Quelle fscrypt.h Sprache: unbekannt

/* SPDX-License-Identifier: GPL-2.0 */
/*
* fscrypt.h: declarations for per-file encryption
*
* Filesystems that implement per-file encryption must include this header
* file.
*
* 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>
#include <linux/mm.h>
#include <linux/slab.h>
#include <uapi/linux/fscrypt.h>

/*
* The lengths of all file contents blocks must be divisible by this value.
* This is needed to ensure that all contents encryption modes will work, as
* some of the supported modes don't support arbitrarily byte-aligned messages.
*
* Since the needed alignment is 16 bytes, most filesystems will meet this
* requirement naturally, as typical block sizes are powers of 2.  However, if a
* filesystem can generate arbitrarily byte-aligned block lengths (e.g., via
* compression), then it will need to pad to this alignment before encryption.
*/
#define FSCRYPT_CONTENTS_ALIGNMENT 16

union fscrypt_policy;
struct fscrypt_inode_info;
struct fs_parameter;
struct seq_file;

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;
bool is_nokey_name;
};

#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)

/* Maximum value for the third parameter of fscrypt_operations.set_context(). */
#define FSCRYPT_SET_CONTEXT_MAX_SIZE 40

#ifdef CONFIG_FS_ENCRYPTION

/* Crypto operations for filesystems */
struct fscrypt_operations {

/*
* If set, then fs/crypto/ will allocate a global bounce page pool the
* first time an encryption key is set up for a file.  The bounce page
* pool is required by the following functions:
*
* - fscrypt_encrypt_pagecache_blocks()
* - fscrypt_zeroout_range() for files not using inline crypto
*
* If the filesystem doesn't use those, it doesn't need to set this.
*/
unsigned int needs_bounce_pages : 1;

/*
* If set, then fs/crypto/ will allow the use of encryption settings
* that assume inode numbers fit in 32 bits (i.e.
* FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64}), provided that the other
* prerequisites for these settings are also met.  This is only useful
* if the filesystem wants to support inline encryption hardware that is
* limited to 32-bit or 64-bit data unit numbers and where programming
* keyslots is very slow.
*/
unsigned int has_32bit_inodes : 1;

/*
* If set, then fs/crypto/ will allow users to select a crypto data unit
* size that is less than the filesystem block size.  This is done via
* the log2_data_unit_size field of the fscrypt policy.  This flag is
* not compatible with filesystems that encrypt variable-length blocks
* (i.e. blocks that aren't all equal to filesystem's block size), for
* example as a result of compression.  It's also not compatible with
* the fscrypt_encrypt_block_inplace() and
* fscrypt_decrypt_block_inplace() functions.
*/
unsigned int supports_subblock_data_units : 1;

/*
* This field exists only for backwards compatibility reasons and should
* only be set by the filesystems that are setting it already.  It
* contains the filesystem-specific key description prefix that is
* accepted for "logon" keys for v1 fscrypt policies.  This
* functionality is deprecated in favor of the generic prefix
* "fscrypt:", which itself is deprecated in favor of the filesystem
* keyring ioctls such as FS_IOC_ADD_ENCRYPTION_KEY.  Filesystems that
* are newly adding fscrypt support should not set this field.
*/
const char *legacy_key_prefix;

/*
* Get the fscrypt context of the given inode.
*
* @inode: the inode whose context to get
* @ctx: the buffer into which to get the context
* @len: length of the @ctx buffer in bytes
*
* Return: On success, returns the length of the context in bytes; this
*    may be less than @len.  On failure, returns -ENODATA if the
*    inode doesn't have a context, -ERANGE if the context is
*    longer than @len, or another -errno code.
*/
int (*get_context)(struct inode *inode, void *ctx, size_t len);

/*
* Set an fscrypt context on the given inode.
*
* @inode: the inode whose context to set.  The inode won't already have
*    an fscrypt context.
* @ctx: the context to set
* @len: length of @ctx in bytes (at most FSCRYPT_SET_CONTEXT_MAX_SIZE)
* @fs_data: If called from fscrypt_set_context(), this will be the
*      value the filesystem passed to fscrypt_set_context().
*      Otherwise (i.e. when called from
*      FS_IOC_SET_ENCRYPTION_POLICY) this will be NULL.
*
* i_rwsem will be held for write.
*
* Return: 0 on success, -errno on failure.
*/
int (*set_context)(struct inode *inode, const void *ctx, size_t len,
      void *fs_data);

