include/linux/fscrypt.h - kernel/msm-4.9 - Gitiles

 /*
  * 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.
  *
  * Copyright (C) 2015, Google, Inc.
  *
  * Written by Michael Halcrow, 2015.
  * Modified by Jaegeuk Kim, 2015.
  */
 #ifndef _LINUX_FSCRYPT_H
 #define _LINUX_FSCRYPT_H

 #include <linux/fs.h>

 #define FS_CRYPTO_BLOCK_SIZE		16

 struct fscrypt_ctx;
 struct fscrypt_info;

 struct fscrypt_str {
 	unsigned char *name;
 	u32 len;
 };

 struct fscrypt_name {
 	const struct qstr *usr_fname;
 	struct fscrypt_str disk_name;
 	u32 hash;
 	u32 minor_hash;
 	struct fscrypt_str crypto_buf;
 };

 #define FSTR_INIT(n, l)		{ .name = n, .len = l }
 #define FSTR_TO_QSTR(f)		QSTR_INIT((f)->name, (f)->len)
 #define fname_name(p)		((p)->disk_name.name)
 #define fname_len(p)		((p)->disk_name.len)

 #if __FS_HAS_ENCRYPTION
 #include <linux/fscrypt_supp.h>
 #else
 #include <linux/fscrypt_notsupp.h>
 #endif

 /**
  * fscrypt_require_key - require an inode's encryption key
  * @inode: the inode we need the key for
  *
  * If the inode is encrypted, set up its encryption key if not already done.
  * Then require that the key be present and return -ENOKEY otherwise.
  *
  * No locks are needed, and the key will live as long as the struct inode --- so
  * it won't go away from under you.
  *
  * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
  * if a problem occurred while setting up the encryption key.
  */
 static inline int fscrypt_require_key(struct inode *inode)
 {
 	if (IS_ENCRYPTED(inode)) {
 		int err = fscrypt_get_encryption_info(inode);

 		if (err)
 			return err;
 		if (!fscrypt_has_encryption_key(inode))
 			return -ENOKEY;
 	}
 	return 0;
 }

 /**
  * fscrypt_prepare_link - prepare to link an inode into a possibly-encrypted directory
  * @old_dentry: an existing dentry for the inode being linked
  * @dir: the target directory
  * @dentry: negative dentry for the target filename
  *
  * A new link can only be added to an encrypted directory if the directory's
  * encryption key is available --- since otherwise we'd have no way to encrypt
  * the filename.  Therefore, we first set up the directory's encryption key (if
  * not already done) and return an error if it's unavailable.
  *
  * We also verify that the link will not violate the constraint that all files
  * in an encrypted directory tree use the same encryption policy.
  *
  * Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
  * -EPERM if the link would result in an inconsistent encryption policy, or
  * another -errno code.
  */
 static inline int fscrypt_prepare_link(struct dentry *old_dentry,
 				       struct inode *dir,
 				       struct dentry *dentry)
 {
 	if (IS_ENCRYPTED(dir))
 		return __fscrypt_prepare_link(d_inode(old_dentry), dir);
 	return 0;
 }

 /**
  * fscrypt_prepare_rename - prepare for a rename between possibly-encrypted directories
  * @old_dir: source directory
  * @old_dentry: dentry for source file
  * @new_dir: target directory
  * @new_dentry: dentry for target location (may be negative unless exchanging)
  * @flags: rename flags (we care at least about %RENAME_EXCHANGE)
  *
  * Prepare for ->rename() where the source and/or target directories may be
  * encrypted.  A new link can only be added to an encrypted directory if the
  * directory's encryption key is available --- since otherwise we'd have no way
  * to encrypt the filename.  A rename to an existing name, on the other hand,
  * *is* cryptographically possible without the key.  However, we take the more
  * conservative approach and just forbid all no-key renames.
  *
  * We also verify that the rename will not violate the constraint that all files
  * in an encrypted directory tree use the same encryption policy.
  *
  * Return: 0 on success, -ENOKEY if an encryption key is missing, -EPERM if the
  * rename would cause inconsistent encryption policies, or another -errno code.
  */
 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)
 {
 	if (IS_ENCRYPTED(old_dir) || IS_ENCRYPTED(new_dir))
 		return __fscrypt_prepare_rename(old_dir, old_dentry,
 						new_dir, new_dentry, flags);
 	return 0;
 }

