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ed318a6cc0
v1 encryption policies are deprecated in favor of v2, and some new features (e.g. encryption+casefolding) are only being added for v2. Therefore, the "test_dummy_encryption" mount option (which is used for encryption I/O testing with xfstests) needs to support v2 policies. To do this, extend its syntax to be "test_dummy_encryption=v1" or "test_dummy_encryption=v2". The existing "test_dummy_encryption" (no argument) also continues to be accepted, to specify the default setting -- currently v1, but the next patch changes it to v2. To cleanly support both v1 and v2 while also making it easy to support specifying other encryption settings in the future (say, accepting "$contents_mode:$filenames_mode:v2"), make ext4 and f2fs maintain a pointer to the dummy fscrypt_context rather than using mount flags. To avoid concurrency issues, don't allow test_dummy_encryption to be set or changed during a remount. (The former restriction is new, but xfstests doesn't run into it, so no one should notice.) Tested with 'gce-xfstests -c {ext4,f2fs}/encrypt -g auto'. On ext4, there are two regressions, both of which are test bugs: ext4/023 and ext4/028 fail because they set an xattr and expect it to be stored inline, but the increase in size of the fscrypt_context from 24 to 40 bytes causes this xattr to be spilled into an external block. Link: https://lore.kernel.org/r/20200512233251.118314-4-ebiggers@kernel.org Acked-by: Jaegeuk Kim <jaegeuk@kernel.org> Reviewed-by: Theodore Ts'o <tytso@mit.edu> Signed-off-by: Eric Biggers <ebiggers@google.com>
764 lines
22 KiB
C
764 lines
22 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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/*
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* fscrypt.h: declarations for per-file encryption
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*
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* Filesystems that implement per-file encryption must include this header
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* file.
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*
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* Copyright (C) 2015, Google, Inc.
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*
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* Written by Michael Halcrow, 2015.
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* Modified by Jaegeuk Kim, 2015.
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*/
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#ifndef _LINUX_FSCRYPT_H
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#define _LINUX_FSCRYPT_H
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#include <linux/fs.h>
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#include <linux/mm.h>
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#include <linux/parser.h>
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#include <linux/slab.h>
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#include <uapi/linux/fscrypt.h>
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#define FS_CRYPTO_BLOCK_SIZE 16
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union fscrypt_context;
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struct fscrypt_info;
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struct seq_file;
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struct fscrypt_str {
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unsigned char *name;
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u32 len;
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};
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struct fscrypt_name {
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const struct qstr *usr_fname;
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struct fscrypt_str disk_name;
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u32 hash;
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u32 minor_hash;
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struct fscrypt_str crypto_buf;
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bool is_ciphertext_name;
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};
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#define FSTR_INIT(n, l) { .name = n, .len = l }
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#define FSTR_TO_QSTR(f) QSTR_INIT((f)->name, (f)->len)
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#define fname_name(p) ((p)->disk_name.name)
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#define fname_len(p) ((p)->disk_name.len)
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/* Maximum value for the third parameter of fscrypt_operations.set_context(). */
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#define FSCRYPT_SET_CONTEXT_MAX_SIZE 40
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#ifdef CONFIG_FS_ENCRYPTION
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/*
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* fscrypt superblock flags
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*/
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#define FS_CFLG_OWN_PAGES (1U << 1)
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/*
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* crypto operations for filesystems
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*/
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struct fscrypt_operations {
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unsigned int flags;
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const char *key_prefix;
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int (*get_context)(struct inode *inode, void *ctx, size_t len);
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int (*set_context)(struct inode *inode, const void *ctx, size_t len,
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void *fs_data);
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const union fscrypt_context *(*get_dummy_context)(
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struct super_block *sb);
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bool (*empty_dir)(struct inode *inode);
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unsigned int max_namelen;
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bool (*has_stable_inodes)(struct super_block *sb);
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void (*get_ino_and_lblk_bits)(struct super_block *sb,
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int *ino_bits_ret, int *lblk_bits_ret);
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};
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static inline bool fscrypt_has_encryption_key(const struct inode *inode)
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{
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/* pairs with cmpxchg_release() in fscrypt_get_encryption_info() */
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return READ_ONCE(inode->i_crypt_info) != NULL;
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}
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/**
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* fscrypt_needs_contents_encryption() - check whether an inode needs
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* contents encryption
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* @inode: the inode to check
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*
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* Return: %true iff the inode is an encrypted regular file and the kernel was
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* built with fscrypt support.