/*
* Get the dummy fscrypt policy in use on the filesystem (if any).
*
* Filesystems only need to implement this function if they support the
* test_dummy_encryption mount option.
*
* Return: A pointer to the dummy fscrypt policy, if the filesystem is
*    mounted with test_dummy_encryption; otherwise NULL.
*/
const union fscrypt_policy *(*get_dummy_policy)(struct super_block *sb);

/*
* Check whether a directory is empty.  i_rwsem will be held for write.
*/
bool (*empty_dir)(struct inode *inode);

/*
* Check whether the filesystem's inode numbers and UUID are stable,
* meaning that they will never be changed even by offline operations
* such as filesystem shrinking and therefore can be used in the
* encryption without the possibility of files becoming unreadable.
*
* Filesystems only need to implement this function if they want to
* support the FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64} flags.  These
* flags are designed to work around the limitations of UFS and eMMC
* inline crypto hardware, and they shouldn't be used in scenarios where
* such hardware isn't being used.
*
* Leaving this NULL is equivalent to always returning false.
*/
bool (*has_stable_inodes)(struct super_block *sb);

/*
* Return an array of pointers to the block devices to which the
* filesystem may write encrypted file contents, NULL if the filesystem
* only has a single such block device, or an ERR_PTR() on error.
*
* On successful non-NULL return, *num_devs is set to the number of
* devices in the returned array.  The caller must free the returned
* array using kfree().
*
* If the filesystem can use multiple block devices (other than block
* devices that aren't used for encrypted file contents, such as
* external journal devices), and wants to support inline encryption,
* then it must implement this function.  Otherwise it's not needed.
*/
struct block_device **(*get_devices)(struct super_block *sb,
          unsigned int *num_devs);
};

int fscrypt_d_revalidate(struct inode *dir, const struct qstr *name,
    struct dentry *dentry, unsigned int flags);

static inline struct fscrypt_inode_info *
fscrypt_get_inode_info(const struct inode *inode)
{
/*
* Pairs with the cmpxchg_release() in fscrypt_setup_encryption_info().
* I.e., another task may publish ->i_crypt_info concurrently, executing
* a RELEASE barrier.  We need to use smp_load_acquire() here to safely
* ACQUIRE the memory the other task published.
*/
return smp_load_acquire(&inode->i_crypt_info);
}

/**
* fscrypt_needs_contents_encryption() - check whether an inode needs
* contents encryption
* @inode: the inode to check
*
* Return: %true iff the inode is an encrypted regular file and the kernel was
* built with fscrypt support.
*
* If you need to know whether the encrypt bit is set even when the kernel was
* built without fscrypt support, you must use IS_ENCRYPTED() directly instead.
*/
static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
{
return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
}

/*
* When d_splice_alias() moves a directory's no-key alias to its
* plaintext alias as a result of the encryption key being added,
* DCACHE_NOKEY_NAME must be cleared and there might be an opportunity
* to disable d_revalidate.  Note that we don't have to support the
* inverse operation because fscrypt doesn't allow no-key names to be
* the source or target of a rename().
*/
static inline void fscrypt_handle_d_move(struct dentry *dentry)
{
/*
* VFS calls fscrypt_handle_d_move even for non-fscrypt
* filesystems.
*/
if (dentry->d_flags & DCACHE_NOKEY_NAME) {
  dentry->d_flags &= ~DCACHE_NOKEY_NAME;

  /*
* Other filesystem features might be handling dentry
* revalidation, in which case it cannot be disabled.
*/
  if (dentry->d_op->d_revalidate == fscrypt_d_revalidate)
   dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
}
}

