linux/fs/ceph/crypto.c

// 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] = …;

int ceph_base64_encode(const u8 *src, int srclen, char *dst)
{ … }

int ceph_base64_decode(const char *src, int srclen, u8 *dst)
{ … }

static int ceph_crypt_get_context(struct inode *inode, void *ctx, size_t len)
{ … }

static int ceph_crypt_set_context(struct inode *inode, const void *ctx,
				  size_t len, void *fs_data)
{ … }

static bool ceph_crypt_empty_dir(struct inode *inode)
{ … }

static const union fscrypt_policy *ceph_get_dummy_policy(struct super_block *sb)
{ … }

static struct fscrypt_operations ceph_fscrypt_ops = …;

void ceph_fscrypt_set_ops(struct super_block *sb)
{ … }

void ceph_fscrypt_free_dummy_policy(struct ceph_fs_client *fsc)
{ … }

int ceph_fscrypt_prepare_context(struct inode *dir, struct inode *inode,
				 struct ceph_acl_sec_ctx *as)
{ … }

void ceph_fscrypt_as_ctx_to_req(struct ceph_mds_request *req,
				struct ceph_acl_sec_ctx *as)
{ … }

/*
 * 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)
{ … }

int ceph_encode_encrypted_dname(struct inode *parent, struct qstr *d_name,
				char *buf)
{ … }

int ceph_encode_encrypted_fname(struct inode *parent, struct dentry *dentry,
				char *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)
{ … }

/**
 * 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)
{ … }

int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
				  struct page *page, unsigned int len,
				  unsigned int offs, u64 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }