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1/*
2 * V9FS FID Management
3 *
4 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
5 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
6 *
7 * This program is free software; you can redistribute it and/or modify
8 * it under the terms of the GNU General Public License version 2
9 * as published by the Free Software Foundation.
10 *
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
15 *
16 * You should have received a copy of the GNU General Public License
17 * along with this program; if not, write to:
18 * Free Software Foundation
19 * 51 Franklin Street, Fifth Floor
20 * Boston, MA 02111-1301 USA
21 *
22 */
23
24#include <linux/module.h>
25#include <linux/errno.h>
26#include <linux/fs.h>
27#include <linux/slab.h>
28#include <linux/sched.h>
29#include <linux/idr.h>
30#include <net/9p/9p.h>
31#include <net/9p/client.h>
32
33#include "v9fs.h"
34#include "v9fs_vfs.h"
35#include "fid.h"
36
37/**
38 * v9fs_fid_add - add a fid to a dentry
39 * @dentry: dentry that the fid is being added to
40 * @fid: fid to add
41 *
42 */
43
44int v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
45{
46 struct v9fs_dentry *dent;
47
48 P9_DPRINTK(P9_DEBUG_VFS, "fid %d dentry %s\n",
49 fid->fid, dentry->d_name.name);
50
51 dent = dentry->d_fsdata;
52 if (!dent) {
53 dent = kmalloc(sizeof(struct v9fs_dentry), GFP_KERNEL);
54 if (!dent)
55 return -ENOMEM;
56
57 spin_lock_init(&dent->lock);
58 INIT_LIST_HEAD(&dent->fidlist);
59 dentry->d_fsdata = dent;
60 }
61
62 spin_lock(&dent->lock);
63 list_add(&fid->dlist, &dent->fidlist);
64 spin_unlock(&dent->lock);
65
66 return 0;
67}
68
69/**
70 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
71 * @dentry: dentry to look for fid in
72 * @uid: return fid that belongs to the specified user
73 * @any: if non-zero, return any fid associated with the dentry
74 *
75 */
76
77static struct p9_fid *v9fs_fid_find(struct dentry *dentry, u32 uid, int any)
78{
79 struct v9fs_dentry *dent;
80 struct p9_fid *fid, *ret;
81
82 P9_DPRINTK(P9_DEBUG_VFS, " dentry: %s (%p) uid %d any %d\n",
83 dentry->d_name.name, dentry, uid, any);
84 dent = (struct v9fs_dentry *) dentry->d_fsdata;
85 ret = NULL;
86 if (dent) {
87 spin_lock(&dent->lock);
88 list_for_each_entry(fid, &dent->fidlist, dlist) {
89 if (any || fid->uid == uid) {
90 ret = fid;
91 break;
92 }
93 }
94 spin_unlock(&dent->lock);
95 }
96
97 return ret;
98}
99
100/*
101 * We need to hold v9ses->rename_sem as long as we hold references
102 * to returned path array. Array element contain pointers to
103 * dentry names.
104 */
105static int build_path_from_dentry(struct v9fs_session_info *v9ses,
106 struct dentry *dentry, char ***names)
107{
108 int n = 0, i;
109 char **wnames;
110 struct dentry *ds;
111
112 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
113 n++;
114
115 wnames = kmalloc(sizeof(char *) * n, GFP_KERNEL);
116 if (!wnames)
117 goto err_out;
118
119 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
120 wnames[i] = (char *)ds->d_name.name;
121
122 *names = wnames;
123 return n;
124err_out:
125 return -ENOMEM;
126}
127
128static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
129 uid_t uid, int any)
130{
131 struct dentry *ds;
132 char **wnames, *uname;
133 int i, n, l, clone, access;
134 struct v9fs_session_info *v9ses;
135 struct p9_fid *fid, *old_fid = NULL;
136
137 v9ses = v9fs_dentry2v9ses(dentry);
138 access = v9ses->flags & V9FS_ACCESS_MASK;
139 fid = v9fs_fid_find(dentry, uid, any);
140 if (fid)
141 return fid;
142 /*
143 * we don't have a matching fid. To do a TWALK we need
144 * parent fid. We need to prevent rename when we want to
145 * look at the parent.