/**
* fscrypt_is_nokey_name() - test whether a dentry is a no-key name
* @dentry: the dentry to check
*
* This returns true if the dentry is a no-key dentry.  A no-key dentry is a
* dentry that was created in an encrypted directory that hasn't had its
* encryption key added yet.  Such dentries may be either positive or negative.
*
* When a filesystem is asked to create a new filename in an encrypted directory
* and the new filename's dentry is a no-key dentry, it must fail the operation
* with ENOKEY.  This includes ->create(), ->mkdir(), ->mknod(), ->symlink(),
* ->rename(), and ->link().  (However, ->rename() and ->link() are already
* handled by fscrypt_prepare_rename() and fscrypt_prepare_link().)
*
* This is necessary because creating a filename requires the directory's
* encryption key, but just checking for the key on the directory inode during
* the final filesystem operation doesn't guarantee that the key was available
* during the preceding dentry lookup.  And the key must have already been
* available during the dentry lookup in order for it to have been checked
* whether the filename already exists in the directory and for the new file's
* dentry not to be invalidated due to it incorrectly having the no-key flag.
*
* Return: %true if the dentry is a no-key name
*/
static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
{
return dentry->d_flags & DCACHE_NOKEY_NAME;
}

static inline void fscrypt_prepare_dentry(struct dentry *dentry,
       bool is_nokey_name)
{
/*
* This code tries to only take ->d_lock when necessary to write
* to ->d_flags.  We shouldn't be peeking on d_flags for
* DCACHE_OP_REVALIDATE unlocked, but in the unlikely case
* there is a race, the worst it can happen is that we fail to
* unset DCACHE_OP_REVALIDATE and pay the cost of an extra
* d_revalidate.
*/
if (is_nokey_name) {
  spin_lock(&dentry->d_lock);
  dentry->d_flags |= DCACHE_NOKEY_NAME;
  spin_unlock(&dentry->d_lock);
} else if (dentry->d_flags & DCACHE_OP_REVALIDATE &&
     dentry->d_op->d_revalidate == fscrypt_d_revalidate) {
  /*
* Unencrypted dentries and encrypted dentries where the
* key is available are always valid from fscrypt
* perspective. Avoid the cost of calling
* fscrypt_d_revalidate unnecessarily.
*/
  spin_lock(&dentry->d_lock);
  dentry->d_flags &= ~DCACHE_OP_REVALIDATE;
  spin_unlock(&dentry->d_lock);
}
}

/* crypto.c */
void fscrypt_enqueue_decrypt_work(struct work_struct *);

struct page *fscrypt_encrypt_pagecache_blocks(struct folio *folio,
  size_t len, size_t offs, gfp_t gfp_flags);
int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
      unsigned int len, unsigned int offs,
      u64 lblk_num);

int fscrypt_decrypt_pagecache_blocks(struct folio *folio, size_t len,
         size_t offs);
int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
      unsigned int len, unsigned int offs,
      u64 lblk_num);

static inline bool fscrypt_is_bounce_page(struct page *page)
{
return page->mapping == NULL;
}

static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
{
return (struct page *)page_private(bounce_page);
}

static inline bool fscrypt_is_bounce_folio(const struct folio *folio)
{
return folio->mapping == NULL;
}

static inline
struct folio *fscrypt_pagecache_folio(const struct folio *bounce_folio)
{
return bounce_folio->private;
}

void fscrypt_free_bounce_page(struct page *bounce_page);

/* policy.c */
int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg);
int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg);
int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg);
int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
int fscrypt_context_for_new_inode(void *ctx, struct inode *inode);
int fscrypt_set_context(struct inode *inode, void *fs_data);

struct fscrypt_dummy_policy {
const union fscrypt_policy *policy;
};

int fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param,
        struct fscrypt_dummy_policy *dummy_policy);
bool fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1,
      const struct fscrypt_dummy_policy *p2);
void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
     struct super_block *sb);
static inline bool
fscrypt_is_dummy_policy_set(const struct fscrypt_dummy_policy *dummy_policy)
{
return dummy_policy->policy != NULL;
}
static inline void
fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
{
kfree(dummy_policy->policy);
dummy_policy->policy = NULL;
}

/* keyring.c */
void fscrypt_destroy_keyring(struct super_block *sb);
int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);

/* keysetup.c */
int fscrypt_prepare_new_inode(struct inode *dir, struct inode *inode,
         bool *encrypt_ret);
void fscrypt_put_encryption_info(struct inode *inode);
void fscrypt_free_inode(struct inode *inode);
int fscrypt_drop_inode(struct inode *inode);

