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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 <net/9p/9p.h>
15#include <net/9p/client.h>
16
17#include "v9fs.h"
18#include "v9fs_vfs.h"
19#include "fid.h"
20
21static inline void __add_fid(struct dentry *dentry, struct p9_fid *fid)
22{
23 hlist_add_head(&fid->dlist, (struct hlist_head *)&dentry->d_fsdata);
24}
25
26
27/**
28 * v9fs_fid_add - add a fid to a dentry
29 * @dentry: dentry that the fid is being added to
30 * @pfid: fid to add, NULLed out
31 *
32 */
33void v9fs_fid_add(struct dentry *dentry, struct p9_fid **pfid)
34{
35 struct p9_fid *fid = *pfid;
36
37 spin_lock(&dentry->d_lock);
38 __add_fid(dentry, fid);
39 spin_unlock(&dentry->d_lock);
40
41 *pfid = NULL;
42}
43
44static bool v9fs_is_writeable(int mode)
45{
46 if (mode & (P9_OWRITE|P9_ORDWR))
47 return true;
48 else
49 return false;
50}
51
52/**
53 * v9fs_fid_find_inode - search for an open fid off of the inode list
54 * @inode: return a fid pointing to a specific inode
55 * @want_writeable: only consider fids which are writeable
56 * @uid: return a fid belonging to the specified user
57 * @any: ignore uid as a selection criteria
58 *
59 */
60struct p9_fid *v9fs_fid_find_inode(struct inode *inode, bool want_writeable,
61 kuid_t uid, bool any)
62{
63 struct hlist_head *h;
64 struct p9_fid *fid, *ret = NULL;
65
66 p9_debug(P9_DEBUG_VFS, " inode: %p\n", inode);
67
68 spin_lock(&inode->i_lock);
69 h = (struct hlist_head *)&inode->i_private;
70 hlist_for_each_entry(fid, h, ilist) {
71 if (any || uid_eq(fid->uid, uid)) {
72 if (want_writeable && !v9fs_is_writeable(fid->mode)) {
73 p9_debug(P9_DEBUG_VFS, " mode: %x not writeable?\n",
74 fid->mode);
75 continue;
76 }
77 p9_fid_get(fid);
78 ret = fid;
79 break;
80 }
81 }
82 spin_unlock(&inode->i_lock);
83 return ret;
84}
85
86/**
87 * v9fs_open_fid_add - add an open fid to an inode
88 * @inode: inode that the fid is being added to
89 * @pfid: fid to add, NULLed out
90 *
91 */
92
93void v9fs_open_fid_add(struct inode *inode, struct p9_fid **pfid)
94{
95 struct p9_fid *fid = *pfid;
96
97 spin_lock(&inode->i_lock);
98 hlist_add_head(&fid->ilist, (struct hlist_head *)&inode->i_private);
99 spin_unlock(&inode->i_lock);
100
101 *pfid = NULL;
102}
103
104
105/**
106 * v9fs_fid_find - retrieve a fid that belongs to the specified uid
107 * @dentry: dentry to look for fid in
108 * @uid: return fid that belongs to the specified user
109 * @any: if non-zero, return any fid associated with the dentry
110 *
111 */
112
113static struct p9_fid *v9fs_fid_find(struct dentry *dentry, kuid_t uid, int any)
114{
115 struct p9_fid *fid, *ret;
116
117 p9_debug(P9_DEBUG_VFS, " dentry: %pd (%p) uid %d any %d\n",
118 dentry, dentry, from_kuid(&init_user_ns, uid),
119 any);
120 ret = NULL;
121 /* we'll recheck under lock if there's anything to look in */
122 if (dentry->d_fsdata) {
123 struct hlist_head *h = (struct hlist_head *)&dentry->d_fsdata;
124
125 spin_lock(&dentry->d_lock);
126 hlist_for_each_entry(fid, h, dlist) {
127 if (any || uid_eq(fid->uid, uid)) {
128 ret = fid;
129 p9_fid_get(ret);
130 break;
131 }
132 }
133 spin_unlock(&dentry->d_lock);
134 } else {
135 if (dentry->d_inode)
136 ret = v9fs_fid_find_inode(dentry->d_inode, false, uid, any);
137 }
138
139 return ret;
140}
141
142/*
143 * We need to hold v9ses->rename_sem as long as we hold references
144 * to returned path array. Array element contain pointers to
145 * dentry names.
