Merge tag 'pull-qstr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs

Pull d_name audit update from Al Viro:
 "Simplifying ->d_name audits, easy part.

  Turn dentry->d_name into an anon union of const struct qsrt (d_name
  itself) and a writable alias (__d_name).

  With constification of some struct qstr * arguments of functions that
  get &dentry->d_name passed to them, that ends up with all
  modifications provably done only in fs/dcache.c (and a fairly small
  part of it).

  Any new places doing modifications will be easy to find - grep for
  __d_name will suffice"

* tag 'pull-qstr' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs:
  make it easier to catch those who try to modify ->d_name
  generic_ci_validate_strict_name(): constify name argument
  afs_dir_search: constify qstr argument
  afs_edit_dir_{add,remove}(): constify qstr argument
  exfat_find(): constify qstr argument
  security_dentry_init_security(): constify qstr argument

Author: torvalds

fs/afs/dir_edit.c

@@ -239,7 +239,7 @@ static void afs_edit_init_block(union afs_xdr_dir_block *meta,
  * The caller must hold the inode locked.
  */
 void afs_edit_dir_add(struct afs_vnode *vnode,
-		      struct qstr *name, struct afs_fid *new_fid,
+		      const struct qstr *name, struct afs_fid *new_fid,
 		      enum afs_edit_dir_reason why)
 {
 	union afs_xdr_dir_block *meta, *block;
@@ -391,7 +391,7 @@ void afs_edit_dir_add(struct afs_vnode *vnode,
  * The caller must hold the inode locked.
  */
 void afs_edit_dir_remove(struct afs_vnode *vnode,
-			 struct qstr *name, enum afs_edit_dir_reason why)
+			 const struct qstr *name, enum afs_edit_dir_reason why)
 {
 	union afs_xdr_dir_block *meta, *block, *pblock;
 	union afs_xdr_dirent *de, *pde;

fs/afs/dir_search.c

@@ -188,7 +188,7 @@ int afs_dir_search_bucket(struct afs_dir_iter *iter, const struct qstr *name,
 /*
  * Search the appropriate hash chain in the contents of an AFS directory.
  */
-int afs_dir_search(struct afs_vnode *dvnode, struct qstr *name,
+int afs_dir_search(struct afs_vnode *dvnode, const struct qstr *name,
 		   struct afs_fid *_fid, afs_dataversion_t *_dir_version)
 {
 	struct afs_dir_iter iter = { .dvnode = dvnode, };

fs/afs/internal.h

@@ -1099,9 +1099,9 @@ int afs_single_writepages(struct address_space *mapping,
 /*
  * dir_edit.c
  */
-extern void afs_edit_dir_add(struct afs_vnode *, struct qstr *, struct afs_fid *,
+extern void afs_edit_dir_add(struct afs_vnode *, const struct qstr *, struct afs_fid *,
 			     enum afs_edit_dir_reason);
-extern void afs_edit_dir_remove(struct afs_vnode *, struct qstr *, enum afs_edit_dir_reason);
+extern void afs_edit_dir_remove(struct afs_vnode *, const struct qstr *, enum afs_edit_dir_reason);
 void afs_edit_dir_update(struct afs_vnode *vnode, const struct qstr *name,
 			 struct afs_vnode *new_dvnode, enum afs_edit_dir_reason why);
 void afs_mkdir_init_dir(struct afs_vnode *dvnode, struct afs_vnode *parent_vnode);
@@ -1114,7 +1114,7 @@ bool afs_dir_init_iter(struct afs_dir_iter *iter, const struct qstr *name);
 union afs_xdr_dir_block *afs_dir_find_block(struct afs_dir_iter *iter, size_t block);
 int afs_dir_search_bucket(struct afs_dir_iter *iter, const struct qstr *name,
 			  struct afs_fid *_fid);
-int afs_dir_search(struct afs_vnode *dvnode, struct qstr *name,
+int afs_dir_search(struct afs_vnode *dvnode, const struct qstr *name,
 		   struct afs_fid *_fid, afs_dataversion_t *_dir_version);
 
