Merge tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux

Pull fscrypt updates from Eric Biggers:
 "This update adds support for configuring the crypto data unit size
  (i.e. the granularity of file contents encryption) to be less than the
  filesystem block size. This can allow users to use inline encryption
  hardware in some cases when it wouldn't otherwise be possible.

  In addition, there are two commits that are prerequisites for the
  extent-based encryption support that the btrfs folks are working on"

* tag 'fscrypt-for-linus' of git://git.kernel.org/pub/scm/fs/fscrypt/linux:
  fscrypt: track master key presence separately from secret
  fscrypt: rename fscrypt_info => fscrypt_inode_info
  fscrypt: support crypto data unit size less than filesystem block size
  fscrypt: replace get_ino_and_lblk_bits with just has_32bit_inodes
  fscrypt: compute max_lblk_bits from s_maxbytes and block size
  fscrypt: make the bounce page pool opt-in instead of opt-out
  fscrypt: make it clearer that key_prefix is deprecated

Documentation/filesystems/fscrypt.rst

@@ -261,9 +261,9 @@ DIRECT_KEY policies
 
 The Adiantum encryption mode (see `Encryption modes and usage`_) is
 suitable for both contents and filenames encryption, and it accepts
-long IVs --- long enough to hold both an 8-byte logical block number
-and a 16-byte per-file nonce.  Also, the overhead of each Adiantum key
-is greater than that of an AES-256-XTS key.
+long IVs --- long enough to hold both an 8-byte data unit index and a
+16-byte per-file nonce.  Also, the overhead of each Adiantum key is
+greater than that of an AES-256-XTS key.
 
 Therefore, to improve performance and save memory, for Adiantum a
 "direct key" configuration is supported.  When the user has enabled
@@ -300,8 +300,8 @@ IV_INO_LBLK_32 policies
 
 IV_INO_LBLK_32 policies work like IV_INO_LBLK_64, except that for
 IV_INO_LBLK_32, the inode number is hashed with SipHash-2-4 (where the
-SipHash key is derived from the master key) and added to the file
-logical block number mod 2^32 to produce a 32-bit IV.
+SipHash key is derived from the master key) and added to the file data
+unit index mod 2^32 to produce a 32-bit IV.
 
 This format is optimized for use with inline encryption hardware
 compliant with the eMMC v5.2 standard, which supports only 32 IV bits
@@ -451,31 +451,62 @@ acceleration is recommended:
 Contents encryption
 -------------------
 
-For file contents, each filesystem block is encrypted independently.
-Starting from Linux kernel 5.5, encryption of filesystems with block
-size less than system's page size is supported.
-
-Each block's IV is set to the logical block number within the file as
-a little endian number, except that:
-
-- With CBC mode encryption, ESSIV is also used.  Specifically, each IV
-  is encrypted with AES-256 where the AES-256 key is the SHA-256 hash
-  of the file's data encryption key.
-
-- With `DIRECT_KEY policies`_, the file's nonce is appended to the IV.
-  Currently this is only allowed with the Adiantum encryption mode.
-
-- With `IV_INO_LBLK_64 policies`_, the logical block number is limited
-  to 32 bits and is placed in bits 0-31 of the IV.  The inode number
-  (which is also limited to 32 bits) is placed in bits 32-63.
-
-- With `IV_INO_LBLK_32 policies`_, the logical block number is limited
-  to 32 bits and is placed in bits 0-31 of the IV.  The inode number
-  is then hashed and added mod 2^32.
-
-Note that because file logical block numbers are included in the IVs,
-filesystems must enforce that blocks are never shifted around within
-encrypted files, e.g. via "collapse range" or "insert range".
+For contents encryption, each file's contents is divided into "data
+units".  Each data unit is encrypted independently.  The IV for each
+data unit incorporates the zero-based index of the data unit within
+the file.  This ensures that each data unit within a file is encrypted
+differently, which is essential to prevent leaking information.
+
+Note: the encryption depending on the offset into the file means that
+operations like "collapse range" and "insert range" that rearrange the
+extent mapping of files are not supported on encrypted files.
+
+There are two cases for the sizes of the data units:
+
+* Fixed-size data units.  This is how all filesystems other than UBIFS
+  work.  A file's data units are all the same size; the last data unit
+  is zero-padded if needed.  By default, the data unit size is equal
+  to the filesystem block size.  On some filesystems, users can select
+  a sub-block data unit size via the ``log2_data_unit_size`` field of
+  the encryption policy; see `FS_IOC_SET_ENCRYPTION_POLICY`_.
+
+* Variable-size data units.  This is what UBIFS does.  Each "UBIFS
+  data node" is treated as a crypto data unit.  Each contains variable
+  length, possibly compressed data, zero-padded to the next 16-byte
+  boundary.  Users cannot select a sub-block data unit size on UBIFS.
+
+In the case of compression + encryption, the compressed data is
+encrypted.  UBIFS compression works as described above.  f2fs
+compression works a bit differently; it compresses a number of
+filesystem blocks into a smaller number of filesystem blocks.
+Therefore a f2fs-compressed file still uses fixed-size data units, and
+it is encrypted in a similar way to a file containing holes.
+
+As mentioned in `Key hierarchy`_, the default encryption setting uses
+per-file keys.  In this case, the IV for each data unit is simply the
+index of the data unit in the file.  However, users can select an
+encryption setting that does not use per-file keys.  For these, some
+kind of file identifier is incorporated into the IVs as follows:
+
+- With `DIRECT_KEY policies`_, the data unit index is placed in bits
+  0-63 of the IV, and the file's nonce is placed in bits 64-191.
+
+- With `IV_INO_LBLK_64 policies`_, the data unit index is placed in
+  bits 0-31 of the IV, and the file's inode number is placed in bits
+  32-63.  This setting is only allowed when data unit indices and
+  inode numbers fit in 32 bits.
+
+- With `IV_INO_LBLK_32 policies`_, the file's inode number is hashed
+  and added to the data unit index.  The resulting value is truncated
+  to 32 bits and placed in bits 0-31 of the IV.  This setting is only
+  allowed when data unit indices and inode numbers fit in 32 bits.
+
+The byte order of the IV is always little endian.
+
+If the user selects FSCRYPT_MODE_AES_128_CBC for the contents mode, an
+ESSIV layer is automatically included.  In this case, before the IV is
+passed to AES-128-CBC, it is encrypted with AES-256 where the AES-256
+key is the SHA-256 hash of the file's contents encryption key.
 
 Filenames encryption
 --------------------
@@ -544,7 +575,8 @@ follows::
             __u8 contents_encryption_mode;
             __u8 filenames_encryption_mode;
             __u8 flags;
-            __u8 __reserved[4];
+            __u8 log2_data_unit_size;
+            __u8 __reserved[3];
             __u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
     };
 
@@ -586,6 +618,29 @@ This structure must be initialized as follows:
   The DIRECT_KEY, IV_INO_LBLK_64, and IV_INO_LBLK_32 flags are
   mutually exclusive.
 