146 */
147 down_read(&v9ses->rename_sem);
148 ds = dentry->d_parent;
149 fid = v9fs_fid_find(ds, uid, any);
150 if (fid) {
151 /* Found the parent fid do a lookup with that */
152 fid = p9_client_walk(fid, 1, (char **)&dentry->d_name.name, 1);
153 goto fid_out;
154 }
155 up_read(&v9ses->rename_sem);
156
157 /* start from the root and try to do a lookup */
158 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
159 if (!fid) {
160 /* the user is not attached to the fs yet */
161 if (access == V9FS_ACCESS_SINGLE)
162 return ERR_PTR(-EPERM);
163
164 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
165 uname = NULL;
166 else
167 uname = v9ses->uname;
168
169 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
170 v9ses->aname);
171 if (IS_ERR(fid))
172 return fid;
173
174 v9fs_fid_add(dentry->d_sb->s_root, fid);
175 }
176 /* If we are root ourself just return that */
177 if (dentry->d_sb->s_root == dentry)
178 return fid;
179 /*
180 * Do a multipath walk with attached root.
181 * When walking parent we need to make sure we
182 * don't have a parallel rename happening
183 */
184 down_read(&v9ses->rename_sem);
185 n = build_path_from_dentry(v9ses, dentry, &wnames);
186 if (n < 0) {
187 fid = ERR_PTR(n);
188 goto err_out;
189 }
190 clone = 1;
191 i = 0;
192 while (i < n) {
193 l = min(n - i, P9_MAXWELEM);
194 /*
195 * We need to hold rename lock when doing a multipath
196 * walk to ensure none of the patch component change
197 */
198 fid = p9_client_walk(fid, l, &wnames[i], clone);
199 if (IS_ERR(fid)) {
200 if (old_fid) {
201 /*
202 * If we fail, clunk fid which are mapping
203 * to path component and not the last component
204 * of the path.
205 */
206 p9_client_clunk(old_fid);
207 }
208 kfree(wnames);
209 goto err_out;
210 }
211 old_fid = fid;
212 i += l;
213 clone = 0;
214 }
215 kfree(wnames);
216fid_out:
217 if (!IS_ERR(fid))
218 v9fs_fid_add(dentry, fid);
219err_out:
220 up_read(&v9ses->rename_sem);
221 return fid;
222}
223
224/**
225 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
226 * @dentry: dentry to look for fid in
227 *
228 * Look for a fid in the specified dentry for the current user.
229 * If no fid is found, try to create one walking from a fid from the parent
230 * dentry (if it has one), or the root dentry. If the user haven't accessed
231 * the fs yet, attach now and walk from the root.
232 */
233
234struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
235{
236 uid_t uid;
237 int any, access;
238 struct v9fs_session_info *v9ses;
239
240 v9ses = v9fs_dentry2v9ses(dentry);
241 access = v9ses->flags & V9FS_ACCESS_MASK;
242 switch (access) {
243 case V9FS_ACCESS_SINGLE:
244 case V9FS_ACCESS_USER:
245 case V9FS_ACCESS_CLIENT:
246 uid = current_fsuid();
247 any = 0;
248 break;
249
250 case V9FS_ACCESS_ANY:
251 uid = v9ses->uid;
252 any = 1;
253 break;
254
255 default:
256 uid = ~0;
257 any = 0;
258 break;
259 }
260 return v9fs_fid_lookup_with_uid(dentry, uid, any);
261}
262
263struct p9_fid *v9fs_fid_clone(struct dentry *dentry)
264{
265 struct p9_fid *fid, *ret;
266
267 fid = v9fs_fid_lookup(dentry);
268 if (IS_ERR(fid))
269 return fid;
270
271 ret = p9_client_walk(fid, 0, NULL, 1);
272 return ret;
273}
274
275static struct p9_fid *v9fs_fid_clone_with_uid(struct dentry *dentry, uid_t uid)
276{
277 struct p9_fid *fid, *ret;
278
279 fid = v9fs_fid_lookup_with_uid(dentry, uid, 0);
280 if (IS_ERR(fid))
281 return fid;
282
283 ret = p9_client_walk(fid, 0, NULL, 1);
284 return ret;
285}
286
287struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
288{
289 int err;
290 struct p9_fid *fid;
291
292 fid = v9fs_fid_clone_with_uid(dentry, 0);
293 if (IS_ERR(fid))
294 goto error_out;
295 /*
296 * writeback fid will only be used to write back the
297 * dirty pages. We always request for the open fid in read-write
298 * mode so that a partial page write which result in page
299 * read can work.
