Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 671 insertions, 0 deletions

diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
new file mode 100644
index 0000000000..5b5112c784
--- /dev/null
+++ b/fs/ceph/crypto.c
@@ -0,0 +1,671 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * The base64 encode/decode code was copied from fscrypt:
+ * Copyright (C) 2015, Google, Inc.
+ * Copyright (C) 2015, Motorola Mobility
+ * Written by Uday Savagaonkar, 2014.
+ * Modified by Jaegeuk Kim, 2015.
+ */
+#include <linux/ceph/ceph_debug.h>
+#include <linux/xattr.h>
+#include <linux/fscrypt.h>
+#include <linux/ceph/striper.h>
+
+#include "super.h"
+#include "mds_client.h"
+#include "crypto.h"
+
+/*
+ * The base64url encoding used by fscrypt includes the '_' character, which may
+ * cause problems in snapshot names (which can not start with '_').  Thus, we
+ * used the base64 encoding defined for IMAP mailbox names (RFC 3501) instead,
+ * which replaces '-' and '_' by '+' and ','.
+ */
+static const char base64_table[65] =
+	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+,";
+
+int ceph_base64_encode(const u8 *src, int srclen, char *dst)
+{
+	u32 ac = 0;
+	int bits = 0;
+	int i;
+	char *cp = dst;
+
+	for (i = 0; i < srclen; i++) {
+		ac = (ac << 8) | src[i];
+		bits += 8;
+		do {
+			bits -= 6;
+			*cp++ = base64_table[(ac >> bits) & 0x3f];
+		} while (bits >= 6);
+	}
+	if (bits)
+		*cp++ = base64_table[(ac << (6 - bits)) & 0x3f];
+	return cp - dst;
+}
+
+int ceph_base64_decode(const char *src, int srclen, u8 *dst)
+{
+	u32 ac = 0;
+	int bits = 0;
+	int i;
+	u8 *bp = dst;
+
+	for (i = 0; i < srclen; i++) {
+		const char *p = strchr(base64_table, src[i]);
+
+		if (p == NULL || src[i] == 0)
+			return -1;
+		ac = (ac << 6) | (p - base64_table);
+		bits += 6;
+		if (bits >= 8) {
+			bits -= 8;
+			*bp++ = (u8)(ac >> bits);
+		}
+	}
+	if (ac & ((1 << bits) - 1))
+		return -1;
+	return bp - dst;
+}
+
+static int ceph_crypt_get_context(struct inode *inode, void *ctx, size_t len)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	struct ceph_fscrypt_auth *cfa = (struct ceph_fscrypt_auth *)ci->fscrypt_auth;
+	u32 ctxlen;
+
+	/* Non existent or too short? */
+	if (!cfa || (ci->fscrypt_auth_len < (offsetof(struct ceph_fscrypt_auth, cfa_blob) + 1)))
+		return -ENOBUFS;
+
+	/* Some format we don't recognize? */
+	if (le32_to_cpu(cfa->cfa_version) != CEPH_FSCRYPT_AUTH_VERSION)
+		return -ENOBUFS;
+
+	ctxlen = le32_to_cpu(cfa->cfa_blob_len);
+	if (len < ctxlen)
+		return -ERANGE;
+
+	memcpy(ctx, cfa->cfa_blob, ctxlen);
+	return ctxlen;
+}
+
+static int ceph_crypt_set_context(struct inode *inode, const void *ctx,
+				  size_t len, void *fs_data)
+{
+	int ret;
+	struct iattr attr = { };
+	struct ceph_iattr cia = { };
+	struct ceph_fscrypt_auth *cfa;
+
+	WARN_ON_ONCE(fs_data);
+
+	if (len > FSCRYPT_SET_CONTEXT_MAX_SIZE)
+		return -EINVAL;