+- ``log2_data_unit_size`` is the log2 of the data unit size in bytes,
+  or 0 to select the default data unit size.  The data unit size is
+  the granularity of file contents encryption.  For example, setting
+  ``log2_data_unit_size`` to 12 causes file contents be passed to the
+  underlying encryption algorithm (such as AES-256-XTS) in 4096-byte
+  data units, each with its own IV.
+
+  Not all filesystems support setting ``log2_data_unit_size``.  ext4
+  and f2fs support it since Linux v6.7.  On filesystems that support
+  it, the supported nonzero values are 9 through the log2 of the
+  filesystem block size, inclusively.  The default value of 0 selects
+  the filesystem block size.
+
+  The main use case for ``log2_data_unit_size`` is for selecting a
+  data unit size smaller than the filesystem block size for
+  compatibility with inline encryption hardware that only supports
+  smaller data unit sizes.  ``/sys/block/$disk/queue/crypto/`` may be
+  useful for checking which data unit sizes are supported by a
+  particular system's inline encryption hardware.
+
+  Leave this field zeroed unless you are certain you need it.  Using
+  an unnecessarily small data unit size reduces performance.
+
 - For v2 encryption policies, ``__reserved`` must be zeroed.
 
 - For v1 encryption policies, ``master_key_descriptor`` specifies how
@@ -1079,8 +1134,8 @@ The caller must zero all input fields, then fill in ``key_spec``:
 On success, 0 is returned and the kernel fills in the output fields:
 
 - ``status`` indicates whether the key is absent, present, or
-  incompletely removed.  Incompletely removed means that the master
-  secret has been removed, but some files are still in use; i.e.,
+  incompletely removed.  Incompletely removed means that removal has
+  been initiated, but some files are still in use; i.e.,
   `FS_IOC_REMOVE_ENCRYPTION_KEY`_ returned 0 but set the informational
   status flag FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY.
 

fs/ceph/crypto.c

@@ -133,6 +133,7 @@ static const union fscrypt_policy *ceph_get_dummy_policy(struct super_block *sb)
 }
 
 static struct fscrypt_operations ceph_fscrypt_ops = {
+	.needs_bounce_pages	= 1,
 	.get_context		= ceph_crypt_get_context,
 	.set_context		= ceph_crypt_set_context,
 	.get_dummy_policy	= ceph_get_dummy_policy,

fs/crypto/bio.c

@@ -111,10 +111,14 @@ static int fscrypt_zeroout_range_inline_crypt(const struct inode *inode,
 int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 			  sector_t pblk, unsigned int len)
 {
-	const unsigned int blockbits = inode->i_blkbits;
-	const unsigned int blocksize = 1 << blockbits;
-	const unsigned int blocks_per_page_bits = PAGE_SHIFT - blockbits;
-	const unsigned int blocks_per_page = 1 << blocks_per_page_bits;
+	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
+	const unsigned int du_bits = ci->ci_data_unit_bits;
+	const unsigned int du_size = 1U << du_bits;
+	const unsigned int du_per_page_bits = PAGE_SHIFT - du_bits;
+	const unsigned int du_per_page = 1U << du_per_page_bits;
+	u64 du_index = (u64)lblk << (inode->i_blkbits - du_bits);
+	u64 du_remaining = (u64)len << (inode->i_blkbits - du_bits);
+	sector_t sector = pblk << (inode->i_blkbits - SECTOR_SHIFT);
 	struct page *pages[16]; /* write up to 16 pages at a time */
 	unsigned int nr_pages;
 	unsigned int i;
@@ -130,8 +134,8 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 							  len);
 
 	BUILD_BUG_ON(ARRAY_SIZE(pages) > BIO_MAX_VECS);
-	nr_pages = min_t(unsigned int, ARRAY_SIZE(pages),
-			 (len + blocks_per_page - 1) >> blocks_per_page_bits);
+	nr_pages = min_t(u64, ARRAY_SIZE(pages),
+			 (du_remaining + du_per_page - 1) >> du_per_page_bits);
 
 	/*
 	 * We need at least one page for ciphertext.  Allocate the first one
@@ -154,21 +158,22 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 	bio = bio_alloc(inode->i_sb->s_bdev, nr_pages, REQ_OP_WRITE, GFP_NOFS);
 
 	do {
-		bio->bi_iter.bi_sector = pblk << (blockbits - 9);
+		bio->bi_iter.bi_sector = sector;
 
 		i = 0;
 		offset = 0;
 		do {
-			err = fscrypt_crypt_block(inode, FS_ENCRYPT, lblk,
-						  ZERO_PAGE(0), pages[i],
-						  blocksize, offset, GFP_NOFS);
+			err = fscrypt_crypt_data_unit(ci, FS_ENCRYPT, du_index,
+						      ZERO_PAGE(0), pages[i],
+						      du_size, offset,
+						      GFP_NOFS);
 			if (err)
 				goto out;
-			lblk++;
-			pblk++;
-			len--;
-			offset += blocksize;
-			if (offset == PAGE_SIZE || len == 0) {
+			du_index++;
+			sector += 1U << (du_bits - SECTOR_SHIFT);
+			du_remaining--;
+			offset += du_size;
+			if (offset == PAGE_SIZE || du_remaining == 0) {
 				ret = bio_add_page(bio, pages[i++], offset, 0);
 				if (WARN_ON_ONCE(ret != offset)) {
 					err = -EIO;
@@ -176,13 +181,13 @@ int fscrypt_zeroout_range(const struct inode *inode, pgoff_t lblk,
 				}
 				offset = 0;
 			}
-		} while (i != nr_pages && len != 0);
+		} while (i != nr_pages && du_remaining != 0);
 
 		err = submit_bio_wait(bio);
 		if (err)
 			goto out;
 		bio_reset(bio, inode->i_sb->s_bdev, REQ_OP_WRITE);
-	} while (len != 0);
+	} while (du_remaining != 0);
 	err = 0;
 out:
 	bio_put(bio);

fs/crypto/fname.c

@@ -100,7 +100,7 @@ int fscrypt_fname_encrypt(const struct inode *inode, const struct qstr *iname,
 {
 	struct skcipher_request *req = NULL;
 	DECLARE_CRYPTO_WAIT(wait);
-	const struct fscrypt_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
 	struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
 	union fscrypt_iv iv;
 	struct scatterlist sg;
@@ -157,7 +157,7 @@ static int fname_decrypt(const struct inode *inode,
 	struct skcipher_request *req = NULL;
 	DECLARE_CRYPTO_WAIT(wait);
 	struct scatterlist src_sg, dst_sg;
-	const struct fscrypt_info *ci = inode->i_crypt_info;
+	const struct fscrypt_inode_info *ci = inode->i_crypt_info;
 	struct crypto_skcipher *tfm = ci->ci_enc_key.tfm;
 	union fscrypt_iv iv;
 	int res;
@@ -568,7 +568,7 @@ EXPORT_SYMBOL_GPL(fscrypt_match_name);
  */
 u64 fscrypt_fname_siphash(const struct inode *dir, const struct qstr *name)
 {
-	const struct fscrypt_info *ci = dir->i_crypt_info;
+	const struct fscrypt_inode_info *ci = dir->i_crypt_info;
 
 	WARN_ON_ONCE(!ci->ci_dirhash_key_initialized);
 

fs/crypto/hooks.c

@@ -169,7 +169,7 @@ EXPORT_SYMBOL_GPL(__fscrypt_prepare_setattr);
 int fscrypt_prepare_setflags(struct inode *inode,
 			     unsigned int oldflags, unsigned int flags)
 {
-	struct fscrypt_info *ci;
+	struct fscrypt_inode_info *ci;
 	struct fscrypt_master_key *mk;
 	int err;
 
