1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* mountpoint management 3 * 4 * Copyright (C) 2002 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/kernel.h> 9 #include <linux/module.h> 10 #include <linux/init.h> 11 #include <linux/fs.h> 12 #include <linux/pagemap.h> 13 #include <linux/mount.h> 14 #include <linux/namei.h> 15 #include <linux/gfp.h> 16 #include <linux/fs_context.h> 17 #include "internal.h" 18 19 20 static struct dentry *afs_mntpt_lookup(struct inode *dir, 21 struct dentry *dentry, 22 unsigned int flags); 23 static int afs_mntpt_open(struct inode *inode, struct file *file); 24 static void afs_mntpt_expiry_timed_out(struct work_struct *work); 25 26 const struct file_operations afs_mntpt_file_operations = { 27 .open = afs_mntpt_open, 28 .llseek = noop_llseek, 29 }; 30 31 const struct inode_operations afs_mntpt_inode_operations = { 32 .lookup = afs_mntpt_lookup, 33 .readlink = page_readlink, 34 .getattr = afs_getattr, 35 .listxattr = afs_listxattr, 36 }; 37 38 const struct inode_operations afs_autocell_inode_operations = { 39 .getattr = afs_getattr, 40 }; 41 42 static LIST_HEAD(afs_vfsmounts); 43 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); 44 45 static unsigned long afs_mntpt_expiry_timeout = 10 * 60; 46 47 static const char afs_root_volume[] = "root.cell"; 48 49 /* 50 * no valid lookup procedure on this sort of dir 51 */ 52 static struct dentry *afs_mntpt_lookup(struct inode *dir, 53 struct dentry *dentry, 54 unsigned int flags) 55 { 56 _enter("%p,%p{%pd2}", dir, dentry, dentry); 57 return ERR_PTR(-EREMOTE); 58 } 59 60 /* 61 * no valid open procedure on this sort of dir 62 */ 63 static int afs_mntpt_open(struct inode *inode, struct file *file) 64 { 65 _enter("%p,%p{%pD2}", inode, file, file); 66 return -EREMOTE; 67 } 68 69 /* 70 * Set the parameters for the proposed superblock. 71 */ 72 static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt) 73 { 74 struct afs_fs_context *ctx = fc->fs_private; 75 struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb); 76 struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt)); 77 struct afs_cell *cell; 78 const char *p; 79 int ret; 80 81 if (fc->net_ns != src_as->net_ns) { 82 put_net(fc->net_ns); 83 fc->net_ns = get_net(src_as->net_ns); 84 } 85 86 if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) { 87 ctx->type = AFSVL_RWVOL; 88 ctx->force = true; 89 } 90 if (ctx->cell) { 91 afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt); 92 ctx->cell = NULL; 93 } 94 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) { 95 /* if the directory is a pseudo directory, use the d_name */ 96 unsigned size = mntpt->d_name.len; 97 98 if (size < 2) 99 return -ENOENT; 100 101 p = mntpt->d_name.name; 102 if (mntpt->d_name.name[0] == '.') { 103 size--; 104 p++; 105 ctx->type = AFSVL_RWVOL; 106 ctx->force = true; 107 } 108 if (size > AFS_MAXCELLNAME) 109 return -ENAMETOOLONG; 110 111 cell = afs_lookup_cell(ctx->net, p, size, NULL, false); 112 if (IS_ERR(cell)) { 113 pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt); 114 return PTR_ERR(cell); 115 } 116 ctx->cell = cell; 117 118 ctx->volname = afs_root_volume; 119 ctx->volnamesz = sizeof(afs_root_volume) - 1; 120 } else { 121 /* read the contents of the AFS special symlink */ 122 struct page *page; 123 loff_t size = i_size_read(d_inode(mntpt)); 124 char *buf; 125 126 if (src_as->cell) 127 ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt); 128 129 if (size < 2 || size > PAGE_SIZE - 1) 130 return -EINVAL; 131 132 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL); 133 if (IS_ERR(page)) 134 return PTR_ERR(page); 135 136 if (PageError(page)) { 137 ret = afs_bad(AFS_FS_I(d_inode(mntpt)), afs_file_error_mntpt); 138 put_page(page); 139 return ret; 140 } 141 142 buf = kmap(page); 143 ret = -EINVAL; 144 if (buf[size - 1] == '.') 145 ret = vfs_parse_fs_string(fc, "source", buf, size - 1); 146 kunmap(page); 147 put_page(page); 148 if (ret < 0) 149 return ret; 150 } 151 152 return 0; 153 } 154 155 /* 156 * create a vfsmount to be automounted 157 */ 158 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) 159 { 160 struct fs_context *fc; 161 struct vfsmount *mnt; 162 int ret; 163 164 BUG_ON(!d_inode(mntpt)); 165 166 fc = fs_context_for_submount(&afs_fs_type, mntpt); 167 if (IS_ERR(fc)) 168 return ERR_CAST(fc); 169 170 ret = afs_mntpt_set_params(fc, mntpt); 171 if (!ret) 172 mnt = fc_mount(fc); 173 else 174 mnt = ERR_PTR(ret); 175 176 put_fs_context(fc); 177 return mnt; 178 } 179 180 /* 181 * handle an automount point 182 */ 183 struct vfsmount *afs_d_automount(struct path *path) 184 { 185 struct vfsmount *newmnt; 186 187 _enter("{%pd}", path->dentry); 188 189 newmnt = afs_mntpt_do_automount(path->dentry); 190 if (IS_ERR(newmnt)) 191 return newmnt; 192 193 mntget(newmnt); /* prevent immediate expiration */ 194 mnt_set_expiry(newmnt, &afs_vfsmounts); 195 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 196 afs_mntpt_expiry_timeout * HZ); 197 _leave(" = %p", newmnt); 198 return newmnt; 199 } 200 201 /* 202 * handle mountpoint expiry timer going off 203 */ 204 static void afs_mntpt_expiry_timed_out(struct work_struct *work) 205 { 206 _enter(""); 207 208 if (!list_empty(&afs_vfsmounts)) { 209 mark_mounts_for_expiry(&afs_vfsmounts); 210 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 211 afs_mntpt_expiry_timeout * HZ); 212 } 213 214 _leave(""); 215 } 216 217 /* 218 * kill the AFS mountpoint timer if it's still running 219 */ 220 void afs_mntpt_kill_timer(void) 221 { 222 _enter(""); 223 224 ASSERT(list_empty(&afs_vfsmounts)); 225 cancel_delayed_work_sync(&afs_mntpt_expiry_timer); 226 } 227