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 }; 36 37 const struct inode_operations afs_autocell_inode_operations = { 38 .getattr = afs_getattr, 39 }; 40 41 static LIST_HEAD(afs_vfsmounts); 42 static DECLARE_DELAYED_WORK(afs_mntpt_expiry_timer, afs_mntpt_expiry_timed_out); 43 44 static unsigned long afs_mntpt_expiry_timeout = 10 * 60; 45 46 static const char afs_root_volume[] = "root.cell"; 47 48 /* 49 * no valid lookup procedure on this sort of dir 50 */ 51 static struct dentry *afs_mntpt_lookup(struct inode *dir, 52 struct dentry *dentry, 53 unsigned int flags) 54 { 55 _enter("%p,%p{%pd2}", dir, dentry, dentry); 56 return ERR_PTR(-EREMOTE); 57 } 58 59 /* 60 * no valid open procedure on this sort of dir 61 */ 62 static int afs_mntpt_open(struct inode *inode, struct file *file) 63 { 64 _enter("%p,%p{%pD2}", inode, file, file); 65 return -EREMOTE; 66 } 67 68 /* 69 * Set the parameters for the proposed superblock. 70 */ 71 static int afs_mntpt_set_params(struct fs_context *fc, struct dentry *mntpt) 72 { 73 struct afs_fs_context *ctx = fc->fs_private; 74 struct afs_super_info *src_as = AFS_FS_S(mntpt->d_sb); 75 struct afs_vnode *vnode = AFS_FS_I(d_inode(mntpt)); 76 struct afs_cell *cell; 77 const char *p; 78 int ret; 79 80 if (fc->net_ns != src_as->net_ns) { 81 put_net(fc->net_ns); 82 fc->net_ns = get_net(src_as->net_ns); 83 } 84 85 if (src_as->volume && src_as->volume->type == AFSVL_RWVOL) { 86 ctx->type = AFSVL_RWVOL; 87 ctx->force = true; 88 } 89 if (ctx->cell) { 90 afs_unuse_cell(ctx->net, ctx->cell, afs_cell_trace_unuse_mntpt); 91 ctx->cell = NULL; 92 } 93 if (test_bit(AFS_VNODE_PSEUDODIR, &vnode->flags)) { 94 /* if the directory is a pseudo directory, use the d_name */ 95 unsigned size = mntpt->d_name.len; 96 97 if (size < 2) 98 return -ENOENT; 99 100 p = mntpt->d_name.name; 101 if (mntpt->d_name.name[0] == '.') { 102 size--; 103 p++; 104 ctx->type = AFSVL_RWVOL; 105 ctx->force = true; 106 } 107 if (size > AFS_MAXCELLNAME) 108 return -ENAMETOOLONG; 109 110 cell = afs_lookup_cell(ctx->net, p, size, NULL, false); 111 if (IS_ERR(cell)) { 112 pr_err("kAFS: unable to lookup cell '%pd'\n", mntpt); 113 return PTR_ERR(cell); 114 } 115 ctx->cell = cell; 116 117 ctx->volname = afs_root_volume; 118 ctx->volnamesz = sizeof(afs_root_volume) - 1; 119 } else { 120 /* read the contents of the AFS special symlink */ 121 struct page *page; 122 loff_t size = i_size_read(d_inode(mntpt)); 123 char *buf; 124 125 if (src_as->cell) 126 ctx->cell = afs_use_cell(src_as->cell, afs_cell_trace_use_mntpt); 127 128 if (size < 2 || size > PAGE_SIZE - 1) 129 return -EINVAL; 130 131 page = read_mapping_page(d_inode(mntpt)->i_mapping, 0, NULL); 132 if (IS_ERR(page)) 133 return PTR_ERR(page); 134 135 buf = kmap(page); 136 ret = -EINVAL; 137 if (buf[size - 1] == '.') 138 ret = vfs_parse_fs_string(fc, "source", buf, size - 1); 139 kunmap(page); 140 put_page(page); 141 if (ret < 0) 142 return ret; 143 144 /* Don't cross a backup volume mountpoint from a backup volume */ 145 if (src_as->volume && src_as->volume->type == AFSVL_BACKVOL && 146 ctx->type == AFSVL_BACKVOL) 147 return -ENODEV; 148 } 149 150 return 0; 151 } 152 153 /* 154 * create a vfsmount to be automounted 155 */ 156 static struct vfsmount *afs_mntpt_do_automount(struct dentry *mntpt) 157 { 158 struct fs_context *fc; 159 struct vfsmount *mnt; 160 int ret; 161 162 BUG_ON(!d_inode(mntpt)); 163 164 fc = fs_context_for_submount(&afs_fs_type, mntpt); 165 if (IS_ERR(fc)) 166 return ERR_CAST(fc); 167 168 ret = afs_mntpt_set_params(fc, mntpt); 169 if (!ret) 170 mnt = fc_mount(fc); 171 else 172 mnt = ERR_PTR(ret); 173 174 put_fs_context(fc); 175 return mnt; 176 } 177 178 /* 179 * handle an automount point 180 */ 181 struct vfsmount *afs_d_automount(struct path *path) 182 { 183 struct vfsmount *newmnt; 184 185 _enter("{%pd}", path->dentry); 186 187 newmnt = afs_mntpt_do_automount(path->dentry); 188 if (IS_ERR(newmnt)) 189 return newmnt; 190 191 mntget(newmnt); /* prevent immediate expiration */ 192 mnt_set_expiry(newmnt, &afs_vfsmounts); 193 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 194 afs_mntpt_expiry_timeout * HZ); 195 _leave(" = %p", newmnt); 196 return newmnt; 197 } 198 199 /* 200 * handle mountpoint expiry timer going off 201 */ 202 static void afs_mntpt_expiry_timed_out(struct work_struct *work) 203 { 204 _enter(""); 205 206 if (!list_empty(&afs_vfsmounts)) { 207 mark_mounts_for_expiry(&afs_vfsmounts); 208 queue_delayed_work(afs_wq, &afs_mntpt_expiry_timer, 209 afs_mntpt_expiry_timeout * HZ); 210 } 211 212 _leave(""); 213 } 214 215 /* 216 * kill the AFS mountpoint timer if it's still running 217 */ 218 void afs_mntpt_kill_timer(void) 219 { 220 _enter(""); 221 222 ASSERT(list_empty(&afs_vfsmounts)); 223 cancel_delayed_work_sync(&afs_mntpt_expiry_timer); 224 } 225