@@ -187,7 +187,7 @@ int fscrypt_prepare_setflags(struct inode *inode,
 			return -EINVAL;
 		mk = ci->ci_master_key;
 		down_read(&mk->mk_sem);
-		if (is_master_key_secret_present(&mk->mk_secret))
+		if (mk->mk_present)
 			err = fscrypt_derive_dirhash_key(ci, mk);
 		else
 			err = -ENOKEY;

fs/crypto/inline_crypt.c

@@ -39,11 +39,11 @@ static struct block_device **fscrypt_get_devices(struct super_block *sb,
 	return devs;
 }
 
-static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci)
+static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_inode_info *ci)
 {
-	struct super_block *sb = ci->ci_inode->i_sb;
+	const struct super_block *sb = ci->ci_inode->i_sb;
 	unsigned int flags = fscrypt_policy_flags(&ci->ci_policy);
-	int ino_bits = 64, lblk_bits = 64;
+	int dun_bits;
 
 	if (flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
 		return offsetofend(union fscrypt_iv, nonce);
@@ -54,10 +54,9 @@ static unsigned int fscrypt_get_dun_bytes(const struct fscrypt_info *ci)
 	if (flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)
 		return sizeof(__le32);
 
-	/* Default case: IVs are just the file logical block number */
-	if (sb->s_cop->get_ino_and_lblk_bits)
-		sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits);
-	return DIV_ROUND_UP(lblk_bits, 8);
+	/* Default case: IVs are just the file data unit index */
+	dun_bits = fscrypt_max_file_dun_bits(sb, ci->ci_data_unit_bits);
+	return DIV_ROUND_UP(dun_bits, 8);
 }
 
 /*
@@ -90,7 +89,7 @@ static void fscrypt_log_blk_crypto_impl(struct fscrypt_mode *mode,
 }
 
 /* Enable inline encryption for this file if supported. */
-int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
+int fscrypt_select_encryption_impl(struct fscrypt_inode_info *ci)
 {
 	const struct inode *inode = ci->ci_inode;
 	struct super_block *sb = inode->i_sb;
@@ -129,7 +128,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
 	 * crypto configuration that the file would use.
 	 */
 	crypto_cfg.crypto_mode = ci->ci_mode->blk_crypto_mode;
-	crypto_cfg.data_unit_size = sb->s_blocksize;
+	crypto_cfg.data_unit_size = 1U << ci->ci_data_unit_bits;
 	crypto_cfg.dun_bytes = fscrypt_get_dun_bytes(ci);
 
 	devs = fscrypt_get_devices(sb, &num_devs);
@@ -152,7 +151,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci)
 
 int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
 				     const u8 *raw_key,
-				     const struct fscrypt_info *ci)
+				     const struct fscrypt_inode_info *ci)
 {
 	const struct inode *inode = ci->ci_inode;
 	struct super_block *sb = inode->i_sb;
@@ -168,7 +167,8 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key,
 		return -ENOMEM;
 
 	err = blk_crypto_init_key(blk_key, raw_key, crypto_mode,
-				  fscrypt_get_dun_bytes(ci), sb->s_blocksize);
+				  fscrypt_get_dun_bytes(ci),
+				  1U << ci->ci_data_unit_bits);
 	if (err) {
 		fscrypt_err(inode, "error %d initializing blk-crypto key", err);
 		goto fail;
@@ -232,13 +232,15 @@ bool __fscrypt_inode_uses_inline_crypto(const struct inode *inode)
 }
 EXPORT_SYMBOL_GPL(__fscrypt_inode_uses_inline_crypto);
 
-static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num,
+static void fscrypt_generate_dun(const struct fscrypt_inode_info *ci,
+				 u64 lblk_num,
 				 u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE])
 {
+	u64 index = lblk_num << ci->ci_data_units_per_block_bits;
 	union fscrypt_iv iv;
 	int i;
 
-	fscrypt_generate_iv(&iv, lblk_num, ci);
+	fscrypt_generate_iv(&iv, index, ci);
 
 	BUILD_BUG_ON(FSCRYPT_MAX_IV_SIZE > BLK_CRYPTO_MAX_IV_SIZE);
 	memset(dun, 0, BLK_CRYPTO_MAX_IV_SIZE);
@@ -265,7 +267,7 @@ static void fscrypt_generate_dun(const struct fscrypt_info *ci, u64 lblk_num,
 void fscrypt_set_bio_crypt_ctx(struct bio *bio, const struct inode *inode,
 			       u64 first_lblk, gfp_t gfp_mask)
 {
-	const struct fscrypt_info *ci;
+	const struct fscrypt_inode_info *ci;
 	u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE];
 
 	if (!fscrypt_inode_uses_inline_crypto(inode))
@@ -456,7 +458,7 @@ EXPORT_SYMBOL_GPL(fscrypt_dio_supported);
  */
 u64 fscrypt_limit_io_blocks(const struct inode *inode, u64 lblk, u64 nr_blocks)
 {
-	const struct fscrypt_info *ci;
+	const struct fscrypt_inode_info *ci;
 	u32 dun;
 
 	if (!fscrypt_inode_uses_inline_crypto(inode))

fs/crypto/keyring.c

@@ -99,10 +99,10 @@ void fscrypt_put_master_key_activeref(struct super_block *sb,
 	spin_unlock(&sb->s_master_keys->lock);
 
 	/*
-	 * ->mk_active_refs == 0 implies that ->mk_secret is not present and
-	 * that ->mk_decrypted_inodes is empty.
+	 * ->mk_active_refs == 0 implies that ->mk_present is false and
+	 * ->mk_decrypted_inodes is empty.
 	 */
-	WARN_ON_ONCE(is_master_key_secret_present(&mk->mk_secret));
+	WARN_ON_ONCE(mk->mk_present);
 	WARN_ON_ONCE(!list_empty(&mk->mk_decrypted_inodes));
 
 	for (i = 0; i <= FSCRYPT_MODE_MAX; i++) {
@@ -121,6 +121,18 @@ void fscrypt_put_master_key_activeref(struct super_block *sb,
 	fscrypt_put_master_key(mk);
 }
 
+/*
+ * This transitions the key state from present to incompletely removed, and then
+ * potentially to absent (depending on whether inodes remain).
+ */
+static void fscrypt_initiate_key_removal(struct super_block *sb,
+					 struct fscrypt_master_key *mk)
+{
+	WRITE_ONCE(mk->mk_present, false);
+	wipe_master_key_secret(&mk->mk_secret);
+	fscrypt_put_master_key_activeref(sb, mk);
+}
+
 static inline bool valid_key_spec(const struct fscrypt_key_specifier *spec)
 {
 	if (spec->__reserved)
@@ -234,14 +246,13 @@ void fscrypt_destroy_keyring(struct super_block *sb)
 			 * evicted, every key remaining in the keyring should
 			 * have an empty inode list, and should only still be in
 			 * the keyring due to the single active ref associated
-			 * with ->mk_secret.  There should be no structural refs
-			 * beyond the one associated with the active ref.
+			 * with ->mk_present.  There should be no structural
+			 * refs beyond the one associated with the active ref.
 			 */
 			WARN_ON_ONCE(refcount_read(&mk->mk_active_refs) != 1);
 			WARN_ON_ONCE(refcount_read(&mk->mk_struct_refs) != 1);
-			WARN_ON_ONCE(!is_master_key_secret_present(&mk->mk_secret));
-			wipe_master_key_secret(&mk->mk_secret);
-			fscrypt_put_master_key_activeref(sb, mk);
+			WARN_ON_ONCE(!mk->mk_present);
+			fscrypt_initiate_key_removal(sb, mk);
 		}
 	}
 	kfree_sensitive(keyring);
@@ -439,7 +450,8 @@ static int add_new_master_key(struct super_block *sb,
 	}
 
 	move_master_key_secret(&mk->mk_secret, secret);
-	refcount_set(&mk->mk_active_refs, 1); /* ->mk_secret is present */
+	mk->mk_present = true;
+	refcount_set(&mk->mk_active_refs, 1); /* ->mk_present is true */
 
 	spin_lock(&keyring->lock);
 	hlist_add_head_rcu(&mk->mk_node,
@@ -478,11 +490,18 @@ static int add_existing_master_key(struct fscrypt_master_key *mk,
 			return err;
 	}
 
