Viewing: llcrypt.h
/* SPDX-License-Identifier: GPL-2.0 */
/*
* llcrypt.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.
*/
/*
* Linux commit 219d54332a09
* tags/v5.4
*/
#ifndef _LINUX_LLCRYPT_H
#define _LINUX_LLCRYPT_H
#ifndef DCACHE_ENCRYPTED_NAME
#define DCACHE_ENCRYPTED_NAME 0x02000000
#endif
#include <linux/fs.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <lustre_disk.h>
#include <lustre_compat/uapi/linux/llcrypt.h>
#include <lustre_compat/linux/folio.h>
#define LL_CRYPTO_BLOCK_SIZE 16
/* Extracts the second-to-last ciphertext block; see explanation below */
#define LLCRYPT_FNAME_DIGEST(name, len) \
((name) + round_down((len) - LL_CRYPTO_BLOCK_SIZE - 1, \
LL_CRYPTO_BLOCK_SIZE))
struct llcrypt_ctx;
struct llcrypt_info;
struct llcrypt_str {
unsigned char *name;
u32 len;
};
struct llcrypt_name {
const struct qstr *usr_fname;
struct llcrypt_str disk_name;
u32 hash;
u32 minor_hash;
struct llcrypt_str crypto_buf;
bool is_ciphertext_name;
};
#define LLTR_INIT(n, l) { .name = n, .len = l }
#define LLTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
#define lname_name(p) ((p)->disk_name.name)
#define lname_len(p) ((p)->disk_name.len)
/* Maximum value for the third parameter of llcrypt_operations.set_context(). */
#define LLCRYPT_SET_CONTEXT_MAX_SIZE 40
#define LLCRYPT_DIGESTED_CHAR_OLD '_'
#define LLCRYPT_DIGESTED_CHAR '+'
#ifdef CONFIG_LL_ENCRYPTION
/*
* llcrypt superblock flags
*/
#define LL_CFLG_OWN_PAGES (1U << 1)
/*
* crypto operations for filesystems
*/
struct llcrypt_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;
};
/* Decryption work */
struct llcrypt_ctx {
union {
struct {
struct bio *bio;
struct work_struct work;
};
struct list_head free_list; /* Free list */
};
u8 flags; /* Flags */
};
extern bool llcrypt_has_encryption_key(const struct inode *inode);
static inline bool llcrypt_dummy_context_enabled(struct inode *inode)
{
struct lustre_sb_info *lsi = s2lsi(inode->i_sb);
if (unlikely(!lsi))
return false;
return lsi->lsi_cop->dummy_context &&
lsi->lsi_cop->dummy_context(inode);
}
/*
* When d_splice_alias() moves a directory's encrypted alias to its decrypted
* alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME
* must be cleared. Note that we don't have to support arbitrary moves of this
* flag because llcrypt doesn't allow encrypted aliases to be the source or
* target of a rename().
*/
static inline void llcrypt_handle_d_move(struct dentry *dentry)
{
dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
}
static inline void folio_bounce_private(struct folio *dst, s32 dstpg,
struct folio *src, s32 srcpg)
{
s32 spg __maybe_unused = srcpg > 0 ? srcpg : 0;
s32 dpg __maybe_unused = dstpg > 0 ? srcpg : 0;
if (dpg) {
struct page *vmpg;
vmpg = folio_page(dst, dpg);
SetPagePrivate(vmpg);
vmpg->private = (unsigned long)folio_page(src, spg);
return;
}
folio_set_private(dst);
folio_change_private(dst, src);
}
/* crypto.c */
extern int __init llcrypt_init(void);
extern void __exit llcrypt_exit(void);
extern void llcrypt_enqueue_decrypt_work(struct work_struct *);
extern struct llcrypt_ctx *llcrypt_get_ctx(gfp_t);
extern void llcrypt_release_ctx(struct llcrypt_ctx *);
extern struct folio *llcrypt_encrypt_pagecache_blocks(struct folio *folio,
s32 pgno,
unsigned int len,
unsigned int offs,
gfp_t gfp_flags);
