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bcachefs: Stricter checks on "key allowed in this btree"

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Syzbot managed to come up with a filesystem where check/repair got
rather confused at finding a reflink pointer in the inodes btree.

Currently, the "key allowed in this btree" checks only apply at commit
time, not read time - for forwards compatibility. It seems this is too
loose.

Now, strict key type allowed checks apply:
 - at commit time (no forward compatibility issues)
 - for btree node pointers
 - if it's a known btree, known key type, and the key type has the
   "BKEY_TYPE_strict_btree_checks" flag.

This means we still have the option of using generic key types - e.g.
KEY_TYPE_error, KEY_TYPE_set - on more existing btrees in the future,
while most key types that are intended for only a specific btree get
stricter checks.

Reported-by: syzbot+baee8591f336cab0958b@syzkaller.appspotmail.com
Signed-off-by: Kent Overstreet <kent.overstreet@linux.dev>
This commit is contained in:
Kent Overstreet
2025-04-18 12:49:00 -04:00
parent 417f01e726
commit 71f8e806a5
2 changed files with 62 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files
fs/bcachefs/bcachefs_format.h
+42 -38
View File
@@ -366,6 +366,10 @@ static inline void bkey_init(struct bkey *k)
#define __BKEY_PADDED(key, pad) \
struct bkey_i key; __u64 key ## _pad[pad]
enum bch_bkey_type_flags {
BKEY_TYPE_strict_btree_checks = BIT(0),
};
/*
* - DELETED keys are used internally to mark keys that should be ignored but
* override keys in composition order. Their version number is ignored.
@@ -383,46 +387,46 @@ static inline void bkey_init(struct bkey *k)
*
* - WHITEOUT: for hash table btrees
*/
#define BCH_BKEY_TYPES() \
x(deleted, 0) \
x(whiteout, 1) \
x(error, 2) \
x(cookie, 3) \
x(hash_whiteout, 4) \
x(btree_ptr, 5) \
x(extent, 6) \
x(reservation, 7) \
x(inode, 8) \
x(inode_generation, 9) \
x(dirent, 10) \
x(xattr, 11) \
x(alloc, 12) \
x(quota, 13) \
x(stripe, 14) \
x(reflink_p, 15) \
x(reflink_v, 16) \
x(inline_data, 17) \
x(btree_ptr_v2, 18) \
x(indirect_inline_data, 19) \
x(alloc_v2, 20) \
x(subvolume, 21) \
x(snapshot, 22) \
x(inode_v2, 23) \
x(alloc_v3, 24) \
x(set, 25) \
x(lru, 26) \
x(alloc_v4, 27) \
x(backpointer, 28) \
x(inode_v3, 29) \
x(bucket_gens, 30) \
x(snapshot_tree, 31) \
x(logged_op_truncate, 32) \
x(logged_op_finsert, 33) \
x(accounting, 34) \
x(inode_alloc_cursor, 35)
#define BCH_BKEY_TYPES() \
x(deleted, 0, 0) \
x(whiteout, 1, 0) \
x(error, 2, 0) \
x(cookie, 3, 0) \
x(hash_whiteout, 4, BKEY_TYPE_strict_btree_checks) \
x(btree_ptr, 5, BKEY_TYPE_strict_btree_checks) \
x(extent, 6, BKEY_TYPE_strict_btree_checks) \
x(reservation, 7, BKEY_TYPE_strict_btree_checks) \
x(inode, 8, BKEY_TYPE_strict_btree_checks) \
x(inode_generation, 9, BKEY_TYPE_strict_btree_checks) \
x(dirent, 10, BKEY_TYPE_strict_btree_checks) \
x(xattr, 11, BKEY_TYPE_strict_btree_checks) \