-	/* Re-add the secret if needed. */
-	if (!is_master_key_secret_present(&mk->mk_secret)) {
-		if (!refcount_inc_not_zero(&mk->mk_active_refs))
+	/* If the key is incompletely removed, make it present again. */
+	if (!mk->mk_present) {
+		if (!refcount_inc_not_zero(&mk->mk_active_refs)) {
+			/*
+			 * Raced with the last active ref being dropped, so the
+			 * key has become, or is about to become, "absent".
+			 * Therefore, we need to allocate a new key struct.
+			 */
 			return KEY_DEAD;
+		}
 		move_master_key_secret(&mk->mk_secret, secret);
+		WRITE_ONCE(mk->mk_present, true);
 	}
 
 	return 0;
@@ -506,8 +525,8 @@ static int do_add_master_key(struct super_block *sb,
 			err = add_new_master_key(sb, secret, mk_spec);
 	} else {
 		/*
-		 * Found the key in ->s_master_keys.  Re-add the secret if
-		 * needed, and add the user to ->mk_users if needed.
+		 * Found the key in ->s_master_keys.  Add the user to ->mk_users
+		 * if needed, and make the key "present" again if possible.
 		 */
 		down_write(&mk->mk_sem);
 		err = add_existing_master_key(mk, secret);
@@ -867,7 +886,7 @@ static void shrink_dcache_inode(struct inode *inode)
 
 static void evict_dentries_for_decrypted_inodes(struct fscrypt_master_key *mk)
 {
-	struct fscrypt_info *ci;
+	struct fscrypt_inode_info *ci;
 	struct inode *inode;
 	struct inode *toput_inode = NULL;
 
@@ -917,7 +936,7 @@ static int check_for_busy_inodes(struct super_block *sb,
 		/* select an example file to show for debugging purposes */
 		struct inode *inode =
 			list_first_entry(&mk->mk_decrypted_inodes,
-					 struct fscrypt_info,
+					 struct fscrypt_inode_info,
 					 ci_master_key_link)->ci_inode;
 		ino = inode->i_ino;
 	}
@@ -989,9 +1008,8 @@ static int try_to_lock_encrypted_files(struct super_block *sb,
  *
  * If all inodes were evicted, then we unlink the fscrypt_master_key from the
  * keyring.  Otherwise it remains in the keyring in the "incompletely removed"
- * state (without the actual secret key) where it tracks the list of remaining
- * inodes.  Userspace can execute the ioctl again later to retry eviction, or
- * alternatively can re-add the secret key again.
+ * state where it tracks the list of remaining inodes.  Userspace can execute
+ * the ioctl again later to retry eviction, or alternatively can re-add the key.
  *
  * For more details, see the "Removing keys" section of
  * Documentation/filesystems/fscrypt.rst.
@@ -1053,11 +1071,10 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users)
 		}
 	}
 
-	/* No user claims remaining.  Go ahead and wipe the secret. */
+	/* No user claims remaining.  Initiate removal of the key. */
 	err = -ENOKEY;
-	if (is_master_key_secret_present(&mk->mk_secret)) {
-		wipe_master_key_secret(&mk->mk_secret);
-		fscrypt_put_master_key_activeref(sb, mk);
+	if (mk->mk_present) {
+		fscrypt_initiate_key_removal(sb, mk);
 		err = 0;
 	}
 	inodes_remain = refcount_read(&mk->mk_active_refs) > 0;
@@ -1074,9 +1091,9 @@ static int do_remove_key(struct file *filp, void __user *_uarg, bool all_users)
 	}
 	/*
 	 * We return 0 if we successfully did something: removed a claim to the
-	 * key, wiped the secret, or tried locking the files again.  Users need
-	 * to check the informational status flags if they care whether the key
-	 * has been fully removed including all files locked.
+	 * key, initiated removal of the key, or tried locking the files again.
+	 * Users need to check the informational status flags if they care
+	 * whether the key has been fully removed including all files locked.
 	 */
 out_put_key:
 	fscrypt_put_master_key(mk);
@@ -1103,12 +1120,11 @@ EXPORT_SYMBOL_GPL(fscrypt_ioctl_remove_key_all_users);
  * Retrieve the status of an fscrypt master encryption key.
  *
  * We set ->status to indicate whether the key is absent, present, or
- * incompletely removed.  "Incompletely removed" means that the master key
- * secret has been removed, but some files which had been unlocked with it are
- * still in use.  This field allows applications to easily determine the state
- * of an encrypted directory without using a hack such as trying to open a
- * regular file in it (which can confuse the "incompletely removed" state with
- * absent or present).
+ * incompletely removed.  (For an explanation of what these statuses mean and
+ * how they are represented internally, see struct fscrypt_master_key.)  This
+ * field allows applications to easily determine the status of an encrypted
+ * directory without using a hack such as trying to open a regular file in it
+ * (which can confuse the "incompletely removed" status with absent or present).
  *
  * In addition, for v2 policy keys we allow applications to determine, via
  * ->status_flags and ->user_count, whether the key has been added by the
@@ -1150,7 +1166,7 @@ int fscrypt_ioctl_get_key_status(struct file *filp, void __user *uarg)
 	}
 	down_read(&mk->mk_sem);
 
-	if (!is_master_key_secret_present(&mk->mk_secret)) {
+	if (!mk->mk_present) {
 		arg.status = refcount_read(&mk->mk_active_refs) > 0 ?
 			FSCRYPT_KEY_STATUS_INCOMPLETELY_REMOVED :
 			FSCRYPT_KEY_STATUS_ABSENT /* raced with full removal */;

fs/crypto/keysetup.c

@@ -148,7 +148,7 @@ fscrypt_allocate_skcipher(struct fscrypt_mode *mode, const u8 *raw_key,
  * and IV generation method (@ci->ci_policy.flags).
  */
 int fscrypt_prepare_key(struct fscrypt_prepared_key *prep_key,
-			const u8 *raw_key, const struct fscrypt_info *ci)
+			const u8 *raw_key, const struct fscrypt_inode_info *ci)
 {
 	struct crypto_skcipher *tfm;
 
@@ -178,13 +178,14 @@ void fscrypt_destroy_prepared_key(struct super_block *sb,
 }
 
 /* Given a per-file encryption key, set up the file's crypto transform object */
-int fscrypt_set_per_file_enc_key(struct fscrypt_info *ci, const u8 *raw_key)
+int fscrypt_set_per_file_enc_key(struct fscrypt_inode_info *ci,
+				 const u8 *raw_key)
 {
 	ci->ci_owns_key = true;
 	return fscrypt_prepare_key(&ci->ci_enc_key, raw_key, ci);
 }
 
