selftests/bpf: Test packet range of pointers sharing an idgrafted

Add tests where two packet pointers share an id and tightening one
pointer's umax from its var_off would put it less than their constant
distance from the other's umax: with an index & 0x38 capped at 50, the
base pointer keeps umax 50, so the pointer 8 bytes further on must keep
umax 58, even though its known bits allow at most 56.

These refused a valid program or accepted an out-of-bounds access before
the fix:

- check the advanced copy, load through the base: valid, was refused;
- check the base, load the byte at base + 1 through a copy advanced by
  8: was accepted;
- check base + 4, load 4 bytes at base + 2 through base + 8: reads two
  bytes past the checked range, was accepted;
- the same as the second with data_meta pointers checked against data:
  was accepted.

These pass with and without the fix and cover nearby paths:

- subtract an unknown scalar from a checked pointer and load below it
  (the range is kept across a new id);
- reach a load through two paths whose checks cover 8 and 7 bytes after
  the loaded pointer; the second path must not be pruned by the first;
- spill a copy of a pointer, check the pointer, fill the copy and load
  one byte past the checked range: the load is refused, and the copy
  has the range of the check.

Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20261001145255.855630-2-alexei.starovoitov@gmail.com
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>

1 files changed, 76 insertions, 0 deletions

diff --git a/fs/nfsd/blocklayoutxdr.h b/fs/nfsd/blocklayoutxdr.h
new file mode 100644
index 000000000..2e0c6c7d2
--- /dev/null
+++ b/fs/nfsd/blocklayoutxdr.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#ifndef _NFSD_BLOCKLAYOUTXDR_H
+#define _NFSD_BLOCKLAYOUTXDR_H 1
+
+#include <linux/blkdev.h>
+#include "xdr4.h"
+
+struct iomap;
+struct xdr_stream;
+
+/* On the wire size of the layout4 struct with zero number of extents */
+#define PNFS_BLOCK_LAYOUT4_SIZE \
+	(sizeof(__be32) * 2 +	/* offset4 */ \
+	 sizeof(__be32) * 2 +	/* length4 */ \
+	 sizeof(__be32) +	/* layoutiomode4 */ \
+	 sizeof(__be32) +	/* layouttype4 */ \
+	 sizeof(__be32) +	/* number of bytes */ \
+	 sizeof(__be32))	/* number of extents */
+
+struct pnfs_block_extent {
+	struct nfsd4_deviceid		vol_id;
+	u64				foff;
+	u64				len;
+	u64				soff;
+	enum pnfs_block_extent_state	es;
+};
+
+struct pnfs_block_range {
+	u64				foff;
+	u64				len;
+};
+
+struct pnfs_block_layout {
+	u32				nr_extents;
+	struct pnfs_block_extent	extents[] __counted_by(nr_extents);
+};
+
+/*
+ * Random upper cap for the uuid length to avoid unbounded allocation.
+ * Not actually limited by the protocol.
+ */
+#define PNFS_BLOCK_UUID_LEN	128
+
+struct pnfs_block_volume {
+	enum pnfs_block_volume_type	type;
+	union {
+		struct {
+			u64		offset;
+			u32		sig_len;
+			u8		sig[PNFS_BLOCK_UUID_LEN];
+		} simple;
+		struct {
+			enum scsi_code_set		code_set;
+			enum scsi_designator_type	designator_type;
+			int				designator_len;
+			u8				designator[256];
+			u64				pr_key;
+		} scsi;
+	};
+};
+
+struct pnfs_block_deviceaddr {
+	u32				nr_volumes;
+	struct pnfs_block_volume	volumes[] __counted_by(nr_volumes);
+};
+
+__be32 nfsd4_block_encode_getdeviceinfo(struct xdr_stream *xdr,
+		const struct nfsd4_getdeviceinfo *gdp);
+__be32 nfsd4_block_encode_layoutget(struct xdr_stream *xdr,
+		const struct nfsd4_layoutget *lgp);
+__be32 nfsd4_block_decode_layoutupdate(struct xdr_stream *xdr,
+		struct iomap **iomapp, int *nr_iomapsp, u32 block_size);
+__be32 nfsd4_scsi_decode_layoutupdate(struct xdr_stream *xdr,
+		struct iomap **iomapp, int *nr_iomapsp, u32 block_size);
+
+#endif /* _NFSD_BLOCKLAYOUTXDR_H */