fscrypt: remove filesystem specific build config option

In order to have a common code base for fscrypt "post read" processing
for all filesystems which support encryption, this commit removes
filesystem specific build config option (e.g. CONFIG_EXT4_FS_ENCRYPTION)
and replaces it with a build option (i.e. CONFIG_FS_ENCRYPTION) whose
value affects all the filesystems making use of fscrypt.

Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Chandan Rajendra <chandan@linux.vnet.ibm.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>

4 files changed, 410 insertions, 445 deletions

diff --git a/include/linux/fs.h b/include/linux/fs.h
index 811c77743dad..ba7889bb9ef6 100644
--- a/include/linux/fs.h
+++ b/include/linux/fs.h
@@ -698,7 +698,7 @@ struct inode {
 	struct fsnotify_mark_connector __rcu	*i_fsnotify_marks;
 #endif
 
-#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+#ifdef CONFIG_FS_ENCRYPTION
 	struct fscrypt_info	*i_crypt_info;
 #endif
 
@@ -1403,7 +1403,7 @@ struct super_block {
 	void                    *s_security;
 #endif
 	const struct xattr_handler **s_xattr;
-#if IS_ENABLED(CONFIG_FS_ENCRYPTION)
+#ifdef CONFIG_FS_ENCRYPTION
 	const struct fscrypt_operations	*s_cop;
 #endif
 	struct hlist_bl_head	s_roots;	/* alternate root dentries for NFS */
diff --git a/include/linux/fscrypt.h b/include/linux/fscrypt.h
index 952ab97af325..eec604840568 100644
--- a/include/linux/fscrypt.h
+++ b/include/linux/fscrypt.h
@@ -2,9 +2,8 @@
 /*
  * fscrypt.h: declarations for per-file encryption
  *
- * Filesystems that implement per-file encryption include this header
- * file with the __FS_HAS_ENCRYPTION set according to whether that filesystem
- * is being built with encryption support or not.
+ * Filesystems that implement per-file encryption must include this header
+ * file.
  *
  * Copyright (C) 2015, Google, Inc.
  *
@@ -15,6 +14,8 @@
 #define _LINUX_FSCRYPT_H
 
 #include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/slab.h>
 
 #define FS_CRYPTO_BLOCK_SIZE		16
 
@@ -42,11 +43,410 @@ struct fscrypt_name {
 /* Maximum value for the third parameter of fscrypt_operations.set_context(). */
 #define FSCRYPT_SET_CONTEXT_MAX_SIZE	28
 