 /**
  * fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
  * @dir: directory being searched
  * @dentry: filename being looked up
  * @flags: lookup flags
  *
  * Prepare for ->lookup() in a directory which may be encrypted.  Lookups can be
  * done with or without the directory's encryption key; without the key,
  * filenames are presented in encrypted form.  Therefore, we'll try to set up
  * the directory's encryption key, but even without it the lookup can continue.
  *
  * To allow invalidating stale dentries if the directory's encryption key is
  * added later, we also install a custom ->d_revalidate() method and use the
  * DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
  * plaintext name (flag set) or a ciphertext name (flag cleared).
  *
  * Return: 0 on success, -errno if a problem occurred while setting up the
  * encryption key
  */
 static inline int fscrypt_prepare_lookup(struct inode *dir,
 					 struct dentry *dentry,
 					 unsigned int flags)
 {
 	if (IS_ENCRYPTED(dir))
 		return __fscrypt_prepare_lookup(dir, dentry);
 	return 0;
 }

 /**
  * fscrypt_prepare_setattr - prepare to change a possibly-encrypted inode's attributes
  * @dentry: dentry through which the inode is being changed
  * @attr: attributes to change
  *
  * Prepare for ->setattr() on a possibly-encrypted inode.  On an encrypted file,
  * most attribute changes are allowed even without the encryption key.  However,
  * without the encryption key we do have to forbid truncates.  This is needed
  * because the size being truncated to may not be a multiple of the filesystem
  * block size, and in that case we'd have to decrypt the final block, zero the
  * portion past i_size, and re-encrypt it.  (We *could* allow truncating to a
  * filesystem block boundary, but it's simpler to just forbid all truncates ---
  * and we already forbid all other contents modifications without the key.)
  *
  * Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
  * if a problem occurred while setting up the encryption key.
  */
 static inline int fscrypt_prepare_setattr(struct dentry *dentry,
 					  struct iattr *attr)
 {
 	if (attr->ia_valid & ATTR_SIZE)
 		return fscrypt_require_key(d_inode(dentry));
 	return 0;
 }

 /**
  * fscrypt_prepare_symlink - prepare to create a possibly-encrypted symlink
  * @dir: directory in which the symlink is being created
  * @target: plaintext symlink target
  * @len: length of @target excluding null terminator
  * @max_len: space the filesystem has available to store the symlink target
  * @disk_link: (out) the on-disk symlink target being prepared
  *
  * This function computes the size the symlink target will require on-disk,
  * stores it in @disk_link->len, and validates it against @max_len.  An
  * encrypted symlink may be longer than the original.
  *
  * Additionally, @disk_link->name is set to @target if the symlink will be
  * unencrypted, but left NULL if the symlink will be encrypted.  For encrypted
  * symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the
  * on-disk target later.  (The reason for the two-step process is that some
  * filesystems need to know the size of the symlink target before creating the
  * inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
  *
  * Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
  * -ENOKEY if the encryption key is missing, or another -errno code if a problem
  * occurred while setting up the encryption key.
  */
 static inline int fscrypt_prepare_symlink(struct inode *dir,
 					  const char *target,
 					  unsigned int len,
 					  unsigned int max_len,
 					  struct fscrypt_str *disk_link)
 {
 	if (IS_ENCRYPTED(dir) || fscrypt_dummy_context_enabled(dir))
 		return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);

 	disk_link->name = (unsigned char *)target;
 	disk_link->len = len + 1;
 	if (disk_link->len > max_len)
 		return -ENAMETOOLONG;
 	return 0;
 }

 /**
  * fscrypt_encrypt_symlink - encrypt the symlink target if needed
  * @inode: symlink inode
  * @target: plaintext symlink target
  * @len: length of @target excluding null terminator
  * @disk_link: (in/out) the on-disk symlink target being prepared
  *
  * If the symlink target needs to be encrypted, then this function encrypts it
  * into @disk_link->name.  fscrypt_prepare_symlink() must have been called
  * previously to compute @disk_link->len.  If the filesystem did not allocate a
  * buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
  * will be kmalloc()'ed and the filesystem will be responsible for freeing it.
  *
  * Return: 0 on success, -errno on failure
  */
 static inline int fscrypt_encrypt_symlink(struct inode *inode,
 					  const char *target,
 					  unsigned int len,
 					  struct fscrypt_str *disk_link)
 {
 	if (IS_ENCRYPTED(inode))
 		return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
 	return 0;
 }

