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btrfs: qgroup: validate btrfs_qgroup_inherit parameter

[BUG] Currently btrfs can create subvolume with an invalid qgroup inherit without triggering any error: # mkfs.btrfs -O quota -f $dev # mount $dev $mnt # btrfs subvolume create -i 2/0 $mnt/subv1 # btrfs qgroup show -prce --sync $mnt Qgroupid Referenced Exclusive Path -------- ---------- --------- ---- 0/5 16.00KiB 16.00KiB <toplevel> 0/256 16.00KiB 16.00KiB subv1 [CAUSE] We only do a very basic size check for btrfs_qgroup_inherit structure, but never really verify if the values are correct. Thus in btrfs_qgroup_inherit() function, we have to skip non-existing qgroups, and never return any error. [FIX] Fix the behavior and introduce extra checks: - Introduce early check for btrfs_qgroup_inherit structure Not only the size, but also all the qgroup ids would be verified. And the timing is very early, so we can return error early. This early check is very important for snapshot creation, as snapshot is delayed to transaction commit. - Drop support for btrfs_qgroup_inherit::num_ref_copies and num_excl_copies Those two members are used to specify to copy refr/excl numbers from other qgroups. This would definitely mark qgroup inconsistent, and btrfs-progs has dropped the support for them for a long time. It's time to drop the support for kernel. - Verify the supported btrfs_qgroup_inherit::flags Just in case we want to add extra flags for btrfs_qgroup_inherit. Now above subvolume creation would fail with -ENOENT other than silently ignore the non-existing qgroup.

Qu Wenruo committed 2 years ago

Commit 86211ee1 parent 07823034 files · +58 −13Browse files

Unified · Split

4 files
  1. fs/btrfs/ioctl.c +3 −13
  2. fs/btrfs/qgroup.c +51 −0
  3. fs/btrfs/qgroup.h +3 −0
  4. include/uapi/linux/btrfs.h +1 −0
fs/btrfs/ioctl.c+3−13
@@ -1382,7 +1382,7 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file, · 1381 unmodified lines
13821382 if (vol_args->flags & BTRFS_SUBVOL_RDONLY)
13831383 readonly = true;
13841384 if (vol_args->flags & BTRFS_SUBVOL_QGROUP_INHERIT) {
1385− u64 nums;
1385+ struct btrfs_fs_info *fs_info = inode_to_fs_info(file_inode(file));
13861386
13871387 if (vol_args->size < sizeof(*inherit) ||
13881388 vol_args->size > PAGE_SIZE) {
@@ -1395,19 +1395,9 @@ static noinline int btrfs_ioctl_snap_create_v2(struct file *file, · 6 unmodified lines
13951395 goto free_args;
13961396 }
13971397
1398− if (inherit->num_qgroups > PAGE_SIZE ||
1399− inherit->num_ref_copies > PAGE_SIZE ||
1400− inherit->num_excl_copies > PAGE_SIZE) {
1401− ret = -EINVAL;
1402− goto free_inherit;
1403− }
1404−
1405− nums = inherit->num_qgroups + 2 * inherit->num_ref_copies +
1406− 2 * inherit->num_excl_copies;
1407− if (vol_args->size != struct_size(inherit, qgroups, nums)) {
1408− ret = -EINVAL;
1398+ ret = btrfs_qgroup_check_inherit(fs_info, inherit, vol_args->size);
1399+ if (ret < 0)
14091400 goto free_inherit;
1410− }
14111401 }
14121402
14131403 ret = __btrfs_ioctl_snap_create(file, file_mnt_idmap(file),
fs/btrfs/qgroup.c+51−0
@@ -3046,6 +3046,57 @@ int btrfs_run_qgroups(struct btrfs_trans_handle *trans) · 3045 unmodified lines
30463046 return ret;
30473047 }
30483048
3049+int btrfs_qgroup_check_inherit(struct btrfs_fs_info *fs_info,
3050+ struct btrfs_qgroup_inherit *inherit,
3051+ size_t size)
3052+{
3053+ if (inherit->flags & ~BTRFS_QGROUP_INHERIT_FLAGS_SUPP)
3054+ return -EOPNOTSUPP;
3055+ if (size < sizeof(*inherit) || size > PAGE_SIZE)
3056+ return -EINVAL;
3057+
3058+ /*
3059+ * In the past we allowed btrfs_qgroup_inherit to specify to copy
3060+ * rfer/excl numbers directly from other qgroups. This behavior has
3061+ * been disabled in userspace for a very long time, but here we should
3062+ * also disable it in kernel, as this behavior is known to mark qgroup
3063+ * inconsistent, and a rescan would wipe out the changes anyway.
3064+ *
3065+ * Reject any btrfs_qgroup_inherit with num_ref_copies or num_excl_copies.
3066+ */
3067+ if (inherit->num_ref_copies > 0 || inherit->num_excl_copies > 0)
3068+ return -EINVAL;
3069+
3070+ if (inherit->num_qgroups > PAGE_SIZE)
3071+ return -EINVAL;
3072+
3073+ if (size != struct_size(inherit, qgroups, inherit->num_qgroups))
3074+ return -EINVAL;
3075+
3076+ /*
3077+ * Now check all the remaining qgroups, they should all:
3078+ *
3079+ * - Exist
3080+ * - Be higher level qgroups.
3081+ */
3082+ for (int i = 0; i < inherit->num_qgroups; i++) {
3083+ struct btrfs_qgroup *qgroup;
3084+ u64 qgroupid = inherit->qgroups[i];
3085+
3086+ if (btrfs_qgroup_level(qgroupid) == 0)
3087+ return -EINVAL;
3088+
3089+ spin_lock(&fs_info->qgroup_lock);
3090+ qgroup = find_qgroup_rb(fs_info, qgroupid);
3091+ if (!qgroup) {
3092+ spin_unlock(&fs_info->qgroup_lock);
3093+ return -ENOENT;
3094+ }
3095+ spin_unlock(&fs_info->qgroup_lock);
3096+ }
3097+ return 0;
3098+}
3099+
30493100 static int qgroup_auto_inherit(struct btrfs_fs_info *fs_info,
30503101 u64 inode_rootid,
30513102 struct btrfs_qgroup_inherit **inherit)
fs/btrfs/qgroup.h+3−0
@@ -350,6 +350,9 @@ int btrfs_qgroup_account_extent(struct btrfs_trans_handle *trans, u64 bytenr, · 349 unmodified lines
350350 struct ulist *new_roots);
351351 int btrfs_qgroup_account_extents(struct btrfs_trans_handle *trans);
352352 int btrfs_run_qgroups(struct btrfs_trans_handle *trans);
353+int btrfs_qgroup_check_inherit(struct btrfs_fs_info *fs_info,
354+ struct btrfs_qgroup_inherit *inherit,
355+ size_t size);
353356 int btrfs_qgroup_inherit(struct btrfs_trans_handle *trans, u64 srcid,
354357 u64 objectid, u64 inode_rootid,
355358 struct btrfs_qgroup_inherit *inherit);
include/uapi/linux/btrfs.h+1−0
@@ -92,6 +92,7 @@ struct btrfs_qgroup_limit { · 91 unmodified lines
9292 * struct btrfs_qgroup_inherit.flags
9393 */
9494 #define BTRFS_QGROUP_INHERIT_SET_LIMITS (1ULL << 0)
95+#define BTRFS_QGROUP_INHERIT_FLAGS_SUPP (BTRFS_QGROUP_INHERIT_SET_LIMITS)
9596
9697 struct btrfs_qgroup_inherit {
9798 __u64 flags;