extern int llcrypt_encrypt_block(const struct inode *inode, struct folio *src,
s32 srcpg, struct folio *dst, s32 dstpg,
unsigned int len, unsigned int offs,
u64 lblk_num, gfp_t gfp_flags);
extern int llcrypt_decrypt_pagecache_blocks(struct folio *folio, s32 pgno,
unsigned int len,
unsigned int offs);
extern int llcrypt_decrypt_block(const struct inode *inode,
struct folio *src, s32 src_pgno,
struct folio *dst, s32 dst_pgno,
unsigned int len, unsigned int offs,
u64 lblk_num, gfp_t gfp_flags);
static inline int llcrypt_decrypt_block_inplace(const struct inode *inode,
struct page *vmpage,
unsigned int len,
unsigned int offs,
u64 lblk_num)
{
struct folio *folio = page_folio(vmpage);
s32 pgno = folio_page_idx(folio, vmpage);
return llcrypt_decrypt_block(inode, folio, pgno, folio, pgno,
len, offs, lblk_num, GFP_NOFS);
}
static inline bool llcrypt_is_bounce_page(struct folio *folio, s32 pgno)
{
if (pgno > 0)
return folio_page(folio, pgno)->mapping == NULL;
return folio->mapping == NULL;
}
static inline struct folio *llcrypt_pagecache_page(struct folio *bounce_folio,
s32 pgno)
{
if (pgno > 0)
return (void *)folio_page(bounce_folio, pgno)->private;
return folio_get_private(bounce_folio);
}
extern void llcrypt_free_bounce_folio(struct folio *bounce_folio);
/* policy.c */
extern int llcrypt_ioctl_set_policy(struct file *, const void __user *);
extern int llcrypt_ioctl_get_policy(struct file *, void __user *);
extern int llcrypt_ioctl_get_policy_ex(struct file *, void __user *);
extern int llcrypt_has_permitted_context(struct inode *, struct inode *);
extern int llcrypt_inherit_context(struct inode *, struct inode *,
void *, bool);
extern bool llcrypt_policy_has_filename_enc(struct inode *inode);
/* keyring.c */
extern void llcrypt_sb_free(struct lustre_sb_info *lsi);
extern int llcrypt_ioctl_add_key(struct file *filp, void __user *arg);
extern int llcrypt_ioctl_remove_key(struct file *filp, void __user *arg);
extern int llcrypt_ioctl_remove_key_all_users(struct file *filp,
void __user *arg);
extern int llcrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
/* keysetup.c */
extern int llcrypt_get_encryption_info(struct inode *);
extern void llcrypt_put_encryption_info(struct inode *);
extern void llcrypt_free_inode(struct inode *);
extern int llcrypt_drop_inode(struct inode *inode);
/* fname.c */
extern int llcrypt_setup_filename(struct inode *, const struct qstr *,
int lookup, struct llcrypt_name *);
static inline void llcrypt_free_filename(struct llcrypt_name *fname)
{
kfree(fname->crypto_buf.name);
}
extern int llcrypt_fname_alloc_buffer(const struct inode *, u32,
struct llcrypt_str *);
extern void llcrypt_fname_free_buffer(struct llcrypt_str *);
extern int llcrypt_fname_disk_to_usr(struct inode *, u32, u32,
const struct llcrypt_str *, struct llcrypt_str *);
#define LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32
#define LLCRYPT_FNAME_DIGEST_SIZE LL_CRYPTO_BLOCK_SIZE
/**
* llcrypt_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 LLCRYPT_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 llcrypt_digested_name {
u32 hash;
u32 minor_hash;
u8 digest[LLCRYPT_FNAME_DIGEST_SIZE];
};
/**
* llcrypt_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 llcrypt_digested_name.
*
* Return: %true if the name matches, otherwise %false.