x(alloc, 12, BKEY_TYPE_strict_btree_checks) \
x(quota, 13, BKEY_TYPE_strict_btree_checks) \
x(stripe, 14, BKEY_TYPE_strict_btree_checks) \
x(reflink_p, 15, BKEY_TYPE_strict_btree_checks) \
x(reflink_v, 16, BKEY_TYPE_strict_btree_checks) \
x(inline_data, 17, BKEY_TYPE_strict_btree_checks) \
x(btree_ptr_v2, 18, BKEY_TYPE_strict_btree_checks) \
x(indirect_inline_data, 19, BKEY_TYPE_strict_btree_checks) \
x(alloc_v2, 20, BKEY_TYPE_strict_btree_checks) \
x(subvolume, 21, BKEY_TYPE_strict_btree_checks) \
x(snapshot, 22, BKEY_TYPE_strict_btree_checks) \
x(inode_v2, 23, BKEY_TYPE_strict_btree_checks) \
x(alloc_v3, 24, BKEY_TYPE_strict_btree_checks) \
x(set, 25, 0) \
x(lru, 26, BKEY_TYPE_strict_btree_checks) \
x(alloc_v4, 27, BKEY_TYPE_strict_btree_checks) \
x(backpointer, 28, BKEY_TYPE_strict_btree_checks) \
x(inode_v3, 29, BKEY_TYPE_strict_btree_checks) \
x(bucket_gens, 30, BKEY_TYPE_strict_btree_checks) \
x(snapshot_tree, 31, BKEY_TYPE_strict_btree_checks) \
x(logged_op_truncate, 32, BKEY_TYPE_strict_btree_checks) \
x(logged_op_finsert, 33, BKEY_TYPE_strict_btree_checks) \
x(accounting, 34, BKEY_TYPE_strict_btree_checks) \
x(inode_alloc_cursor, 35, BKEY_TYPE_strict_btree_checks)
enum bch_bkey_type {
#define x(name, nr) KEY_TYPE_##name = nr,
#define x(name, nr, ...) KEY_TYPE_##name = nr,
BCH_BKEY_TYPES()
#undef x
KEY_TYPE_MAX,
fs/bcachefs/bkey_methods.c
+20 -4
View File
@@ -21,7 +21,7 @@
#include "xattr.h"
const char * const bch2_bkey_types[] = {
#define x(name, nr) #name,
#define x(name, nr, ...) #name,
BCH_BKEY_TYPES()
#undef x
NULL
@@ -115,7 +115,7 @@ static bool key_type_set_merge(struct bch_fs *c, struct bkey_s l, struct bkey_s_
})
const struct bkey_ops bch2_bkey_ops[] = {
#define x(name, nr) [KEY_TYPE_##name] = bch2_bkey_ops_##name,
#define x(name, nr, ...) [KEY_TYPE_##name] = bch2_bkey_ops_##name,
BCH_BKEY_TYPES()
#undef x
};
@@ -155,6 +155,12 @@ static u64 bch2_key_types_allowed[] = {
#undef x
};
static const enum bch_bkey_type_flags bch2_bkey_type_flags[] = {
#define x(name, nr, flags) [KEY_TYPE_##name] = flags,
BCH_BKEY_TYPES()
#undef x
};
const char *bch2_btree_node_type_str(enum btree_node_type type)
{
return type == BKEY_TYPE_btree ? "internal btree node" : bch2_btree_id_str(type - 1);
@@ -177,8 +183,18 @@ int __bch2_bkey_validate(struct bch_fs *c, struct bkey_s_c k,
if (type >= BKEY_TYPE_NR)
return 0;
bkey_fsck_err_on(k.k->type < KEY_TYPE_MAX &&
(type == BKEY_TYPE_btree || (from.flags & BCH_VALIDATE_commit)) &&
enum bch_bkey_type_flags bkey_flags = k.k->type < KEY_TYPE_MAX
? bch2_bkey_type_flags[k.k->type]
: 0;
bool strict_key_type_allowed =
(from.flags & BCH_VALIDATE_commit) ||
type == BKEY_TYPE_btree ||
(from.btree < BTREE_ID_NR &&
(bkey_flags & BKEY_TYPE_strict_btree_checks));
bkey_fsck_err_on(strict_key_type_allowed &&
k.k->type < KEY_TYPE_MAX &&
!(bch2_key_types_allowed[type] & BIT_ULL(k.k->type)),
c, bkey_invalid_type_for_btree,
"invalid key type for btree %s (%s)",