-static int setup_per_mode_enc_key(struct fscrypt_info *ci,
+static int setup_per_mode_enc_key(struct fscrypt_inode_info *ci,
 				  struct fscrypt_master_key *mk,
 				  struct fscrypt_prepared_key *keys,
 				  u8 hkdf_context, bool include_fs_uuid)
@@ -265,7 +266,7 @@ static int fscrypt_derive_siphash_key(const struct fscrypt_master_key *mk,
 	return 0;
 }
 
-int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
+int fscrypt_derive_dirhash_key(struct fscrypt_inode_info *ci,
 			       const struct fscrypt_master_key *mk)
 {
 	int err;
@@ -279,7 +280,7 @@ int fscrypt_derive_dirhash_key(struct fscrypt_info *ci,
 	return 0;
 }
 
-void fscrypt_hash_inode_number(struct fscrypt_info *ci,
+void fscrypt_hash_inode_number(struct fscrypt_inode_info *ci,
 			       const struct fscrypt_master_key *mk)
 {
 	WARN_ON_ONCE(ci->ci_inode->i_ino == 0);
@@ -289,7 +290,7 @@ void fscrypt_hash_inode_number(struct fscrypt_info *ci,
 					      &mk->mk_ino_hash_key);
 }
 
-static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci,
+static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_inode_info *ci,
 					    struct fscrypt_master_key *mk)
 {
 	int err;
@@ -329,7 +330,7 @@ static int fscrypt_setup_iv_ino_lblk_32_key(struct fscrypt_info *ci,
 	return 0;
 }
 
-static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
+static int fscrypt_setup_v2_file_key(struct fscrypt_inode_info *ci,
 				     struct fscrypt_master_key *mk,
 				     bool need_dirhash_key)
 {
@@ -404,7 +405,7 @@ static int fscrypt_setup_v2_file_key(struct fscrypt_info *ci,
  * still allow 512-bit master keys if the user chooses to use them, though.)
  */
 static bool fscrypt_valid_master_key_size(const struct fscrypt_master_key *mk,
-					  const struct fscrypt_info *ci)
+					  const struct fscrypt_inode_info *ci)
 {
 	unsigned int min_keysize;
 
@@ -430,11 +431,12 @@ static bool fscrypt_valid_master_key_size(const struct fscrypt_master_key *mk,
  *
  * If the master key is found in the filesystem-level keyring, then it is
  * returned in *mk_ret with its semaphore read-locked.  This is needed to ensure
- * that only one task links the fscrypt_info into ->mk_decrypted_inodes (as
- * multiple tasks may race to create an fscrypt_info for the same inode), and to
- * synchronize the master key being removed with a new inode starting to use it.
+ * that only one task links the fscrypt_inode_info into ->mk_decrypted_inodes
+ * (as multiple tasks may race to create an fscrypt_inode_info for the same
+ * inode), and to synchronize the master key being removed with a new inode
+ * starting to use it.
  */
-static int setup_file_encryption_key(struct fscrypt_info *ci,
+static int setup_file_encryption_key(struct fscrypt_inode_info *ci,
 				     bool need_dirhash_key,
 				     struct fscrypt_master_key **mk_ret)
 {
@@ -484,8 +486,8 @@ static int setup_file_encryption_key(struct fscrypt_info *ci,
 	}
 	down_read(&mk->mk_sem);
 
-	/* Has the secret been removed (via FS_IOC_REMOVE_ENCRYPTION_KEY)? */
-	if (!is_master_key_secret_present(&mk->mk_secret)) {
+	if (!mk->mk_present) {
+		/* FS_IOC_REMOVE_ENCRYPTION_KEY has been executed on this key */
 		err = -ENOKEY;
 		goto out_release_key;
 	}
@@ -519,7 +521,7 @@ static int setup_file_encryption_key(struct fscrypt_info *ci,
 	return err;
 }
 
-static void put_crypt_info(struct fscrypt_info *ci)
+static void put_crypt_info(struct fscrypt_inode_info *ci)
 {
 	struct fscrypt_master_key *mk;
 
@@ -537,8 +539,8 @@ static void put_crypt_info(struct fscrypt_info *ci)
 		/*
 		 * Remove this inode from the list of inodes that were unlocked
 		 * with the master key.  In addition, if we're removing the last
-		 * inode from a master key struct that already had its secret
-		 * removed, then complete the full removal of the struct.
+		 * inode from an incompletely removed key, then complete the
+		 * full removal of the key.
 		 */
 		spin_lock(&mk->mk_decrypted_inodes_lock);
 		list_del(&ci->ci_master_key_link);
@@ -546,7 +548,7 @@ static void put_crypt_info(struct fscrypt_info *ci)
 		fscrypt_put_master_key_activeref(ci->ci_inode->i_sb, mk);
 	}
 	memzero_explicit(ci, sizeof(*ci));
-	kmem_cache_free(fscrypt_info_cachep, ci);
+	kmem_cache_free(fscrypt_inode_info_cachep, ci);
 }
 
 static int
@@ -555,7 +557,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
 			      const u8 nonce[FSCRYPT_FILE_NONCE_SIZE],
 			      bool need_dirhash_key)
 {
-	struct fscrypt_info *crypt_info;
+	struct fscrypt_inode_info *crypt_info;
 	struct fscrypt_mode *mode;
 	struct fscrypt_master_key *mk = NULL;
 	int res;
@@ -564,7 +566,7 @@ fscrypt_setup_encryption_info(struct inode *inode,
 	if (res)
 		return res;
 
-	crypt_info = kmem_cache_zalloc(fscrypt_info_cachep, GFP_KERNEL);
+	crypt_info = kmem_cache_zalloc(fscrypt_inode_info_cachep, GFP_KERNEL);
 	if (!crypt_info)
 		return -ENOMEM;
 
@@ -580,6 +582,11 @@ fscrypt_setup_encryption_info(struct inode *inode,
 	WARN_ON_ONCE(mode->ivsize > FSCRYPT_MAX_IV_SIZE);
 	crypt_info->ci_mode = mode;
 
+	crypt_info->ci_data_unit_bits =
+		fscrypt_policy_du_bits(&crypt_info->ci_policy, inode);
+	crypt_info->ci_data_units_per_block_bits =
+		inode->i_blkbits - crypt_info->ci_data_unit_bits;
+
 	res = setup_file_encryption_key(crypt_info, need_dirhash_key, &mk);
 	if (res)
 		goto out;
@@ -587,8 +594,8 @@ fscrypt_setup_encryption_info(struct inode *inode,
 	/*
 	 * For existing inodes, multiple tasks may race to set ->i_crypt_info.
 	 * So use cmpxchg_release().  This pairs with the smp_load_acquire() in
-	 * fscrypt_get_info().  I.e., here we publish ->i_crypt_info with a
-	 * RELEASE barrier so that other tasks can ACQUIRE it.
+	 * fscrypt_get_inode_info().  I.e., here we publish ->i_crypt_info with
+	 * a RELEASE barrier so that other tasks can ACQUIRE it.
 	 */
 	if (cmpxchg_release(&inode->i_crypt_info, NULL, crypt_info) == NULL) {
 		/*
@@ -735,8 +742,8 @@ EXPORT_SYMBOL_GPL(fscrypt_prepare_new_inode);
  * fscrypt_put_encryption_info() - free most of an inode's fscrypt data
  * @inode: an inode being evicted
  *
- * Free the inode's fscrypt_info.  Filesystems must call this when the inode is
- * being evicted.  An RCU grace period need not have elapsed yet.
+ * Free the inode's fscrypt_inode_info.  Filesystems must call this when the
+ * inode is being evicted.  An RCU grace period need not have elapsed yet.
  */
 void fscrypt_put_encryption_info(struct inode *inode)
 {
@@ -773,7 +780,7 @@ EXPORT_SYMBOL(fscrypt_free_inode);
  */
 int fscrypt_drop_inode(struct inode *inode)
 {
-	const struct fscrypt_info *ci = fscrypt_get_info(inode);
+	const struct fscrypt_inode_info *ci = fscrypt_get_inode_info(inode);
 
