1 // SPDX-License-Identifier: GPL-2.0-or-later <<
2 /* getroot.c: get the root dentry for an NFS m 1 /* getroot.c: get the root dentry for an NFS mount
3 * 2 *
4 * Copyright (C) 2006 Red Hat, Inc. All Rights 3 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
5 * Written by David Howells (dhowells@redhat.c 4 * Written by David Howells (dhowells@redhat.com)
>> 5 *
>> 6 * This program is free software; you can redistribute it and/or
>> 7 * modify it under the terms of the GNU General Public License
>> 8 * as published by the Free Software Foundation; either version
>> 9 * 2 of the License, or (at your option) any later version.
6 */ 10 */
7 11
8 #include <linux/module.h> 12 #include <linux/module.h>
9 #include <linux/init.h> 13 #include <linux/init.h>
10 14
11 #include <linux/time.h> 15 #include <linux/time.h>
12 #include <linux/kernel.h> 16 #include <linux/kernel.h>
13 #include <linux/mm.h> 17 #include <linux/mm.h>
14 #include <linux/string.h> 18 #include <linux/string.h>
15 #include <linux/stat.h> 19 #include <linux/stat.h>
16 #include <linux/errno.h> 20 #include <linux/errno.h>
17 #include <linux/unistd.h> 21 #include <linux/unistd.h>
18 #include <linux/sunrpc/clnt.h> 22 #include <linux/sunrpc/clnt.h>
19 #include <linux/sunrpc/stats.h> 23 #include <linux/sunrpc/stats.h>
20 #include <linux/nfs_fs.h> 24 #include <linux/nfs_fs.h>
21 #include <linux/nfs_mount.h> 25 #include <linux/nfs_mount.h>
>> 26 #include <linux/nfs4_mount.h>
22 #include <linux/lockd/bind.h> 27 #include <linux/lockd/bind.h>
23 #include <linux/seq_file.h> 28 #include <linux/seq_file.h>
24 #include <linux/mount.h> 29 #include <linux/mount.h>
>> 30 #include <linux/nfs_idmap.h>
25 #include <linux/vfs.h> 31 #include <linux/vfs.h>
26 #include <linux/namei.h> 32 #include <linux/namei.h>
27 #include <linux/security.h> 33 #include <linux/security.h>
28 34
29 #include <linux/uaccess.h> !! 35 #include <asm/system.h>
>> 36 #include <asm/uaccess.h>
30 37
>> 38 #include "nfs4_fs.h"
>> 39 #include "delegation.h"
31 #include "internal.h" 40 #include "internal.h"
32 41
33 #define NFSDBG_FACILITY NFSDBG_CLIENT 42 #define NFSDBG_FACILITY NFSDBG_CLIENT
34 43
35 /* 44 /*
36 * Set the superblock root dentry. 45 * Set the superblock root dentry.
37 * Note that this function frees the inode in 46 * Note that this function frees the inode in case of error.
38 */ 47 */
39 static int nfs_superblock_set_dummy_root(struc 48 static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode)
40 { 49 {
41 /* The mntroot acts as the dummy root 50 /* The mntroot acts as the dummy root dentry for this superblock */
42 if (sb->s_root == NULL) { 51 if (sb->s_root == NULL) {
43 sb->s_root = d_make_root(inode !! 52 sb->s_root = d_alloc_root(inode);
44 if (sb->s_root == NULL) !! 53 if (sb->s_root == NULL) {
>> 54 iput(inode);
45 return -ENOMEM; 55 return -ENOMEM;
46 ihold(inode); !! 56 }
>> 57 /* Circumvent igrab(): we know the inode is not being freed */
>> 58 atomic_inc(&inode->i_count);
47 /* 59 /*
48 * Ensure that this dentry is 60 * Ensure that this dentry is invisible to d_find_alias().
49 * Otherwise, it may be splice 61 * Otherwise, it may be spliced into the tree by
50 * d_splice_alias if a parent !! 62 * d_materialise_unique if a parent directory from the same
51 * filesystem gets mounted at 63 * filesystem gets mounted at a later time.
52 * This again causes shrink_dc 64 * This again causes shrink_dcache_for_umount_subtree() to
53 * Oops, since the test for IS 65 * Oops, since the test for IS_ROOT() will fail.
