1561f82a3SPaulo Alcantara // SPDX-License-Identifier: GPL-2.0-or-later
2561f82a3SPaulo Alcantara /*
30a049935SPaulo Alcantara * Contains mounting routines used for handling traversal via SMB junctions.
4561f82a3SPaulo Alcantara *
5561f82a3SPaulo Alcantara * Copyright (c) 2007 Igor Mammedov
6561f82a3SPaulo Alcantara * Copyright (C) International Business Machines Corp., 2008
7561f82a3SPaulo Alcantara * Author(s): Igor Mammedov (niallain@gmail.com)
8561f82a3SPaulo Alcantara * Steve French (sfrench@us.ibm.com)
9348a04a8SPaulo Alcantara * Copyright (c) 2023 Paulo Alcantara <palcantara@suse.de>
10561f82a3SPaulo Alcantara */
11561f82a3SPaulo Alcantara
12561f82a3SPaulo Alcantara #include <linux/dcache.h>
13561f82a3SPaulo Alcantara #include <linux/mount.h>
14561f82a3SPaulo Alcantara #include <linux/namei.h>
15561f82a3SPaulo Alcantara #include <linux/slab.h>
16561f82a3SPaulo Alcantara #include <linux/vfs.h>
17561f82a3SPaulo Alcantara #include <linux/fs.h>
18561f82a3SPaulo Alcantara #include <linux/inet.h>
19561f82a3SPaulo Alcantara #include "cifsglob.h"
20561f82a3SPaulo Alcantara #include "cifsproto.h"
21561f82a3SPaulo Alcantara #include "cifsfs.h"
22561f82a3SPaulo Alcantara #include "cifs_debug.h"
23561f82a3SPaulo Alcantara #include "fs_context.h"
24561f82a3SPaulo Alcantara
250a049935SPaulo Alcantara static LIST_HEAD(cifs_automount_list);
26561f82a3SPaulo Alcantara
270a049935SPaulo Alcantara static void cifs_expire_automounts(struct work_struct *work);
280a049935SPaulo Alcantara static DECLARE_DELAYED_WORK(cifs_automount_task,
290a049935SPaulo Alcantara cifs_expire_automounts);
300a049935SPaulo Alcantara static int cifs_mountpoint_expiry_timeout = 500 * HZ;
31561f82a3SPaulo Alcantara
cifs_expire_automounts(struct work_struct * work)320a049935SPaulo Alcantara static void cifs_expire_automounts(struct work_struct *work)
33561f82a3SPaulo Alcantara {
340a049935SPaulo Alcantara struct list_head *list = &cifs_automount_list;
35561f82a3SPaulo Alcantara
36561f82a3SPaulo Alcantara mark_mounts_for_expiry(list);
37561f82a3SPaulo Alcantara if (!list_empty(list))
380a049935SPaulo Alcantara schedule_delayed_work(&cifs_automount_task,
390a049935SPaulo Alcantara cifs_mountpoint_expiry_timeout);
40561f82a3SPaulo Alcantara }
41561f82a3SPaulo Alcantara
cifs_release_automount_timer(void)420a049935SPaulo Alcantara void cifs_release_automount_timer(void)
43561f82a3SPaulo Alcantara {
440a049935SPaulo Alcantara if (WARN_ON(!list_empty(&cifs_automount_list)))
450a049935SPaulo Alcantara return;
460a049935SPaulo Alcantara cancel_delayed_work_sync(&cifs_automount_task);
47561f82a3SPaulo Alcantara }
48561f82a3SPaulo Alcantara
49561f82a3SPaulo Alcantara /**
50561f82a3SPaulo Alcantara * cifs_build_devname - build a devicename from a UNC and optional prepath
51561f82a3SPaulo Alcantara * @nodename: pointer to UNC string
52561f82a3SPaulo Alcantara * @prepath: pointer to prefixpath (or NULL if there isn't one)
53561f82a3SPaulo Alcantara *
54561f82a3SPaulo Alcantara * Build a new cifs devicename after chasing a DFS referral. Allocate a buffer
55561f82a3SPaulo Alcantara * big enough to hold the final thing. Copy the UNC from the nodename, and
56561f82a3SPaulo Alcantara * concatenate the prepath onto the end of it if there is one.