 	/*
 	 * If ci is NULL, then the inode doesn't have an encryption key set up
@@ -794,13 +801,14 @@ int fscrypt_drop_inode(struct inode *inode)
 		return 0;
 
 	/*
-	 * Note: since we aren't holding the key semaphore, the result here can
+	 * We can't take ->mk_sem here, since this runs in atomic context.
+	 * Therefore, ->mk_present can change concurrently, and our result may
 	 * immediately become outdated.  But there's no correctness problem with
 	 * unnecessarily evicting.  Nor is there a correctness problem with not
 	 * evicting while iput() is racing with the key being removed, since
 	 * then the thread removing the key will either evict the inode itself
 	 * or will correctly detect that it wasn't evicted due to the race.
 	 */
-	return !is_master_key_secret_present(&ci->ci_master_key->mk_secret);
+	return !READ_ONCE(ci->ci_master_key->mk_present);
 }
 EXPORT_SYMBOL_GPL(fscrypt_drop_inode);

fs/crypto/keysetup_v1.c

@@ -178,7 +178,8 @@ void fscrypt_put_direct_key(struct fscrypt_direct_key *dk)
  */
 static struct fscrypt_direct_key *
 find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
-			  const u8 *raw_key, const struct fscrypt_info *ci)
+			  const u8 *raw_key,
+			  const struct fscrypt_inode_info *ci)
 {
 	unsigned long hash_key;
 	struct fscrypt_direct_key *dk;
@@ -218,7 +219,7 @@ find_or_insert_direct_key(struct fscrypt_direct_key *to_insert,
 
 /* Prepare to encrypt directly using the master key in the given mode */
 static struct fscrypt_direct_key *
-fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
+fscrypt_get_direct_key(const struct fscrypt_inode_info *ci, const u8 *raw_key)
 {
 	struct fscrypt_direct_key *dk;
 	int err;
@@ -250,7 +251,7 @@ fscrypt_get_direct_key(const struct fscrypt_info *ci, const u8 *raw_key)
 }
 
 /* v1 policy, DIRECT_KEY: use the master key directly */
-static int setup_v1_file_key_direct(struct fscrypt_info *ci,
+static int setup_v1_file_key_direct(struct fscrypt_inode_info *ci,
 				    const u8 *raw_master_key)
 {
 	struct fscrypt_direct_key *dk;
@@ -264,7 +265,7 @@ static int setup_v1_file_key_direct(struct fscrypt_info *ci,
 }
 
 /* v1 policy, !DIRECT_KEY: derive the file's encryption key */
-static int setup_v1_file_key_derived(struct fscrypt_info *ci,
+static int setup_v1_file_key_derived(struct fscrypt_inode_info *ci,
 				     const u8 *raw_master_key)
 {
 	u8 *derived_key;
@@ -289,7 +290,8 @@ static int setup_v1_file_key_derived(struct fscrypt_info *ci,
 	return err;
 }
 
-int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, const u8 *raw_master_key)
+int fscrypt_setup_v1_file_key(struct fscrypt_inode_info *ci,
+			      const u8 *raw_master_key)
 {
 	if (ci->ci_policy.v1.flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY)
 		return setup_v1_file_key_direct(ci, raw_master_key);
@@ -297,8 +299,10 @@ int fscrypt_setup_v1_file_key(struct fscrypt_info *ci, const u8 *raw_master_key)
 		return setup_v1_file_key_derived(ci, raw_master_key);
 }
 
-int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci)
+int
+fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_inode_info *ci)
 {
+	const struct super_block *sb = ci->ci_inode->i_sb;
 	struct key *key;
 	const struct fscrypt_key *payload;
 	int err;
@@ -306,8 +310,8 @@ int fscrypt_setup_v1_file_key_via_subscribed_keyrings(struct fscrypt_info *ci)
 	key = find_and_lock_process_key(FSCRYPT_KEY_DESC_PREFIX,
 					ci->ci_policy.v1.master_key_descriptor,
 					ci->ci_mode->keysize, &payload);
-	if (key == ERR_PTR(-ENOKEY) && ci->ci_inode->i_sb->s_cop->key_prefix) {
-		key = find_and_lock_process_key(ci->ci_inode->i_sb->s_cop->key_prefix,
+	if (key == ERR_PTR(-ENOKEY) && sb->s_cop->legacy_key_prefix) {
+		key = find_and_lock_process_key(sb->s_cop->legacy_key_prefix,
 						ci->ci_policy.v1.master_key_descriptor,
 						ci->ci_mode->keysize, &payload);
 	}

fs/crypto/policy.c

@@ -118,12 +118,11 @@ static bool supported_direct_key_modes(const struct inode *inode,
 }
 
 static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
-					 const struct inode *inode,
-					 const char *type,
-					 int max_ino_bits, int max_lblk_bits)
+					 const struct inode *inode)
 {
+	const char *type = (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64)
+				? "IV_INO_LBLK_64" : "IV_INO_LBLK_32";
 	struct super_block *sb = inode->i_sb;
-	int ino_bits = 64, lblk_bits = 64;
 
 	/*
 	 * IV_INO_LBLK_* exist only because of hardware limitations, and
@@ -150,17 +149,29 @@ static bool supported_iv_ino_lblk_policy(const struct fscrypt_policy_v2 *policy,
 			     type, sb->s_id);
 		return false;
 	}
-	if (sb->s_cop->get_ino_and_lblk_bits)
-		sb->s_cop->get_ino_and_lblk_bits(sb, &ino_bits, &lblk_bits);
-	if (ino_bits > max_ino_bits) {
+
+	/*
+	 * IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that inode numbers fit
+	 * in 32 bits.  In principle, IV_INO_LBLK_32 could support longer inode
+	 * numbers because it hashes the inode number; however, currently the
+	 * inode number is gotten from inode::i_ino which is 'unsigned long'.
+	 * So for now the implementation limit is 32 bits.
+	 */
+	if (!sb->s_cop->has_32bit_inodes) {
 		fscrypt_warn(inode,
 			     "Can't use %s policy on filesystem '%s' because its inode numbers are too long",
 			     type, sb->s_id);
 		return false;
 	}
-	if (lblk_bits > max_lblk_bits) {
+
+	/*
+	 * IV_INO_LBLK_64 and IV_INO_LBLK_32 both require that file data unit
+	 * indices fit in 32 bits.
+	 */
+	if (fscrypt_max_file_dun_bits(sb,
+			fscrypt_policy_v2_du_bits(policy, inode)) > 32) {
 		fscrypt_warn(inode,
-			     "Can't use %s policy on filesystem '%s' because its block numbers are too long",
+			     "Can't use %s policy on filesystem '%s' because its maximum file size is too large",
 			     type, sb->s_id);
 		return false;
 	}
@@ -233,25 +244,39 @@ static bool fscrypt_supported_v2_policy(const struct fscrypt_policy_v2 *policy,
 		return false;
 	}
 