54 */ 66 */
55 spin_lock(&d_inode(sb->s_root) !! 67 spin_lock(&dcache_lock);
56 spin_lock(&sb->s_root->d_lock) !! 68 list_del_init(&sb->s_root->d_alias);
57 hlist_del_init(&sb->s_root->d_ !! 69 spin_unlock(&dcache_lock);
58 spin_unlock(&sb->s_root->d_loc <<
59 spin_unlock(&d_inode(sb->s_roo <<
60 } 70 }
61 return 0; 71 return 0;
62 } 72 }
63 73
64 /* 74 /*
65 * get an NFS2/NFS3 root dentry from the root 75 * get an NFS2/NFS3 root dentry from the root filehandle
66 */ 76 */
67 int nfs_get_root(struct super_block *s, struct !! 77 struct dentry *nfs_get_root(struct super_block *sb, struct nfs_fh *mntfh)
68 { 78 {
69 struct nfs_fs_context *ctx = nfs_fc2co !! 79 struct nfs_server *server = NFS_SB(sb);
70 struct nfs_server *server = NFS_SB(s), <<
71 struct nfs_fsinfo fsinfo; 80 struct nfs_fsinfo fsinfo;
72 struct dentry *root; !! 81 struct nfs_fattr fattr;
>> 82 struct dentry *mntroot;
73 struct inode *inode; 83 struct inode *inode;
74 char *name; !! 84 int error;
75 int error = -ENOMEM; <<
76 unsigned long kflags = 0, kflags_out = <<
77 <<
78 name = kstrdup(fc->source, GFP_KERNEL) <<
79 if (!name) <<
80 goto out; <<
81 85
82 /* get the actual root for this mount 86 /* get the actual root for this mount */
83 fsinfo.fattr = nfs_alloc_fattr_with_la !! 87 fsinfo.fattr = &fattr;
84 if (fsinfo.fattr == NULL) <<
85 goto out_name; <<
86 88
87 error = server->nfs_client->rpc_ops->g !! 89 error = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
88 if (error < 0) { 90 if (error < 0) {
89 dprintk("nfs_get_root: getattr 91 dprintk("nfs_get_root: getattr error = %d\n", -error);
90 nfs_errorf(fc, "NFS: Couldn't !! 92 return ERR_PTR(error);
91 goto out_fattr; <<
92 } 93 }
93 94
94 inode = nfs_fhget(s, ctx->mntfh, fsinf !! 95 inode = nfs_fhget(sb, mntfh, fsinfo.fattr);
95 if (IS_ERR(inode)) { 96 if (IS_ERR(inode)) {
96 dprintk("nfs_get_root: get roo 97 dprintk("nfs_get_root: get root inode failed\n");
97 error = PTR_ERR(inode); !! 98 return ERR_CAST(inode);
98 nfs_errorf(fc, "NFS: Couldn't <<
99 goto out_fattr; <<
100 } 99 }
101 100
102 error = nfs_superblock_set_dummy_root( !! 101 error = nfs_superblock_set_dummy_root(sb, inode);
103 if (error != 0) 102 if (error != 0)
104 goto out_fattr; !! 103 return ERR_PTR(error);
105 104
106 /* root dentries normally start off an 105 /* root dentries normally start off anonymous and get spliced in later
107 * if the dentry tree reaches them; ho 106 * if the dentry tree reaches them; however if the dentry already
108 * exists, we'll pick it up at this po 107 * exists, we'll pick it up at this point and use it as the root
109 */ 108 */
110 root = d_obtain_root(inode); !! 109 mntroot = d_obtain_alias(inode);
111 if (IS_ERR(root)) { !! 110 if (IS_ERR(mntroot)) {
112 dprintk("nfs_get_root: get roo 111 dprintk("nfs_get_root: get root dentry failed\n");
113 error = PTR_ERR(root); !! 112 return mntroot;
114 nfs_errorf(fc, "NFS: Couldn't !! 113 }
115 goto out_fattr; !! 114
116 } !! 115 security_d_instantiate(mntroot, inode);
117 !! 116
118 security_d_instantiate(root, inode); !! 117 if (!mntroot->d_op)
119 spin_lock(&root->d_lock); !! 118 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
120 if (IS_ROOT(root) && !root->d_fsdata & !! 119
