[PATCH 3/8] btrfs-progs: start tracking extent encryption context info

[Daniel Vacek <neelx@suse.com>]

From: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>

This recapitulates the kernel change named 'btrfs: start tracking extent
encryption context info".

Signed-off-by: Sweet Tea Dorminy <sweettea-kernel@dorminy.me>
---
 kernel-shared/accessors.h       | 43 ++++++++++++++++++++++
 kernel-shared/tree-checker.c    | 65 +++++++++++++++++++++++++++------
 kernel-shared/uapi/btrfs_tree.h | 23 +++++++++++-
 3 files changed, 118 insertions(+), 13 deletions(-)

diff --git a/kernel-shared/accessors.h b/kernel-shared/accessors.h
index cb96f3e2..5d90be76 100644
--- a/kernel-shared/accessors.h
+++ b/kernel-shared/accessors.h
@@ -935,6 +935,9 @@ BTRFS_SETGET_STACK_FUNCS(super_uuid_tree_generation, struct btrfs_super_block,
 BTRFS_SETGET_STACK_FUNCS(super_nr_global_roots, struct btrfs_super_block,
 			 nr_global_roots, 64);
 
+/* struct btrfs_file_extent_encryption_info */
+BTRFS_SETGET_FUNCS(encryption_info_size, struct btrfs_encryption_info, size, 32);
+
 /* struct btrfs_file_extent_item */
 BTRFS_SETGET_STACK_FUNCS(stack_file_extent_type, struct btrfs_file_extent_item,
 			 type, 8);
@@ -973,6 +976,46 @@ BTRFS_SETGET_FUNCS(file_extent_encryption, struct btrfs_file_extent_item,
 BTRFS_SETGET_FUNCS(file_extent_other_encoding, struct btrfs_file_extent_item,
 		   other_encoding, 16);
 
+static inline struct btrfs_encryption_info *btrfs_file_extent_encryption_info(
+					const struct btrfs_file_extent_item *ei)
+{
+	unsigned long offset = (unsigned long)ei;
+
+	offset += offsetof(struct btrfs_file_extent_item, encryption_info);
+	return (struct btrfs_encryption_info *)offset;
+}
+
+static inline unsigned long btrfs_file_extent_encryption_ctx_offset(
+					const struct btrfs_file_extent_item *ei)
+{
+	unsigned long offset = (unsigned long)ei;
+
+	offset += offsetof(struct btrfs_file_extent_item, encryption_info);
+	return offset + offsetof(struct btrfs_encryption_info, context);
+}
+
+static inline u32 btrfs_file_extent_encryption_ctx_size(
+					const struct extent_buffer *eb,
+					const struct btrfs_file_extent_item *ei)
+{
+	return btrfs_encryption_info_size(eb, btrfs_file_extent_encryption_info(ei));
+}
+
+static inline void btrfs_set_file_extent_encryption_ctx_size(
+					struct extent_buffer *eb,
+					struct btrfs_file_extent_item *ei,
+					u32 val)
+{
+	btrfs_set_encryption_info_size(eb, btrfs_file_extent_encryption_info(ei), val);
+}
+
+static inline u32 btrfs_file_extent_encryption_info_size(
+					const struct extent_buffer *eb,
+					const struct btrfs_file_extent_item *ei)
+{
+	return btrfs_encryption_info_size(eb, btrfs_file_extent_encryption_info(ei));
+}
+
 /* btrfs_qgroup_status_item */
 BTRFS_SETGET_FUNCS(qgroup_status_generation, struct btrfs_qgroup_status_item,
 		   generation, 64);
diff --git a/kernel-shared/tree-checker.c b/kernel-shared/tree-checker.c
index ccc1f1ea..93073979 100644
--- a/kernel-shared/tree-checker.c
+++ b/kernel-shared/tree-checker.c
@@ -242,6 +242,8 @@ static int check_extent_data_item(struct extent_buffer *leaf,
 	u32 sectorsize = fs_info->sectorsize;
 	u32 item_size = btrfs_item_size(leaf, slot);
 	u64 extent_end;
+	u8 policy;
+	u8 fe_type;
 
 	if (unlikely(!IS_ALIGNED(key->offset, sectorsize))) {
 		file_extent_err(leaf, slot,
@@ -272,12 +274,12 @@ static int check_extent_data_item(struct extent_buffer *leaf,
 				SZ_4K);
 		return -EUCLEAN;
 	}
-	if (unlikely(btrfs_file_extent_type(leaf, fi) >=
-		     BTRFS_NR_FILE_EXTENT_TYPES)) {
+
+	fe_type = btrfs_file_extent_type(leaf, fi);
+	if (unlikely(fe_type >= BTRFS_NR_FILE_EXTENT_TYPES)) {
 		file_extent_err(leaf, slot,
 		"invalid type for file extent, have %u expect range [0, %u]",
-			btrfs_file_extent_type(leaf, fi),
-			BTRFS_NR_FILE_EXTENT_TYPES - 1);
+			fe_type, BTRFS_NR_FILE_EXTENT_TYPES - 1);
 		return -EUCLEAN;
 	}
 