57561f82a3SPaulo Alcantara *
58561f82a3SPaulo Alcantara * Returns pointer to the built string, or a ERR_PTR. Caller is responsible
59561f82a3SPaulo Alcantara * for freeing the returned string.
60561f82a3SPaulo Alcantara */
61561f82a3SPaulo Alcantara char *
cifs_build_devname(char * nodename,const char * prepath)62561f82a3SPaulo Alcantara cifs_build_devname(char *nodename, const char *prepath)
63561f82a3SPaulo Alcantara {
64561f82a3SPaulo Alcantara size_t pplen;
65561f82a3SPaulo Alcantara size_t unclen;
66561f82a3SPaulo Alcantara char *dev;
67561f82a3SPaulo Alcantara char *pos;
68561f82a3SPaulo Alcantara
69561f82a3SPaulo Alcantara /* skip over any preceding delimiters */
70561f82a3SPaulo Alcantara nodename += strspn(nodename, "\\");
71561f82a3SPaulo Alcantara if (!*nodename)
72561f82a3SPaulo Alcantara return ERR_PTR(-EINVAL);
73561f82a3SPaulo Alcantara
74561f82a3SPaulo Alcantara /* get length of UNC and set pos to last char */
75561f82a3SPaulo Alcantara unclen = strlen(nodename);
76561f82a3SPaulo Alcantara pos = nodename + unclen - 1;
77561f82a3SPaulo Alcantara
78561f82a3SPaulo Alcantara /* trim off any trailing delimiters */
79561f82a3SPaulo Alcantara while (*pos == '\\') {
80561f82a3SPaulo Alcantara --pos;
81561f82a3SPaulo Alcantara --unclen;
82561f82a3SPaulo Alcantara }
83561f82a3SPaulo Alcantara
84561f82a3SPaulo Alcantara /* allocate a buffer:
85561f82a3SPaulo Alcantara * +2 for preceding "//"
86561f82a3SPaulo Alcantara * +1 for delimiter between UNC and prepath
87561f82a3SPaulo Alcantara * +1 for trailing NULL
88561f82a3SPaulo Alcantara */
89561f82a3SPaulo Alcantara pplen = prepath ? strlen(prepath) : 0;
90561f82a3SPaulo Alcantara dev = kmalloc(2 + unclen + 1 + pplen + 1, GFP_KERNEL);
91561f82a3SPaulo Alcantara if (!dev)
92561f82a3SPaulo Alcantara return ERR_PTR(-ENOMEM);
93561f82a3SPaulo Alcantara
94561f82a3SPaulo Alcantara pos = dev;
95561f82a3SPaulo Alcantara /* add the initial "//" */
96561f82a3SPaulo Alcantara *pos = '/';
97561f82a3SPaulo Alcantara ++pos;
98561f82a3SPaulo Alcantara *pos = '/';
99561f82a3SPaulo Alcantara ++pos;
100561f82a3SPaulo Alcantara
101561f82a3SPaulo Alcantara /* copy in the UNC portion from referral */
102561f82a3SPaulo Alcantara memcpy(pos, nodename, unclen);
103561f82a3SPaulo Alcantara pos += unclen;
104561f82a3SPaulo Alcantara
105561f82a3SPaulo Alcantara /* copy the prefixpath remainder (if there is one) */
106561f82a3SPaulo Alcantara if (pplen) {
107561f82a3SPaulo Alcantara *pos = '/';
108561f82a3SPaulo Alcantara ++pos;
109561f82a3SPaulo Alcantara memcpy(pos, prepath, pplen);
110561f82a3SPaulo Alcantara pos += pplen;
111561f82a3SPaulo Alcantara }
112561f82a3SPaulo Alcantara
113561f82a3SPaulo Alcantara /* NULL terminator */
114561f82a3SPaulo Alcantara *pos = '\0';
