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![Linus Torvalds](/assets/img/avatar_default.png)
- fscrypt framework usage updates - One huge fix for xattr unlink - Cleanup of fscrypt ifdefs - Fix for our new UBIFS auth feature -----BEGIN PGP SIGNATURE----- iQJKBAABCAA0FiEEdgfidid8lnn52cLTZvlZhesYu8EFAlzYkIgWHHJpY2hhcmRA c2lnbWEtc3Rhci5hdAAKCRBm+VmF6xi7wTRrD/99iBd4f8F0jF1wmB8/9kDAnz5s KaK+VtC0RVRijRijYzo+/2kDXpXEbmPycg6AVl5EfKxXCVFw1K7pQvuBX43qyv4o BINRv1av8FEBA9eTjvBgZJUrjB1AuvV37716/OeM2bnvuCsp1escnvTEh6S3VFYw oWDBgZJd+DE10CYtZjuLoyDPcYdNrzebbmu3Xbfl2XsPwZFUJIrymMd6NE8Xdk3I EQbZ3guEM5Djui+nrko3iKzfoZ4eK7WguO3DOEjUHpwea4ZfnZtnlH345aYOAqRE N5qrDCzXOsWs6Zs+clODMQgg+aTN3kGBNV534culcpMAbUp7WXynUQ1DDqtOJNJO pGFjhAfGi4E6YgB3UwqxMbXxI4Tg/X2ckc77hWZlC7h/1Y/i89nacT6Ij5rPNOn1 mby1mFxWHI04uSEICWyocFK4m/J2b17Tmte2Mc5ZOigQqREUB7J8wiT4NWm6GhV1 nTb5DA8MepC3zopbsL/iAiKPhSkH1h6AkabBw1ADTksacgNUfhjzALkxqa64tIqv C43QG3n/HqsNZJ4aLdizLLb8KIt4pWsIaqHOeDGSfr3I1GEBrpfKiR72P/h3fSF9 9GIFJU5HiV+3zeAC2024muaV7KjcimZ6t/hPFTCFH9pMGNk2Mtn/gZFfmqnjLKbj TDxUTrZF9Lujonrbwg== =ymCJ -----END PGP SIGNATURE----- Merge tag 'upstream-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/rw/ubifs Pull UBI/UBIFS updates from Richard Weinberger: - fscrypt framework usage updates - One huge fix for xattr unlink - Cleanup of fscrypt ifdefs - Fix for our new UBIFS auth feature * tag 'upstream-5.2-rc1' of ssh://gitolite.kernel.org/pub/scm/linux/kernel/git/rw/ubifs: ubi: wl: Fix uninitialized variable ubifs: Drop unnecessary setting of zbr->znode ubifs: Remove ifdefs around CONFIG_UBIFS_ATIME_SUPPORT ubifs: Remove #ifdef around CONFIG_FS_ENCRYPTION ubifs: Limit number of xattrs per inode ubifs: orphan: Handle xattrs like files ubifs: journal: Handle xattrs like files ubifs: find.c: replace swap function with built-in one ubifs: Do not skip hash checking in data nodes ubifs: work around high stack usage with clang ubifs: remove unused function __ubifs_shash_final ubifs: remove unnecessary #ifdef around fscrypt_ioctl_get_policy() ubifs: remove unnecessary calls to set up directory key
695 lines
22 KiB
C
695 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/slab.h>
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#define FS_CRYPTO_BLOCK_SIZE 16
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struct fscrypt_ctx;
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struct fscrypt_info;
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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 28
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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 *, void *, size_t);
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int (*set_context)(struct inode *, const void *, size_t, void *);
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bool (*dummy_context)(struct inode *);
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bool (*empty_dir)(struct inode *);
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unsigned int max_namelen;
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};
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struct fscrypt_ctx {
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union {
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struct {
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struct page *bounce_page; /* Ciphertext page */
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struct page *control_page; /* Original page */
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} w;
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struct {
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struct bio *bio;
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struct work_struct work;
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} r;
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struct list_head free_list; /* Free list */
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};
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u8 flags; /* Flags */
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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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static inline bool fscrypt_dummy_context_enabled(struct inode *inode)
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{
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return inode->i_sb->s_cop->dummy_context &&
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inode->i_sb->s_cop->dummy_context(inode);
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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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extern void fscrypt_enqueue_decrypt_work(struct work_struct *);
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extern struct fscrypt_ctx *fscrypt_get_ctx(gfp_t);
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extern void fscrypt_release_ctx(struct fscrypt_ctx *);
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extern struct page *fscrypt_encrypt_page(const struct inode *, struct page *,
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unsigned int, unsigned int,
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u64, gfp_t);
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extern int fscrypt_decrypt_page(const struct inode *, struct page *, unsigned int,
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unsigned int, u64);
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static inline struct page *fscrypt_control_page(struct page *page)
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{
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return ((struct fscrypt_ctx *)page_private(page))->w.control_page;
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}
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extern void fscrypt_restore_control_page(struct page *);
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/* policy.c */
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extern int fscrypt_ioctl_set_policy(struct file *, const void __user *);
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extern int fscrypt_ioctl_get_policy(struct file *, void __user *);
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extern int fscrypt_has_permitted_context(struct inode *, struct inode *);
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extern int fscrypt_inherit_context(struct inode *, struct inode *,
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void *, bool);