121 !(root->d_flags & DCACHE_NFSFS_REN !! 120 return mntroot;
122 root->d_fsdata = name; <<
123 name = NULL; <<
124 } <<
125 spin_unlock(&root->d_lock); <<
126 fc->root = root; <<
127 if (server->caps & NFS_CAP_SECURITY_LA <<
128 kflags |= SECURITY_LSM_NATIVE_ <<
129 if (ctx->clone_data.sb) { <<
130 if (d_inode(fc->root)->i_fop ! <<
131 error = -ESTALE; <<
132 goto error_splat_root; <<
133 } <<
134 /* clone lsm security options <<
135 error = security_sb_clone_mnt_ <<
136 <<
137 if (error) <<
138 goto error_splat_root; <<
139 clone_server = NFS_SB(ctx->clo <<
140 server->has_sec_mnt_opts = clo <<
141 } else { <<
142 error = security_sb_set_mnt_op <<
143 <<
144 } <<
145 if (error) <<
146 goto error_splat_root; <<
147 if (server->caps & NFS_CAP_SECURITY_LA <<
148 !(kflags_out & SECURITY_LSM_NA <<
149 server->caps &= ~NFS_CAP_SECUR <<
150 <<
151 nfs_setsecurity(inode, fsinfo.fattr); <<
152 error = 0; <<
153 <<
154 out_fattr: <<
155 nfs_free_fattr(fsinfo.fattr); <<
156 out_name: <<
157 kfree(name); <<
158 out: <<
159 return error; <<
160 error_splat_root: <<
161 dput(fc->root); <<
162 fc->root = NULL; <<
163 goto out_fattr; <<
164 } 121 }
>> 122
>> 123 #ifdef CONFIG_NFS_V4
>> 124
>> 125 /*
>> 126 * Do a simple pathwalk from the root FH of the server to the nominated target
>> 127 * of the mountpoint
>> 128 * - give error on symlinks
>> 129 * - give error on ".." occurring in the path
>> 130 * - follow traversals
>> 131 */
>> 132 int nfs4_path_walk(struct nfs_server *server,
>> 133 struct nfs_fh *mntfh,
>> 134 const char *path)
>> 135 {
>> 136 struct nfs_fsinfo fsinfo;
>> 137 struct nfs_fattr fattr;
>> 138 struct nfs_fh lastfh;
>> 139 struct qstr name;
>> 140 int ret;
>> 141
>> 142 dprintk("--> nfs4_path_walk(,,%s)\n", path);
>> 143
>> 144 fsinfo.fattr = &fattr;
>> 145 nfs_fattr_init(&fattr);
>> 146
>> 147 /* Eat leading slashes */
>> 148 while (*path == '/')
>> 149 path++;
>> 150
>> 151 /* Start by getting the root filehandle from the server */
>> 152 ret = server->nfs_client->rpc_ops->getroot(server, mntfh, &fsinfo);
>> 153 if (ret < 0) {
>> 154 dprintk("nfs4_get_root: getroot error = %d\n", -ret);
>> 155 return ret;
>> 156 }
>> 157
>> 158 if (!S_ISDIR(fattr.mode)) {
>> 159 printk(KERN_ERR "nfs4_get_root:"
>> 160 " getroot encountered non-directory\n");
>> 161 return -ENOTDIR;
>> 162 }
>> 163
>> 164 /* FIXME: It is quite valid for the server to return a referral here */
>> 165 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
>> 166 printk(KERN_ERR "nfs4_get_root:"
>> 167 " getroot obtained referral\n");
>> 168 return -EREMOTE;
>> 169 }
>> 170
>> 171 next_component:
>> 172 dprintk("Next: %s\n", path);
>> 173
>> 174 /* extract the next bit of the path */
>> 175 if (!*path)
>> 176 goto path_walk_complete;
>> 177
>> 178 name.name = path;
>> 179 while (*path && *path != '/')
>> 180 path++;
>> 181 name.len = path - (const char *) name.name;
>> 182
>> 183 if (name.len > NFS4_MAXNAMLEN)
>> 184 return -ENAMETOOLONG;
>> 185
>> 186 eat_dot_dir:
>> 187 while (*path == '/')
>> 188 path++;
>> 189
>> 190 if (path[0] == '.' && (path[1] == '/' || !path[1])) {
>> 191 path += 2;
>> 192 goto eat_dot_dir;
>> 193 }
>> 194