115561f82a3SPaulo Alcantara
116561f82a3SPaulo Alcantara convert_delimiter(dev, '/');
117561f82a3SPaulo Alcantara return dev;
118561f82a3SPaulo Alcantara }
119561f82a3SPaulo Alcantara
is_dfs_mount(struct dentry * dentry)120390c08fdSPaulo Alcantara static bool is_dfs_mount(struct dentry *dentry)
121390c08fdSPaulo Alcantara {
122390c08fdSPaulo Alcantara struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
123390c08fdSPaulo Alcantara struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
124390c08fdSPaulo Alcantara bool ret;
125390c08fdSPaulo Alcantara
126390c08fdSPaulo Alcantara spin_lock(&tcon->tc_lock);
127390c08fdSPaulo Alcantara ret = !!tcon->origin_fullpath;
128390c08fdSPaulo Alcantara spin_unlock(&tcon->tc_lock);
129390c08fdSPaulo Alcantara return ret;
130390c08fdSPaulo Alcantara }
131390c08fdSPaulo Alcantara
132348a04a8SPaulo Alcantara /* Return full path out of a dentry set for automount */
automount_fullpath(struct dentry * dentry,void * page)133348a04a8SPaulo Alcantara static char *automount_fullpath(struct dentry *dentry, void *page)
134561f82a3SPaulo Alcantara {
135348a04a8SPaulo Alcantara struct cifs_sb_info *cifs_sb = CIFS_SB(dentry->d_sb);
136348a04a8SPaulo Alcantara struct cifs_tcon *tcon = cifs_sb_master_tcon(cifs_sb);
137348a04a8SPaulo Alcantara size_t len;
138348a04a8SPaulo Alcantara char *s;
139561f82a3SPaulo Alcantara
140348a04a8SPaulo Alcantara spin_lock(&tcon->tc_lock);
141a18280e7SPaulo Alcantara if (!tcon->origin_fullpath) {
142348a04a8SPaulo Alcantara spin_unlock(&tcon->tc_lock);
143a18280e7SPaulo Alcantara return build_path_from_dentry_optional_prefix(dentry,
144a18280e7SPaulo Alcantara page,
145a18280e7SPaulo Alcantara true);
146348a04a8SPaulo Alcantara }
147348a04a8SPaulo Alcantara spin_unlock(&tcon->tc_lock);
148348a04a8SPaulo Alcantara
149348a04a8SPaulo Alcantara s = dentry_path_raw(dentry, page, PATH_MAX);
150348a04a8SPaulo Alcantara if (IS_ERR(s))
151348a04a8SPaulo Alcantara return s;
152348a04a8SPaulo Alcantara /* for root, we want "" */
153348a04a8SPaulo Alcantara if (!s[1])
154348a04a8SPaulo Alcantara s++;
155348a04a8SPaulo Alcantara
156348a04a8SPaulo Alcantara spin_lock(&tcon->tc_lock);
157348a04a8SPaulo Alcantara len = strlen(tcon->origin_fullpath);
158348a04a8SPaulo Alcantara if (s < (char *)page + len) {
159348a04a8SPaulo Alcantara spin_unlock(&tcon->tc_lock);
160348a04a8SPaulo Alcantara return ERR_PTR(-ENAMETOOLONG);
161348a04a8SPaulo Alcantara }
162348a04a8SPaulo Alcantara
163348a04a8SPaulo Alcantara s -= len;
164348a04a8SPaulo Alcantara memcpy(s, tcon->origin_fullpath, len);
165348a04a8SPaulo Alcantara spin_unlock(&tcon->tc_lock);
166348a04a8SPaulo Alcantara convert_delimiter(s, '/');
167348a04a8SPaulo Alcantara
168348a04a8SPaulo Alcantara return s;