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/* keyinfo.c */
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extern int fscrypt_get_encryption_info(struct inode *);
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extern void fscrypt_put_encryption_info(struct inode *);
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extern void fscrypt_free_inode(struct inode *);
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/* fname.c */
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extern int fscrypt_setup_filename(struct inode *, const struct qstr *,
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int lookup, struct fscrypt_name *);
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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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extern int fscrypt_fname_alloc_buffer(const struct inode *, u32,
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struct fscrypt_str *);
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extern void fscrypt_fname_free_buffer(struct fscrypt_str *);
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extern int fscrypt_fname_disk_to_usr(struct inode *, u32, u32,
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const struct fscrypt_str *, struct fscrypt_str *);
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#define FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE 32
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/* Extracts the second-to-last ciphertext block; see explanation below */
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#define FSCRYPT_FNAME_DIGEST(name, len) \
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((name) + round_down((len) - FS_CRYPTO_BLOCK_SIZE - 1, \
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FS_CRYPTO_BLOCK_SIZE))
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#define FSCRYPT_FNAME_DIGEST_SIZE FS_CRYPTO_BLOCK_SIZE
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/**
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* fscrypt_digested_name - alternate identifier for an on-disk filename
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*
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* When userspace lists an encrypted directory without access to the key,
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* filenames whose ciphertext is longer than FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE
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* bytes are shown in this abbreviated form (base64-encoded) rather than as the
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* full ciphertext (base64-encoded). This is necessary to allow supporting
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* filenames up to NAME_MAX bytes, since base64 encoding expands the length.
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*
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* To make it possible for filesystems to still find the correct directory entry
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* despite not knowing the full on-disk name, we encode any filesystem-specific
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* 'hash' and/or 'minor_hash' which the filesystem may need for its lookups,
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* followed by the second-to-last ciphertext block of the filename. Due to the
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* use of the CBC-CTS encryption mode, the second-to-last ciphertext block
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* depends on the full plaintext. (Note that ciphertext stealing causes the
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* last two blocks to appear "flipped".) This makes accidental collisions very
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* unlikely: just a 1 in 2^128 chance for two filenames to collide even if they
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* share the same filesystem-specific hashes.
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*
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* However, this scheme isn't immune to intentional collisions, which can be
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* created by anyone able to create arbitrary plaintext filenames and view them
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* without the key. Making the "digest" be a real cryptographic hash like
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* SHA-256 over the full ciphertext would prevent this, although it would be
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* less efficient and harder to implement, especially since the filesystem would
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* need to calculate it for each directory entry examined during a search.
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*/
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struct fscrypt_digested_name {
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u32 hash;
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u32 minor_hash;
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u8 digest[FSCRYPT_FNAME_DIGEST_SIZE];
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};
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/**
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* fscrypt_match_name() - test whether the given name matches a directory entry
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* @fname: the name being searched for
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* @de_name: the name from the directory entry
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* @de_name_len: the length of @de_name in bytes
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*
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* Normally @fname->disk_name will be set, and in that case we simply compare
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* that to the name stored in the directory entry. The only exception is that
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* if we don't have the key for an encrypted directory and a filename in it is
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* very long, then we won't have the full disk_name and we'll instead need to
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* match against the fscrypt_digested_name.
