xref: /openbmc/linux/fs/ext4/symlink.c (revision b74d24f7)
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 
ext4_encrypted_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * done)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 
ext4_encrypted_symlink_getattr(struct mnt_idmap * idmap,const struct path * path,struct kstat * stat,u32 request_mask,unsigned int query_flags)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 
ext4_free_link(void * bh)68 static void ext4_free_link(void *bh)
69 {
70 	brelse(bh);
71 }
72 
ext4_get_link(struct dentry * dentry,struct inode * inode,struct delayed_call * callback)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 };
135