169561f82a3SPaulo Alcantara }
170561f82a3SPaulo Alcantara
fs_context_set_ids(struct smb3_fs_context * ctx)171*c2aa2718SPaulo Alcantara static void fs_context_set_ids(struct smb3_fs_context *ctx)
172*c2aa2718SPaulo Alcantara {
173*c2aa2718SPaulo Alcantara kuid_t uid = current_fsuid();
174*c2aa2718SPaulo Alcantara kgid_t gid = current_fsgid();
175*c2aa2718SPaulo Alcantara
176*c2aa2718SPaulo Alcantara if (ctx->multiuser) {
177*c2aa2718SPaulo Alcantara if (!ctx->uid_specified)
178*c2aa2718SPaulo Alcantara ctx->linux_uid = uid;
179*c2aa2718SPaulo Alcantara if (!ctx->gid_specified)
180*c2aa2718SPaulo Alcantara ctx->linux_gid = gid;
181*c2aa2718SPaulo Alcantara }
182*c2aa2718SPaulo Alcantara if (!ctx->cruid_specified)
183*c2aa2718SPaulo Alcantara ctx->cred_uid = uid;
184*c2aa2718SPaulo Alcantara }
185*c2aa2718SPaulo Alcantara
186561f82a3SPaulo Alcantara /*
187561f82a3SPaulo Alcantara * Create a vfsmount that we can automount
188561f82a3SPaulo Alcantara */
cifs_do_automount(struct path * path)1890a049935SPaulo Alcantara static struct vfsmount *cifs_do_automount(struct path *path)
190561f82a3SPaulo Alcantara {
191561f82a3SPaulo Alcantara int rc;
192561f82a3SPaulo Alcantara struct dentry *mntpt = path->dentry;
193561f82a3SPaulo Alcantara struct fs_context *fc;
194561f82a3SPaulo Alcantara void *page = NULL;
195561f82a3SPaulo Alcantara struct smb3_fs_context *ctx, *cur_ctx;
196561f82a3SPaulo Alcantara struct smb3_fs_context tmp;
197561f82a3SPaulo Alcantara char *full_path;
198561f82a3SPaulo Alcantara struct vfsmount *mnt;
199561f82a3SPaulo Alcantara
200561f82a3SPaulo Alcantara if (IS_ROOT(mntpt))
201561f82a3SPaulo Alcantara return ERR_PTR(-ESTALE);
202561f82a3SPaulo Alcantara
203a18280e7SPaulo Alcantara cur_ctx = CIFS_SB(mntpt->d_sb)->ctx;
204561f82a3SPaulo Alcantara
205561f82a3SPaulo Alcantara fc = fs_context_for_submount(path->mnt->mnt_sb->s_type, mntpt);
206561f82a3SPaulo Alcantara if (IS_ERR(fc))
207561f82a3SPaulo Alcantara return ERR_CAST(fc);
208561f82a3SPaulo Alcantara
209561f82a3SPaulo Alcantara ctx = smb3_fc2context(fc);
210561f82a3SPaulo Alcantara
211561f82a3SPaulo Alcantara page = alloc_dentry_path();
212348a04a8SPaulo Alcantara full_path = automount_fullpath(mntpt, page);
213561f82a3SPaulo Alcantara if (IS_ERR(full_path)) {
214561f82a3SPaulo Alcantara mnt = ERR_CAST(full_path);
215561f82a3SPaulo Alcantara goto out;
216561f82a3SPaulo Alcantara }
217561f82a3SPaulo Alcantara
218561f82a3SPaulo Alcantara tmp = *cur_ctx;
219561f82a3SPaulo Alcantara tmp.source = NULL;
220561f82a3SPaulo Alcantara tmp.leaf_fullpath = NULL;
221561f82a3SPaulo Alcantara tmp.UNC = tmp.prepath = NULL;
222561f82a3SPaulo Alcantara tmp.dfs_root_ses = NULL;
223*c2aa2718SPaulo Alcantara fs_context_set_ids(&tmp);