*/
static inline bool llcrypt_match_name(const struct llcrypt_name *fname,
const u8 *de_name, u32 de_name_len)
{
if (unlikely(!fname->disk_name.name)) {
const struct llcrypt_digested_name *n =
(const void *)fname->crypto_buf.name;
if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
return false;
if (de_name_len <= LLCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
return false;
return !memcmp(LLCRYPT_FNAME_DIGEST(de_name, de_name_len),
n->digest, LLCRYPT_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);
}
/* hooks.c */
extern int llcrypt_file_open(struct inode *inode, struct file *filp);
extern int __llcrypt_prepare_link(struct inode *inode, struct inode *dir,
struct dentry *dentry);
extern int __llcrypt_prepare_rename(struct inode *old_dir,
struct dentry *old_dentry,
struct inode *new_dir,
struct dentry *new_dentry,
unsigned int flags);
extern int __llcrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
struct llcrypt_name *fname);
extern int __llcrypt_prepare_symlink(struct inode *dir, unsigned int len,
unsigned int max_len,
struct llcrypt_str *disk_link);
extern int __llcrypt_encrypt_symlink(struct inode *inode, const char *target,
unsigned int len,
struct llcrypt_str *disk_link);
extern const char *llcrypt_get_symlink(struct inode *inode, const void *caddr,
unsigned int max_size,
struct delayed_call *done);
static inline void llcrypt_set_ops(struct super_block *sb,
const struct llcrypt_operations *lsi_cop)
{
struct lustre_sb_info *lsi = s2lsi(sb);
if (lsi)
lsi->lsi_cop = lsi_cop;
}
#else /* !CONFIG_LL_ENCRYPTION */
struct llcrypt_operations;
#define llcrypt_init() 0
#define llcrypt_exit() {}
#undef IS_ENCRYPTED
#define IS_ENCRYPTED(x) 0
static inline bool llcrypt_has_encryption_key(const struct inode *inode)
{
return false;
}
static inline bool llcrypt_dummy_context_enabled(struct inode *inode)
{
return false;
}
static inline void llcrypt_handle_d_move(struct dentry *dentry)
{
}
/* crypto.c */
static inline void llcrypt_enqueue_decrypt_work(struct work_struct *work)
{
}
static inline struct llcrypt_ctx *llcrypt_get_ctx(gfp_t gfp_flags)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline void llcrypt_release_ctx(struct llcrypt_ctx *ctx)
{
return;
}
static inline
struct folio *llcrypt_encrypt_pagecache_blocks(struct folio *folio,
s32 pgno,
unsigned int len,
unsigned int offs,
gfp_t gfp_flags)
{
return ERR_PTR(-EOPNOTSUPP);
}
static inline int llcrypt_encrypt_block(const struct inode *inode,
struct folio *src, s32 srcpg,
struct folio *dst, s32 dstpg,
unsigned int len, unsigned int offs,
u64 lblk_num, gfp_t gfp_flags)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_decrypt_pagecache_blocks(struct folio *folio, s32 pg,
unsigned int len,
unsigned int offs)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_decrypt_block(const struct inode *inode,
struct folio *src, s32 spg,
struct folio *dst, s32 dpg,
unsigned int len, unsigned int offs,
u64 lblk_num, gfp_t gfp_flags)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_decrypt_block_inplace(const struct inode *inode,
struct page *page,
unsigned int len,
unsigned int offs, u64 lblk_num)
{
return -EOPNOTSUPP;
}
static inline bool llcrypt_is_bounce_page(struct folio *folio, s32 pg)
{
return false;
}
static inline struct folio *llcrypt_pagecache_page(struct folio *folio, s32 pg)
{
WARN_ON_ONCE(1);
return ERR_PTR(-EINVAL);
}
static inline void llcrypt_free_bounce_folio(struct folio *bounce_page)
{
}
/* policy.c */
static inline int llcrypt_ioctl_set_policy(struct file *filp,
const void __user *arg)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_ioctl_get_policy(struct file *filp, void __user *arg)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_ioctl_get_policy_ex(struct file *filp,
void __user *arg)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_has_permitted_context(struct inode *parent,
struct inode *child)
{
return 0;
}
static inline int llcrypt_inherit_context(struct inode *parent,
struct inode *child,
void *fs_data, bool preload)
{
return -EOPNOTSUPP;
}
static inline bool llcrypt_policy_has_filename_enc(struct inode *inode)
{
return false;
}
/* keyring.c */
static inline void llcrypt_sb_free(struct lustre_sb_info *lsi)
{
}
static inline int llcrypt_ioctl_add_key(struct file *filp, void __user *arg)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_ioctl_remove_key(struct file *filp, void __user *arg)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_ioctl_remove_key_all_users(struct file *filp,
void __user *arg)
{
return -EOPNOTSUPP;
}
static inline int llcrypt_ioctl_get_key_status(struct file *filp,
void __user *arg)
{
return -EOPNOTSUPP;
}
/* keysetup.c */
static inline int llcrypt_get_encryption_info(struct inode *inode)
{
return -EOPNOTSUPP;
}
static inline void llcrypt_put_encryption_info(struct inode *inode)
{
return;
}
static inline void llcrypt_free_inode(struct inode *inode)
{
}