 #endif	/* _LINUX_FSCRYPT_H */
	/*
	* 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.
	*
	* Copyright (C) 2015, Google, Inc.
	*
	* Written by Michael Halcrow, 2015.
	* Modified by Jaegeuk Kim, 2015.
	*/
	#ifndef _LINUX_FSCRYPT_H
	#define _LINUX_FSCRYPT_H

	#include <linux/fs.h>

	#define FS_CRYPTO_BLOCK_SIZE 16

	struct fscrypt_ctx;
	struct fscrypt_info;

	struct fscrypt_str {
	unsigned char *name;
	u32 len;
	};

	struct fscrypt_name {
	const struct qstr *usr_fname;
	struct fscrypt_str disk_name;
	u32 hash;
	u32 minor_hash;
	struct fscrypt_str crypto_buf;
	};

	#define FSTR_INIT(n, l) { .name = n, .len = l }
	#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
	#define fname_name(p) ((p)->disk_name.name)
	#define fname_len(p) ((p)->disk_name.len)

	#if __FS_HAS_ENCRYPTION
	#include <linux/fscrypt_supp.h>
	#else
	#include <linux/fscrypt_notsupp.h>
	#endif

	/**
	* fscrypt_require_key - require an inode's encryption key
	* @inode: the inode we need the key for
	*
	* If the inode is encrypted, set up its encryption key if not already done.
	* Then require that the key be present and return -ENOKEY otherwise.
	*
	* No locks are needed, and the key will live as long as the struct inode --- so
	* it won't go away from under you.
	*
	* Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
	* if a problem occurred while setting up the encryption key.
	*/
	static inline int fscrypt_require_key(struct inode *inode)
	{
	if (IS_ENCRYPTED(inode)) {
	int err = fscrypt_get_encryption_info(inode);

	if (err)
	return err;
	if (!fscrypt_has_encryption_key(inode))
	return -ENOKEY;
	}
	return 0;
	}

	/**
	* fscrypt_prepare_link - prepare to link an inode into a possibly-encrypted directory
	* @old_dentry: an existing dentry for the inode being linked
	* @dir: the target directory
	* @dentry: negative dentry for the target filename
	*
	* A new link can only be added to an encrypted directory if the directory's
	* encryption key is available --- since otherwise we'd have no way to encrypt
	* the filename. Therefore, we first set up the directory's encryption key (if
	* not already done) and return an error if it's unavailable.
	*
	* We also verify that the link will not violate the constraint that all files
	* in an encrypted directory tree use the same encryption policy.
	*
	* Return: 0 on success, -ENOKEY if the directory's encryption key is missing,
	* -EPERM if the link would result in an inconsistent encryption policy, or
	* another -errno code.
	*/
	static inline int fscrypt_prepare_link(struct dentry *old_dentry,
	struct inode *dir,
	struct dentry *dentry)
	{
	if (IS_ENCRYPTED(dir))
	return __fscrypt_prepare_link(d_inode(old_dentry), dir);
	return 0;
	}

	/**
	* fscrypt_prepare_rename - prepare for a rename between possibly-encrypted directories
	* @old_dir: source directory
	* @old_dentry: dentry for source file
	* @new_dir: target directory
	* @new_dentry: dentry for target location (may be negative unless exchanging)
	* @flags: rename flags (we care at least about %RENAME_EXCHANGE)
	*
	* Prepare for ->rename() where the source and/or target directories may be
	* encrypted. A new link can only be added to an encrypted directory if the
	* directory's encryption key is available --- since otherwise we'd have no way
	* to encrypt the filename. A rename to an existing name, on the other hand,
	* is cryptographically possible without the key. However, we take the more
	* conservative approach and just forbid all no-key renames.
	*
	* We also verify that the rename will not violate the constraint that all files
	* in an encrypted directory tree use the same encryption policy.
	*
	* Return: 0 on success, -ENOKEY if an encryption key is missing, -EPERM if the
	* rename would cause inconsistent encryption policies, or another -errno code.
	*/
	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)
	{
	if (IS_ENCRYPTED(old_dir) \|\| IS_ENCRYPTED(new_dir))
	return __fscrypt_prepare_rename(old_dir, old_dentry,
	new_dir, new_dentry, flags);
	return 0;
	}

