[PATCH 1/3] apfsck: check that xfields are not repeated

[Ernesto A. Fernández]

There doesn't seem to be any reason for an inode to have more than one
extended field of the same type, so verify that it doesn't happen.

Signed-off-by: Ernesto A. Fernández <ernesto.mn...@gmail.com>
---
apfsck/inode.c | 7 +++++++
1 file changed, 7 insertions(+)

diff --git a/apfsck/inode.c b/apfsck/inode.c
index 3e844d7..37332f3 100644
--- a/apfsck/inode.c
+++ b/apfsck/inode.c
@@ -313,6 +313,7 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,
struct inode *inode)
{
struct apfs_x_field *xfield;
+ u16 type_bitmap = 0;
char *xval;
int xcount;
int i;
@@ -340,6 +341,7 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,

for (i = 0; i < le16_to_cpu(xblob->xf_num_exts); ++i) {
int xlen, xpad_len;
+ u16 type_flag;

switch (xfield[i].x_type) {
case APFS_INO_EXT_TYPE_FS_UUID:
@@ -381,6 +383,11 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,
report("Inode xfield", "invalid type.");
}

+ type_flag = 1 << xfield[i].x_type;
+ if (type_bitmap & type_flag)
+ report("Inode record", "two xfields of the same type.");
+ type_bitmap |= type_flag;
+
if (xlen != le16_to_cpu(xfield[i].x_size))
report("Inode xfield", "wrong size");
len -= xlen;
--
2.11.0

[Ernesto A. Fernández]

I don't yet know which xfields will have which flags, but add some basic
checks that are common to all of them.

Signed-off-by: Ernesto A. Fernández <ernesto.mn...@gmail.com>
---

apfsck/dir.c | 2 ++
apfsck/inode.c | 16 ++++++++++++++++
apfsck/inode.h | 11 +++++++++++
3 files changed, 29 insertions(+)

diff --git a/apfsck/dir.c b/apfsck/dir.c
index eaaa7e9..af50320 100644
--- a/apfsck/dir.c
+++ b/apfsck/dir.c
@@ -70,6 +70,8 @@ static void parse_dentry_xfields(struct apfs_xf_blob *xblob, int len,
report("Dentry record",
"value size incompatible with xfields.");

+ check_xfield_flags(xfield->x_flags);
+
if (xfield->x_type != APFS_DREC_EXT_TYPE_SIBLING_ID)
report("Dentry xfield", "invalid type.");
xlen = read_sibling_id_xfield(xval, len, sibling_id);
diff --git a/apfsck/inode.c b/apfsck/inode.c
index 37332f3..2e6a2be 100644
--- a/apfsck/inode.c
+++ b/apfsck/inode.c
@@ -302,6 +302,20 @@ static int read_dstream_xfield(char *xval, int len, struct inode *inode)
}

/**
+ * check_xfield_flags - Run common flag checks for all xfield types
+ * @flags: flags to check
+ */
+void check_xfield_flags(u8 flags)
+{
+ if (flags & APFS_XF_RESERVED_4 || flags & APFS_XF_RESERVED_40 ||
+ flags & APFS_XF_RESERVED_80)
+ report("Inode xfield", "reserved flag in use.");
+
+ if (flags & APFS_XF_USER_FIELD && flags & APFS_XF_SYSTEM_FIELD)
+ report("Inode xfield", "created by both user and kernel.");
+}
+
+/**
* parse_inode_xfields - Parse and check an inode extended fields
* @xblob: pointer to the beginning of the xfields in the inode value
* @len: length of the xfields
@@ -343,6 +357,8 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,
int xlen, xpad_len;
u16 type_flag;

+ check_xfield_flags(xfield[i].x_flags);
+

switch (xfield[i].x_type) {
case APFS_INO_EXT_TYPE_FS_UUID:

xlen = 16;
diff --git a/apfsck/inode.h b/apfsck/inode.h
index c04515a..e6c4dff 100644
--- a/apfsck/inode.h
+++ b/apfsck/inode.h
@@ -78,6 +78,16 @@ struct apfs_inode_val {
#define APFS_INO_EXT_TYPE_SPARSE_BYTES 13
#define APFS_INO_EXT_TYPE_RDEV 14

