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path: root/fs/autofs/root.c
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Diffstat (limited to 'fs/autofs/root.c')
-rw-r--r--fs/autofs/root.c108
1 files changed, 50 insertions, 58 deletions
diff --git a/fs/autofs/root.c b/fs/autofs/root.c
index 91fe4548c256..ca03c1cae2be 100644
--- a/fs/autofs/root.c
+++ b/fs/autofs/root.c
@@ -10,6 +10,7 @@
#include "autofs_i.h"
+static int autofs_dir_permission(struct user_namespace *, struct inode *, int);
static int autofs_dir_symlink(struct user_namespace *, struct inode *,
struct dentry *, const char *);
static int autofs_dir_unlink(struct inode *, struct dentry *);
@@ -50,6 +51,7 @@ const struct file_operations autofs_dir_operations = {
const struct inode_operations autofs_dir_inode_operations = {
.lookup = autofs_lookup,
+ .permission = autofs_dir_permission,
.unlink = autofs_dir_unlink,
.symlink = autofs_dir_symlink,
.mkdir = autofs_dir_mkdir,
@@ -77,6 +79,7 @@ static int autofs_dir_open(struct inode *inode, struct file *file)
{
struct dentry *dentry = file->f_path.dentry;
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
+ struct autofs_info *ino = autofs_dentry_ino(dentry);
pr_debug("file=%p dentry=%p %pd\n", file, dentry, dentry);
@@ -93,7 +96,7 @@ static int autofs_dir_open(struct inode *inode, struct file *file)
* it.
*/
spin_lock(&sbi->lookup_lock);
- if (!path_is_mountpoint(&file->f_path) && simple_empty(dentry)) {
+ if (!path_is_mountpoint(&file->f_path) && autofs_empty(ino)) {
spin_unlock(&sbi->lookup_lock);
return -ENOENT;
}
@@ -288,9 +291,26 @@ static struct dentry *autofs_mountpoint_changed(struct path *path)
struct dentry *dentry = path->dentry;
struct autofs_sb_info *sbi = autofs_sbi(dentry->d_sb);
- /*
- * If this is an indirect mount the dentry could have gone away
- * as a result of an expire and a new one created.
+ /* If this is an indirect mount the dentry could have gone away
+ * and a new one created.
+ *
+ * This is unusual and I can't remember the case for which it
+ * was originally added now. But an example of how this can
+ * happen is an autofs indirect mount that has the "browse"
+ * option set and also has the "symlink" option in the autofs
+ * map entry. In this case the daemon will remove the browse
+ * directory and create a symlink as the mount leaving the
+ * struct path stale.
+ *
+ * Another not so obvious case is when a mount in an autofs
+ * indirect mount that uses the "nobrowse" option is being
+ * expired at the same time as a path walk. If the mount has
+ * been umounted but the mount point directory seen before
+ * becoming unhashed (during a lockless path walk) when a stat
+ * family system call is made the mount won't be re-mounted as
+ * it should. In this case the mount point that's been removed
+ * (by the daemon) will be stale and the a new mount point
+ * dentry created.
*/
if (autofs_type_indirect(sbi->type) && d_unhashed(dentry)) {
struct dentry *parent = dentry->d_parent;
@@ -362,7 +382,7 @@ static struct vfsmount *autofs_d_automount(struct path *path)
* the mount never trigger mounts themselves (they have an
* autofs trigger mount mounted on them). But v4 pseudo direct
* mounts do need the leaves to trigger mounts. In this case
- * we have no choice but to use the list_empty() check and
+ * we have no choice but to use the autofs_empty() check and
* require user space behave.
*/
if (sbi->version > 4) {
@@ -371,7 +391,7 @@ static struct vfsmount *autofs_d_automount(struct path *path)
goto done;
}
} else {
- if (!simple_empty(dentry)) {
+ if (!autofs_empty(ino)) {
spin_unlock(&sbi->fs_lock);
goto done;
}
@@ -426,9 +446,8 @@ static int autofs_d_manage(const struct path *path, bool rcu_walk)
if (rcu_walk) {
/* We don't need fs_lock in rcu_walk mode,
- * just testing 'AUTOFS_INFO_NO_RCU' is enough.
- * simple_empty() takes a spinlock, so leave it
- * to last.
+ * just testing 'AUTOFS_INF_WANT_EXPIRE' is enough.
+ *
* We only return -EISDIR when certain this isn't
* a mount-trap.
*/
@@ -441,9 +460,7 @@ static int autofs_d_manage(const struct path *path, bool rcu_walk)
inode = d_inode_rcu(dentry);
if (inode && S_ISLNK(inode->i_mode))
return -EISDIR;
- if (list_empty(&dentry->d_subdirs))
- return 0;
- if (!simple_empty(dentry))
+ if (!autofs_empty(ino))
return -EISDIR;
return 0;
}
@@ -463,7 +480,7 @@ static int autofs_d_manage(const struct path *path, bool rcu_walk)
* we can avoid needless calls ->d_automount() and avoid
* an incorrect ELOOP error return.