+
+	cfa = kzalloc(sizeof(*cfa), GFP_KERNEL);
+	if (!cfa)
+		return -ENOMEM;
+
+	cfa->cfa_version = cpu_to_le32(CEPH_FSCRYPT_AUTH_VERSION);
+	cfa->cfa_blob_len = cpu_to_le32(len);
+	memcpy(cfa->cfa_blob, ctx, len);
+
+	cia.fscrypt_auth = cfa;
+
+	ret = __ceph_setattr(inode, &attr, &cia);
+	if (ret == 0)
+		inode_set_flags(inode, S_ENCRYPTED, S_ENCRYPTED);
+	kfree(cia.fscrypt_auth);
+	return ret;
+}
+
+static bool ceph_crypt_empty_dir(struct inode *inode)
+{
+	struct ceph_inode_info *ci = ceph_inode(inode);
+
+	return ci->i_rsubdirs + ci->i_rfiles == 1;
+}
+
+static const union fscrypt_policy *ceph_get_dummy_policy(struct super_block *sb)
+{
+	return ceph_sb_to_client(sb)->fsc_dummy_enc_policy.policy;
+}
+
+static struct fscrypt_operations ceph_fscrypt_ops = {
+	.get_context		= ceph_crypt_get_context,
+	.set_context		= ceph_crypt_set_context,
+	.get_dummy_policy	= ceph_get_dummy_policy,
+	.empty_dir		= ceph_crypt_empty_dir,
+};
+
+void ceph_fscrypt_set_ops(struct super_block *sb)
+{
+	fscrypt_set_ops(sb, &ceph_fscrypt_ops);
+}
+
+void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
+{
+	fscrypt_free_dummy_policy(&fsc->fsc_dummy_enc_policy);
+}
+
+int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
+				 struct ceph_acl_sec_ctx *as)
+{
+	int ret, ctxsize;
+	bool encrypted = false;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+
+	ret = fscrypt_prepare_new_inode(dir, inode, &encrypted);
+	if (ret)
+		return ret;
+	if (!encrypted)
+		return 0;
+
+	as->fscrypt_auth = kzalloc(sizeof(*as->fscrypt_auth), GFP_KERNEL);
+	if (!as->fscrypt_auth)
+		return -ENOMEM;
+
+	ctxsize = fscrypt_context_for_new_inode(as->fscrypt_auth->cfa_blob,
+						inode);
+	if (ctxsize < 0)
+		return ctxsize;
+
+	as->fscrypt_auth->cfa_version = cpu_to_le32(CEPH_FSCRYPT_AUTH_VERSION);
+	as->fscrypt_auth->cfa_blob_len = cpu_to_le32(ctxsize);
+
+	WARN_ON_ONCE(ci->fscrypt_auth);
+	kfree(ci->fscrypt_auth);
+	ci->fscrypt_auth_len = ceph_fscrypt_auth_len(as->fscrypt_auth);
+	ci->fscrypt_auth = kmemdup(as->fscrypt_auth, ci->fscrypt_auth_len,
+				   GFP_KERNEL);
+	if (!ci->fscrypt_auth)
+		return -ENOMEM;
+
+	inode->i_flags |= S_ENCRYPTED;
+
+	return 0;
+}
+
+void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
+				struct ceph_acl_sec_ctx *as)
+{
+	swap(req->r_fscrypt_auth, as->fscrypt_auth);
+}
+
+/*
+ * User-created snapshots can't start with '_'.  Snapshots that start with this
+ * character are special (hint: there aren't real snapshots) and use the
+ * following format:
+ *
+ *   _<SNAPSHOT-NAME>_<INODE-NUMBER>
+ *
+ * where:
+ *  - <SNAPSHOT-NAME> - the real snapshot name that may need to be decrypted,
+ *  - <INODE-NUMBER> - the inode number (in decimal) for the actual snapshot
+ *
+ * This function parses these snapshot names and returns the inode
+ * <INODE-NUMBER>.  'name_len' will also bet set with the <SNAPSHOT-NAME>
+ * length.