 /*

fs/dcache.c

@@ -1717,13 +1717,13 @@ static struct dentry *__d_alloc(struct super_block *sb, const struct qstr *name)
 		dname = dentry->d_shortname.string;
 	}	
 
-	dentry->d_name.len = name->len;
-	dentry->d_name.hash = name->hash;
+	dentry->__d_name.len = name->len;
+	dentry->__d_name.hash = name->hash;
 	memcpy(dname, name->name, name->len);
 	dname[name->len] = 0;
 
 	/* Make sure we always see the terminating NUL character */
-	smp_store_release(&dentry->d_name.name, dname); /* ^^^ */
+	smp_store_release(&dentry->__d_name.name, dname); /* ^^^ */
 
 	dentry->d_flags = 0;
 	lockref_init(&dentry->d_lockref);
@@ -2743,25 +2743,25 @@ static void swap_names(struct dentry *dentry, struct dentry *target)
 			/*
 			 * Both external: swap the pointers
 			 */
-			swap(target->d_name.name, dentry->d_name.name);
+			swap(target->__d_name.name, dentry->__d_name.name);
 		} else {
 			/*
 			 * dentry:internal, target:external.  Steal target's
 			 * storage and make target internal.
 			 */
-			dentry->d_name.name = target->d_name.name;
+			dentry->__d_name.name = target->__d_name.name;
 			target->d_shortname = dentry->d_shortname;
-			target->d_name.name = target->d_shortname.string;
+			target->__d_name.name = target->d_shortname.string;
 		}
 	} else {
 		if (unlikely(dname_external(dentry))) {
 			/*
 			 * dentry:external, target:internal.  Give dentry's
 			 * storage to target and make dentry internal
 			 */
-			target->d_name.name = dentry->d_name.name;
+			target->__d_name.name = dentry->__d_name.name;
 			dentry->d_shortname = target->d_shortname;
-			dentry->d_name.name = dentry->d_shortname.string;
+			dentry->__d_name.name = dentry->d_shortname.string;
 		} else {
 			/*
 			 * Both are internal.
@@ -2771,7 +2771,7 @@ static void swap_names(struct dentry *dentry, struct dentry *target)
 				     target->d_shortname.words[i]);
 		}
 	}
-	swap(dentry->d_name.hash_len, target->d_name.hash_len);
+	swap(dentry->__d_name.hash_len, target->__d_name.hash_len);
 }
 
 static void copy_name(struct dentry *dentry, struct dentry *target)
@@ -2781,11 +2781,11 @@ static void copy_name(struct dentry *dentry, struct dentry *target)
 		old_name = external_name(dentry);
 	if (unlikely(dname_external(target))) {
 		atomic_inc(&external_name(target)->count);
-		dentry->d_name = target->d_name;
+		dentry->__d_name = target->__d_name;
 	} else {
 		dentry->d_shortname = target->d_shortname;
-		dentry->d_name.name = dentry->d_shortname.string;
-		dentry->d_name.hash_len = target->d_name.hash_len;
+		dentry->__d_name.name = dentry->d_shortname.string;
+		dentry->__d_name.hash_len = target->__d_name.hash_len;
 	}
 	if (old_name && likely(atomic_dec_and_test(&old_name->count)))
 		kfree_rcu(old_name, head);
@@ -3134,7 +3134,7 @@ void d_mark_tmpfile(struct file *file, struct inode *inode)
 		!d_unlinked(dentry));
 	spin_lock(&dentry->d_parent->d_lock);
 	spin_lock_nested(&dentry->d_lock, DENTRY_D_LOCK_NESTED);
-	dentry->d_name.len = sprintf(dentry->d_shortname.string, "#%llu",
+	dentry->__d_name.len = sprintf(dentry->d_shortname.string, "#%llu",
 				(unsigned long long)inode->i_ino);
 	spin_unlock(&dentry->d_lock);
 	spin_unlock(&dentry->d_parent->d_lock);

fs/exfat/namei.c

@@ -587,7 +587,7 @@ static int exfat_create(struct mnt_idmap *idmap, struct inode *dir,
 }
 