*/
- if ((!path_is_mountpoint(path) && !simple_empty(dentry)) ||
+ if ((!path_is_mountpoint(path) && !autofs_empty(ino)) ||
(d_really_is_positive(dentry) && d_is_symlink(dentry)))
status = -EISDIR;
}
@@ -526,11 +543,30 @@ static struct dentry *autofs_lookup(struct inode *dir,
return NULL;
}
+static int autofs_dir_permission(struct user_namespace *mnt_userns,
+ struct inode *inode, int mask)
+{
+ if (mask & MAY_WRITE) {
+ struct autofs_sb_info *sbi = autofs_sbi(inode->i_sb);
+
+ if (!autofs_oz_mode(sbi))
+ return -EACCES;
+
+ /* autofs_oz_mode() needs to allow path walks when the
+ * autofs mount is catatonic but the state of an autofs
+ * file system needs to be preserved over restarts.
+ */
+ if (sbi->flags & AUTOFS_SBI_CATATONIC)
+ return -EACCES;
+ }
+
+ return generic_permission(mnt_userns, inode, mask);
+}
+
static int autofs_dir_symlink(struct user_namespace *mnt_userns,
struct inode *dir, struct dentry *dentry,
const char *symname)
{
- struct autofs_sb_info *sbi = autofs_sbi(dir->i_sb);
struct autofs_info *ino = autofs_dentry_ino(dentry);
struct autofs_info *p_ino;
struct inode *inode;
@@ -539,16 +575,6 @@ static int autofs_dir_symlink(struct user_namespace *mnt_userns,
pr_debug("%s <- %pd\n", symname, dentry);
- if (!autofs_oz_mode(sbi))
- return -EACCES;
-
- /* autofs_oz_mode() needs to allow path walks when the
- * autofs mount is catatonic but the state of an autofs
- * file system needs to be preserved over restarts.
- */
- if (sbi->flags & AUTOFS_SBI_CATATONIC)
- return -EACCES;
-
BUG_ON(!ino);
autofs_clean_ino(ino);
@@ -571,7 +597,6 @@ static int autofs_dir_symlink(struct user_namespace *mnt_userns,
d_add(dentry, inode);
dget(dentry);
- ino->count++;
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count++;
@@ -601,17 +626,6 @@ static int autofs_dir_unlink(struct inode *dir, struct dentry *dentry)
struct autofs_info *ino = autofs_dentry_ino(dentry);
struct autofs_info *p_ino;
- if (!autofs_oz_mode(sbi))
- return -EACCES;
-
- /* autofs_oz_mode() needs to allow path walks when the
- * autofs mount is catatonic but the state of an autofs
- * file system needs to be preserved over restarts.
- */
- if (sbi->flags & AUTOFS_SBI_CATATONIC)
- return -EACCES;
-
- ino->count--;
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count--;
dput(ino->dentry);
@@ -683,16 +697,6 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
pr_debug("dentry %p, removing %pd\n", dentry, dentry);
- if (!autofs_oz_mode(sbi))
- return -EACCES;
-
- /* autofs_oz_mode() needs to allow path walks when the
- * autofs mount is catatonic but the state of an autofs
- * file system needs to be preserved over restarts.
- */
- if (sbi->flags & AUTOFS_SBI_CATATONIC)
- return -EACCES;
-
if (ino->count != 1)
return -ENOTEMPTY;
@@ -704,7 +708,6 @@ static int autofs_dir_rmdir(struct inode *dir, struct dentry *dentry)
if (sbi->version < 5)
autofs_clear_leaf_automount_flags(dentry);
- ino->count--;
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count--;
dput(ino->dentry);
@@ -726,16 +729,6 @@ static int autofs_dir_mkdir(struct user_namespace *mnt_userns,
struct autofs_info *p_ino;
struct inode *inode;
- if (!autofs_oz_mode(sbi))
- return -EACCES;
-
- /* autofs_oz_mode() needs to allow path walks when the
- * autofs mount is catatonic but the state of an autofs
- * file system needs to be preserved over restarts.
- */
- if (sbi->flags & AUTOFS_SBI_CATATONIC)
- return -EACCES;
-
pr_debug("dentry %p, creating %pd\n", dentry, dentry);
BUG_ON(!ino);
@@ -753,7 +746,6 @@ static int autofs_dir_mkdir(struct user_namespace *mnt_userns,
autofs_set_leaf_automount_flags(dentry);
dget(dentry);
- ino->count++;
p_ino = autofs_dentry_ino(dentry->d_parent);
p_ino->count++;
inc_nlink(dir);