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222 lines
6.6 KiB
222 lines
6.6 KiB
From: Andreas Gruenbacher <agruen@suse.de>
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Date: Fri, 11 Jun 2010 16:12:44 +0530
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Subject: [PATCH 01/16] vfs: Hooks for more fine-grained directory permission checking
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Patch-mainline: not yet
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Add iop->may_create and iop->may_delete for overriding the POSIX file
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permission checks when creating and deleting files. File systems can
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implement these hooks to support permission models which use different
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rules for file creation and deletion.
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When these hooks are not used, the vfs behavior remains unchanged.
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Signed-off-by: Andreas Gruenbacher <agruen@suse.de>
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Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
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---
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fs/namei.c | 82 ++++++++++++++++++++++++++++++++++++++++++-----------
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include/linux/fs.h | 4 ++
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2 files changed, 69 insertions(+), 17 deletions(-)
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--- a/fs/namei.c
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+++ b/fs/namei.c
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@@ -1283,6 +1283,26 @@ static inline int check_sticky(struct in
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}
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/*
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+ * Do the directory specific tests of inode_permission() and call the
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+ * may_delete inode operation. The may_delete inode operation must do the
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+ * sticky check when needed.
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+ */
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+static int may_delete_iop(struct inode *dir, struct inode *inode, int replace)
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+{
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+ int error;
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+
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+ if (IS_RDONLY(dir))
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+ return -EROFS;
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+ if (IS_IMMUTABLE(dir))
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+ return -EACCES;
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+ error = dir->i_op->may_delete(dir, inode, replace);
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+ if (!error)
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+ error = security_inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+
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+ return error;
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+}
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+
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+/*
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* Check whether we can remove a link victim from directory dir, check
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* whether the type of victim is right.
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* 1. We can't do it if dir is read-only (done in permission())
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@@ -1301,7 +1321,8 @@ static inline int check_sticky(struct in
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* 10. We don't allow removal of NFS sillyrenamed files; it's handled by
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* nfs_async_unlink().
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*/
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-static int may_delete(struct inode *dir,struct dentry *victim,int isdir)
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+static int may_delete(struct inode *dir, struct dentry *victim,
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+ int isdir, int replace)
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{
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int error;
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@@ -1310,14 +1331,19 @@ static int may_delete(struct inode *dir,
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BUG_ON(victim->d_parent->d_inode != dir);
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audit_inode_child(victim, dir);
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-
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- error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ if (dir->i_op->may_delete)
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+ error = may_delete_iop(dir, victim->d_inode, replace);
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+ else {
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+ error = inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ if (!error && check_sticky(dir, victim->d_inode))
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+ error = -EPERM;
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+ }
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if (error)
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return error;
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if (IS_APPEND(dir))
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return -EPERM;
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- if (check_sticky(dir, victim->d_inode)||IS_APPEND(victim->d_inode)||
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- IS_IMMUTABLE(victim->d_inode) || IS_SWAPFILE(victim->d_inode))
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+ if (IS_APPEND(victim->d_inode) || IS_IMMUTABLE(victim->d_inode) ||
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+ IS_SWAPFILE(victim->d_inode))
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return -EPERM;
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if (isdir) {
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if (!S_ISDIR(victim->d_inode->i_mode))
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@@ -1333,6 +1359,25 @@ static int may_delete(struct inode *dir,
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return 0;
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}
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+/*
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+ * Do the directory specific tests of inode_permission() and call the
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+ * may_create inode operation.
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+ */
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+static int may_create_iop(struct inode *dir, int isdir)
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+{
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+ int error;
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+
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+ if (IS_RDONLY(dir))
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+ return -EROFS;
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+ if (IS_IMMUTABLE(dir))
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+ return -EACCES;
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+ error = dir->i_op->may_create(dir, isdir);
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+ if (!error)
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+ error = security_inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+
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+ return error;
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+}
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+
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/* Check whether we can create an object with dentry child in directory
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* dir.
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* 1. We can't do it if child already exists (open has special treatment for
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@@ -1341,13 +1386,16 @@ static int may_delete(struct inode *dir,
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* 3. We should have write and exec permissions on dir
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* 4. We can't do it if dir is immutable (done in permission())
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*/
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-static inline int may_create(struct inode *dir, struct dentry *child)
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+static inline int may_create(struct inode *dir, struct dentry *child, int isdir)
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{
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if (child->d_inode)
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return -EEXIST;
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if (IS_DEADDIR(dir))
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return -ENOENT;
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- return inode_permission(dir, MAY_WRITE | MAY_EXEC);
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+ if (dir->i_op->may_create)
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+ return may_create_iop(dir, isdir);
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+ else
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+ return inode_permission(dir, MAY_WRITE | MAY_EXEC);
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}
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/*
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@@ -1395,7 +1443,7 @@ void unlock_rename(struct dentry *p1, st
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int vfs_create(struct inode *dir, struct dentry *dentry, int mode,
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struct nameidata *nd)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 0);
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if (error)
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return error;
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@@ -1957,7 +2005,7 @@ EXPORT_SYMBOL_GPL(lookup_create);
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int vfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 0);
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if (error)
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return error;
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@@ -2061,7 +2109,7 @@ SYSCALL_DEFINE3(mknod, const char __user
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int vfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 1);
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if (error)
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return error;
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@@ -2151,7 +2199,7 @@ void dentry_unhash(struct dentry *dentry
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int vfs_rmdir(struct inode *dir, struct dentry *dentry)
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{
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- int error = may_delete(dir, dentry, 1);
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+ int error = may_delete(dir, dentry, 1, 0);
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if (error)
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return error;
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@@ -2238,7 +2286,7 @@ SYSCALL_DEFINE1(rmdir, const char __user
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int vfs_unlink(struct inode *dir, struct dentry *dentry)
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{
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- int error = may_delete(dir, dentry, 0);
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+ int error = may_delete(dir, dentry, 0, 0);
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if (error)
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return error;
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@@ -2346,7 +2394,7 @@ SYSCALL_DEFINE1(unlink, const char __use
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int vfs_symlink(struct inode *dir, struct dentry *dentry, const char *oldname)
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{
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- int error = may_create(dir, dentry);
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+ int error = may_create(dir, dentry, 0);
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if (error)
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return error;
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@@ -2419,7 +2467,7 @@ int vfs_link(struct dentry *old_dentry,
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if (!inode)
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return -ENOENT;
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- error = may_create(dir, new_dentry);
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+ error = may_create(dir, new_dentry, S_ISDIR(inode->i_mode));
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if (error)
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return error;
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@@ -2630,14 +2678,14 @@ int vfs_rename(struct inode *old_dir, st
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if (old_dentry->d_inode == new_dentry->d_inode)
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return 0;
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- error = may_delete(old_dir, old_dentry, is_dir);
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+ error = may_delete(old_dir, old_dentry, is_dir, 0);
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if (error)
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return error;
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if (!new_dentry->d_inode)
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- error = may_create(new_dir, new_dentry);
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+ error = may_create(new_dir, new_dentry, is_dir);
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else
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- error = may_delete(new_dir, new_dentry, is_dir);
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+ error = may_delete(new_dir, new_dentry, is_dir, 1);
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if (error)
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return error;
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--- a/include/linux/fs.h
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+++ b/include/linux/fs.h
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@@ -1542,6 +1542,10 @@ struct inode_operations {
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void (*truncate_range)(struct inode *, loff_t, loff_t);
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int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
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u64 len);
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+ int (*may_create) (struct inode *, int);
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+ int (*may_delete) (struct inode *, struct inode *, int);
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+
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+
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} ____cacheline_aligned;
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struct seq_file;
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