1 /*
2 * linux/fs/ncpfs/symlink.c
3 *
4 * Code for allowing symbolic links on NCPFS (i.e. NetWare)
5 * Symbolic links are not supported on native NetWare, so we use an
6 * infrequently-used flag (Sh) and store a two-word magic header in
7 * the file to make sure we don't accidentally use a non-link file
8 * as a link.
9 *
10 * When using the NFS namespace, we set the mode to indicate a symlink and
11 * don't bother with the magic numbers.
12 *
13 * from linux/fs/ext2/symlink.c
14 *
15 * Copyright (C) 1998-99, Frank A. Vorstenbosch
16 *
17 * ncpfs symlink handling code
18 * NLS support (c) 1999 Petr Vandrovec
19 * Modified 2000 Ben Harris, University of Cambridge for NFS NS meta-info
20 *
21 */
22
23
24 #include <asm/uaccess.h>
25
26 #include <linux/errno.h>
27 #include <linux/fs.h>
28 #include <linux/time.h>
29 #include <linux/slab.h>
30 #include <linux/mm.h>
31 #include <linux/stat.h>
32 #include "ncp_fs.h"
33
34 /* these magic numbers must appear in the symlink file -- this makes it a bit
35 more resilient against the magic attributes being set on random files. */
36
37 #define NCP_SYMLINK_MAGIC0 cpu_to_le32(0x6c6d7973) /* "symlnk->" */
38 #define NCP_SYMLINK_MAGIC1 cpu_to_le32(0x3e2d6b6e)
39
40 /* ----- read a symbolic link ------------------------------------------ */
41
ncp_symlink_readpage(struct file * file,struct page * page)42 static int ncp_symlink_readpage(struct file *file, struct page *page)
43 {
44 struct inode *inode = page->mapping->host;
45 int error, length, len;
46 char *link, *rawlink;
47 char *buf = kmap(page);
48
49 error = -ENOMEM;
50 rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
51 if (!rawlink)
52 goto fail;
53
54 if (ncp_make_open(inode,O_RDONLY))
55 goto failEIO;
56
57 error=ncp_read_kernel(NCP_SERVER(inode),NCP_FINFO(inode)->file_handle,
58 0,NCP_MAX_SYMLINK_SIZE,rawlink,&length);
59
60 ncp_inode_close(inode);
61 /* Close file handle if no other users... */
62 ncp_make_closed(inode);
63 if (error)
64 goto failEIO;
65
66 if (NCP_FINFO(inode)->flags & NCPI_KLUDGE_SYMLINK) {
67 if (length<NCP_MIN_SYMLINK_SIZE ||
68 ((__le32 *)rawlink)[0]!=NCP_SYMLINK_MAGIC0 ||
69 ((__le32 *)rawlink)[1]!=NCP_SYMLINK_MAGIC1)
70 goto failEIO;
71 link = rawlink + 8;
72 length -= 8;
73 } else {
74 link = rawlink;
75 }
76
77 len = NCP_MAX_SYMLINK_SIZE;
78 error = ncp_vol2io(NCP_SERVER(inode), buf, &len, link, length, 0);
79 kfree(rawlink);
80 if (error)
81 goto fail;
82 SetPageUptodate(page);
83 kunmap(page);
84 unlock_page(page);
85 return 0;
86
87 failEIO:
88 error = -EIO;
89 kfree(rawlink);
90 fail:
91 SetPageError(page);
92 kunmap(page);
93 unlock_page(page);
94 return error;
95 }
96
97 /*
98 * symlinks can't do much...
99 */
100 const struct address_space_operations ncp_symlink_aops = {
101 .readpage = ncp_symlink_readpage,
102 };
103
104 /* ----- create a new symbolic link -------------------------------------- */
105
ncp_symlink(struct inode * dir,struct dentry * dentry,const char * symname)106 int ncp_symlink(struct inode *dir, struct dentry *dentry, const char *symname) {
107 struct inode *inode;
108 char *rawlink;
109 int length, err, i, outlen;
110 int kludge;
111 umode_t mode;
112 __le32 attr;
113 unsigned int hdr;
114
115 ncp_dbg(1, "dir=%p, dentry=%p, symname=%s\n", dir, dentry, symname);
116
117 if (ncp_is_nfs_extras(NCP_SERVER(dir), NCP_FINFO(dir)->volNumber))
118 kludge = 0;
119 else
120 #ifdef CONFIG_NCPFS_EXTRAS
121 if (NCP_SERVER(dir)->m.flags & NCP_MOUNT_SYMLINKS)
122 kludge = 1;
123 else
124 #endif
125 /* EPERM is returned by VFS if symlink procedure does not exist */
126 return -EPERM;
127
128 rawlink = kmalloc(NCP_MAX_SYMLINK_SIZE, GFP_KERNEL);
129 if (!rawlink)
130 return -ENOMEM;
131
132 if (kludge) {
133 mode = 0;
134 attr = aSHARED | aHIDDEN;
135 ((__le32 *)rawlink)[0]=NCP_SYMLINK_MAGIC0;
136 ((__le32 *)rawlink)[1]=NCP_SYMLINK_MAGIC1;
137 hdr = 8;
138 } else {
139 mode = S_IFLNK | S_IRWXUGO;
140 attr = 0;
141 hdr = 0;
142 }
143
144 length = strlen(symname);
145 /* map to/from server charset, do not touch upper/lower case as
146 symlink can point out of ncp filesystem */
147 outlen = NCP_MAX_SYMLINK_SIZE - hdr;
148 err = ncp_io2vol(NCP_SERVER(dir), rawlink + hdr, &outlen, symname, length, 0);
149 if (err)
150 goto failfree;
151
152 outlen += hdr;
153
154 err = -EIO;
155 if (ncp_create_new(dir,dentry,mode,0,attr)) {
156 goto failfree;
157 }
158
159 inode=d_inode(dentry);
160
161 if (ncp_make_open(inode, O_WRONLY))
162 goto failfree;
163
164 if (ncp_write_kernel(NCP_SERVER(inode), NCP_FINFO(inode)->file_handle,
165 0, outlen, rawlink, &i) || i!=outlen) {
166 goto fail;
167 }
168
169 ncp_inode_close(inode);
170 ncp_make_closed(inode);
171 kfree(rawlink);
172 return 0;
173 fail:;
174 ncp_inode_close(inode);
175 ncp_make_closed(inode);
176 failfree:;
177 kfree(rawlink);
178 return err;
179 }
180
181 /* ----- EOF ----- */
182