/* fname.c */
int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
     u8 *out, unsigned int olen);
bool fscrypt_fname_encrypted_size(const struct inode *inode, u32 orig_len,
      u32 max_len, u32 *encrypted_len_ret);
int fscrypt_setup_filename(struct inode *inode, const struct qstr *iname,
      int lookup, struct fscrypt_name *fname);

static inline void fscrypt_free_filename(struct fscrypt_name *fname)
{
kfree(fname->crypto_buf.name);
}

int fscrypt_fname_alloc_buffer(u32 max_encrypted_len,
          struct fscrypt_str *crypto_str);
void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str);
int fscrypt_fname_disk_to_usr(const struct inode *inode,
         u32 hash, u32 minor_hash,
         const struct fscrypt_str *iname,
         struct fscrypt_str *oname);
bool fscrypt_match_name(const struct fscrypt_name *fname,
   const u8 *de_name, u32 de_name_len);
u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);

/* bio.c */
bool fscrypt_decrypt_bio(struct bio *bio);
int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
     sector_t pblk, unsigned int len);

/* hooks.c */
int fscrypt_file_open(struct inode *inode, struct file *filp);
int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
      struct dentry *dentry);
int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
        struct inode *new_dir, struct dentry *new_dentry,
        unsigned int flags);
int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
        struct fscrypt_name *fname);
int fscrypt_prepare_lookup_partial(struct inode *dir, struct dentry *dentry);
int __fscrypt_prepare_readdir(struct inode *dir);
int __fscrypt_prepare_setattr(struct dentry *dentry, struct iattr *attr);
int fscrypt_prepare_setflags(struct inode *inode,
        unsigned int oldflags, unsigned int flags);
int fscrypt_prepare_symlink(struct inode *dir, const char *target,
       unsigned int len, unsigned int max_len,
       struct fscrypt_str *disk_link);
int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
         unsigned int len, struct fscrypt_str *disk_link);
const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
    unsigned int max_size,
    struct delayed_call *done);
int fscrypt_symlink_getattr(const struct path *path, struct kstat *stat);
static inline void fscrypt_set_ops(struct super_block *sb,
       const struct fscrypt_operations *s_cop)
{
sb->s_cop = s_cop;
}
#else  /* !CONFIG_FS_ENCRYPTION */

static inline struct fscrypt_inode_info *
fscrypt_get_inode_info(const struct inode *inode)
{
return NULL;
}

static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
{
return false;
}

static inline void fscrypt_handle_d_move(struct dentry *dentry)
{
}

static inline bool fscrypt_is_nokey_name(const struct dentry *dentry)
{
return false;
}

static inline void fscrypt_prepare_dentry(struct dentry *dentry,
       bool is_nokey_name)
{
}

/* crypto.c */
static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
{
}

static inline struct page *fscrypt_encrypt_pagecache_blocks(struct folio *folio,
  size_t len, size_t offs, gfp_t gfp_flags)
{
return ERR_PTR(-EOPNOTSUPP);
}

static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
      struct page *page,
      unsigned int len,
      unsigned int offs, u64 lblk_num)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_decrypt_pagecache_blocks(struct folio *folio,
         size_t len, size_t offs)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
      struct page *page,
      unsigned int len,
      unsigned int offs, u64 lblk_num)
{
return -EOPNOTSUPP;
}

static inline bool fscrypt_is_bounce_page(struct page *page)
{
return false;
}

static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
{
WARN_ON_ONCE(1);
return ERR_PTR(-EINVAL);
}

static inline bool fscrypt_is_bounce_folio(const struct folio *folio)
{
return false;
}

static inline
struct folio *fscrypt_pagecache_folio(const struct folio *bounce_folio)
{
WARN_ON_ONCE(1);
return ERR_PTR(-EINVAL);
}

static inline void fscrypt_free_bounce_page(struct page *bounce_page)
{
}

/* 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_ioctl_get_policy_ex(struct file *filp,
           void __user *arg)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_ioctl_get_nonce(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_set_context(struct inode *inode, void *fs_data)
{
return -EOPNOTSUPP;
}

struct fscrypt_dummy_policy {
};

static inline int
fscrypt_parse_test_dummy_encryption(const struct fs_parameter *param,
        struct fscrypt_dummy_policy *dummy_policy)
{
return -EINVAL;
}

static inline bool
fscrypt_dummy_policies_equal(const struct fscrypt_dummy_policy *p1,
        const struct fscrypt_dummy_policy *p2)
{
return true;
}

static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
            char sep,
            struct super_block *sb)
{
}

static inline bool
fscrypt_is_dummy_policy_set(const struct fscrypt_dummy_policy *dummy_policy)
{
return false;
}

static inline void
fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
{
}

/* keyring.c */
static inline void fscrypt_destroy_keyring(struct super_block *sb)
{
}

static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_ioctl_remove_key_all_users(struct file *filp,
           void __user *arg)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_ioctl_get_key_status(struct file *filp,
            void __user *arg)
{
return -EOPNOTSUPP;
}

