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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
54ceac45 DH |
2 | /* getroot.c: get the root dentry for an NFS mount |
3 | * | |
4 | * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. | |
5 | * Written by David Howells (dhowells@redhat.com) | |
54ceac45 DH |
6 | */ |
7 | ||
54ceac45 DH |
8 | #include <linux/module.h> |
9 | #include <linux/init.h> | |
10 | ||
11 | #include <linux/time.h> | |
12 | #include <linux/kernel.h> | |
13 | #include <linux/mm.h> | |
14 | #include <linux/string.h> | |
15 | #include <linux/stat.h> | |
16 | #include <linux/errno.h> | |
17 | #include <linux/unistd.h> | |
18 | #include <linux/sunrpc/clnt.h> | |
19 | #include <linux/sunrpc/stats.h> | |
20 | #include <linux/nfs_fs.h> | |
21 | #include <linux/nfs_mount.h> | |
54ceac45 | 22 | #include <linux/lockd/bind.h> |
54ceac45 DH |
23 | #include <linux/seq_file.h> |
24 | #include <linux/mount.h> | |
54ceac45 DH |
25 | #include <linux/vfs.h> |
26 | #include <linux/namei.h> | |
738a3519 | 27 | #include <linux/security.h> |
54ceac45 | 28 | |
7c0f6ba6 | 29 | #include <linux/uaccess.h> |
54ceac45 | 30 | |
4e437e95 SK |
31 | #include "internal.h" |
32 | ||
54ceac45 | 33 | #define NFSDBG_FACILITY NFSDBG_CLIENT |
54ceac45 | 34 | |
b09b9417 TM |
35 | /* |
36 | * Set the superblock root dentry. | |
37 | * Note that this function frees the inode in case of error. | |
38 | */ | |
39 | static int nfs_superblock_set_dummy_root(struct super_block *sb, struct inode *inode) | |
40 | { | |
41 | /* The mntroot acts as the dummy root dentry for this superblock */ | |
42 | if (sb->s_root == NULL) { | |
48fde701 AV |
43 | sb->s_root = d_make_root(inode); |
44 | if (sb->s_root == NULL) | |
b09b9417 | 45 | return -ENOMEM; |
7de9c6ee | 46 | ihold(inode); |
a10db50a TM |
47 | /* |
48 | * Ensure that this dentry is invisible to d_find_alias(). | |
49 | * Otherwise, it may be spliced into the tree by | |
41d28bca | 50 | * d_splice_alias if a parent directory from the same |
a10db50a TM |
51 | * filesystem gets mounted at a later time. |
52 | * This again causes shrink_dcache_for_umount_subtree() to | |
53 | * Oops, since the test for IS_ROOT() will fail. | |
54 | */ | |
2b0143b5 | 55 | spin_lock(&d_inode(sb->s_root)->i_lock); |
b23fb0a6 | 56 | spin_lock(&sb->s_root->d_lock); |
946e51f2 | 57 | hlist_del_init(&sb->s_root->d_u.d_alias); |
b23fb0a6 | 58 | spin_unlock(&sb->s_root->d_lock); |
2b0143b5 | 59 | spin_unlock(&d_inode(sb->s_root)->i_lock); |
b09b9417 TM |
60 | } |
61 | return 0; | |
62 | } | |
63 | ||
54ceac45 DH |
64 | /* |
65 | * get an NFS2/NFS3 root dentry from the root filehandle | |
66 | */ | |
62a55d08 | 67 | int nfs_get_root(struct super_block *s, struct fs_context *fc) |
54ceac45 | 68 | { |
62a55d08 SM |
69 | struct nfs_fs_context *ctx = nfs_fc2context(fc); |
70 | struct nfs_server *server = NFS_SB(s); | |
54ceac45 | 71 | struct nfs_fsinfo fsinfo; |
62a55d08 | 72 | struct dentry *root; |
54ceac45 | 73 | struct inode *inode; |
62a55d08 SM |
74 | char *name; |
75 | int error = -ENOMEM; | |
779df6a5 | 76 | unsigned long kflags = 0, kflags_out = 0; |
54ceac45 | 77 | |
62a55d08 | 78 | name = kstrdup(fc->source, GFP_KERNEL); |
b1942c5f | 79 | if (!name) |
62a55d08 | 80 | goto out; |
b1942c5f | 81 | |
54ceac45 | 82 | /* get the actual root for this mount */ |
8bac9db9 | 83 | fsinfo.fattr = nfs_alloc_fattr(); |