 /* lookup a file */
-static int exfat_find(struct inode *dir, struct qstr *qname,
+static int exfat_find(struct inode *dir, const struct qstr *qname,
 		struct exfat_dir_entry *info)
 {
 	int ret, dentry, count;

include/linux/dcache.h

@@ -95,7 +95,10 @@ struct dentry {
 	seqcount_spinlock_t d_seq;	/* per dentry seqlock */
 	struct hlist_bl_node d_hash;	/* lookup hash list */
 	struct dentry *d_parent;	/* parent directory */
-	struct qstr d_name;
+	union {
+	struct qstr __d_name;		/* for use ONLY in fs/dcache.c */
+	const struct qstr d_name;
+	};
 	struct inode *d_inode;		/* Where the name belongs to - NULL is
 					 * negative */
 	union shortname_store d_shortname;

include/linux/fs.h

@@ -3716,7 +3716,8 @@ int generic_ci_d_compare(const struct dentry *dentry, unsigned int len,
  *   happens when a directory is casefolded and the filesystem is strict
  *   about its encoding.
  */
-static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qstr *name)
+static inline bool generic_ci_validate_strict_name(struct inode *dir,
+						   const struct qstr *name)
 {
 	if (!IS_CASEFOLDED(dir) || !sb_has_strict_encoding(dir->i_sb))
 		return true;
@@ -3731,7 +3732,8 @@ static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qst
 	return !utf8_validate(dir->i_sb->s_encoding, name);
 }
 #else
-static inline bool generic_ci_validate_strict_name(struct inode *dir, struct qstr *name)
+static inline bool generic_ci_validate_strict_name(struct inode *dir,
+						   const struct qstr *name)
 {
 	return true;
 }

include/linux/lsm_hook_defs.h

@@ -85,7 +85,7 @@ LSM_HOOK(int, -EOPNOTSUPP, dentry_init_security, struct dentry *dentry,
 	 int mode, const struct qstr *name, const char **xattr_name,
 	 struct lsm_context *cp)
 LSM_HOOK(int, 0, dentry_create_files_as, struct dentry *dentry, int mode,
-	 struct qstr *name, const struct cred *old, struct cred *new)
+	 const struct qstr *name, const struct cred *old, struct cred *new)
 
 #ifdef CONFIG_SECURITY_PATH
 LSM_HOOK(int, 0, path_unlink, const struct path *dir, struct dentry *dentry)

include/linux/security.h

@@ -391,7 +391,7 @@ int security_dentry_init_security(struct dentry *dentry, int mode,
 				  const char **xattr_name,
 				  struct lsm_context *lsmcxt);
 int security_dentry_create_files_as(struct dentry *dentry, int mode,
-					struct qstr *name,
+					const struct qstr *name,
 					const struct cred *old,
 					struct cred *new);
 int security_path_notify(const struct path *path, u64 mask,
@@ -872,7 +872,7 @@ static inline int security_dentry_init_security(struct dentry *dentry,
 }
 
 static inline int security_dentry_create_files_as(struct dentry *dentry,
-						  int mode, struct qstr *name,
+						  int mode, const struct qstr *name,
 						  const struct cred *old,
 						  struct cred *new)
 {

security/security.c

@@ -1814,7 +1814,7 @@ EXPORT_SYMBOL(security_dentry_init_security);
  * Return: Returns 0 on success, error on failure.
  */
 int security_dentry_create_files_as(struct dentry *dentry, int mode,
-				    struct qstr *name,
+				    const struct qstr *name,
 				    const struct cred *old, struct cred *new)
 {
 	return call_int_hook(dentry_create_files_as, dentry, mode,