+ */
+static struct inode *parse_longname(const struct inode *parent,
+				    const char *name, int *name_len)
+{
+	struct inode *dir = NULL;
+	struct ceph_vino vino = { .snap = CEPH_NOSNAP };
+	char *inode_number;
+	char *name_end;
+	int orig_len = *name_len;
+	int ret = -EIO;
+
+	/* Skip initial '_' */
+	name++;
+	name_end = strrchr(name, '_');
+	if (!name_end) {
+		dout("Failed to parse long snapshot name: %s\n", name);
+		return ERR_PTR(-EIO);
+	}
+	*name_len = (name_end - name);
+	if (*name_len <= 0) {
+		pr_err("Failed to parse long snapshot name\n");
+		return ERR_PTR(-EIO);
+	}
+
+	/* Get the inode number */
+	inode_number = kmemdup_nul(name_end + 1,
+				   orig_len - *name_len - 2,
+				   GFP_KERNEL);
+	if (!inode_number)
+		return ERR_PTR(-ENOMEM);
+	ret = kstrtou64(inode_number, 10, &vino.ino);
+	if (ret) {
+		dout("Failed to parse inode number: %s\n", name);
+		dir = ERR_PTR(ret);
+		goto out;
+	}
+
+	/* And finally the inode */
+	dir = ceph_find_inode(parent->i_sb, vino);
+	if (!dir) {
+		/* This can happen if we're not mounting cephfs on the root */
+		dir = ceph_get_inode(parent->i_sb, vino, NULL);
+		if (IS_ERR(dir))
+			dout("Can't find inode %s (%s)\n", inode_number, name);
+	}
+
+out:
+	kfree(inode_number);
+	return dir;
+}
+
+int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
+				char *buf)
+{
+	struct inode *dir = parent;
+	struct qstr iname;
+	u32 len;
+	int name_len;
+	int elen;
+	int ret;
+	u8 *cryptbuf = NULL;
+
+	iname.name = d_name->name;
+	name_len = d_name->len;
+
+	/* Handle the special case of snapshot names that start with '_' */
+	if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
+	    (iname.name[0] == '_')) {
+		dir = parse_longname(parent, iname.name, &name_len);
+		if (IS_ERR(dir))
+			return PTR_ERR(dir);
+		iname.name++; /* skip initial '_' */
+	}
+	iname.len = name_len;
+
+	if (!fscrypt_has_encryption_key(dir)) {
+		memcpy(buf, d_name->name, d_name->len);
+		elen = d_name->len;
+		goto out;
+	}
+
+	/*
+	 * Convert cleartext d_name to ciphertext. If result is longer than
+	 * CEPH_NOHASH_NAME_MAX, sha256 the remaining bytes
+	 *
+	 * See: fscrypt_setup_filename
+	 */
+	if (!fscrypt_fname_encrypted_size(dir, iname.len, NAME_MAX, &len)) {
+		elen = -ENAMETOOLONG;
+		goto out;
+	}
+
+	/* Allocate a buffer appropriate to hold the result */
+	cryptbuf = kmalloc(len > CEPH_NOHASH_NAME_MAX ? NAME_MAX : len,
+			   GFP_KERNEL);
+	if (!cryptbuf) {
+		elen = -ENOMEM;
+		goto out;
+	}
+
+	ret = fscrypt_fname_encrypt(dir, &iname, cryptbuf, len);
+	if (ret) {
+		elen = ret;
+		goto out;
+	}
+
+	/* hash the end if the name is long enough */
+	if (len > CEPH_NOHASH_NAME_MAX) {
+		u8 hash[SHA256_DIGEST_SIZE];
+		u8 *extra = cryptbuf + CEPH_NOHASH_NAME_MAX;
+
+		/*
+		 * hash the extra bytes and overwrite crypttext beyond that
+		 * point with it
+		 */
+		sha256(extra, len - CEPH_NOHASH_NAME_MAX, hash);
+		memcpy(extra, hash, SHA256_DIGEST_SIZE);
+		len = CEPH_NOHASH_NAME_MAX + SHA256_DIGEST_SIZE;
+	}
+
+	/* base64 encode the encrypted name */
+	elen = ceph_base64_encode(cryptbuf, len, buf);
+	dout("base64-encoded ciphertext name = %.*s\n", elen, buf);
+
+	/* To understand the 240 limit, see CEPH_NOHASH_NAME_MAX comments */
+	WARN_ON(elen > 240);
+	if ((elen > 0) && (dir != parent)) {
+		char tmp_buf[NAME_MAX];
+
+		elen = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
+				elen, buf, dir->i_ino);
+		memcpy(buf, tmp_buf, elen);
+	}
+
+out:
+	kfree(cryptbuf);
+	if (dir != parent) {
+		if ((dir->i_state & I_NEW))
+			discard_new_inode(dir);
+		else
+			iput(dir);
+	}
+	return elen;
+}
+
+int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
+				char *buf)
+{
+	WARN_ON_ONCE(!fscrypt_has_encryption_key(parent));
+
+	return ceph_encode_encrypted_dname(parent, &dentry->d_name, buf);
+}
+
+/**
+ * ceph_fname_to_usr - convert a filename for userland presentation
+ * @fname: ceph_fname to be converted
+ * @tname: temporary name buffer to use for conversion (may be NULL)
+ * @oname: where converted name should be placed
+ * @is_nokey: set to true if key wasn't available during conversion (may be NULL)
+ *
+ * Given a filename (usually from the MDS), format it for presentation to
+ * userland. If @parent is not encrypted, just pass it back as-is.