+	if (policy->log2_data_unit_size) {
+		if (!inode->i_sb->s_cop->supports_subblock_data_units) {
+			fscrypt_warn(inode,
+				     "Filesystem does not support configuring crypto data unit size");
+			return false;
+		}
+		if (policy->log2_data_unit_size > inode->i_blkbits ||
+		    policy->log2_data_unit_size < SECTOR_SHIFT /* 9 */) {
+			fscrypt_warn(inode,
+				     "Unsupported log2_data_unit_size in encryption policy: %d",
+				     policy->log2_data_unit_size);
+			return false;
+		}
+		if (policy->log2_data_unit_size != inode->i_blkbits &&
+		    (policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) {
+			/*
+			 * Not safe to enable yet, as we need to ensure that DUN
+			 * wraparound can only occur on a FS block boundary.
+			 */
+			fscrypt_warn(inode,
+				     "Sub-block data units not yet supported with IV_INO_LBLK_32");
+			return false;
+		}
+	}
+
 	if ((policy->flags & FSCRYPT_POLICY_FLAG_DIRECT_KEY) &&
 	    !supported_direct_key_modes(inode, policy->contents_encryption_mode,
 					policy->filenames_encryption_mode))
 		return false;
 
-	if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64) &&
-	    !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_64",
-					  32, 32))
-		return false;
-
-	/*
-	 * IV_INO_LBLK_32 hashes the inode number, so in principle it can
-	 * support any ino_bits.  However, currently the inode number is gotten
-	 * from inode::i_ino which is 'unsigned long'.  So for now the
-	 * implementation limit is 32 bits.
-	 */
-	if ((policy->flags & FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32) &&
-	    !supported_iv_ino_lblk_policy(policy, inode, "IV_INO_LBLK_32",
-					  32, 32))
+	if ((policy->flags & (FSCRYPT_POLICY_FLAG_IV_INO_LBLK_64 |
+			      FSCRYPT_POLICY_FLAG_IV_INO_LBLK_32)) &&
+	    !supported_iv_ino_lblk_policy(policy, inode))
 		return false;
 
 	if (memchr_inv(policy->__reserved, 0, sizeof(policy->__reserved))) {
@@ -330,6 +355,7 @@ static int fscrypt_new_context(union fscrypt_context *ctx_u,
 		ctx->filenames_encryption_mode =
 			policy->filenames_encryption_mode;
 		ctx->flags = policy->flags;
+		ctx->log2_data_unit_size = policy->log2_data_unit_size;
 		memcpy(ctx->master_key_identifier,
 		       policy->master_key_identifier,
 		       sizeof(ctx->master_key_identifier));
@@ -390,6 +416,7 @@ int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
 		policy->filenames_encryption_mode =
 			ctx->filenames_encryption_mode;
 		policy->flags = ctx->flags;
+		policy->log2_data_unit_size = ctx->log2_data_unit_size;
 		memcpy(policy->__reserved, ctx->__reserved,
 		       sizeof(policy->__reserved));
 		memcpy(policy->master_key_identifier,
@@ -405,11 +432,11 @@ int fscrypt_policy_from_context(union fscrypt_policy *policy_u,
 /* Retrieve an inode's encryption policy */
 static int fscrypt_get_policy(struct inode *inode, union fscrypt_policy *policy)
 {
-	const struct fscrypt_info *ci;
+	const struct fscrypt_inode_info *ci;
 	union fscrypt_context ctx;
 	int ret;
 
-	ci = fscrypt_get_info(inode);
+	ci = fscrypt_get_inode_info(inode);
 	if (ci) {
 		/* key available, use the cached policy */
 		*policy = ci->ci_policy;
@@ -647,7 +674,7 @@ int fscrypt_has_permitted_context(struct inode *parent, struct inode *child)
 
 	/*
 	 * Both parent and child are encrypted, so verify they use the same
-	 * encryption policy.  Compare the fscrypt_info structs if the keys are
+	 * encryption policy.  Compare the cached policies if the keys are
 	 * available, otherwise retrieve and compare the fscrypt_contexts.
 	 *
 	 * Note that the fscrypt_context retrieval will be required frequently
@@ -717,7 +744,7 @@ const union fscrypt_policy *fscrypt_policy_to_inherit(struct inode *dir)
  */
 int fscrypt_context_for_new_inode(void *ctx, struct inode *inode)
 {
-	struct fscrypt_info *ci = inode->i_crypt_info;
+	struct fscrypt_inode_info *ci = inode->i_crypt_info;
 
 	BUILD_BUG_ON(sizeof(union fscrypt_context) !=
 			FSCRYPT_SET_CONTEXT_MAX_SIZE);
@@ -742,7 +769,7 @@ EXPORT_SYMBOL_GPL(fscrypt_context_for_new_inode);
  */
 int fscrypt_set_context(struct inode *inode, void *fs_data)
 {
-	struct fscrypt_info *ci = inode->i_crypt_info;
+	struct fscrypt_inode_info *ci = inode->i_crypt_info;
 	union fscrypt_context ctx;
 	int ctxsize;
 

fs/ext4/crypto.c

@@ -232,19 +232,14 @@ static bool ext4_has_stable_inodes(struct super_block *sb)
 	return ext4_has_feature_stable_inodes(sb);
 }
 
-static void ext4_get_ino_and_lblk_bits(struct super_block *sb,
-				       int *ino_bits_ret, int *lblk_bits_ret)
-{
-	*ino_bits_ret = 8 * sizeof(EXT4_SB(sb)->s_es->s_inodes_count);
-	*lblk_bits_ret = 8 * sizeof(ext4_lblk_t);
-}
-
 const struct fscrypt_operations ext4_cryptops = {
-	.key_prefix		= "ext4:",
+	.needs_bounce_pages	= 1,
+	.has_32bit_inodes	= 1,
+	.supports_subblock_data_units = 1,
+	.legacy_key_prefix	= "ext4:",
 	.get_context		= ext4_get_context,
 	.set_context		= ext4_set_context,
 	.get_dummy_policy	= ext4_get_dummy_policy,
 	.empty_dir		= ext4_empty_dir,
 	.has_stable_inodes	= ext4_has_stable_inodes,
-	.get_ino_and_lblk_bits	= ext4_get_ino_and_lblk_bits,
 };

fs/f2fs/super.c

@@ -3203,13 +3203,6 @@ static bool f2fs_has_stable_inodes(struct super_block *sb)
 	return true;
 }
 
-static void f2fs_get_ino_and_lblk_bits(struct super_block *sb,
-				       int *ino_bits_ret, int *lblk_bits_ret)
-{
-	*ino_bits_ret = 8 * sizeof(nid_t);
-	*lblk_bits_ret = 8 * sizeof(block_t);
-}
-
 static struct block_device **f2fs_get_devices(struct super_block *sb,
 					      unsigned int *num_devs)
 {
@@ -3231,13 +3224,15 @@ static struct block_device **f2fs_get_devices(struct super_block *sb,
 }
 
 static const struct fscrypt_operations f2fs_cryptops = {
-	.key_prefix		= "f2fs:",
+	.needs_bounce_pages	= 1,
+	.has_32bit_inodes	= 1,
+	.supports_subblock_data_units = 1,
+	.legacy_key_prefix	= "f2fs:",
 	.get_context		= f2fs_get_context,
 	.set_context		= f2fs_set_context,
 	.get_dummy_policy	= f2fs_get_dummy_policy,
 	.empty_dir		= f2fs_empty_dir,
 	.has_stable_inodes	= f2fs_has_stable_inodes,
-	.get_ino_and_lblk_bits	= f2fs_get_ino_and_lblk_bits,
 	.get_devices		= f2fs_get_devices,
 };
 #endif

fs/ubifs/crypto.c

@@ -88,8 +88,7 @@ int ubifs_decrypt(const struct inode *inode, struct ubifs_data_node *dn,
 }
 
 const struct fscrypt_operations ubifs_crypt_operations = {
-	.flags			= FS_CFLG_OWN_PAGES,
-	.key_prefix		= "ubifs:",
+	.legacy_key_prefix	= "ubifs:",
 	.get_context		= ubifs_crypt_get_context,
 	.set_context		= ubifs_crypt_set_context,
 	.empty_dir		= ubifs_crypt_empty_dir,

include/linux/fs.h

@@ -67,7 +67,7 @@ struct swap_info_struct;
 struct seq_file;
 struct workqueue_struct;
 struct iov_iter;
-struct fscrypt_info;
+struct fscrypt_inode_info;
 struct fscrypt_operations;
 struct fsverity_info;
 struct fsverity_operations;
@@ -738,7 +738,7 @@ struct inode {
 #endif
 