62a55d08 SM |
84 | if (fsinfo.fattr == NULL) |
85 | goto out_name; | |
54ceac45 | 86 | |
779df6a5 SM |
87 | fsinfo.fattr->label = nfs4_label_alloc(server, GFP_KERNEL); |
88 | if (IS_ERR(fsinfo.fattr->label)) | |
89 | goto out_fattr; | |
62a55d08 | 90 | error = server->nfs_client->rpc_ops->getroot(server, ctx->mntfh, &fsinfo); |
54ceac45 DH |
91 | if (error < 0) { |
92 | dprintk("nfs_get_root: getattr error = %d\n", -error); | |
ce8866f0 | 93 | nfs_errorf(fc, "NFS: Couldn't getattr on root"); |
779df6a5 | 94 | goto out_label; |
54ceac45 DH |
95 | } |
96 | ||
62a55d08 | 97 | inode = nfs_fhget(s, ctx->mntfh, fsinfo.fattr, NULL); |
54ceac45 DH |
98 | if (IS_ERR(inode)) { |
99 | dprintk("nfs_get_root: get root inode failed\n"); | |
62a55d08 | 100 | error = PTR_ERR(inode); |
ce8866f0 | 101 | nfs_errorf(fc, "NFS: Couldn't get root inode"); |
779df6a5 | 102 | goto out_label; |
54ceac45 DH |
103 | } |
104 | ||
62a55d08 SM |
105 | error = nfs_superblock_set_dummy_root(s, inode); |
106 | if (error != 0) | |
779df6a5 | 107 | goto out_label; |
b09b9417 | 108 | |
54ceac45 DH |
109 | /* root dentries normally start off anonymous and get spliced in later |
110 | * if the dentry tree reaches them; however if the dentry already | |
111 | * exists, we'll pick it up at this point and use it as the root | |
112 | */ | |
62a55d08 SM |
113 | root = d_obtain_root(inode); |
114 | if (IS_ERR(root)) { | |
54ceac45 | 115 | dprintk("nfs_get_root: get root dentry failed\n"); |
62a55d08 | 116 | error = PTR_ERR(root); |
ce8866f0 | 117 | nfs_errorf(fc, "NFS: Couldn't get root dentry"); |
779df6a5 | 118 | goto out_label; |
54ceac45 DH |
119 | } |
120 | ||
62a55d08 SM |
121 | security_d_instantiate(root, inode); |
122 | spin_lock(&root->d_lock); | |
123 | if (IS_ROOT(root) && !root->d_fsdata && | |
124 | !(root->d_flags & DCACHE_NFSFS_RENAMED)) { | |
125 | root->d_fsdata = name; | |
b1942c5f AV |
126 | name = NULL; |
127 | } | |
62a55d08 SM |
128 | spin_unlock(&root->d_lock); |
129 | fc->root = root; | |
779df6a5 SM |
130 | if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL) |
131 | kflags |= SECURITY_LSM_NATIVE_LABELS; | |
132 | if (ctx->clone_data.sb) { | |
133 | if (d_inode(fc->root)->i_fop != &nfs_dir_operations) { | |
134 | error = -ESTALE; | |
135 | goto error_splat_root; | |
136 | } | |
137 | /* clone lsm security options from the parent to the new sb */ | |
138 | error = security_sb_clone_mnt_opts(ctx->clone_data.sb, | |
139 | s, kflags, &kflags_out); | |
140 | } else { | |
141 | error = security_sb_set_mnt_opts(s, fc->security, | |
142 | kflags, &kflags_out); | |
143 | } | |
144 | if (error) | |
145 | goto error_splat_root; | |
146 | if (NFS_SB(s)->caps & NFS_CAP_SECURITY_LABEL && | |
147 | !(kflags_out & SECURITY_LSM_NATIVE_LABELS)) | |
148 | NFS_SB(s)->caps &= ~NFS_CAP_SECURITY_LABEL; | |
149 | ||
150 | nfs_setsecurity(inode, fsinfo.fattr, fsinfo.fattr->label); | |
62a55d08 SM |
151 | error = 0; |
152 | ||
779df6a5 SM |
153 | out_label: |
154 | nfs4_label_free(fsinfo.fattr->label); | |
62a55d08 | 155 | out_fattr: |
8bac9db9 | 156 | nfs_free_fattr(fsinfo.fattr); |
62a55d08 SM |
157 | out_name: |
158 | kfree(name); | |
159 | out: | |
160 | return error; | |
779df6a5 SM |
161 | error_splat_root: |
162 | dput(fc->root); | |
163 | fc->root = NULL; | |
164 | goto out_label; | |
54ceac45 | 165 | } |