+ *
+ * Otherwise, base64 decode the string, and then ask fscrypt to format it
+ * for userland presentation.
+ *
+ * Returns 0 on success or negative error code on error.
+ */
+int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
+		      struct fscrypt_str *oname, bool *is_nokey)
+{
+	struct inode *dir = fname->dir;
+	struct fscrypt_str _tname = FSTR_INIT(NULL, 0);
+	struct fscrypt_str iname;
+	char *name = fname->name;
+	int name_len = fname->name_len;
+	int ret;
+
+	/* Sanity check that the resulting name will fit in the buffer */
+	if (fname->name_len > NAME_MAX || fname->ctext_len > NAME_MAX)
+		return -EIO;
+
+	/* Handle the special case of snapshot names that start with '_' */
+	if ((ceph_snap(dir) == CEPH_SNAPDIR) && (name_len > 0) &&
+	    (name[0] == '_')) {
+		dir = parse_longname(dir, name, &name_len);
+		if (IS_ERR(dir))
+			return PTR_ERR(dir);
+		name++; /* skip initial '_' */
+	}
+
+	if (!IS_ENCRYPTED(dir)) {
+		oname->name = fname->name;
+		oname->len = fname->name_len;
+		ret = 0;
+		goto out_inode;
+	}
+
+	ret = ceph_fscrypt_prepare_readdir(dir);
+	if (ret)
+		goto out_inode;
+
+	/*
+	 * Use the raw dentry name as sent by the MDS instead of
+	 * generating a nokey name via fscrypt.
+	 */
+	if (!fscrypt_has_encryption_key(dir)) {
+		if (fname->no_copy)
+			oname->name = fname->name;
+		else
+			memcpy(oname->name, fname->name, fname->name_len);
+		oname->len = fname->name_len;
+		if (is_nokey)
+			*is_nokey = true;
+		ret = 0;
+		goto out_inode;
+	}
+
+	if (fname->ctext_len == 0) {
+		int declen;
+
+		if (!tname) {
+			ret = fscrypt_fname_alloc_buffer(NAME_MAX, &_tname);
+			if (ret)
+				goto out_inode;
+			tname = &_tname;
+		}
+
+		declen = ceph_base64_decode(name, name_len, tname->name);
+		if (declen <= 0) {
+			ret = -EIO;
+			goto out;
+		}
+		iname.name = tname->name;
+		iname.len = declen;
+	} else {
+		iname.name = fname->ctext;
+		iname.len = fname->ctext_len;
+	}
+
+	ret = fscrypt_fname_disk_to_usr(dir, 0, 0, &iname, oname);
+	if (!ret && (dir != fname->dir)) {
+		char tmp_buf[CEPH_BASE64_CHARS(NAME_MAX)];
+
+		name_len = snprintf(tmp_buf, sizeof(tmp_buf), "_%.*s_%ld",
+				    oname->len, oname->name, dir->i_ino);
+		memcpy(oname->name, tmp_buf, name_len);
+		oname->len = name_len;
+	}
+
+out:
+	fscrypt_fname_free_buffer(&_tname);
+out_inode:
+	if (dir != fname->dir) {
+		if ((dir->i_state & I_NEW))
+			discard_new_inode(dir);
+		else
+			iput(dir);
+	}
+	return ret;
+}
+
+/**
+ * ceph_fscrypt_prepare_readdir - simple __fscrypt_prepare_readdir() wrapper
+ * @dir: directory inode for readdir prep
+ *
+ * Simple wrapper around __fscrypt_prepare_readdir() that will mark directory as
+ * non-complete if this call results in having the directory unlocked.