-#if __FS_HAS_ENCRYPTION
-#include <linux/fscrypt_supp.h>
-#else
-#include <linux/fscrypt_notsupp.h>
-#endif
+#ifdef CONFIG_FS_ENCRYPTION
+/*
+ * fscrypt superblock flags
+ */
+#define FS_CFLG_OWN_PAGES (1U << 1)
+
+/*
+ * crypto operations for filesystems
+ */
+struct fscrypt_operations {
+	unsigned int flags;
+	const char *key_prefix;
+	int (*get_context)(struct inode *, void *, size_t);
+	int (*set_context)(struct inode *, const void *, size_t, void *);
+	bool (*dummy_context)(struct inode *);
+	bool (*empty_dir)(struct inode *);
+	unsigned int max_namelen;
+};
+
+struct fscrypt_ctx {
+	union {
+		struct {
+			struct page *bounce_page;	/* Ciphertext page */
+			struct page *control_page;	/* Original page  */
+		} w;
+		struct {
+			struct bio *bio;
+			struct work_struct work;
+		} r;
+		struct list_head free_list;	/* Free list */
+	};
+	u8 flags;				/* Flags */
+};
+
+static inline bool fscrypt_has_encryption_key(const struct inode *inode)
+{
+	return (inode->i_crypt_info != NULL);
+}
+
+static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+{
+	return inode->i_sb->s_cop->dummy_context &&
+		inode->i_sb->s_cop->dummy_context(inode);
+}
+
+/* crypto.c */
+extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
+extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
+extern void fscrypt_release_ctx(struct fscrypt_ctx *);
+extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
+						unsigned int, unsigned int,
+						u64, gfp_t);
+extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
+				unsigned int, u64);
+
+static inline struct page *fscrypt_control_page(struct page *page)
+{
+	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
+}
+
+extern void fscrypt_restore_control_page(struct page *);
+
+/* policy.c */
+extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
+extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
+extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
+extern int fscrypt_inherit_context(struct inode *, struct inode *,
+					void *, bool);
+/* keyinfo.c */
+extern int fscrypt_get_encryption_info(struct inode *);
+extern void fscrypt_put_encryption_info(struct inode *);
+
+/* fname.c */
+extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
+				int lookup, struct fscrypt_name *);
+
+static inline void fscrypt_free_filename(struct fscrypt_name *fname)
+{
+	kfree(fname->crypto_buf.name);
+}
+
+extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
+				struct fscrypt_str *);
+extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
+extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
+			const struct fscrypt_str *, struct fscrypt_str *);
+
+#define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE	32
+
+/* Extracts the second-to-last ciphertext block; see explanation below */
+#define FSCRYPT_FNAME_DIGEST(name, len)	\
+	((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \
+			     FS_CRYPTO_BLOCK_SIZE))
+
+#define FSCRYPT_FNAME_DIGEST_SIZE	FS_CRYPTO_BLOCK_SIZE
+
+/**
+ * fscrypt_digested_name - alternate identifier for an on-disk filename
+ *
+ * When userspace lists an encrypted directory without access to the key,
+ * filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE
+ * bytes are shown in this abbreviated form (base64-encoded) rather than as the
+ * full ciphertext (base64-encoded).  This is necessary to allow supporting
+ * filenames up to NAME_MAX bytes, since base64 encoding expands the length.
+ *
+ * To make it possible for filesystems to still find the correct directory entry
+ * despite not knowing the full on-disk name, we encode any filesystem-specific
+ * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
+ * followed by the second-to-last ciphertext block of the filename.  Due to the
+ * use of the CBC-CTS encryption mode, the second-to-last ciphertext block
+ * depends on the full plaintext.  (Note that ciphertext stealing causes the
+ * last two blocks to appear "flipped".)  This makes accidental collisions very
+ * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
+ * share the same filesystem-specific hashes.
+ *
+ * However, this scheme isn't immune to intentional collisions, which can be
+ * created by anyone able to create arbitrary plaintext filenames and view them
+ * without the key.  Making the "digest" be a real cryptographic hash like
+ * SHA-256 over the full ciphertext would prevent this, although it would be
+ * less efficient and harder to implement, especially since the filesystem would
+ * need to calculate it for each directory entry examined during a search.
+ */
+struct fscrypt_digested_name {
+	u32 hash;
+	u32 minor_hash;
+	u8 digest[FSCRYPT_FNAME_DIGEST_SIZE];
+};
+
+/**
+ * fscrypt_match_name() - test whether the given name matches a directory entry
+ * @fname: the name being searched for
+ * @de_name: the name from the directory entry
+ * @de_name_len: the length of @de_name in bytes
+ *
+ * Normally @fname->disk_name will be set, and in that case we simply compare
+ * that to the name stored in the directory entry.  The only exception is that
+ * if we don't have the key for an encrypted directory and a filename in it is
+ * very long, then we won't have the full disk_name and we'll instead need to
+ * match against the fscrypt_digested_name.
+ *
+ * Return: %true if the name matches, otherwise %false.
+ */
+static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
+				      const u8 *de_name, u32 de_name_len)
+{
+	if (unlikely(!fname->disk_name.name)) {
+		const struct fscrypt_digested_name *n =
+			(const void *)fname->crypto_buf.name;
+		if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
+			return false;
+		if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
+			return false;
+		return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
+			       n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