/* keysetup.c */

static inline int fscrypt_prepare_new_inode(struct inode *dir,
         struct inode *inode,
         bool *encrypt_ret)
{
if (IS_ENCRYPTED(dir))
  return -EOPNOTSUPP;
return 0;
}

static inline void fscrypt_put_encryption_info(struct inode *inode)
{
return;
}

static inline void fscrypt_free_inode(struct inode *inode)
{
}

static inline int fscrypt_drop_inode(struct inode *inode)
{
return 0;
}

/* 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(*fname));
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(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(const 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);
}

static inline u64 fscrypt_fname_siphash(const struct inode *dir,
     const struct qstr *name)
{
WARN_ON_ONCE(1);
return 0;
}

static inline int fscrypt_d_revalidate(struct inode *dir, const struct qstr *name,
           struct dentry *dentry, unsigned int flags)
{
return 1;
}

/* bio.c */
static inline bool fscrypt_decrypt_bio(struct bio *bio)
{
return true;
}

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,
      struct dentry *dentry)
{
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,
        struct fscrypt_name *fname)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_prepare_lookup_partial(struct inode *dir,
       struct dentry *dentry)
{
return -EOPNOTSUPP;
}

static inline int __fscrypt_prepare_readdir(struct inode *dir)
{
return -EOPNOTSUPP;
}

static inline int __fscrypt_prepare_setattr(struct dentry *dentry,
         struct iattr *attr)
{
return -EOPNOTSUPP;
}

static inline int fscrypt_prepare_setflags(struct inode *inode,
        unsigned int oldflags,
        unsigned int flags)
{
return 0;
}

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

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);
}

static inline int fscrypt_symlink_getattr(const struct path *path,
       struct kstat *stat)
{
return -EOPNOTSUPP;
}

static inline void fscrypt_set_ops(struct super_block *sb,
       const struct fscrypt_operations *s_cop)
{
}

#endif /* !CONFIG_FS_ENCRYPTION */

/* inline_crypt.c */
#ifdef CONFIG_FS_ENCRYPTION_INLINE_CRYPT

bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode);

void fscrypt_set_bio_crypt_ctx(struct bio *bio,
          const struct inode *inode, u64 first_lblk,
          gfp_t gfp_mask);

void fscrypt_set_bio_crypt_ctx_bh(struct bio *bio,
      const struct buffer_head *first_bh,
      gfp_t gfp_mask);

bool fscrypt_mergeable_bio(struct bio *bio, const struct inode *inode,
      u64 next_lblk);

bool fscrypt_mergeable_bio_bh(struct bio *bio,
         const struct buffer_head *next_bh);

bool fscrypt_dio_supported(struct inode *inode);

u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks);

#else /* CONFIG_FS_ENCRYPTION_INLINE_CRYPT */

static inline bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
{
return false;
}

static inline void fscrypt_set_bio_crypt_ctx(struct bio *bio,
          const struct inode *inode,
          u64 first_lblk, gfp_t gfp_mask) { }

static inline void fscrypt_set_bio_crypt_ctx_bh(
      struct bio *bio,
      const struct buffer_head *first_bh,
      gfp_t gfp_mask) { }

static inline bool fscrypt_mergeable_bio(struct bio *bio,
      const struct inode *inode,
      u64 next_lblk)
{
return true;
}

static inline bool fscrypt_mergeable_bio_bh(struct bio *bio,
         const struct buffer_head *next_bh)
{
return true;
}

static inline bool fscrypt_dio_supported(struct inode *inode)
{
return !fscrypt_needs_contents_encryption(inode);
}

static inline u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk,
       u64 nr_blocks)
{
return nr_blocks;
}
#endif /* !CONFIG_FS_ENCRYPTION_INLINE_CRYPT */

