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, 79 insertions, 0 deletions

diff --git a/io_uring/net.h b/io_uring/net.h
new file mode 100644
index 000000000..51fda715d
--- /dev/null
+++ b/io_uring/net.h
@@ -0,0 +1,79 @@
+// SPDX-License-Identifier: GPL-2.0
+
+#include <linux/net.h>
+#include <linux/uio.h>
+#include <linux/io_uring_types.h>
+#include <uapi/linux/io_uring/bpf_filter.h>
+
+struct io_async_msghdr {
+#if defined(CONFIG_NET)
+	struct iou_vec				vec;
+
+	struct_group(clear,
+		int				namelen;
+		struct iovec			fast_iov;
+		__kernel_size_t			controllen;
+		__kernel_size_t			payloadlen;
+		struct sockaddr __user		*uaddr;
+		struct msghdr			msg;
+		struct sockaddr_storage		addr;
+	);
+#else
+	struct_group(clear);
+#endif
+};
+
+#if defined(CONFIG_NET)
+
+int io_shutdown_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_shutdown(struct io_kiocb *req, unsigned int issue_flags);
+
+void io_sendmsg_recvmsg_cleanup(struct io_kiocb *req);
+int io_sendmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_sendmsg(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_send(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_recvmsg_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_recvmsg(struct io_kiocb *req, unsigned int issue_flags);
+int io_recv(struct io_kiocb *req, unsigned int issue_flags);
+
+void io_sendrecv_fail(struct io_kiocb *req);
+
+int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_accept(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_socket_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_socket(struct io_kiocb *req, unsigned int issue_flags);
+void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req);
+void io_connect_bpf_populate(struct io_uring_bpf_ctx *bctx, struct io_kiocb *req);
+
+int io_connect_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_connect(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_sendmsg_zc(struct io_kiocb *req, unsigned int issue_flags);
+int io_send_zc_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+void io_send_zc_cleanup(struct io_kiocb *req);
+
+int io_bind_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_bind(struct io_kiocb *req, unsigned int issue_flags);
+
+int io_listen_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe);
+int io_listen(struct io_kiocb *req, unsigned int issue_flags);
+
+void io_netmsg_cache_free(const void *entry);
+#else
+static inline void io_netmsg_cache_free(const void *entry)
+{
+}
+static inline void io_socket_bpf_populate(struct io_uring_bpf_ctx *bctx,
+					  struct io_kiocb *req)
+{
+}
+
+static inline void io_connect_bpf_populate(struct io_uring_bpf_ctx *bctx,
+					   struct io_kiocb *req)
+{
+}
+
+#endif