+	}
+
+	if (de_name_len != fname->disk_name.len)
+		return false;
+	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
+}
+
+/* bio.c */
+extern void fscrypt_decrypt_bio(struct bio *);
+extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
+					struct bio *bio);
+extern void fscrypt_pullback_bio_page(struct page **, bool);
+extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
+				 unsigned int);
+
+/* hooks.c */
+extern int fscrypt_file_open(struct inode *inode, struct file *filp);
+extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir);
+extern int __fscrypt_prepare_rename(struct inode *old_dir,
+				    struct dentry *old_dentry,
+				    struct inode *new_dir,
+				    struct dentry *new_dentry,
+				    unsigned int flags);
+extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
+extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
+				     unsigned int max_len,
+				     struct fscrypt_str *disk_link);
+extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
+				     unsigned int len,
+				     struct fscrypt_str *disk_link);
+extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
+				       unsigned int max_size,
+				       struct delayed_call *done);
+#else  /* !CONFIG_FS_ENCRYPTION */
+
+static inline bool fscrypt_has_encryption_key(const struct inode *inode)
+{
+	return false;
+}
+
+static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
+{
+	return false;
+}
+
+/* crypto.c */
+static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
+{
+}
+
+static inline struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode,
+						  gfp_t gfp_flags)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
+{
+	return;
+}
+
+static inline struct page *fscrypt_encrypt_page(const struct inode *inode,
+						struct page *page,
+						unsigned int len,
+						unsigned int offs,
+						u64 lblk_num, gfp_t gfp_flags)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+
+static inline int fscrypt_decrypt_page(const struct inode *inode,
+				       struct page *page,
+				       unsigned int len, unsigned int offs,
+				       u64 lblk_num)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline struct page *fscrypt_control_page(struct page *page)
+{
+	WARN_ON_ONCE(1);
+	return ERR_PTR(-EINVAL);
+}
+
+static inline void fscrypt_restore_control_page(struct page *page)
+{
+	return;
+}
+
+/* policy.c */
+static inline int fscrypt_ioctl_set_policy(struct file *filp,
+					   const void __user *arg)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int fscrypt_has_permitted_context(struct inode *parent,
+						struct inode *child)
+{
+	return 0;
+}
+
+static inline int fscrypt_inherit_context(struct inode *parent,
+					  struct inode *child,
+					  void *fs_data, bool preload)
+{
+	return -EOPNOTSUPP;
+}
+
+/* keyinfo.c */
+static inline int fscrypt_get_encryption_info(struct inode *inode)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void fscrypt_put_encryption_info(struct inode *inode)
+{
+	return;
+}
+
+ /* fname.c */
+static inline int fscrypt_setup_filename(struct inode *dir,
+					 const struct qstr *iname,
+					 int lookup, struct fscrypt_name *fname)
+{
+	if (IS_ENCRYPTED(dir))
+		return -EOPNOTSUPP;
+
+	memset(fname, 0, sizeof(struct fscrypt_name));
+	fname->usr_fname = iname;
+	fname->disk_name.name = (unsigned char *)iname->name;
+	fname->disk_name.len = iname->len;
+	return 0;
+}
+
+static inline void fscrypt_free_filename(struct fscrypt_name *fname)
+{
+	return;
+}
+
+static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
+					     u32 max_encrypted_len,
+					     struct fscrypt_str *crypto_str)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
+{
+	return;
+}
+
+static inline int fscrypt_fname_disk_to_usr(struct inode *inode,
+					    u32 hash, u32 minor_hash,
+					    const struct fscrypt_str *iname,
+					    struct fscrypt_str *oname)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
+				      const u8 *de_name, u32 de_name_len)
+{
+	/* Encryption support disabled; use standard comparison */
+	if (de_name_len != fname->disk_name.len)
+		return false;
+	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
+}
+
+/* bio.c */
+static inline void fscrypt_decrypt_bio(struct bio *bio)
+{
+}
+
+static inline void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
+					       struct bio *bio)
+{
+}
+
+static inline void fscrypt_pullback_bio_page(struct page **page, bool restore)
+{
+	return;
+}
+
+static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
+					sector_t pblk, unsigned int len)
+{
+	return -EOPNOTSUPP;
+}
+
+/* hooks.c */
+
+static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
+{
+	if (IS_ENCRYPTED(inode))
+		return -EOPNOTSUPP;
+	return 0;
+}
+
+static inline int __fscrypt_prepare_link(struct inode *inode,
+					 struct inode *dir)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_prepare_rename(struct inode *old_dir,
+					   struct dentry *old_dentry,
+					   struct inode *new_dir,
+					   struct dentry *new_dentry,
+					   unsigned int flags)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_prepare_lookup(struct inode *dir,
+					   struct dentry *dentry)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline int __fscrypt_prepare_symlink(struct inode *dir,
+					    unsigned int len,
+					    unsigned int max_len,
+					    struct fscrypt_str *disk_link)
+{
+	return -EOPNOTSUPP;
+}
+
+
+static inline int __fscrypt_encrypt_symlink(struct inode *inode,
+					    const char *target,
+					    unsigned int len,
+					    struct fscrypt_str *disk_link)
+{
+	return -EOPNOTSUPP;
+}
+
+static inline const char *fscrypt_get_symlink(struct inode *inode,
+					      const void *caddr,
+					      unsigned int max_size,
+					      struct delayed_call *done)
+{
+	return ERR_PTR(-EOPNOTSUPP);
+}
+#endif	/* !CONFIG_FS_ENCRYPTION */
 