 #ifdef CONFIG_FS_ENCRYPTION
-	struct fscrypt_info	*i_crypt_info;
+	struct fscrypt_inode_info	*i_crypt_info;
 #endif
 
 #ifdef CONFIG_FS_VERITY

include/linux/fscrypt.h

@@ -31,7 +31,7 @@
 #define FSCRYPT_CONTENTS_ALIGNMENT 16
 
 union fscrypt_policy;
-struct fscrypt_info;
+struct fscrypt_inode_info;
 struct fs_parameter;
 struct seq_file;
 
@@ -59,26 +59,55 @@ struct fscrypt_name {
 
 #ifdef CONFIG_FS_ENCRYPTION
 
-/*
- * If set, the fscrypt bounce page pool won't be allocated (unless another
- * filesystem needs it).  Set this if the filesystem always uses its own bounce
- * pages for writes and therefore won't need the fscrypt bounce page pool.
- */
-#define FS_CFLG_OWN_PAGES (1U << 1)
-
 /* Crypto operations for filesystems */
 struct fscrypt_operations {
 
-	/* Set of optional flags; see above for allowed flags */
-	unsigned int flags;
+	/*
+	 * If set, then fs/crypto/ will allocate a global bounce page pool the
+	 * first time an encryption key is set up for a file.  The bounce page
+	 * pool is required by the following functions:
+	 *
+	 * - fscrypt_encrypt_pagecache_blocks()
+	 * - fscrypt_zeroout_range() for files not using inline crypto
+	 *
+	 * If the filesystem doesn't use those, it doesn't need to set this.
+	 */
+	unsigned int needs_bounce_pages : 1;
 
 	/*
-	 * If set, this is a filesystem-specific key description prefix that
-	 * will be accepted for "logon" keys for v1 fscrypt policies, in
-	 * addition to the generic prefix "fscrypt:".  This functionality is
-	 * deprecated, so new filesystems shouldn't set this field.
+	 * If set, then fs/crypto/ will allow the use of encryption settings
+	 * that assume inode numbers fit in 32 bits (i.e.
+	 * FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64}), provided that the other
+	 * prerequisites for these settings are also met.  This is only useful
+	 * if the filesystem wants to support inline encryption hardware that is
+	 * limited to 32-bit or 64-bit data unit numbers and where programming
+	 * keyslots is very slow.
 	 */
-	const char *key_prefix;
+	unsigned int has_32bit_inodes : 1;
+
+	/*
+	 * If set, then fs/crypto/ will allow users to select a crypto data unit
+	 * size that is less than the filesystem block size.  This is done via
+	 * the log2_data_unit_size field of the fscrypt policy.  This flag is
+	 * not compatible with filesystems that encrypt variable-length blocks
+	 * (i.e. blocks that aren't all equal to filesystem's block size), for
+	 * example as a result of compression.  It's also not compatible with
+	 * the fscrypt_encrypt_block_inplace() and
+	 * fscrypt_decrypt_block_inplace() functions.
+	 */
+	unsigned int supports_subblock_data_units : 1;
+
+	/*
+	 * This field exists only for backwards compatibility reasons and should
+	 * only be set by the filesystems that are setting it already.  It
+	 * contains the filesystem-specific key description prefix that is
+	 * accepted for "logon" keys for v1 fscrypt policies.  This
+	 * functionality is deprecated in favor of the generic prefix
+	 * "fscrypt:", which itself is deprecated in favor of the filesystem
+	 * keyring ioctls such as FS_IOC_ADD_ENCRYPTION_KEY.  Filesystems that
+	 * are newly adding fscrypt support should not set this field.
+	 */
+	const char *legacy_key_prefix;
 
 	/*
 	 * Get the fscrypt context of the given inode.
@@ -145,21 +174,6 @@ struct fscrypt_operations {
 	 */
 	bool (*has_stable_inodes)(struct super_block *sb);
 
-	/*
-	 * Get the number of bits that the filesystem uses to represent inode
-	 * numbers and file logical block numbers.
-	 *
-	 * By default, both of these are assumed to be 64-bit.  This function
-	 * can be implemented to declare that either or both of these numbers is
-	 * shorter, which may allow the use of the
-	 * FSCRYPT_POLICY_FLAG_IV_INO_LBLK_{32,64} flags and/or the use of
-	 * inline crypto hardware whose maximum DUN length is less than 64 bits
-	 * (e.g., eMMC v5.2 spec compliant hardware).  This function only needs
-	 * to be implemented if support for one of these features is needed.
-	 */
-	void (*get_ino_and_lblk_bits)(struct super_block *sb,
-				      int *ino_bits_ret, int *lblk_bits_ret);
-
 	/*
 	 * Return an array of pointers to the block devices to which the
 	 * filesystem may write encrypted file contents, NULL if the filesystem
@@ -178,7 +192,8 @@ struct fscrypt_operations {
 					     unsigned int *num_devs);
 };
 
-static inline struct fscrypt_info *fscrypt_get_info(const struct inode *inode)
+static inline struct fscrypt_inode_info *
+fscrypt_get_inode_info(const struct inode *inode)
 {
 	/*
 	 * Pairs with the cmpxchg_release() in fscrypt_setup_encryption_info().
@@ -390,7 +405,8 @@ static inline void fscrypt_set_ops(struct super_block *sb,
 }
 #else  /* !CONFIG_FS_ENCRYPTION */
 
-static inline struct fscrypt_info *fscrypt_get_info(const struct inode *inode)
+static inline struct fscrypt_inode_info *
+fscrypt_get_inode_info(const struct inode *inode)
 {
 	return NULL;
 }
@@ -868,7 +884,7 @@ static inline bool fscrypt_inode_uses_fs_layer_crypto(const struct inode *inode)
  */
 static inline bool fscrypt_has_encryption_key(const struct inode *inode)
 {
-	return fscrypt_get_info(inode) != NULL;
+	return fscrypt_get_inode_info(inode) != NULL;
 }
 
 /**

include/uapi/linux/fscrypt.h

@@ -71,7 +71,8 @@ struct fscrypt_policy_v2 {
 	__u8 contents_encryption_mode;
 	__u8 filenames_encryption_mode;
 	__u8 flags;
-	__u8 __reserved[4];
+	__u8 log2_data_unit_size;
+	__u8 __reserved[3];
 	__u8 master_key_identifier[FSCRYPT_KEY_IDENTIFIER_SIZE];
 };