kbuild: rust: keep Rust objects out of Clang LTO with inline helpersgrafted

Under `CONFIG_LTO_CLANG` + `CONFIG_RUST_INLINE_HELPERS`, one may hit
`objtool` errors such as:

    vmlinux.o: error: objtool: _R..._3Gsp4boot+0xd6a:
    can't find jump dest instruction at .text._R..._3Gsp4boot+0x1dfd

The reason is that in such builds, the Clang invocation that compiles
the combined Rust plus helpers bitcode emits LLVM bitcode (again) --
the final code generation happens in the linker's LTO step, which the
`-mllvm` trap options passed to Clang do not reach.

This, in turn, means that unreachable traps are missing, and the
impossible paths do not merely fallthrough to the next symbol, but past
the end of their own section, since LTO builds place each function in
its own section.

Thus filter `CC_FLAGS_LTO` out of the Clang invocation, so that it always
emits machine code directly, with the traps in place.

Assisted-by: LLM
Cc: Gary Guo <gary@garyguo.net>
Cc: Boqun Feng <boqun@kernel.org>
Cc: Alice Ryhl <aliceryhl@google.com>
Cc: Matthew Maurer <mmaurer@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: stable@vger.kernel.org
Fixes: 3a2486cc1da5 ("kbuild: rust: provide an option to inline C helpers into Rust")
Acked-by: Gary Guo <gary@garyguo.net>
Link: https://patch.msgid.link/20260816133233.197500-2-ojeda@kernel.org
Signed-off-by: Miguel Ojeda <ojeda@kernel.org>

1 files changed, 137 insertions, 0 deletions

diff --git a/security/selinux/include/netlabel.h b/security/selinux/include/netlabel.h
new file mode 100644
index 000000000..5731c0dcd
--- /dev/null
+++ b/security/selinux/include/netlabel.h
@@ -0,0 +1,137 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ * SELinux interface to the NetLabel subsystem
+ *
+ * Author: Paul Moore <paul@paul-moore.com>
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ */
+
+#ifndef _SELINUX_NETLABEL_H_
+#define _SELINUX_NETLABEL_H_
+
+#include <linux/types.h>
+#include <linux/fs.h>
+#include <linux/net.h>
+#include <linux/skbuff.h>
+#include <net/sock.h>
+#include <net/request_sock.h>
+#include <net/sctp/structs.h>
+
+#include "avc.h"
+#include "objsec.h"
+
+#ifdef CONFIG_NETLABEL
+void selinux_netlbl_cache_invalidate(void);
+
+void selinux_netlbl_err(struct sk_buff *skb, u16 family, int error,
+			int gateway);
+
+void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec);
+void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec);
+
+int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u16 family, u32 *type,
+				 u32 *sid);
+int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, u16 family, u32 sid);
+int selinux_netlbl_sctp_assoc_request(struct sctp_association *asoc,
+				      struct sk_buff *skb);
+int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family);
+void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family);
+void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk);
+int selinux_netlbl_socket_post_create(struct sock *sk, u16 family);
+int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
+				struct sk_buff *skb, u16 family,
+				struct common_audit_data *ad);
+int selinux_netlbl_socket_setsockopt(struct socket *sock, int level,
+				     int optname);
+int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr);
+int selinux_netlbl_socket_connect_locked(struct sock *sk,
+					 struct sockaddr *addr);
+
+#else
+static inline void selinux_netlbl_cache_invalidate(void)
+{
+	return;
+}
+
+static inline void selinux_netlbl_err(struct sk_buff *skb, u16 family,
+				      int error, int gateway)
+{
+	return;
+}
+
+static inline void
+selinux_netlbl_sk_security_free(struct sk_security_struct *sksec)
+{
+	return;
+}
+
+static inline void
+selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec)
+{
+	return;
+}
+
+static inline int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u16 family,
+					       u32 *type, u32 *sid)
+{
+	*type = NETLBL_NLTYPE_NONE;
+	*sid = SECSID_NULL;
+	return 0;
+}
+static inline int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, u16 family,
+					       u32 sid)
+{
+	return 0;
+}
+
+static inline int
+selinux_netlbl_sctp_assoc_request(struct sctp_association *asoc,
+				  struct sk_buff *skb)
+{
+	return 0;
+}
+static inline int selinux_netlbl_inet_conn_request(struct request_sock *req,
+						   u16 family)
+{
+	return 0;
+}
+static inline void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
+{
+	return;
+}
+static inline void selinux_netlbl_sctp_sk_clone(struct sock *sk,
+						struct sock *newsk)
+{
+	return;
+}
+static inline int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
+{
+	return 0;
+}
+static inline int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
+					      struct sk_buff *skb, u16 family,
+					      struct common_audit_data *ad)
+{
+	return 0;
+}
+static inline int selinux_netlbl_socket_setsockopt(struct socket *sock,
+						   int level, int optname)
+{
+	return 0;
+}
+static inline int selinux_netlbl_socket_connect(struct sock *sk,
+						struct sockaddr *addr)
+{
+	return 0;
+}
+static inline int selinux_netlbl_socket_connect_locked(struct sock *sk,
+						       struct sockaddr *addr)
+{
+	return 0;
+}
+#endif /* CONFIG_NETLABEL */
+
+#endif