 /**
  * fscrypt_require_key - require an inode's encryption key
diff --git a/include/linux/fscrypt_notsupp.h b/include/linux/fscrypt_notsupp.h
deleted file mode 100644
index ee8b43e4c15a..000000000000
--- a/include/linux/fscrypt_notsupp.h
+++ /dev/null
@@ -1,231 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * fscrypt_notsupp.h
- *
- * This stubs out the fscrypt functions for filesystems configured without
- * encryption support.
- *
- * Do not include this file directly. Use fscrypt.h instead!
- */
-#ifndef _LINUX_FSCRYPT_H
-#error "Incorrect include of linux/fscrypt_notsupp.h!"
-#endif
-
-#ifndef _LINUX_FSCRYPT_NOTSUPP_H
-#define _LINUX_FSCRYPT_NOTSUPP_H
-
-static inline bool fscrypt_has_encryption_key(const struct inode *inode)
-{
-	return false;
-}
-
-static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
-{
-	return false;
-}
-
-/* crypto.c */
-static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
-{
-}
-
-static inline struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *inode,
-						  gfp_t gfp_flags)
-{
-	return ERR_PTR(-EOPNOTSUPP);
-}
-
-static inline void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
-{
-	return;
-}
-
-static inline struct page *fscrypt_encrypt_page(const struct inode *inode,
-						struct page *page,
-						unsigned int len,
-						unsigned int offs,
-						u64 lblk_num, gfp_t gfp_flags)
-{
-	return ERR_PTR(-EOPNOTSUPP);
-}
-
-static inline int fscrypt_decrypt_page(const struct inode *inode,
-				       struct page *page,
-				       unsigned int len, unsigned int offs,
-				       u64 lblk_num)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline struct page *fscrypt_control_page(struct page *page)
-{
-	WARN_ON_ONCE(1);
-	return ERR_PTR(-EINVAL);
-}
-
-static inline void fscrypt_restore_control_page(struct page *page)
-{
-	return;
-}
-
-/* policy.c */
-static inline int fscrypt_ioctl_set_policy(struct file *filp,
-					   const void __user *arg)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline int fscrypt_has_permitted_context(struct inode *parent,
-						struct inode *child)
-{
-	return 0;
-}
-
-static inline int fscrypt_inherit_context(struct inode *parent,
-					  struct inode *child,
-					  void *fs_data, bool preload)
-{
-	return -EOPNOTSUPP;
-}
-
-/* keyinfo.c */
-static inline int fscrypt_get_encryption_info(struct inode *inode)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline void fscrypt_put_encryption_info(struct inode *inode)
-{
-	return;
-}
-
- /* fname.c */
-static inline int fscrypt_setup_filename(struct inode *dir,
-					 const struct qstr *iname,
-					 int lookup, struct fscrypt_name *fname)
-{
-	if (IS_ENCRYPTED(dir))
-		return -EOPNOTSUPP;
-
-	memset(fname, 0, sizeof(struct fscrypt_name));
-	fname->usr_fname = iname;
-	fname->disk_name.name = (unsigned char *)iname->name;
-	fname->disk_name.len = iname->len;
-	return 0;
-}
-
-static inline void fscrypt_free_filename(struct fscrypt_name *fname)
-{
-	return;
-}
-
-static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
-					     u32 max_encrypted_len,
-					     struct fscrypt_str *crypto_str)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
-{
-	return;
-}
-
-static inline int fscrypt_fname_disk_to_usr(struct inode *inode,
-					    u32 hash, u32 minor_hash,
-					    const struct fscrypt_str *iname,
-					    struct fscrypt_str *oname)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
-				      const u8 *de_name, u32 de_name_len)
-{
-	/* Encryption support disabled; use standard comparison */
-	if (de_name_len != fname->disk_name.len)
-		return false;
-	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
-}
-
-/* bio.c */
-static inline void fscrypt_decrypt_bio(struct bio *bio)
-{
-}
-
-static inline void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
-					       struct bio *bio)
-{
-}
-
-static inline void fscrypt_pullback_bio_page(struct page **page, bool restore)
-{
-	return;
-}
-
-static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
-					sector_t pblk, unsigned int len)
-{
-	return -EOPNOTSUPP;
-}
-
-/* hooks.c */
-
-static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
-{
-	if (IS_ENCRYPTED(inode))
-		return -EOPNOTSUPP;
-	return 0;
-}
-
-static inline int __fscrypt_prepare_link(struct inode *inode,