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*
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* If you need to know whether the encrypt bit is set even when the kernel was
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* built without fscrypt support, you must use IS_ENCRYPTED() directly instead.
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*/
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static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
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{
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return IS_ENCRYPTED(inode) && S_ISREG(inode->i_mode);
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}
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static inline const union fscrypt_context *
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fscrypt_get_dummy_context(struct super_block *sb)
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{
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if (!sb->s_cop->get_dummy_context)
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return NULL;
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return sb->s_cop->get_dummy_context(sb);
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}
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/*
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* When d_splice_alias() moves a directory's encrypted alias to its decrypted
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* alias as a result of the encryption key being added, DCACHE_ENCRYPTED_NAME
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* must be cleared. Note that we don't have to support arbitrary moves of this
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* flag because fscrypt doesn't allow encrypted aliases to be the source or
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* target of a rename().
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*/
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static inline void fscrypt_handle_d_move(struct dentry *dentry)
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{
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dentry->d_flags &= ~DCACHE_ENCRYPTED_NAME;
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}
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/* crypto.c */
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void fscrypt_enqueue_decrypt_work(struct work_struct *);
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struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
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unsigned int len,
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unsigned int offs,
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gfp_t gfp_flags);
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int fscrypt_encrypt_block_inplace(const struct inode *inode, struct page *page,
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unsigned int len, unsigned int offs,
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u64 lblk_num, gfp_t gfp_flags);
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int fscrypt_decrypt_pagecache_blocks(struct page *page, unsigned int len,
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unsigned int offs);
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int fscrypt_decrypt_block_inplace(const struct inode *inode, struct page *page,
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unsigned int len, unsigned int offs,
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u64 lblk_num);
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static inline bool fscrypt_is_bounce_page(struct page *page)
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{
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return page->mapping == NULL;
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}
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static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
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{
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return (struct page *)page_private(bounce_page);
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}
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void fscrypt_free_bounce_page(struct page *bounce_page);
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/* policy.c */
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int fscrypt_ioctl_set_policy(struct file *filp, const void __user *arg);
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int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg);
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int fscrypt_ioctl_get_policy_ex(struct file *filp, void __user *arg);
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int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg);
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int fscrypt_has_permitted_context(struct inode *parent, struct inode *child);
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int fscrypt_inherit_context(struct inode *parent, struct inode *child,
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void *fs_data, bool preload);
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struct fscrypt_dummy_context {
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const union fscrypt_context *ctx;
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};
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int fscrypt_set_test_dummy_encryption(struct super_block *sb,
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const substring_t *arg,
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struct fscrypt_dummy_context *dummy_ctx);
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void fscrypt_show_test_dummy_encryption(struct seq_file *seq, char sep,
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struct super_block *sb);
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static inline void
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fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
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{
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kfree(dummy_ctx->ctx);
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dummy_ctx->ctx = NULL;
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}
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/* keyring.c */
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void fscrypt_sb_free(struct super_block *sb);
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int fscrypt_ioctl_add_key(struct file *filp, void __user *arg);
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int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg);
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int fscrypt_ioctl_remove_key_all_users(struct file *filp, void __user *arg);
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int fscrypt_ioctl_get_key_status(struct file *filp, void __user *arg);
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/* keysetup.c */
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int fscrypt_get_encryption_info(struct inode *inode);
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void fscrypt_put_encryption_info(struct inode *inode);
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void fscrypt_free_inode(struct inode *inode);
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int fscrypt_drop_inode(struct inode *inode);
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/* fname.c */
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int fscrypt_setup_filename(struct inode *inode, const struct qstr *iname,
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int lookup, struct fscrypt_name *fname);
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static inline void fscrypt_free_filename(struct fscrypt_name *fname)
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{
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kfree(fname->crypto_buf.name);
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}
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int fscrypt_fname_alloc_buffer(const struct inode *inode, u32 max_encrypted_len,
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struct fscrypt_str *crypto_str);
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void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str);
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int fscrypt_fname_disk_to_usr(const struct inode *inode,
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u32 hash, u32 minor_hash,
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const struct fscrypt_str *iname,
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struct fscrypt_str *oname);
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bool fscrypt_match_name(const struct fscrypt_name *fname,
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const u8 *de_name, u32 de_name_len);
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u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name);
