openrisc: fix arbitrary kernel memory access via or1k_atomic syscallgrafted

sys_or1k_atomic() (syscall 244 in the "or1k" ABI) takes two user
pointers, v1 and v2, and swaps the words they point to in hand-written
assembly.

    l.lwz   r29,0(r4)
    l.lwz   r27,0(r5)
    l.sw    0(r4),r27
    l.sw    0(r5),r29

The pointers are not checked with access_ok(). The four memory
accesses also have no exception table entries.

A caller passes a kernel address as either pointer, and the syscall
reads from and writes to it directly.

This gives an unprivileged process a kernel read/write primitive. It
overwrites kernel data such as the sys_call_table, gaining code
execution in kernel context.

Check both pointers before entering the critical section. Add fixups
for the four memory accesses so faults on valid but unmapped user
addresses return -EFAULT.

[shorne@gmail.com: fix comment style]
Fixes: 9d02a4283e9c ("OpenRISC: Boot code")
Cc: stable@vger.kernel.org
Signed-off-by: Ali Ahmet Memis <ali@iusegentoo.com>
Signed-off-by: Stafford Horne <shorne@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