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*
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* Return: %true if the name matches, otherwise %false.
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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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if (unlikely(!fname->disk_name.name)) {
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const struct fscrypt_digested_name *n =
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(const void *)fname->crypto_buf.name;
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if (WARN_ON_ONCE(fname->usr_fname->name[0] != '_'))
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return false;
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if (de_name_len <= FSCRYPT_FNAME_MAX_UNDIGESTED_SIZE)
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return false;
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return !memcmp(FSCRYPT_FNAME_DIGEST(de_name, de_name_len),
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n->digest, FSCRYPT_FNAME_DIGEST_SIZE);
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}
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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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/* bio.c */
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extern void fscrypt_decrypt_bio(struct bio *);
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extern void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
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struct bio *bio);
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extern void fscrypt_pullback_bio_page(struct page **, bool);
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extern int fscrypt_zeroout_range(const struct inode *, pgoff_t, sector_t,
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unsigned int);
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/* hooks.c */
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extern int fscrypt_file_open(struct inode *inode, struct file *filp);
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extern int __fscrypt_prepare_link(struct inode *inode, struct inode *dir,
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struct dentry *dentry);
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extern int __fscrypt_prepare_rename(struct inode *old_dir,
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struct dentry *old_dentry,
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struct inode *new_dir,
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struct dentry *new_dentry,
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unsigned int flags);
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extern int __fscrypt_prepare_lookup(struct inode *dir, struct dentry *dentry,
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struct fscrypt_name *fname);
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extern 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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extern int __fscrypt_encrypt_symlink(struct inode *inode, const char *target,
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unsigned int len,
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struct fscrypt_str *disk_link);
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extern 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_dummy_context_enabled(struct inode *inode)
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{
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return false;
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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 fscrypt_ctx *fscrypt_get_ctx(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 void fscrypt_release_ctx(struct fscrypt_ctx *ctx)
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{
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return;
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}
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static inline struct page *fscrypt_encrypt_page(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,
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u64 lblk_num, 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_decrypt_page(const struct inode *inode,
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struct page *page,
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unsigned int len, unsigned int offs,
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u64 lblk_num)
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{
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return -EOPNOTSUPP;
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}
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static inline struct page *fscrypt_control_page(struct page *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_restore_control_page(struct page *page)
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{
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return;
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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_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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/* keyinfo.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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/* 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(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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/* 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 void fscrypt_enqueue_decrypt_bio(struct fscrypt_ctx *ctx,
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struct bio *bio)
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{
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}
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static inline void fscrypt_pullback_bio_page(struct page **page, bool restore)
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{
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return;
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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,
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struct dentry *old_dentry,
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struct inode *new_dir,
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struct dentry *new_dentry,
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unsigned int flags)
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{
|
|
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_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_dummy_context_enabled(dir))
|
|
return __fscrypt_prepare_symlink(dir, len, max_len, disk_link);
|
|
|
|
disk_link->name = (unsigned char *)target;
|
|
disk_link->len = len + 1;
|
|
if (disk_link->len > max_len)
|
|
return -ENAMETOOLONG;
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* fscrypt_encrypt_symlink - encrypt the symlink target if needed
|
|
* @inode: symlink inode
|
|
* @target: plaintext symlink target
|
|
* @len: length of @target excluding null terminator
|
|
* @disk_link: (in/out) the on-disk symlink target being prepared
|
|
*
|
|
* If the symlink target needs to be encrypted, then this function encrypts it
|
|
* into @disk_link->name. fscrypt_prepare_symlink() must have been called
|
|
* previously to compute @disk_link->len. If the filesystem did not allocate a
|
|
* buffer for @disk_link->name after calling fscrypt_prepare_link(), then one
|
|
* will be kmalloc()'ed and the filesystem will be responsible for freeing it.
|
|
*
|
|
* Return: 0 on success, -errno on failure
|
|
*/
|
|
static inline int fscrypt_encrypt_symlink(struct inode *inode,
|
|
const char *target,
|
|
unsigned int len,
|
|
struct fscrypt_str *disk_link)
|
|
{
|
|
if (IS_ENCRYPTED(inode))
|
|
return __fscrypt_encrypt_symlink(inode, target, len, disk_link);
|
|
return 0;
|
|
}
|
|
|
|
#endif /* _LINUX_FSCRYPT_H */
|