+/* Extended field flags */
+#define APFS_XF_DATA_DEPENDENT 0x01
+#define APFS_XF_DO_NOT_COPY 0x02
+#define APFS_XF_RESERVED_4 0x04
+#define APFS_XF_CHILDREN_INHERIT 0x08
+#define APFS_XF_USER_FIELD 0x10
+#define APFS_XF_SYSTEM_FIELD 0x20
+#define APFS_XF_RESERVED_40 0x40
+#define APFS_XF_RESERVED_80 0x80
+
/* Constants for extended fields */
#define APFS_MIN_DOC_ID 3 /* Smallest not reserved document id */

@@ -192,5 +202,6 @@ extern void set_or_check_sibling(u64 parent_id, int namelen, u8 *name,
struct sibling *sibling);
extern void parse_sibling_record(struct apfs_sibling_link_key *key,
struct apfs_sibling_val *val, int len);
+extern void check_xfield_flags(u8 flags);

#endif /* _INODE_H */
--
2.11.0

[Ernesto A. Fernández]

Verify that extended fields of known types have the expected set of
flags. This information has been obtained via testing, and some choices
don't seem to make sense yet.

Signed-off-by: Ernesto A. Fernández <ernesto.mn...@gmail.com>
---

apfsck/inode.c | 12 +++++++++++-
1 file changed, 11 insertions(+), 1 deletion(-)

diff --git a/apfsck/inode.c b/apfsck/inode.c
index 2e6a2be..cce1e87 100644
--- a/apfsck/inode.c
+++ b/apfsck/inode.c
@@ -356,8 +356,9 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,

for (i = 0; i < le16_to_cpu(xblob->xf_num_exts); ++i) {
int xlen, xpad_len;

u16 type_flag;
+ u8 xflags = xfield[i].x_flags;

- check_xfield_flags(xfield[i].x_flags);
+ check_xfield_flags(xflags);

switch (xfield[i].x_type) {
case APFS_INO_EXT_TYPE_FS_UUID:

@@ -365,12 +366,17 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,
break;
case APFS_INO_EXT_TYPE_PREV_FSIZE:
printf("Inode xfield: filesystem has crashed.\n");
+ if (xflags != 0)
+ report("Previous size xfield", "wrong flags.");
case APFS_INO_EXT_TYPE_SNAP_XID:
case APFS_INO_EXT_TYPE_DELTA_TREE_OID:
xlen = 8;
break;
case APFS_INO_EXT_TYPE_SPARSE_BYTES:
xlen = read_sparse_bytes_xfield(xval, len, inode);
+ if (xflags != (APFS_XF_SYSTEM_FIELD |
+ APFS_XF_CHILDREN_INHERIT))
+ report("Sparse bytes xfield", "wrong flags.");
break;
case APFS_INO_EXT_TYPE_DOCUMENT_ID:
xlen = read_document_id_xfield(xval, len, inode);
@@ -383,9 +389,13 @@ static void parse_inode_xfields(struct apfs_xf_blob *xblob, int len,
break;
case APFS_INO_EXT_TYPE_NAME:
xlen = read_name_xfield(xval, len, inode);
+ if (xflags != APFS_XF_DO_NOT_COPY)
+ report("Name xfield", "wrong flags.");
break;
case APFS_INO_EXT_TYPE_DSTREAM:
xlen = read_dstream_xfield(xval, len, inode);
+ if (xflags != APFS_XF_SYSTEM_FIELD)
+ report("Data stream xfield", "wrong flags.");
break;
case APFS_INO_EXT_TYPE_DIR_STATS_KEY:
xlen = sizeof(struct apfs_dir_stats_val);
--
2.11.0