224561f82a3SPaulo Alcantara
225561f82a3SPaulo Alcantara rc = smb3_fs_context_dup(ctx, &tmp);
226561f82a3SPaulo Alcantara if (rc) {
227561f82a3SPaulo Alcantara mnt = ERR_PTR(rc);
228561f82a3SPaulo Alcantara goto out;
229561f82a3SPaulo Alcantara }
230561f82a3SPaulo Alcantara
231561f82a3SPaulo Alcantara rc = smb3_parse_devname(full_path, ctx);
232561f82a3SPaulo Alcantara if (rc) {
233561f82a3SPaulo Alcantara mnt = ERR_PTR(rc);
234561f82a3SPaulo Alcantara goto out;
235561f82a3SPaulo Alcantara }
236561f82a3SPaulo Alcantara
237561f82a3SPaulo Alcantara ctx->source = smb3_fs_context_fullpath(ctx, '/');
238561f82a3SPaulo Alcantara if (IS_ERR(ctx->source)) {
239561f82a3SPaulo Alcantara mnt = ERR_CAST(ctx->source);
240561f82a3SPaulo Alcantara ctx->source = NULL;
241561f82a3SPaulo Alcantara goto out;
242561f82a3SPaulo Alcantara }
243390c08fdSPaulo Alcantara ctx->dfs_automount = is_dfs_mount(mntpt);
244390c08fdSPaulo Alcantara cifs_dbg(FYI, "%s: ctx: source=%s UNC=%s prepath=%s dfs_automount=%d\n",
245390c08fdSPaulo Alcantara __func__, ctx->source, ctx->UNC, ctx->prepath, ctx->dfs_automount);
246561f82a3SPaulo Alcantara
247561f82a3SPaulo Alcantara mnt = fc_mount(fc);
248561f82a3SPaulo Alcantara out:
249561f82a3SPaulo Alcantara put_fs_context(fc);
250561f82a3SPaulo Alcantara free_dentry_path(page);
251561f82a3SPaulo Alcantara return mnt;
252561f82a3SPaulo Alcantara }
253561f82a3SPaulo Alcantara
254561f82a3SPaulo Alcantara /*
255561f82a3SPaulo Alcantara * Attempt to automount the referral
256561f82a3SPaulo Alcantara */
cifs_d_automount(struct path * path)2570a049935SPaulo Alcantara struct vfsmount *cifs_d_automount(struct path *path)
258561f82a3SPaulo Alcantara {
259561f82a3SPaulo Alcantara struct vfsmount *newmnt;
260561f82a3SPaulo Alcantara
261561f82a3SPaulo Alcantara cifs_dbg(FYI, "%s: %pd\n", __func__, path->dentry);
262561f82a3SPaulo Alcantara
2630a049935SPaulo Alcantara newmnt = cifs_do_automount(path);
264561f82a3SPaulo Alcantara if (IS_ERR(newmnt)) {
265561f82a3SPaulo Alcantara cifs_dbg(FYI, "leaving %s [automount failed]\n" , __func__);
266561f82a3SPaulo Alcantara return newmnt;
267561f82a3SPaulo Alcantara }
268561f82a3SPaulo Alcantara
269561f82a3SPaulo Alcantara mntget(newmnt); /* prevent immediate expiration */
2700a049935SPaulo Alcantara mnt_set_expiry(newmnt, &cifs_automount_list);
2710a049935SPaulo Alcantara schedule_delayed_work(&cifs_automount_task,
2720a049935SPaulo Alcantara cifs_mountpoint_expiry_timeout);
273561f82a3SPaulo Alcantara cifs_dbg(FYI, "leaving %s [ok]\n" , __func__);
274561f82a3SPaulo Alcantara return newmnt;
275561f82a3SPaulo Alcantara }
276561f82a3SPaulo Alcantara
2770a049935SPaulo Alcantara const struct inode_operations cifs_namespace_inode_operations = {
278561f82a3SPaulo Alcantara };
279