	/**
	* fscrypt_prepare_lookup - prepare to lookup a name in a possibly-encrypted directory
	* @dir: directory being searched
	* @dentry: filename being looked up
	* @flags: lookup flags
	*
	* Prepare for ->lookup() in a directory which may be encrypted. Lookups can be
	* done with or without the directory's encryption key; without the key,
	* filenames are presented in encrypted form. Therefore, we'll try to set up
	* the directory's encryption key, but even without it the lookup can continue.
	*
	* To allow invalidating stale dentries if the directory's encryption key is
	* added later, we also install a custom ->d_revalidate() method and use the
	* DCACHE_ENCRYPTED_WITH_KEY flag to indicate whether a given dentry is a
	* plaintext name (flag set) or a ciphertext name (flag cleared).
	*
	* Return: 0 on success, -errno if a problem occurred while setting up the
	* encryption key
	*/
	static inline int fscrypt_prepare_lookup(struct inode *dir,
	struct dentry *dentry,
	unsigned int flags)
	{
	if (IS_ENCRYPTED(dir))
	return __fscrypt_prepare_lookup(dir, dentry);
	return 0;
	}

	/**
	* fscrypt_prepare_setattr - prepare to change a possibly-encrypted inode's attributes
	* @dentry: dentry through which the inode is being changed
	* @attr: attributes to change
	*
	* Prepare for ->setattr() on a possibly-encrypted inode. On an encrypted file,
	* most attribute changes are allowed even without the encryption key. However,
	* without the encryption key we do have to forbid truncates. This is needed
	* because the size being truncated to may not be a multiple of the filesystem
	* block size, and in that case we'd have to decrypt the final block, zero the
	* portion past i_size, and re-encrypt it. (We could allow truncating to a
	* filesystem block boundary, but it's simpler to just forbid all truncates ---
	* and we already forbid all other contents modifications without the key.)
	*
	* Return: 0 on success, -ENOKEY if the key is missing, or another -errno code
	* if a problem occurred while setting up the encryption key.
	*/
	static inline int fscrypt_prepare_setattr(struct dentry *dentry,
	struct iattr *attr)
	{
	if (attr->ia_valid & ATTR_SIZE)
	return fscrypt_require_key(d_inode(dentry));
	return 0;
	}

	/**
	* fscrypt_prepare_symlink - prepare to create a possibly-encrypted symlink
	* @dir: directory in which the symlink is being created
	* @target: plaintext symlink target
	* @len: length of @target excluding null terminator
	* @max_len: space the filesystem has available to store the symlink target
	* @disk_link: (out) the on-disk symlink target being prepared
	*
	* This function computes the size the symlink target will require on-disk,
	* stores it in @disk_link->len, and validates it against @max_len. An
	* encrypted symlink may be longer than the original.
	*
	* Additionally, @disk_link->name is set to @target if the symlink will be
	* unencrypted, but left NULL if the symlink will be encrypted. For encrypted
	* symlinks, the filesystem must call fscrypt_encrypt_symlink() to create the
	* on-disk target later. (The reason for the two-step process is that some
	* filesystems need to know the size of the symlink target before creating the
	* inode, e.g. to determine whether it will be a "fast" or "slow" symlink.)
	*
	* Return: 0 on success, -ENAMETOOLONG if the symlink target is too long,
	* -ENOKEY if the encryption key is missing, or another -errno code if a problem
	* occurred while setting up the encryption key.
	*/
	static inline int fscrypt_prepare_symlink(struct inode *dir,
	const char *target,
	unsigned int len,
	unsigned int max_len,
	struct fscrypt_str *disk_link)
	{
	if (IS_ENCRYPTED(dir) \|\| fscrypt_dummy_context_enabled(dir))
	return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);

	disk_link->name = (unsigned char *)target;
	disk_link->len = len + 1;
	if (disk_link->len > max_len)
	return -ENAMETOOLONG;
	return 0;
	}

	/**
	* fscrypt_encrypt_symlink - encrypt the symlink target if needed
	* @inode: symlink inode
	* @target: plaintext symlink target
	* @len: length of @target excluding null terminator
	* @disk_link: (in/out) the on-disk symlink target being prepared
	*
	* If the symlink target needs to be encrypted, then this function encrypts it
	* into @disk_link->name. fscrypt_prepare_symlink() must have been called
	* previously to compute @disk_link->len. If the filesystem did not allocate a
	* buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
	* will be kmalloc()'ed and the filesystem will be responsible for freeing it.
	*
	* Return: 0 on success, -errno on failure
	*/
	static inline int fscrypt_encrypt_symlink(struct inode *inode,
	const char *target,
	unsigned int len,
	struct fscrypt_str *disk_link)
	{
	if (IS_ENCRYPTED(inode))
	return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
	return 0;
	}

	#endif /* _LINUX_FSCRYPT_H */