@@ -293,10 +295,11 @@ static int check_extent_data_item(struct extent_buffer *leaf,
 			BTRFS_NR_COMPRESS_TYPES - 1);
 		return -EUCLEAN;
 	}
-	if (unlikely(btrfs_file_extent_encryption(leaf, fi))) {
+	policy = btrfs_file_extent_encryption(leaf, fi);
+	if (unlikely(policy >= BTRFS_NR_ENCRYPTION_TYPES)) {
 		file_extent_err(leaf, slot,
-			"invalid encryption for file extent, have %u expect 0",
-			btrfs_file_extent_encryption(leaf, fi));
+			"invalid encryption for file extent, have %u expect range [0, %u]",
+			policy, BTRFS_NR_ENCRYPTION_TYPES - 1);
 		return -EUCLEAN;
 	}
 	if (btrfs_file_extent_type(leaf, fi) == BTRFS_FILE_EXTENT_INLINE) {
@@ -325,12 +328,50 @@ static int check_extent_data_item(struct extent_buffer *leaf,
 		return 0;
 	}
 
-	/* Regular or preallocated extent has fixed item size */
-	if (unlikely(item_size != sizeof(*fi))) {
-		file_extent_err(leaf, slot,
+	if (policy == BTRFS_ENCRYPTION_FSCRYPT) {
+		size_t fe_size = sizeof(*fi) + sizeof(struct btrfs_encryption_info);
+		u32 ctxsize;
+
+		if (unlikely(item_size < fe_size)) {
+			file_extent_err(leaf, slot,
+	"invalid item size for encrypted file extent, have %u expect = %zu + size of u32",
+					item_size, sizeof(*fi));
+			return -EUCLEAN;
+		}
+
+		ctxsize = btrfs_file_extent_encryption_info_size(leaf, fi);
+		if (unlikely(item_size != (fe_size + ctxsize))) {
+			file_extent_err(leaf, slot,
+	"invalid item size for encrypted file extent, have %u expect = %zu + context of size %u",
+					item_size, fe_size, ctxsize);
+			return -EUCLEAN;
+		}
+
+		if (unlikely(ctxsize > BTRFS_MAX_EXTENT_CTX_SIZE)) {
+			file_extent_err(leaf, slot,
+	"invalid file extent context size, have %u expect a maximum of %u",
+					ctxsize, BTRFS_MAX_EXTENT_CTX_SIZE);
+			return -EUCLEAN;
+		}
+
+		/*
+		 * Only regular and prealloc extents should have an encryption
+		 * context.
+		 */
+		if (unlikely(fe_type != BTRFS_FILE_EXTENT_REG &&
+			     fe_type != BTRFS_FILE_EXTENT_PREALLOC)) {
+			file_extent_err(leaf, slot,
+		"invalid type for encrypted file extent, have %u",
+					btrfs_file_extent_type(leaf, fi));
+			return -EUCLEAN;
+		}
+	} else {
+		if (unlikely(item_size != sizeof(*fi))) {
+			file_extent_err(leaf, slot,
 	"invalid item size for reg/prealloc file extent, have %u expect %zu",
-			item_size, sizeof(*fi));
-		return -EUCLEAN;
+					item_size, sizeof(*fi));
+			return -EUCLEAN;
+		}
 	}
 	if (unlikely(CHECK_FE_ALIGNED(leaf, slot, fi, ram_bytes, sectorsize) ||
 		     CHECK_FE_ALIGNED(leaf, slot, fi, disk_bytenr, sectorsize) ||
diff --git a/kernel-shared/uapi/btrfs_tree.h b/kernel-shared/uapi/btrfs_tree.h
index 7f3dffe6..4b4f45aa 100644
--- a/kernel-shared/uapi/btrfs_tree.h
+++ b/kernel-shared/uapi/btrfs_tree.h
@@ -1066,6 +1066,24 @@ enum {
 	BTRFS_NR_FILE_EXTENT_TYPES = 3,
 };
 
+/*
+ * Currently just the FSCRYPT_SET_CONTEXT_MAX_SIZE, which is larger than the
+ * current extent context size from fscrypt, so this should give us plenty of
+ * breathing room for expansion later.
+ */
+#define BTRFS_MAX_EXTENT_CTX_SIZE 40
+
+enum {
+	BTRFS_ENCRYPTION_NONE,
+	BTRFS_ENCRYPTION_FSCRYPT,
+	BTRFS_NR_ENCRYPTION_TYPES,
+};
+
+struct btrfs_encryption_info {
+	__le32 size;
+	__u8 context[0];
+};
+
 struct btrfs_file_extent_item {
 	/*
 	 * transaction id that created this extent
@@ -1115,7 +1133,10 @@ struct btrfs_file_extent_item {
 	 * always reflects the size uncompressed and without encoding.
 	 */
 	__le64 num_bytes;
-
+	/*
+	 * the encryption info, if any
+	 */
+	struct btrfs_encryption_info encryption_info[0];
 } __attribute__ ((__packed__));
 
 struct btrfs_csum_item {
-- 
2.51.0