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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
6d5ae0de IM |
2 | /* |
3 | * Contains the CIFS DFS referral mounting routines used for handling | |
4 | * traversal via DFS junction point | |
5 | * | |
6 | * Copyright (c) 2007 Igor Mammedov | |
366781c1 | 7 | * Copyright (C) International Business Machines Corp., 2008 |
6d5ae0de | 8 | * Author(s): Igor Mammedov (niallain@gmail.com) |
366781c1 | 9 | * Steve French (sfrench@us.ibm.com) |
6d5ae0de IM |
10 | */ |
11 | ||
12 | #include <linux/dcache.h> | |
13 | #include <linux/mount.h> | |
14 | #include <linux/namei.h> | |
5a0e3ad6 | 15 | #include <linux/slab.h> |
6d5ae0de IM |
16 | #include <linux/vfs.h> |
17 | #include <linux/fs.h> | |
166faf21 | 18 | #include <linux/inet.h> |
6d5ae0de IM |
19 | #include "cifsglob.h" |
20 | #include "cifsproto.h" | |
21 | #include "cifsfs.h" | |
22 | #include "dns_resolve.h" | |
23 | #include "cifs_debug.h" | |
7ad54b98 | 24 | #include "dfs.h" |
a2a52a8a | 25 | #include "fs_context.h" |
6d5ae0de | 26 | |
8d142137 | 27 | static LIST_HEAD(cifs_dfs_automount_list); |
6d5ae0de | 28 | |
78d31a3a IM |
29 | static void cifs_dfs_expire_automounts(struct work_struct *work); |
30 | static DECLARE_DELAYED_WORK(cifs_dfs_automount_task, | |
31 | cifs_dfs_expire_automounts); | |
32 | static int cifs_dfs_mountpoint_expiry_timeout = 500 * HZ; | |
33 | ||
34 | static void cifs_dfs_expire_automounts(struct work_struct *work) | |
35 | { | |
36 | struct list_head *list = &cifs_dfs_automount_list; | |
37 | ||
38 | mark_mounts_for_expiry(list); | |
39 | if (!list_empty(list)) | |
40 | schedule_delayed_work(&cifs_dfs_automount_task, | |
41 | cifs_dfs_mountpoint_expiry_timeout); | |
42 | } | |
6d5ae0de | 43 | |
78d31a3a | 44 | void cifs_dfs_release_automount_timer(void) |
6d5ae0de | 45 | { |
78d31a3a | 46 | BUG_ON(!list_empty(&cifs_dfs_automount_list)); |
3e24e132 | 47 | cancel_delayed_work_sync(&cifs_dfs_automount_task); |
6d5ae0de IM |
48 | } |
49 | ||
50 | /** | |
d9deef0a JL |
51 | * cifs_build_devname - build a devicename from a UNC and optional prepath |
52 | * @nodename: pointer to UNC string | |
53 | * @prepath: pointer to prefixpath (or NULL if there isn't one) | |
6d5ae0de | 54 | * |
d9deef0a JL |
55 | * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer |
56 | * big enough to hold the final thing. Copy the UNC from the nodename, and | |
57 | * concatenate the prepath onto the end of it if there is one. | |
58 | * | |
59 | * Returns pointer to the built string, or a ERR_PTR. Caller is responsible | |
60 | * for freeing the returned string. | |
6d5ae0de | 61 | */ |
abdb1742 | 62 | char * |
d9deef0a | 63 | cifs_build_devname(char *nodename, const char *prepath) |
6d5ae0de | 64 | { |
d9deef0a JL |
65 | size_t pplen; |
66 | size_t unclen; | |
67 | char *dev; | |
68 | char *pos; | |
6d5ae0de | 69 | |
d9deef0a JL |
70 | /* skip over any preceding delimiters */ |
71 | nodename += strspn(nodename, "\\"); | |
72 | if (!*nodename) | |
7b91e266 | 73 | return ERR_PTR(-EINVAL); |
d9deef0a JL |
74 | |
75 | /* get length of UNC and set pos to last char */ | |
76 | unclen = strlen(nodename); | |
77 | pos = nodename + unclen - 1; | |
78 | ||
79 | /* trim off any trailing delimiters */ | |
80 | while (*pos == '\\') { | |
81 | --pos; | |
82 | --unclen; | |
6d5ae0de IM |
83 | } |
84 | ||
d9deef0a JL |
85 | /* allocate a buffer: |
86 | * +2 for preceding "//" | |
87 | * +1 for delimiter between UNC and prepath | |
88 | * +1 for trailing NULL | |
89 | */ | |
90 | pplen = prepath ? strlen(prepath) : 0; | |
91 | dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL); | |
92 | if (!dev) | |
93 | return ERR_PTR(-ENOMEM); | |
94 | ||
95 | pos = dev; | |
96 | /* add the initial "//" */ | |
97 | *pos = '/'; | |
98 | ++pos; | |
99 | *pos = '/'; | |
100 | ++pos; | |
101 | ||
102 | /* copy in the UNC portion from referral */ | |
103 | memcpy(pos, nodename, unclen); | |
104 | pos += unclen; | |
105 | ||
106 | /* copy the prefixpath remainder (if there is one) */ | |
107 | if (pplen) { | |
108 | *pos = '/'; | |
109 | ++pos; | |
110 | memcpy(pos, prepath, pplen); | |
111 | pos += pplen; | |
6d5ae0de | 112 | } |