-					 struct inode *dir)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline int __fscrypt_prepare_rename(struct inode *old_dir,
-					   struct dentry *old_dentry,
-					   struct inode *new_dir,
-					   struct dentry *new_dentry,
-					   unsigned int flags)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline int __fscrypt_prepare_lookup(struct inode *dir,
-					   struct dentry *dentry)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline int __fscrypt_prepare_symlink(struct inode *dir,
-					    unsigned int len,
-					    unsigned int max_len,
-					    struct fscrypt_str *disk_link)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline int __fscrypt_encrypt_symlink(struct inode *inode,
-					    const char *target,
-					    unsigned int len,
-					    struct fscrypt_str *disk_link)
-{
-	return -EOPNOTSUPP;
-}
-
-static inline const char *fscrypt_get_symlink(struct inode *inode,
-					      const void *caddr,
-					      unsigned int max_size,
-					      struct delayed_call *done)
-{
-	return ERR_PTR(-EOPNOTSUPP);
-}
-
-#endif	/* _LINUX_FSCRYPT_NOTSUPP_H */
diff --git a/include/linux/fscrypt_supp.h b/include/linux/fscrypt_supp.h
deleted file mode 100644
index 6456c6b2005f..000000000000
--- a/include/linux/fscrypt_supp.h
+++ /dev/null
@@ -1,204 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0 */
-/*
- * fscrypt_supp.h
- *
- * Do not include this file directly. Use fscrypt.h instead!
- */
-#ifndef _LINUX_FSCRYPT_H
-#error "Incorrect include of linux/fscrypt_supp.h!"
-#endif
-
-#ifndef _LINUX_FSCRYPT_SUPP_H
-#define _LINUX_FSCRYPT_SUPP_H
-
-#include <linux/mm.h>
-#include <linux/slab.h>
-
-/*
- * fscrypt superblock flags
- */
-#define FS_CFLG_OWN_PAGES (1U << 1)
-
-/*
- * crypto operations for filesystems
- */
-struct fscrypt_operations {
-	unsigned int flags;
-	const char *key_prefix;
-	int (*get_context)(struct inode *, void *, size_t);
-	int (*set_context)(struct inode *, const void *, size_t, void *);
-	bool (*dummy_context)(struct inode *);
-	bool (*empty_dir)(struct inode *);
-	unsigned int max_namelen;
-};
-
-struct fscrypt_ctx {
-	union {
-		struct {
-			struct page *bounce_page;	/* Ciphertext page */
-			struct page *control_page;	/* Original page  */
-		} w;
-		struct {
-			struct bio *bio;
-			struct work_struct work;
-		} r;
-		struct list_head free_list;	/* Free list */
-	};
-	u8 flags;				/* Flags */
-};
-
-static inline bool fscrypt_has_encryption_key(const struct inode *inode)
-{
-	return (inode->i_crypt_info != NULL);
-}
-
-static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
-{
-	return inode->i_sb->s_cop->dummy_context &&
-		inode->i_sb->s_cop->dummy_context(inode);
-}
-
-/* crypto.c */
-extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
-extern struct fscrypt_ctx *fscrypt_get_ctx(const struct inode *, gfp_t);
-extern void fscrypt_release_ctx(struct fscrypt_ctx *);
-extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
-						unsigned int, unsigned int,
-						u64, gfp_t);
-extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
-				unsigned int, u64);
-
-static inline struct page *fscrypt_control_page(struct page *page)
-{
-	return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
-}
-
-extern void fscrypt_restore_control_page(struct page *);
-
-/* policy.c */
-extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
-extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
-extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
-extern int fscrypt_inherit_context(struct inode *, struct inode *,
-					void *, bool);
-/* keyinfo.c */
-extern int fscrypt_get_encryption_info(struct inode *);
-extern void fscrypt_put_encryption_info(struct inode *);
-
-/* fname.c */
-extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
-				int lookup, struct fscrypt_name *);
-
-static inline void fscrypt_free_filename(struct fscrypt_name *fname)
-{
-	kfree(fname->crypto_buf.name);
-}
-
-extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
-				struct fscrypt_str *);
-extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
-extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
-			const struct fscrypt_str *, struct fscrypt_str *);
-
-#define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE	32
-
-/* Extracts the second-to-last ciphertext block; see explanation below */
-#define FSCRYPT_FNAME_DIGEST(name, len)	\