300 */
301 err = p9_client_open(fid, O_RDWR);
302 if (err < 0) {
303 p9_client_clunk(fid);
304 fid = ERR_PTR(err);
305 goto error_out;
306 }
307error_out:
308 return fid;
309}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * V9FS FID Management
4 *
5 * Copyright (C) 2007 by Latchesar Ionkov <lucho@ionkov.net>
6 * Copyright (C) 2005, 2006 by Eric Van Hensbergen <ericvh@gmail.com>
7 */
8
9#include <linux/module.h>
10#include <linux/errno.h>
11#include <linux/fs.h>
12#include <linux/slab.h>
13#include <linux/sched.h>
14#include <linux/idr.h>
15#include <net/9p/9p.h>
16#include <net/9p/client.h>
17
18#include "v9fs.h"
19#include "v9fs_vfs.h"
20#include "fid.h"
21
22/**
23 * v9fs_fid_add - add a fid to a dentry
24 * @dentry: dentry that the fid is being added to
25 * @fid: fid to add
26 *
27 */
28
29static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
30{
31 hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
32}
33
34void v9fs_fid_add(struct dentry *dentry, struct p9_fid *fid)
35{
36 spin_lock(&dentry->d_lock);
37 __add_fid(dentry, fid);
38 spin_unlock(&dentry->d_lock);
39}
40
41/**
42 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
43 * @dentry: dentry to look for fid in
44 * @uid: return fid that belongs to the specified user
45 * @any: if non-zero, return any fid associated with the dentry
46 *
47 */
48
49static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
50{
51 struct p9_fid *fid, *ret;
52
53 p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
54 dentry, dentry, from_kuid(&init_user_ns, uid),
55 any);
56 ret = NULL;
57 /* we'll recheck under lock if there's anything to look in */
58 if (dentry->d_fsdata) {
59 struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
60 spin_lock(&dentry->d_lock);
61 hlist_for_each_entry(fid, h, dlist) {
62 if (any || uid_eq(fid->uid, uid)) {
63 ret = fid;
64 break;
65 }
66 }
67 spin_unlock(&dentry->d_lock);
68 }
69
70 return ret;
71}
72
73/*
74 * We need to hold v9ses->rename_sem as long as we hold references
75 * to returned path array. Array element contain pointers to
76 * dentry names.
77 */
78static int build_path_from_dentry(struct v9fs_session_info *v9ses,
79 struct dentry *dentry, const unsigned char ***names)
80{
81 int n = 0, i;
82 const unsigned char **wnames;
83 struct dentry *ds;
84
85 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
86 n++;
87
88 wnames = kmalloc_array(n, sizeof(char *), GFP_KERNEL);
89 if (!wnames)
90 goto err_out;
91
92 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
93 wnames[i] = ds->d_name.name;
94
95 *names = wnames;
96 return n;
97err_out:
98 return -ENOMEM;
99}
100
101static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
102 kuid_t uid, int any)
103{
104 struct dentry *ds;
105 const unsigned char **wnames, *uname;
106 int i, n, l, clone, access;
107 struct v9fs_session_info *v9ses;
108 struct p9_fid *fid, *old_fid = NULL;
109
110 v9ses = v9fs_dentry2v9ses(dentry);
111 access = v9ses->flags & V9FS_ACCESS_MASK;
112 fid = v9fs_fid_find(dentry, uid, any);
113 if (fid)
114 return fid;
115 /*
116 * we don't have a matching fid. To do a TWALK we need
117 * parent fid. We need to prevent rename when we want to
118 * look at the parent.