146 */
147static int build_path_from_dentry(struct v9fs_session_info *v9ses,
148 struct dentry *dentry, const unsigned char ***names)
149{
150 int n = 0, i;
151 const unsigned char **wnames;
152 struct dentry *ds;
153
154 for (ds = dentry; !IS_ROOT(ds); ds = ds->d_parent)
155 n++;
156
157 wnames = kmalloc_array(n, sizeof(char *), GFP_KERNEL);
158 if (!wnames)
159 goto err_out;
160
161 for (ds = dentry, i = (n-1); i >= 0; i--, ds = ds->d_parent)
162 wnames[i] = ds->d_name.name;
163
164 *names = wnames;
165 return n;
166err_out:
167 return -ENOMEM;
168}
169
170static struct p9_fid *v9fs_fid_lookup_with_uid(struct dentry *dentry,
171 kuid_t uid, int any)
172{
173 struct dentry *ds;
174 const unsigned char **wnames, *uname;
175 int i, n, l, access;
176 struct v9fs_session_info *v9ses;
177 struct p9_fid *fid, *root_fid, *old_fid;
178
179 v9ses = v9fs_dentry2v9ses(dentry);
180 access = v9ses->flags & V9FS_ACCESS_MASK;
181 fid = v9fs_fid_find(dentry, uid, any);
182 if (fid)
183 return fid;
184 /*
185 * we don't have a matching fid. To do a TWALK we need
186 * parent fid. We need to prevent rename when we want to
187 * look at the parent.
188 */
189 down_read(&v9ses->rename_sem);
190 ds = dentry->d_parent;
191 fid = v9fs_fid_find(ds, uid, any);
192 if (fid) {
193 /* Found the parent fid do a lookup with that */
194 old_fid = fid;
195
196 fid = p9_client_walk(old_fid, 1, &dentry->d_name.name, 1);
197 p9_fid_put(old_fid);
198 goto fid_out;
199 }
200 up_read(&v9ses->rename_sem);
201
202 /* start from the root and try to do a lookup */
203 root_fid = v9fs_fid_find(dentry->d_sb->s_root, uid, any);
204 if (!root_fid) {
205 /* the user is not attached to the fs yet */
206 if (access == V9FS_ACCESS_SINGLE)
207 return ERR_PTR(-EPERM);
208
209 if (v9fs_proto_dotu(v9ses) || v9fs_proto_dotl(v9ses))
210 uname = NULL;
211 else
212 uname = v9ses->uname;
213
214 fid = p9_client_attach(v9ses->clnt, NULL, uname, uid,
215 v9ses->aname);
216 if (IS_ERR(fid))
217 return fid;
218
219 root_fid = p9_fid_get(fid);
220 v9fs_fid_add(dentry->d_sb->s_root, &fid);
221 }
222 /* If we are root ourself just return that */
223 if (dentry->d_sb->s_root == dentry)
224 return root_fid;
225
226 /*
227 * Do a multipath walk with attached root.
228 * When walking parent we need to make sure we
229 * don't have a parallel rename happening
230 */
231 down_read(&v9ses->rename_sem);
232 n = build_path_from_dentry(v9ses, dentry, &wnames);
233 if (n < 0) {
234 fid = ERR_PTR(n);
235 goto err_out;
236 }
237 fid = root_fid;
238 old_fid = root_fid;
239 i = 0;
240 while (i < n) {
241 l = min(n - i, P9_MAXWELEM);
242 /*
243 * We need to hold rename lock when doing a multipath
244 * walk to ensure none of the path components change
245 */
246 fid = p9_client_walk(old_fid, l, &wnames[i],
247 old_fid == root_fid /* clone */);
248 /* non-cloning walk will return the same fid */
249 if (fid != old_fid) {
250 p9_fid_put(old_fid);
251 old_fid = fid;
252 }
253 if (IS_ERR(fid)) {
254 kfree(wnames);
255 goto err_out;
256 }
257 i += l;
258 }
259 kfree(wnames);
260fid_out:
261 if (!IS_ERR(fid)) {
262 spin_lock(&dentry->d_lock);
263 if (d_unhashed(dentry)) {
264 spin_unlock(&dentry->d_lock);
265 p9_fid_put(fid);
266 fid = ERR_PTR(-ENOENT);
267 } else {
268 __add_fid(dentry, fid);
269 p9_fid_get(fid);
270 spin_unlock(&dentry->d_lock);
271 }
272 }
273err_out:
274 up_read(&v9ses->rename_sem);
275 return fid;
276}
277
278/**
279 * v9fs_fid_lookup - lookup for a fid, try to walk if not found
280 * @dentry: dentry to look for fid in
281 *
282 * Look for a fid in the specified dentry for the current user.
283 * If no fid is found, try to create one walking from a fid from the parent
284 * dentry (if it has one), or the root dentry. If the user haven't accessed
285 * the fs yet, attach now and walk from the root.
286 */
287
288struct p9_fid *v9fs_fid_lookup(struct dentry *dentry)
289{
290 kuid_t uid;
291 int any, access;
292 struct v9fs_session_info *v9ses;
293
294 v9ses = v9fs_dentry2v9ses(dentry);
295 access = v9ses->flags & V9FS_ACCESS_MASK;
296 switch (access) {
297 case V9FS_ACCESS_SINGLE:
298 case V9FS_ACCESS_USER:
299 case V9FS_ACCESS_CLIENT:
300 uid = current_fsuid();
301 any = 0;
302 break;
303
304 case V9FS_ACCESS_ANY:
305 uid = v9ses->uid;
306 any = 1;
307 break;
308
309 default:
310 uid = INVALID_UID;
311 any = 0;
312 break;
313 }
314 return v9fs_fid_lookup_with_uid(dentry, uid, any);
315}
316