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/* bio.c */
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void fscrypt_decrypt_bio(struct bio *bio);
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int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
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sector_t pblk, unsigned int len);
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/* hooks.c */
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int fscrypt_file_open(struct inode *inode, struct file *filp);
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int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
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struct dentry *dentry);
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int __fscrypt_prepare_rename(struct inode *old_dir, struct dentry *old_dentry,
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struct inode *new_dir, struct dentry *new_dentry,
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unsigned int flags);
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int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
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struct fscrypt_name *fname);
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int fscrypt_prepare_setflags(struct inode *inode,
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unsigned int oldflags, unsigned int flags);
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int __fscrypt_prepare_symlink(struct inode *dir, unsigned int len,
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unsigned int max_len,
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struct fscrypt_str *disk_link);
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int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
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unsigned int len, struct fscrypt_str *disk_link);
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const char *fscrypt_get_symlink(struct inode *inode, const void *caddr,
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unsigned int max_size,
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struct delayed_call *done);
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static inline void fscrypt_set_ops(struct super_block *sb,
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const struct fscrypt_operations *s_cop)
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{
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sb->s_cop = s_cop;
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}
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#else /* !CONFIG_FS_ENCRYPTION */
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static inline bool fscrypt_has_encryption_key(const struct inode *inode)
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{
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return false;
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}
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static inline bool fscrypt_needs_contents_encryption(const struct inode *inode)
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{
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return false;
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}
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static inline const union fscrypt_context *
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fscrypt_get_dummy_context(struct super_block *sb)
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{
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return NULL;
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}
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static inline void fscrypt_handle_d_move(struct dentry *dentry)
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{
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}
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/* crypto.c */
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static inline void fscrypt_enqueue_decrypt_work(struct work_struct *work)
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{
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}
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static inline struct page *fscrypt_encrypt_pagecache_blocks(struct page *page,
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unsigned int len,
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unsigned int offs,
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gfp_t gfp_flags)
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{
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return ERR_PTR(-EOPNOTSUPP);
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}
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static inline int fscrypt_encrypt_block_inplace(const struct inode *inode,
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struct page *page,
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unsigned int len,
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unsigned int offs, u64 lblk_num,
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gfp_t gfp_flags)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_decrypt_pagecache_blocks(struct page *page,
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unsigned int len,
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unsigned int offs)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_decrypt_block_inplace(const struct inode *inode,
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struct page *page,
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unsigned int len,
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unsigned int offs, u64 lblk_num)
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{
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return -EOPNOTSUPP;
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}
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static inline bool fscrypt_is_bounce_page(struct page *page)
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{
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return false;
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}
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static inline struct page *fscrypt_pagecache_page(struct page *bounce_page)
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{
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WARN_ON_ONCE(1);
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return ERR_PTR(-EINVAL);
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}
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static inline void fscrypt_free_bounce_page(struct page *bounce_page)
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{
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}
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/* policy.c */
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static inline int fscrypt_ioctl_set_policy(struct file *filp,
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const void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_ioctl_get_policy(struct file *filp, void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_ioctl_get_policy_ex(struct file *filp,
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void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_ioctl_get_nonce(struct file *filp, void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_has_permitted_context(struct inode *parent,
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struct inode *child)
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{
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return 0;
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}
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static inline int fscrypt_inherit_context(struct inode *parent,
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struct inode *child,
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void *fs_data, bool preload)
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{
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return -EOPNOTSUPP;
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}
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struct fscrypt_dummy_context {
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};
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static inline void fscrypt_show_test_dummy_encryption(struct seq_file *seq,
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char sep,
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struct super_block *sb)
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{
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}
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static inline void
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fscrypt_free_dummy_context(struct fscrypt_dummy_context *dummy_ctx)
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{
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}