static inline int llcrypt_drop_inode(struct inode *inode)
{
return 0;
}
/* fname.c */
static inline int llcrypt_setup_filename(struct inode *dir,
const struct qstr *iname,
int lookup, struct llcrypt_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 llcrypt_free_filename(struct llcrypt_name *fname)
{
return;
}
static inline int llcrypt_fname_alloc_buffer(const struct inode *inode,
u32 max_encrypted_len,
struct llcrypt_str *crypto_str)
{
return -EOPNOTSUPP;
}
static inline void llcrypt_fname_free_buffer(struct llcrypt_str *crypto_str)
{
return;
}
static inline int llcrypt_fname_disk_to_usr(struct inode *inode,
u32 hash, u32 minor_hash,
const struct llcrypt_str *iname,
struct llcrypt_str *oname)
{
return -EOPNOTSUPP;
}
static inline bool llcrypt_match_name(const struct llcrypt_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);
}
/* hooks.c */
static inline int llcrypt_file_open(struct inode *inode, struct file *filp)
{
if (IS_ENCRYPTED(inode))
return -EOPNOTSUPP;
return 0;
}
static inline int __llcrypt_prepare_link(struct inode *inode, struct inode *dir,
struct dentry *dentry)
{
return -EOPNOTSUPP;
}
static inline int __llcrypt_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 __llcrypt_prepare_lookup(struct inode *dir,
struct dentry *dentry,
struct llcrypt_name *fname)
{
return -EOPNOTSUPP;
}
static inline int __llcrypt_prepare_symlink(struct inode *dir,
unsigned int len,
unsigned int max_len,
struct llcrypt_str *disk_link)
{
return -EOPNOTSUPP;
}
static inline int __llcrypt_encrypt_symlink(struct inode *inode,
const char *target,
unsigned int len,
struct llcrypt_str *disk_link)
{
return -EOPNOTSUPP;
}
#define llcrypt_get_symlink(inode, caddr, max_size, done) ERR_PTR(-EOPNOTSUPP)
static inline void llcrypt_set_ops(struct super_block *sb,
const struct llcrypt_operations *lsi_cop)
{
}
#endif /* !CONFIG_LL_ENCRYPTION */
/**
* llcrypt_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 llcrypt_require_key(struct inode *inode)
{
if (IS_ENCRYPTED(inode)) {
int err = llcrypt_get_encryption_info(inode);
if (err)
return err;
if (!llcrypt_has_encryption_key(inode))
return -ENOKEY;
}
return 0;
}
/**
* llcrypt_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,
* -EXDEV if the link would result in an inconsistent encryption policy, or
* another -errno code.
*/
static inline int llcrypt_prepare_link(struct dentry *old_dentry,
struct inode *dir,
struct dentry *dentry)
{
if (IS_ENCRYPTED(dir))
return __llcrypt_prepare_link(d_inode(old_dentry), dir, dentry);
return 0;
}
/**
* llcrypt_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 llcrypt_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 __llcrypt_prepare_rename(old_dir, old_dentry,
new_dir, new_dentry, flags);
return 0;
}
/**
* llcrypt_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. 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.
*
* This also installs a custom ->d_revalidate() method which will invalidate the
* dentry if it was created without the key and the key is later added.
*
* Return: 0 on success; -ENOENT if key is unavailable but the filename isn't a
* correctly formed encoded ciphertext name, so a negative dentry should be
* created; or another -errno code.
*/
static inline int llcrypt_prepare_lookup(struct inode *dir,
struct dentry *dentry,
struct llcrypt_name *fname)
{
if (IS_ENCRYPTED(dir))
return __llcrypt_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;
}
/**
* llcrypt_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 llcrypt_prepare_setattr(struct dentry *dentry,
struct iattr *attr)
{
if (attr->ia_valid & ATTR_SIZE)
return llcrypt_require_key(d_inode(dentry));
return 0;
}
/**
* llcrypt_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 llcrypt_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 llcrypt_prepare_symlink(struct inode *dir,
const char *target,
unsigned int len,
unsigned int max_len,
struct llcrypt_str *disk_link)
{
if ((IS_ENCRYPTED(dir) || llcrypt_dummy_context_enabled(dir)) &&
llcrypt_policy_has_filename_enc(dir))
return __llcrypt_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;
}
/**
* llcrypt_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. llcrypt_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 llcrypt_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 llcrypt_encrypt_symlink(struct inode *inode,
const char *target,
unsigned int len,
struct llcrypt_str *disk_link)
{
if (IS_ENCRYPTED(inode))
return __llcrypt_encrypt_symlink(inode, target, len, disk_link);
return 0;
}
/* If *foliop is a bounce folio, free it and set *foliop to the cache folio */
static inline void llcrypt_finalize_bounce_page(struct folio **foliop,
s32 *pgno)
{
struct folio *folio = *foliop;
s32 no = *pgno > 0 ? *pgno : 0;
if (llcrypt_is_bounce_page(folio, no)) {
*foliop = llcrypt_pagecache_page(folio, no);
*pgno = -no;
llcrypt_free_bounce_folio(folio);
}
}
#endif /* _LINUX_LLCRYPT_H */
