[PATCH v13 47/59] ceph: add infrastructure for file encryption and decryption

Jeff Layton
2022-04-06T01:00:22Z

...and allow test_dummy_encryption to bypass content encryption
if mounted with test_dummy_encryption=clear.

Signed-off-by: Jeff Layton <jlayton@kernel.org>
---
fs/ceph/crypto.c | 177 +++++++++++++++++++++++++++++++++++++++++++++++
fs/ceph/crypto.h | 71 +++++++++++++++++++
fs/ceph/super.c | 8 +++
fs/ceph/super.h | 1 +
4 files changed, 257 insertions(+)

diff --git a/fs/ceph/crypto.c b/fs/ceph/crypto.c
index 19c113afb400..e24e61c51118 100644
--- a/fs/ceph/crypto.c
+++ b/fs/ceph/crypto.c
@@ -2,6 +2,7 @@
#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"
@@ -263,3 +264,179 @@ int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
fscrypt_fname_free_buffer(&_tname);
return ret;
}
+
+int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
+ struct page *page, unsigned int len,
+ unsigned int offs, u64 lblk_num)
+{
+ struct ceph_mount_options *opt = ceph_inode_to_client(inode)->mount_options;
+
+ if (opt->flags & CEPH_MOUNT_OPT_DUMMY_ENC_CLEAR)
+ return 0;
+
+ 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)
+{
+ struct ceph_mount_options *opt = ceph_inode_to_client(inode)->mount_options;
+
+ if (opt->flags & CEPH_MOUNT_OPT_DUMMY_ENC_CLEAR)
+ return 0;
+
+ 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;
+}
diff --git a/fs/ceph/crypto.h b/fs/ceph/crypto.h
index 56a61ba64edc..fdd73c50487f 100644
--- a/fs/ceph/crypto.h
+++ b/fs/ceph/crypto.h
@@ -91,6 +91,40 @@ static inline void ceph_fname_free_buffer(struct inode *parent, struct fscrypt_s
int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscrypt_str *tname,
struct fscrypt_str *oname, bool *is_nokey);

+static inline unsigned int ceph_fscrypt_blocks(u64 off, u64 len)
+{
+ /* crypto blocks cannot span more than one page */
+ BUILD_BUG_ON(CEPH_FSCRYPT_BLOCK_SHIFT > PAGE_SHIFT);
+
+ return ((off+len+CEPH_FSCRYPT_BLOCK_SIZE-1) >> CEPH_FSCRYPT_BLOCK_SHIFT) -
+ (off >> CEPH_FSCRYPT_BLOCK_SHIFT);
+}
+
+/*
+ * If we have an encrypted inode then we must adjust the offset and
+ * range of the on-the-wire read to cover an entire encryption block.
+ * The copy will be done using the original offset and length, after
+ * we've decrypted the result.
+ */
+static inline void ceph_fscrypt_adjust_off_and_len(struct inode *inode, u64 *off, u64 *len)
+{
+ if (IS_ENCRYPTED(inode)) {
+ *len = ceph_fscrypt_blocks(*off, *len) * CEPH_FSCRYPT_BLOCK_SIZE;
+ *off &= CEPH_FSCRYPT_BLOCK_MASK;
+ }
+}
+
+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);
+int ceph_fscrypt_decrypt_pages(struct inode *inode, struct page **page, u64 off, int len);
+int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page, u64 off,
+ struct ceph_sparse_extent *map, u32 ext_cnt);
+int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page, u64 off,
+ int len, gfp_t gfp);
#else /* CONFIG_FS_ENCRYPTION */

static inline void ceph_fscrypt_set_ops(struct super_block *sb)
@@ -143,6 +177,43 @@ static inline int ceph_fname_to_usr(const struct ceph_fname *fname, struct fscry
oname->len = fname->name_len;
return 0;
}
+
+static inline void ceph_fscrypt_adjust_off_and_len(struct inode *inode, u64 *off, u64 *len)
+{
+}
+
+static inline int ceph_fscrypt_decrypt_block_inplace(const struct inode *inode,
+ struct page *page, unsigned int len,
+ unsigned int offs, u64 lblk_num)
+{
+ return 0;
+}
+
+static inline 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)
+{
+ return 0;
+}
+
+static inline int ceph_fscrypt_decrypt_pages(struct inode *inode, struct page **page,
+ u64 off, int len)
+{
+ return 0;
+}
+
+static inline int ceph_fscrypt_decrypt_extents(struct inode *inode, struct page **page,
+ u64 off, struct ceph_sparse_extent *map,
+ u32 ext_cnt)
+{
+ return 0;
+}
+
+static inline int ceph_fscrypt_encrypt_pages(struct inode *inode, struct page **page,
+ u64 off, int len, gfp_t gfp)
+{
+ return 0;
+}
#endif /* CONFIG_FS_ENCRYPTION */

#endif
diff --git a/fs/ceph/super.c b/fs/ceph/super.c
index a1f921d5675d..70cd1dcad645 100644
--- a/fs/ceph/super.c
+++ b/fs/ceph/super.c
@@ -1093,6 +1093,14 @@ static int ceph_set_test_dummy_encryption(struct super_block *sb, struct fs_cont
return -EEXIST;
}

+ /* HACK: allow for cleartext "encryption" in files for testing */
+ if (fsc->mount_options->test_dummy_encryption &&
+ !strcmp(fsc->mount_options->test_dummy_encryption, "clear")) {
+ fsopt->flags |= CEPH_MOUNT_OPT_DUMMY_ENC_CLEAR;
+ kfree(fsc->mount_options->test_dummy_encryption);
+ fsc->mount_options->test_dummy_encryption = NULL;
+ }
+
err = fscrypt_set_test_dummy_encryption(sb,
fsc->mount_options->test_dummy_encryption,
&fsc->dummy_enc_policy);
diff --git a/fs/ceph/super.h b/fs/ceph/super.h
index 9809bc97b89e..9c205c6967b7 100644
--- a/fs/ceph/super.h
+++ b/fs/ceph/super.h
@@ -44,6 +44,7 @@
#define CEPH_MOUNT_OPT_NOPAGECACHE (1<<16) /* bypass pagecache altogether */
#define CEPH_MOUNT_OPT_SPARSEREAD (1<<17) /* always do sparse reads */
#define CEPH_MOUNT_OPT_TEST_DUMMY_ENC (1<<18) /* enable dummy encryption (for testing) */
+#define CEPH_MOUNT_OPT_DUMMY_ENC_CLEAR (1<<19) /* don't actually encrypt content */

#define CEPH_MOUNT_OPT_DEFAULT \
(CEPH_MOUNT_OPT_DCACHE | \
--
2.35.1