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/* keyring.c */
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static inline void fscrypt_sb_free(struct super_block *sb)
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{
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}
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static inline int fscrypt_ioctl_add_key(struct file *filp, void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_ioctl_remove_key(struct file *filp, void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_ioctl_remove_key_all_users(struct file *filp,
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void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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static inline int fscrypt_ioctl_get_key_status(struct file *filp,
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void __user *arg)
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{
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return -EOPNOTSUPP;
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}
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/* keysetup.c */
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static inline int fscrypt_get_encryption_info(struct inode *inode)
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{
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return -EOPNOTSUPP;
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}
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static inline void fscrypt_put_encryption_info(struct inode *inode)
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{
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return;
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}
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static inline void fscrypt_free_inode(struct inode *inode)
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{
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}
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static inline int fscrypt_drop_inode(struct inode *inode)
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{
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return 0;
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}
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/* fname.c */
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static inline int fscrypt_setup_filename(struct inode *dir,
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const struct qstr *iname,
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int lookup, struct fscrypt_name *fname)
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{
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if (IS_ENCRYPTED(dir))
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return -EOPNOTSUPP;
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memset(fname, 0, sizeof(*fname));
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fname->usr_fname = iname;
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fname->disk_name.name = (unsigned char *)iname->name;
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fname->disk_name.len = iname->len;
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return 0;
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}
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static inline void fscrypt_free_filename(struct fscrypt_name *fname)
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{
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return;
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}
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static inline int fscrypt_fname_alloc_buffer(const struct inode *inode,
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u32 max_encrypted_len,
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struct fscrypt_str *crypto_str)
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{
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return -EOPNOTSUPP;
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}
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static inline void fscrypt_fname_free_buffer(struct fscrypt_str *crypto_str)
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{
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return;
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}
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static inline int fscrypt_fname_disk_to_usr(const struct inode *inode,
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u32 hash, u32 minor_hash,
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const struct fscrypt_str *iname,
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struct fscrypt_str *oname)
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{
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return -EOPNOTSUPP;
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}
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static inline bool fscrypt_match_name(const struct fscrypt_name *fname,
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const u8 *de_name, u32 de_name_len)
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{
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/* Encryption support disabled; use standard comparison */
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if (de_name_len != fname->disk_name.len)
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return false;
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return !memcmp(de_name, fname->disk_name.name, fname->disk_name.len);
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}
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static inline u64 fscrypt_fname_siphash(const struct inode *dir,
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const struct qstr *name)
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{
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WARN_ON_ONCE(1);
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return 0;
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}
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/* bio.c */
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static inline void fscrypt_decrypt_bio(struct bio *bio)
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{
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}
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static inline int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
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sector_t pblk, unsigned int len)
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{
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return -EOPNOTSUPP;
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}
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/* hooks.c */
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static inline int fscrypt_file_open(struct inode *inode, struct file *filp)
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{
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if (IS_ENCRYPTED(inode))
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return -EOPNOTSUPP;
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return 0;
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}
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static inline int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
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struct dentry *dentry)
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{
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return -EOPNOTSUPP;
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}
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|
|
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_setflags(struct inode *inode,
|
|
unsigned int oldflags,
|
|
unsigned int flags)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int __fscrypt_prepare_symlink(struct inode *dir,
|
|
unsigned int len,
|
|
unsigned int max_len,
|
|
struct fscrypt_str *disk_link)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
|
|
static inline int __fscrypt_encrypt_symlink(struct inode *inode,
|
|
const char *target,
|
|
unsigned int len,
|
|
struct fscrypt_str *disk_link)
|
|
{
|
|
return -EOPNOTSUPP;
|
|
}
|
|
|
|
static inline const char *fscrypt_get_symlink(struct inode *inode,
|
|
const void *caddr,
|
|
unsigned int max_size,
|
|
struct delayed_call *done)
|
|
{
|
|
return ERR_PTR(-EOPNOTSUPP);
|
|
}
|
|
|
|
static inline void fscrypt_set_ops(struct super_block *sb,
|
|
const struct fscrypt_operations *s_cop)
|
|
{
|
|
}
|
|
|
|
#endif /* !CONFIG_FS_ENCRYPTION */
|
|
|
|
/**
|
|
* 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,
|
|
* -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. 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 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_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_get_dummy_context(dir->i_sb) != NULL)
|
|
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;
|
|
}
|
|
|
|
/* 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 */
|