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, 209 insertions, 0 deletions

diff --git a/security/tomoyo/group.c b/security/tomoyo/group.c
new file mode 100644
index 000000000..1cecdd797
--- /dev/null
+++ b/security/tomoyo/group.c
@@ -0,0 +1,209 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * security/tomoyo/group.c
+ *
+ * Copyright (C) 2005-2011  NTT DATA CORPORATION
+ */
+
+#include <linux/slab.h>
+#include <linux/rculist.h>
+
+#include "common.h"
+
+/**
+ * tomoyo_same_path_group - Check for duplicated "struct tomoyo_path_group" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_head".
+ * @b: Pointer to "struct tomoyo_acl_head".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static bool tomoyo_same_path_group(const struct tomoyo_acl_head *a,
+				   const struct tomoyo_acl_head *b)
+{
+	return container_of(a, struct tomoyo_path_group, head)->member_name ==
+		container_of(b, struct tomoyo_path_group, head)->member_name;
+}
+
+/**
+ * tomoyo_same_number_group - Check for duplicated "struct tomoyo_number_group" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_head".
+ * @b: Pointer to "struct tomoyo_acl_head".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static bool tomoyo_same_number_group(const struct tomoyo_acl_head *a,
+				     const struct tomoyo_acl_head *b)
+{
+	return !memcmp(&container_of(a, struct tomoyo_number_group, head)
+		       ->number,
+		       &container_of(b, struct tomoyo_number_group, head)
+		       ->number,
+		       sizeof(container_of(a, struct tomoyo_number_group, head)
+			      ->number));
+}
+
+/**
+ * tomoyo_same_address_group - Check for duplicated "struct tomoyo_address_group" entry.
+ *
+ * @a: Pointer to "struct tomoyo_acl_head".
+ * @b: Pointer to "struct tomoyo_acl_head".
+ *
+ * Returns true if @a == @b, false otherwise.
+ */
+static bool tomoyo_same_address_group(const struct tomoyo_acl_head *a,
+				      const struct tomoyo_acl_head *b)
+{
+	const struct tomoyo_address_group *p1 = container_of(a, typeof(*p1),
+							     head);
+	const struct tomoyo_address_group *p2 = container_of(b, typeof(*p2),
+							     head);
+
+	return tomoyo_same_ipaddr_union(&p1->address, &p2->address);
+}
+
+/**
+ * tomoyo_write_group - Write "struct tomoyo_path_group"/"struct tomoyo_number_group"/"struct tomoyo_address_group" list.
+ *
+ * @param: Pointer to "struct tomoyo_acl_param".
+ * @type:  Type of this group.
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+int tomoyo_write_group(struct tomoyo_acl_param *param, const u8 type)
+{
+	struct tomoyo_group *group = tomoyo_get_group(param, type);
+	int error = -EINVAL;
+
+	if (!group)
+		return -ENOMEM;
+	param->list = &group->member_list;
+	if (type == TOMOYO_PATH_GROUP) {
+		struct tomoyo_path_group e = { };
+
+		e.member_name = tomoyo_get_name(tomoyo_read_token(param));
+		if (!e.member_name) {
+			error = -ENOMEM;
+			goto out;
+		}
+		error = tomoyo_update_policy(&e.head, sizeof(e), param,
+					  tomoyo_same_path_group);
+		tomoyo_put_name(e.member_name);
+	} else if (type == TOMOYO_NUMBER_GROUP) {
+		struct tomoyo_number_group e = { };
+
+		if (param->data[0] == '@' ||
+		    !tomoyo_parse_number_union(param, &e.number))
+			goto out;
+		error = tomoyo_update_policy(&e.head, sizeof(e), param,
+					  tomoyo_same_number_group);
+		/*
+		 * tomoyo_put_number_union() is not needed because
+		 * param->data[0] != '@'.
+		 */
+	} else {
+		struct tomoyo_address_group e = { };
+
+		if (param->data[0] == '@' ||
+		    !tomoyo_parse_ipaddr_union(param, &e.address))
+			goto out;
+		error = tomoyo_update_policy(&e.head, sizeof(e), param,
+					     tomoyo_same_address_group);
+	}
+out:
+	tomoyo_put_group(group);
+	return error;
+}
+
+/**
+ * tomoyo_path_matches_group - Check whether the given pathname matches members of the given pathname group.
+ *
+ * @pathname: The name of pathname.
+ * @group:    Pointer to "struct tomoyo_path_group".
+ *
+ * Returns matched member's pathname if @pathname matches pathnames in @group,
+ * NULL otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+const struct tomoyo_path_info *
+tomoyo_path_matches_group(const struct tomoyo_path_info *pathname,
+			  const struct tomoyo_group *group)
+{
+	struct tomoyo_path_group *member;
+
+	list_for_each_entry_rcu(member, &group->member_list, head.list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (member->head.is_deleted)
+			continue;
+		if (!tomoyo_path_matches_pattern(pathname, member->member_name))
+			continue;
+		return member->member_name;
+	}
+	return NULL;
+}
+
+/**
+ * tomoyo_number_matches_group - Check whether the given number matches members of the given number group.
+ *
+ * @min:   Min number.
+ * @max:   Max number.
+ * @group: Pointer to "struct tomoyo_number_group".
+ *
+ * Returns true if @min and @max partially overlaps @group, false otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+bool tomoyo_number_matches_group(const unsigned long min,
+				 const unsigned long max,
+				 const struct tomoyo_group *group)
+{
+	struct tomoyo_number_group *member;
+	bool matched = false;
+
+	list_for_each_entry_rcu(member, &group->member_list, head.list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (member->head.is_deleted)
+			continue;
+		if (min > member->number.values[1] ||
+		    max < member->number.values[0])
+			continue;
+		matched = true;
+		break;
+	}
+	return matched;
+}
+
+/**
+ * tomoyo_address_matches_group - Check whether the given address matches members of the given address group.
+ *
+ * @is_ipv6: True if @address is an IPv6 address.
+ * @address: An IPv4 or IPv6 address.
+ * @group:   Pointer to "struct tomoyo_address_group".
+ *
+ * Returns true if @address matches addresses in @group group, false otherwise.
+ *
+ * Caller holds tomoyo_read_lock().
+ */
+bool tomoyo_address_matches_group(const bool is_ipv6, const __be32 *address,
+				  const struct tomoyo_group *group)
+{
+	struct tomoyo_address_group *member;
+	bool matched = false;
+	const u8 size = is_ipv6 ? 16 : 4;
+
+	list_for_each_entry_rcu(member, &group->member_list, head.list,
+				srcu_read_lock_held(&tomoyo_ss)) {
+		if (member->head.is_deleted)
+			continue;
+		if (member->address.is_ipv6 != is_ipv6)
+			continue;
+		if (memcmp(&member->address.ip[0], address, size) > 0 ||
+		    memcmp(address, &member->address.ip[1], size) > 0)
+			continue;
+		matched = true;
+		break;
+	}
+	return matched;
+}