6d5ae0de | 113 | |
d9deef0a JL |
114 | /* NULL terminator */ |
115 | *pos = '\0'; | |
116 | ||
117 | convert_delimiter(dev, '/'); | |
118 | return dev; | |
6d5ae0de IM |
119 | } |
120 | ||
7ad54b98 PA |
121 | static int set_dest_addr(struct smb3_fs_context *ctx, const char *full_path) |
122 | { | |
123 | struct sockaddr *addr = (struct sockaddr *)&ctx->dstaddr; | |
124 | int rc; | |
125 | ||
126 | rc = dns_resolve_server_name_to_ip(full_path, addr, NULL); | |
127 | if (!rc) | |
128 | cifs_set_port(addr, ctx->port); | |
129 | return rc; | |
130 | } | |
131 | ||
01c64fea DH |
132 | /* |
133 | * Create a vfsmount that we can automount | |
134 | */ | |
9fd29a5b | 135 | static struct vfsmount *cifs_dfs_do_automount(struct path *path) |
6d5ae0de | 136 | { |
9fd29a5b PA |
137 | int rc; |
138 | struct dentry *mntpt = path->dentry; | |
139 | struct fs_context *fc; | |
6d5ae0de | 140 | struct cifs_sb_info *cifs_sb; |
9fd29a5b PA |
141 | void *page = NULL; |
142 | struct smb3_fs_context *ctx, *cur_ctx; | |
143 | struct smb3_fs_context tmp; | |
c88f7dcd | 144 | char *full_path; |
01c64fea | 145 | struct vfsmount *mnt; |
6d5ae0de | 146 | |
9fd29a5b PA |
147 | if (IS_ROOT(mntpt)) |
148 | return ERR_PTR(-ESTALE); | |
6d5ae0de | 149 | |
c6fbba05 SF |
150 | /* |
151 | * The MSDFS spec states that paths in DFS referral requests and | |
152 | * responses must be prefixed by a single '\' character instead of | |
153 | * the double backslashes usually used in the UNC. This function | |
154 | * gives us the latter, so we must adjust the result. | |
155 | */ | |
8393072b | 156 | cifs_sb = CIFS_SB(mntpt->d_sb); |
9fd29a5b PA |
157 | if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_NO_DFS) |
158 | return ERR_PTR(-EREMOTE); | |
159 | ||
160 | cur_ctx = cifs_sb->ctx; | |
161 | ||
162 | fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, mntpt); | |
163 | if (IS_ERR(fc)) | |
164 | return ERR_CAST(fc); | |
165 | ||
166 | ctx = smb3_fc2context(fc); | |
8393072b | 167 | |
f6a9bc33 | 168 | page = alloc_dentry_path(); |
7ad54b98 | 169 | full_path = dfs_get_automount_devname(mntpt, page); |
f6a9bc33 AV |
170 | if (IS_ERR(full_path)) { |
171 | mnt = ERR_CAST(full_path); | |
9fd29a5b | 172 | goto out; |
f6a9bc33 | 173 | } |
1c780228 PA |
174 | cifs_dbg(FYI, "%s: full_path: %s\n", __func__, full_path); |
175 | ||
9fd29a5b PA |
176 | tmp = *cur_ctx; |
177 | tmp.source = full_path; | |
7ad54b98 | 178 | tmp.leaf_fullpath = NULL; |
9fd29a5b | 179 | tmp.UNC = tmp.prepath = NULL; |
b56bce50 | 180 | tmp.dfs_root_ses = NULL; |
9fd29a5b PA |
181 | |
182 | rc = smb3_fs_context_dup(ctx, &tmp); | |
183 | if (rc) { | |
184 | mnt = ERR_PTR(rc); | |
185 | goto out; | |
186 | } | |
187 | ||
7ad54b98 PA |
188 | rc = set_dest_addr(ctx, full_path); |
189 | if (rc) { | |
190 | mnt = ERR_PTR(rc); | |
191 | goto out; | |
192 | } | |
193 | ||
9fd29a5b PA |
194 | rc = smb3_parse_devname(full_path, ctx); |
195 | if (!rc) | |
196 | mnt = fc_mount(fc); | |
197 | else | |
198 | mnt = ERR_PTR(rc); | |
1c780228 | 199 | |
9fd29a5b PA |
200 | out: |
201 | put_fs_context(fc); | |
f6a9bc33 | 202 | free_dentry_path(page); |
01c64fea DH |
203 | return mnt; |
204 | } | |
205 | ||
206 | /* | |
207 | * Attempt to automount the referral | |
208 | */ | |
209 | struct vfsmount *cifs_dfs_d_automount(struct path *path) | |
210 | { | |
211 | struct vfsmount *newmnt; | |
01c64fea | 212 | |
9fd29a5b | 213 | cifs_dbg(FYI, "%s: %pd\n", __func__, path->dentry); |
01c64fea | 214 | |
9fd29a5b | 215 | newmnt = cifs_dfs_do_automount(path); |
01c64fea | 216 | if (IS_ERR(newmnt)) { |
f96637be | 217 | cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__); |
01c64fea DH |
218 | return newmnt; |
219 | } | |
220 | ||
ea5b778a DH |
221 | mntget(newmnt); /* prevent immediate expiration */ |
222 | mnt_set_expiry(newmnt, &cifs_dfs_automount_list); | |
223 | schedule_delayed_work(&cifs_dfs_automount_task, | |
224 | cifs_dfs_mountpoint_expiry_timeout); | |
f96637be | 225 | cifs_dbg(FYI, "leaving %s [ok]\n" , __func__); |
ea5b778a | 226 | return newmnt; |
6d5ae0de IM |
227 | } |
228 | ||
6e1d5dcc | 229 | const struct inode_operations cifs_dfs_referral_inode_operations = { |
6d5ae0de | 230 | }; |