+ *
+ * Returns:
+ *     1 - if directory was locked and key is now loaded (i.e. dir is unlocked)
+ *     0 - if directory is still locked
+ *   < 0 - if __fscrypt_prepare_readdir() fails
+ */
+int ceph_fscrypt_prepare_readdir(struct inode *dir)
+{
+	bool had_key = fscrypt_has_encryption_key(dir);
+	int err;
+
+	if (!IS_ENCRYPTED(dir))
+		return 0;
+
+	err = __fscrypt_prepare_readdir(dir);
+	if (err)
+		return err;
+	if (!had_key && fscrypt_has_encryption_key(dir)) {
+		/* directory just got unlocked, mark it as not complete */
+		ceph_dir_clear_complete(dir);
+		return 1;
+	}
+	return 0;
+}
+
+int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
+				  struct page *page, unsigned int len,
+				  unsigned int offs, u64 lblk_num)
+{
+	dout("%s: len %u offs %u blk %llu\n", __func__, len, offs, lblk_num);
+	return fscrypt_decrypt_block_inplace(inode, page, len, offs, lblk_num);
+}
+
+int ceph_fscrypt_encrypt_block_inplace(const struct inode *inode,
+				  struct page *page, unsigned int len,
+				  unsigned int offs, u64 lblk_num,
+				  gfp_t gfp_flags)
+{
+	dout("%s: len %u offs %u blk %llu\n", __func__, len, offs, lblk_num);
+	return fscrypt_encrypt_block_inplace(inode, page, len, offs, lblk_num,
+					     gfp_flags);
+}
+
+/**
+ * ceph_fscrypt_decrypt_pages - decrypt an array of pages
+ * @inode: pointer to inode associated with these pages
+ * @page: pointer to page array
+ * @off: offset into the file that the read data starts
+ * @len: max length to decrypt
+ *
+ * Decrypt an array of fscrypt'ed pages and return the amount of
+ * data decrypted. Any data in the page prior to the start of the
+ * first complete block in the read is ignored. Any incomplete
+ * crypto blocks at the end of the array are ignored (and should
+ * probably be zeroed by the caller).
+ *
+ * Returns the length of the decrypted data or a negative errno.
+ */
+int ceph_fscrypt_decrypt_pages(struct inode *inode, struct page **page,
+			       u64 off, int len)
+{
+	int i, num_blocks;
+	u64 baseblk = off >> CEPH_FSCRYPT_BLOCK_SHIFT;
+	int ret = 0;
+
+	/*
+	 * We can't deal with partial blocks on an encrypted file, so mask off
+	 * the last bit.
+	 */
+	num_blocks = ceph_fscrypt_blocks(off, len & CEPH_FSCRYPT_BLOCK_MASK);
+
+	/* Decrypt each block */
+	for (i = 0; i < num_blocks; ++i) {
+		int blkoff = i << CEPH_FSCRYPT_BLOCK_SHIFT;
+		int pgidx = blkoff >> PAGE_SHIFT;
+		unsigned int pgoffs = offset_in_page(blkoff);
+		int fret;
+
+		fret = ceph_fscrypt_decrypt_block_inplace(inode, page[pgidx],
+				CEPH_FSCRYPT_BLOCK_SIZE, pgoffs,
+				baseblk + i);
+		if (fret < 0) {
+			if (ret == 0)
+				ret = fret;
+			break;
+		}
+		ret += CEPH_FSCRYPT_BLOCK_SIZE;
+	}
+	return ret;
+}
+
+/**
+ * ceph_fscrypt_decrypt_extents: decrypt received extents in given buffer
+ * @inode: inode associated with pages being decrypted
+ * @page: pointer to page array
+ * @off: offset into the file that the data in page[0] starts
+ * @map: pointer to extent array
+ * @ext_cnt: length of extent array
+ *
+ * Given an extent map and a page array, decrypt the received data in-place,
+ * skipping holes. Returns the offset into buffer of end of last decrypted
+ * block.