/**
* fscrypt_inode_uses_inline_crypto() - test whether an inode uses inline
* encryption
* @inode: an inode. If encrypted, its key must be set up.
*
* Return: true if the inode requires file contents encryption and if the
*    encryption should be done in the block layer via blk-crypto rather
*    than in the filesystem layer.
*/
static inline bool fscrypt_inode_uses_inline_crypto(const struct inode *inode)
{
return fscrypt_needs_contents_encryption(inode) &&
        __fscrypt_inode_uses_inline_crypto(inode);
}

/**
* fscrypt_inode_uses_fs_layer_crypto() - test whether an inode uses fs-layer
*   encryption
* @inode: an inode. If encrypted, its key must be set up.
*
* Return: true if the inode requires file contents encryption and if the
*    encryption should be done in the filesystem layer rather than in the
*    block layer via blk-crypto.
*/
static inline bool fscrypt_inode_uses_fs_layer_crypto(const struct inode *inode)
{
return fscrypt_needs_contents_encryption(inode) &&
        !__fscrypt_inode_uses_inline_crypto(inode);
}

/**
* fscrypt_has_encryption_key() - check whether an inode has had its key set up
* @inode: the inode to check
*
* Return: %true if the inode has had its encryption key set up, else %false.
*
* Usually this should be preceded by fscrypt_get_encryption_info() to try to
* set up the key first.
*/
static inline bool fscrypt_has_encryption_key(const struct inode *inode)
{
return fscrypt_get_inode_info(inode) != NULL;
}

/**
* 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.
*
* 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,
* -EXDEV 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, dentry);
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, -EXDEV 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
* @fname: (output) the name to use to search the on-disk directory
*
* Prepare for ->lookup() in a directory which may be encrypted by determining
* the name that will actually be used to search the directory on-disk.  If the
* directory's encryption policy is supported by this kernel and its encryption
* key is available, then the lookup is assumed to be by plaintext name;
* otherwise, it is assumed to be by no-key name.
*
* This will set DCACHE_NOKEY_NAME on the dentry if the lookup is by no-key
* name.  In this case the filesystem must assign the dentry a dentry_operations
* which contains fscrypt_d_revalidate (or contains a d_revalidate method that
* calls fscrypt_d_revalidate), so that the dentry will be invalidated if the
* directory's encryption key is later added.
*
* Return: 0 on success; -ENOENT if the directory's key is unavailable but the
* filename isn't a valid no-key name, so a negative dentry should be created;
* or another -errno code.
*/
static inline int fscrypt_prepare_lookup(struct inode *dir,
      struct dentry *dentry,
      struct fscrypt_name *fname)
{
if (IS_ENCRYPTED(dir))
  return __fscrypt_prepare_lookup(dir, dentry, fname);

memset(fname, 0, sizeof(*fname));
fname->usr_fname = &dentry->d_name;
fname->disk_name.name = (unsigned char *)dentry->d_name.name;
fname->disk_name.len = dentry->d_name.len;

fscrypt_prepare_dentry(dentry, false);

return 0;
}

/**
* fscrypt_prepare_readdir() - prepare to read a possibly-encrypted directory
* @dir: the directory inode
*
* If the directory is encrypted and it doesn't already have its encryption key
* set up, try to set it up so that the filenames will be listed in plaintext
* form rather than in no-key form.
*
* Return: 0 on success; -errno on error.  Note that the encryption key being
*    unavailable is not considered an error.  It is also not an error if
*    the encryption policy is unsupported by this kernel; that is treated
*    like the key being unavailable, so that files can still be deleted.
*/
static inline int fscrypt_prepare_readdir(struct inode *dir)
{
if (IS_ENCRYPTED(dir))
  return __fscrypt_prepare_readdir(dir);
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 (IS_ENCRYPTED(d_inode(dentry)))
  return __fscrypt_prepare_setattr(dentry, attr);
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;
}

/* If *pagep is a bounce page, free it and set *pagep to the pagecache page */
static inline void fscrypt_finalize_bounce_page(struct page **pagep)
{
struct page *page = *pagep;

if (fscrypt_is_bounce_page(page)) {
  *pagep = fscrypt_pagecache_page(page);
  fscrypt_free_bounce_page(page);
}
}

#endif /* _LINUX_FSCRYPT_H */

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