119 */
120 down_read(&v9ses->rename_sem);
121 ds = dentry->d_parent;
122 fid = v9fs_fid_find(ds, uid, any);
123 if (fid) {
124 /* Found the parent fid do a lookup with that */
125 fid = p9_client_walk(fid, 1, &dentry->d_name.name, 1);
126 goto fid_out;
127 }
128 up_read(&v9ses->rename_sem);
129
130 /* start from the root and try to do a lookup */
131 fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
132 if (!fid) {
133 /* the user is not attached to the fs yet */
134 if (access == V9FS_ACCESS_SINGLE)
135 return ERR_PTR(-EPERM);
136
137 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
138 uname = NULL;
139 else
140 uname = v9ses->uname;
141
142 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
143 v9ses->aname);
144 if (IS_ERR(fid))
145 return fid;
146
147 v9fs_fid_add(dentry->d_sb->s_root, fid);
148 }
149 /* If we are root ourself just return that */
150 if (dentry->d_sb->s_root == dentry)
151 return fid;
152 /*
153 * Do a multipath walk with attached root.
154 * When walking parent we need to make sure we
155 * don't have a parallel rename happening
156 */
157 down_read(&v9ses->rename_sem);
158 n = build_path_from_dentry(v9ses, dentry, &wnames);
159 if (n < 0) {
160 fid = ERR_PTR(n);
161 goto err_out;
162 }
163 clone = 1;
164 i = 0;
165 while (i < n) {
166 l = min(n - i, P9_MAXWELEM);
167 /*
168 * We need to hold rename lock when doing a multipath
169 * walk to ensure none of the patch component change
170 */
171 fid = p9_client_walk(fid, l, &wnames[i], clone);
172 if (IS_ERR(fid)) {
173 if (old_fid) {
174 /*
175 * If we fail, clunk fid which are mapping
176 * to path component and not the last component
177 * of the path.
178 */
179 p9_client_clunk(old_fid);
180 }
181 kfree(wnames);
182 goto err_out;
183 }
184 old_fid = fid;
185 i += l;
186 clone = 0;
187 }
188 kfree(wnames);
189fid_out:
190 if (!IS_ERR(fid)) {
191 spin_lock(&dentry->d_lock);
192 if (d_unhashed(dentry)) {
193 spin_unlock(&dentry->d_lock);
194 p9_client_clunk(fid);
195 fid = ERR_PTR(-ENOENT);
196 } else {
197 __add_fid(dentry, fid);
198 spin_unlock(&dentry->d_lock);
199 }
200 }
201err_out:
202 up_read(&v9ses->rename_sem);
203 return fid;
204}
205
206/**
207 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
208 * @dentry: dentry to look for fid in
209 *
210 * Look for a fid in the specified dentry for the current user.
211 * If no fid is found, try to create one walking from a fid from the parent
212 * dentry (if it has one), or the root dentry. If the user haven't accessed
213 * the fs yet, attach now and walk from the root.
214 */
215
216struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
217{
218 kuid_t uid;
219 int any, access;
220 struct v9fs_session_info *v9ses;
221
222 v9ses = v9fs_dentry2v9ses(dentry);
223 access = v9ses->flags & V9FS_ACCESS_MASK;
224 switch (access) {
225 case V9FS_ACCESS_SINGLE:
226 case V9FS_ACCESS_USER:
227 case V9FS_ACCESS_CLIENT:
228 uid = current_fsuid();
229 any = 0;
230 break;
231
232 case V9FS_ACCESS_ANY:
233 uid = v9ses->uid;
234 any = 1;
235 break;
236
237 default:
238 uid = INVALID_UID;
239 any = 0;
240 break;
241 }
242 return v9fs_fid_lookup_with_uid(dentry, uid, any);
243}
244
245struct p9_fid *v9fs_writeback_fid(struct dentry *dentry)
246{
247 int err;
248 struct p9_fid *fid;
249
250 fid = clone_fid(v9fs_fid_lookup_with_uid(dentry, GLOBAL_ROOT_UID, 0));
251 if (IS_ERR(fid))
252 goto error_out;
253 /*
254 * writeback fid will only be used to write back the
255 * dirty pages. We always request for the open fid in read-write
256 * mode so that a partial page write which result in page
257 * read can work.
258 */
259 err = p9_client_open(fid, O_RDWR);
260 if (err < 0) {
261 p9_client_clunk(fid);
262 fid = ERR_PTR(err);
263 goto error_out;
264 }
265error_out:
266 return fid;
267}