+ */
+int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page,
+				 u64 off, struct ceph_sparse_extent *map,
+				 u32 ext_cnt)
+{
+	int i, ret = 0;
+	struct ceph_inode_info *ci = ceph_inode(inode);
+	u64 objno, objoff;
+	u32 xlen;
+
+	/* Nothing to do for empty array */
+	if (ext_cnt == 0) {
+		dout("%s: empty array, ret 0\n", __func__);
+		return 0;
+	}
+
+	ceph_calc_file_object_mapping(&ci->i_layout, off, map[0].len,
+				      &objno, &objoff, &xlen);
+
+	for (i = 0; i < ext_cnt; ++i) {
+		struct ceph_sparse_extent *ext = &map[i];
+		int pgsoff = ext->off - objoff;
+		int pgidx = pgsoff >> PAGE_SHIFT;
+		int fret;
+
+		if ((ext->off | ext->len) & ~CEPH_FSCRYPT_BLOCK_MASK) {
+			pr_warn("%s: bad encrypted sparse extent idx %d off %llx len %llx\n",
+				__func__, i, ext->off, ext->len);
+			return -EIO;
+		}
+		fret = ceph_fscrypt_decrypt_pages(inode, &page[pgidx],
+						 off + pgsoff, ext->len);
+		dout("%s: [%d] 0x%llx~0x%llx fret %d\n", __func__, i,
+				ext->off, ext->len, fret);
+		if (fret < 0) {
+			if (ret == 0)
+				ret = fret;
+			break;
+		}
+		ret = pgsoff + fret;
+	}
+	dout("%s: ret %d\n", __func__, ret);
+	return ret;
+}
+
+/**
+ * ceph_fscrypt_encrypt_pages - encrypt an array of pages
+ * @inode: pointer to inode associated with these pages
+ * @page: pointer to page array
+ * @off: offset into the file that the data starts
+ * @len: max length to encrypt
+ * @gfp: gfp flags to use for allocation
+ *
+ * Decrypt an array of cleartext pages and return the amount of
+ * data encrypted. Any data in the page prior to the start of the
+ * first complete block in the read is ignored. Any incomplete
+ * crypto blocks at the end of the array are ignored.
+ *
+ * Returns the length of the encrypted data or a negative errno.
+ */
+int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off,
+				int len, gfp_t gfp)
+{
+	int i, num_blocks;
+	u64 baseblk = off >> CEPH_FSCRYPT_BLOCK_SHIFT;
+	int ret = 0;
+
+	/*
+	 * We can't deal with partial blocks on an encrypted file, so mask off
+	 * the last bit.
+	 */
+	num_blocks = ceph_fscrypt_blocks(off, len & CEPH_FSCRYPT_BLOCK_MASK);
+
+	/* Encrypt each block */
+	for (i = 0; i < num_blocks; ++i) {
+		int blkoff = i << CEPH_FSCRYPT_BLOCK_SHIFT;
+		int pgidx = blkoff >> PAGE_SHIFT;
+		unsigned int pgoffs = offset_in_page(blkoff);
+		int fret;
+
+		fret = ceph_fscrypt_encrypt_block_inplace(inode, page[pgidx],
+				CEPH_FSCRYPT_BLOCK_SIZE, pgoffs,
+				baseblk + i, gfp);
+		if (fret < 0) {
+			if (ret == 0)
+				ret = fret;
+			break;
+		}
+		ret += CEPH_FSCRYPT_BLOCK_SIZE;
+	}
+	return ret;
+}