>> 195 /* FIXME: Why shouldn't the user be able to use ".." in the path? */
>> 196 if (path[0] == '.' && path[1] == '.' && (path[2] == '/' || !path[2])
>> 197 ) {
>> 198 printk(KERN_ERR "nfs4_get_root:"
>> 199 " Mount path contains reference to \"..\"\n");
>> 200 return -EINVAL;
>> 201 }
>> 202
>> 203 /* lookup the next FH in the sequence */
>> 204 memcpy(&lastfh, mntfh, sizeof(lastfh));
>> 205
>> 206 dprintk("LookupFH: %*.*s [%s]\n", name.len, name.len, name.name, path);
>> 207
>> 208 ret = server->nfs_client->rpc_ops->lookupfh(server, &lastfh, &name,
>> 209 mntfh, &fattr);
>> 210 if (ret < 0) {
>> 211 dprintk("nfs4_get_root: getroot error = %d\n", -ret);
>> 212 return ret;
>> 213 }
>> 214
>> 215 if (!S_ISDIR(fattr.mode)) {
>> 216 printk(KERN_ERR "nfs4_get_root:"
>> 217 " lookupfh encountered non-directory\n");
>> 218 return -ENOTDIR;
>> 219 }
>> 220
>> 221 /* FIXME: Referrals are quite valid here too */
>> 222 if (fattr.valid & NFS_ATTR_FATTR_V4_REFERRAL) {
>> 223 printk(KERN_ERR "nfs4_get_root:"
>> 224 " lookupfh obtained referral\n");
>> 225 return -EREMOTE;
>> 226 }
>> 227
>> 228 goto next_component;
>> 229
>> 230 path_walk_complete:
>> 231 memcpy(&server->fsid, &fattr.fsid, sizeof(server->fsid));
>> 232 dprintk("<-- nfs4_path_walk() = 0\n");
>> 233 return 0;
>> 234 }
>> 235
>> 236 /*
>> 237 * get an NFS4 root dentry from the root filehandle
>> 238 */
>> 239 struct dentry *nfs4_get_root(struct super_block *sb, struct nfs_fh *mntfh)
>> 240 {
>> 241 struct nfs_server *server = NFS_SB(sb);
>> 242 struct nfs_fattr fattr;
>> 243 struct dentry *mntroot;
>> 244 struct inode *inode;
>> 245 int error;
>> 246
>> 247 dprintk("--> nfs4_get_root()\n");
>> 248
>> 249 /* get the info about the server and filesystem */
>> 250 error = nfs4_server_capabilities(server, mntfh);
>> 251 if (error < 0) {
>> 252 dprintk("nfs_get_root: getcaps error = %d\n",
>> 253 -error);
>> 254 return ERR_PTR(error);
>> 255 }
>> 256
>> 257 /* get the actual root for this mount */
>> 258 error = server->nfs_client->rpc_ops->getattr(server, mntfh, &fattr);
>> 259 if (error < 0) {
>> 260 dprintk("nfs_get_root: getattr error = %d\n", -error);
>> 261 return ERR_PTR(error);
>> 262 }
>> 263
>> 264 inode = nfs_fhget(sb, mntfh, &fattr);
>> 265 if (IS_ERR(inode)) {
>> 266 dprintk("nfs_get_root: get root inode failed\n");
>> 267 return ERR_CAST(inode);
>> 268 }
>> 269
>> 270 error = nfs_superblock_set_dummy_root(sb, inode);
>> 271 if (error != 0)
>> 272 return ERR_PTR(error);
>> 273
>> 274 /* root dentries normally start off anonymous and get spliced in later
>> 275 * if the dentry tree reaches them; however if the dentry already
>> 276 * exists, we'll pick it up at this point and use it as the root
>> 277 */
>> 278 mntroot = d_obtain_alias(inode);
>> 279 if (IS_ERR(mntroot)) {
>> 280 dprintk("nfs_get_root: get root dentry failed\n");
>> 281 return mntroot;
>> 282 }
>> 283
>> 284 security_d_instantiate(mntroot, inode);
>> 285
>> 286 if (!mntroot->d_op)
>> 287 mntroot->d_op = server->nfs_client->rpc_ops->dentry_ops;
>> 288
>> 289 dprintk("<-- nfs4_get_root()\n");
>> 290 return mntroot;
>> 291 }
>> 292
>> 293 #endif /* CONFIG_NFS_V4 */
165 294
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