAGE_SIZE - 1);
	int res;
	u32 plen, max_size = inode->i_sb->s_blocksize;

	if (!ext4_encrypted_inode(inode))
		return page_follow_link_light(dentry, nd);

	ctx = ext4_get_fname_crypto_ctx(inode, inode->i_sb->s_blocksize);
	if (IS_ERR(ctx))
		return ctx;

	if (ext4_inode_is_fast_symlink(inode)) {
		caddr = (char *) EXT4_I(inode)->i_data;
		max_size = sizeof(EXT4_I(inode)->i_data);
	} else {
		cpage = read_mapping_page(inode->i_mapping, 0, NULL);
		if (IS_ERR(cpage)) {
			ext4_put_fname_crypto_ctx(&ctx);
			return cpage;
		}
		caddr = kmap(cpage);
		caddr[size] = 0;
	}

	/* Symlink is encrypted */
	sd = (struct ext4_encrypted_symlink_data *)caddr;
	cstr.name = sd->encrypted_path;
	cstr.len  = le32_to_cpu(sd->len);
	if ((cstr.len +
	     sizeof(struct ext4_encrypted_symlink_data) - 1) >
	    max_size) {
		/* Symlink data on the disk is corrupted */
		res = -EIO;
		goto errout;
	}
	plen = (cstr.len < EXT4_FNAME_CRYPTO_DIGEST_SIZE*2) ?
		EXT4_FNAME_CRYPTO_DIGEST_SIZE*2 : cstr.len;
	paddr = kmalloc(plen + 1, GFP_NOFS);
	if (!paddr) {
		res = -ENOMEM;
		goto errout;
	}
	pstr.name = paddr;
	res = _ext4_fname_disk_to_usr(ctx, &cstr, &pstr);
	if (res < 0)
		goto errout;
	/* Null-terminate the name */
	if (res <= plen)
		paddr[res] = '\0';
	nd_set_link(nd, paddr);
	ext4_put_fname_crypto_ctx(&ctx);
	if (cpage) {
		kunmap(cpage);
		page_cache_release(cpage);
	}
	return NULL;
errout:
	ext4_put_fname_crypto_ctx(&ctx);
	if (cpage) {
		kunmap(cpage);
		page_cache_release(cpage);
	}
	kfree(paddr);
	return ERR_PTR(res);
}

static void ext4_put_link(struct dentry *dentry, struct nameidata *nd,
			  void *cookie)
{
	struct page *page = cookie;

	if (!page) {
		kfree(nd_get_link(nd));
	} else {
		kunmap(page);
		page_cache_release(page);
	}
}
#endif

static void *ext4_follow_fast_link(struct dentry *dentry, struct nameidata *nd)
{
	struct ext4_inode_info *ei = EXT4_I(d_inode(dentry));
	nd_set_link(nd, (char *) ei->i_data);
	return NULL;
}

const struct inode_operations ext4_symlink_inode_operations = {
	.readlink	= generic_readlink,
#ifdef CONFIG_EXT4_FS_ENCRYPTION
	.follow_link    = ext4_follow_link,
	.put_link       = ext4_put_link,
#else
	.follow_link	= page_follow_link_light,
	.put_link	= page_put_link,
#endif
	.setattr	= ext4_setattr,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= ext4_listxattr,
	.removexattr	= generic_removexattr,
};

const struct inode_operations ext4_fast_symlink_inode_operations = {
	.readlink	= generic_readlink,
	.follow_link    = ext4_follow_fast_link,
	.setattr	= ext4_setattr,
	.setxattr	= generic_setxattr,
	.getxattr	= generic_getxattr,
	.listxattr	= ext4_listxattr,
	.removexattr	= generic_removexattr,
};