-	((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \
-			     FS_CRYPTO_BLOCK_SIZE))
-
-#define FSCRYPT_FNAME_DIGEST_SIZE	FS_CRYPTO_BLOCK_SIZE
-
-/**
- * fscrypt_digested_name - alternate identifier for an on-disk filename
- *
- * When userspace lists an encrypted directory without access to the key,
- * filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE
- * bytes are shown in this abbreviated form (base64-encoded) rather than as the
- * full ciphertext (base64-encoded).  This is necessary to allow supporting
- * filenames up to NAME_MAX bytes, since base64 encoding expands the length.
- *
- * To make it possible for filesystems to still find the correct directory entry
- * despite not knowing the full on-disk name, we encode any filesystem-specific
- * 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
- * followed by the second-to-last ciphertext block of the filename.  Due to the
- * use of the CBC-CTS encryption mode, the second-to-last ciphertext block
- * depends on the full plaintext.  (Note that ciphertext stealing causes the
- * last two blocks to appear "flipped".)  This makes accidental collisions very
- * unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
- * share the same filesystem-specific hashes.
- *
- * However, this scheme isn't immune to intentional collisions, which can be
- * created by anyone able to create arbitrary plaintext filenames and view them
- * without the key.  Making the "digest" be a real cryptographic hash like
- * SHA-256 over the full ciphertext would prevent this, although it would be
- * less efficient and harder to implement, especially since the filesystem would
- * need to calculate it for each directory entry examined during a search.
- */
-struct fscrypt_digested_name {
-	u32 hash;
-	u32 minor_hash;
-	u8 digest[FSCRYPT_FNAME_DIGEST_SIZE];
-};
-
-/**
- * fscrypt_match_name() - test whether the given name matches a directory entry
- * @fname: the name being searched for
- * @de_name: the name from the directory entry
- * @de_name_len: the length of @de_name in bytes
- *
- * Normally @fname->disk_name will be set, and in that case we simply compare
- * that to the name stored in the directory entry.  The only exception is that
- * if we don't have the key for an encrypted directory and a filename in it is
- * very long, then we won't have the full disk_name and we'll instead need to
- * match against the fscrypt_digested_name.
- *
- * Return: %true if the name matches, otherwise %false.
- */
-static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
-				      const u8 *de_name, u32 de_name_len)
-{
-	if (unlikely(!fname->disk_name.name)) {
-		const struct fscrypt_digested_name *n =
-			(const void *)fname->crypto_buf.name;
-		if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
-			return false;
-		if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
-			return false;
-		return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
-			       n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
-	}
-
-	if (de_name_len != fname->disk_name.len)
-		return false;
-	return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
-}
-
-/* bio.c */
-extern void fscrypt_decrypt_bio(struct bio *);
-extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
-					struct bio *bio);
-extern void fscrypt_pullback_bio_page(struct page **, bool);
-extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
-				 unsigned int);
-
-/* hooks.c */
-extern int fscrypt_file_open(struct inode *inode, struct file *filp);
-extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir);
-extern int __fscrypt_prepare_rename(struct inode *old_dir,
-				    struct dentry *old_dentry,
-				    struct inode *new_dir,
-				    struct dentry *new_dentry,
-				    unsigned int flags);
-extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry);
-extern int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
-				     unsigned int max_len,
-				     struct fscrypt_str *disk_link);
-extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
-				     unsigned int len,
-				     struct fscrypt_str *disk_link);
-extern const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
-				       unsigned int max_size,
-				       struct delayed_call *done);
-
-#endif	/* _LINUX_FSCRYPT_SUPP_H */