Current File : //proc/thread-self/root/usr/src/linux-headers-5.15.0-43/include/linux/fscrypt.h
/* 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>
#define FS_CRYPTO_BLOCK_SIZE 16
union fscrypt_policy;
struct fscrypt_info;
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
/*
* If set, the fscrypt bounce page pool won't be allocated (unless another
* filesystem needs it). Set this if the filesystem always uses its own bounce
* pages for writes and therefore won't need the fscrypt bounce page pool.
*/
#define FS_CFLG_OWN_PAGES (1U << 1)
/* Crypto operations for filesystems */
struct fscrypt_operations {
/* Set of optional flags; see above for allowed flags */
unsigned int flags;
/*
* If set, this is a filesystem-specific key description prefix that
* will be accepted for "logon" keys for v1 fscrypt policies, in
* addition to the generic prefix "fscrypt:". This functionality is
* deprecated, so new filesystems shouldn't set this field.
*/
const char *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);
/* The filesystem's maximum ciphertext filename length, in bytes */
unsigned int max_namelen;
/*
* 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);
/*
* Get the number of bits that the filesystem uses to represent inode
* numbers and file logical block numbers.
*
* By default, both of these are assumed to be 64-bit. This function
* can be implemented to declare that either or both of these numbers is
* shorter, which may allow the use of the
* FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64} flags and/or the use of
* inline crypto hardware whose maximum DUN length is less than 64 bits
* (e.g., eMMC v5.2 spec compliant hardware). This function only needs
* to be implemented if support for one of these features is needed.
*/
void (*get_ino_and_lblk_bits)(struct super_block *sb,
int *ino_bits_ret, int *lblk_bits_ret);
/*
* Return the number of block devices to which the filesystem may write
* encrypted file contents.
*
* 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.
*/
int (*get_num_devices)(struct super_block *sb);
/*
* If ->get_num_devices() returns a value greater than 1, then this
* function is called to get the array of request_queues that the
* filesystem is using -- one per block device. (There may be duplicate
* entries in this array, as block devices can share a request_queue.)
*/
void (*get_devices)(struct super_block *sb,
struct request_queue **devs);
};
static inline struct fscrypt_info *fscrypt_get_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. Note that we don't have to support arbitrary moves of this flag
* 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)
{
dentry->d_flags &= ~DCACHE_NOKEY_NAME;
}
/**
* 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;
}
/* crypto.c */
void fscrypt_enqueue_decrypt_work(struct work_struct *);
struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
unsigned int len,
unsigned int 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, gfp_t gfp_flags);
int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
unsigned int 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);
}
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_set_context(struct inode *inode, void *fs_data);
struct fscrypt_dummy_policy {
const union fscrypt_policy *policy;
};
int fscrypt_set_test_dummy_encryption(struct super_block *sb, const char *arg,
struct fscrypt_dummy_policy *dummy_policy);
void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
struct super_block *sb);
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_sb_free(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_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);
int fscrypt_d_revalidate(struct dentry *dentry, unsigned int flags);
/* bio.c */
void 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_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_info *fscrypt_get_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;
}
/* crypto.c */
static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
{
}
static inline struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
unsigned int len,
unsigned int 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,
gfp_t gfp_flags)
{
return -EOPNOTSUPP;
}
static inline int fscrypt_decrypt_pagecache_blocks(struct page *page,
unsigned int len,
unsigned int 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 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 void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
char sep,
struct super_block *sb)
{
}
static inline void
fscrypt_free_dummy_policy(struct fscrypt_dummy_policy *dummy_policy)
{
}
/* keyring.c */
static inline void fscrypt_sb_free(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 dentry *dentry,
unsigned int flags)
{
return 1;
}
/* bio.c */
static inline void fscrypt_decrypt_bio(struct bio *bio)
{
}
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_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);
#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;
}
#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_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;
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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