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, 291 insertions, 0 deletions

diff --git a/security/apparmor/audit.c b/security/apparmor/audit.c
new file mode 100644
index 000000000..4a60b6fda
--- /dev/null
+++ b/security/apparmor/audit.c
@@ -0,0 +1,291 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor auditing functions
+ *
+ * Copyright (C) 1998-2008 Novell/SUSE
+ * Copyright 2009-2010 Canonical Ltd.
+ */
+
+#include <linux/audit.h>
+#include <linux/socket.h>
+
+#include "include/apparmor.h"
+#include "include/audit.h"
+#include "include/policy.h"
+#include "include/policy_ns.h"
+#include "include/secid.h"
+
+const char *const audit_mode_names[] = {
+	"normal",
+	"quiet_denied",
+	"quiet",
+	"noquiet",
+	"all"
+};
+
+static const char *const aa_audit_type[] = {
+	"AUDIT",
+	"ALLOWED",
+	"DENIED",
+	"HINT",
+	"STATUS",
+	"ERROR",
+	"KILLED",
+	"AUTO"
+};
+
+static const char *const aa_class_names[] = {
+	"none",
+	"unknown",
+	"file",
+	"cap",
+	"net",
+	"rlimits",
+	"domain",
+	"mount",
+	"unknown",
+	"ptrace",
+	"signal",
+	"xmatch",
+	"unknown",
+	"unknown",
+	"net",
+	"unknown",
+	"label",
+	"posix_mqueue",
+	"io_uring",
+	"module",
+	"lsm",
+	"namespace",
+	"io_uring",
+	"unknown",
+	"unknown",
+	"unknown",
+	"unknown",
+	"unknown",
+	"unknown",
+	"unknown",
+	"unknown",
+	"X",
+	"dbus",
+};
+
+
+/*
+ * Currently AppArmor auditing is fed straight into the audit framework.
+ *
+ * TODO:
+ * netlink interface for complain mode
+ * user auditing, - send user auditing to netlink interface
+ * system control of whether user audit messages go to system log
+ */
+
+/**
+ * audit_pre() - core AppArmor function.
+ * @ab: audit buffer to fill (NOT NULL)
+ * @va: audit structure containing data to audit (NOT NULL)
+ *
+ * Record common AppArmor audit data from @va
+ */
+static void audit_pre(struct audit_buffer *ab, void *va)
+{
+	struct apparmor_audit_data *ad = aad_of_va(va);
+
+	if (aa_g_audit_header) {
+		audit_log_format(ab, "apparmor=\"%s\"",
+				 aa_audit_type[ad->type]);
+	}
+
+	if (ad->op)
+		audit_log_format(ab, " operation=\"%s\"", ad->op);
+
+	if (ad->class)
+		audit_log_format(ab, " class=\"%s\"",
+				 ad->class <= AA_CLASS_LAST ?
+				 aa_class_names[ad->class] :
+				 "unknown");
+
+	if (ad->info) {
+		audit_log_format(ab, " info=\"%s\"", ad->info);
+		if (ad->error)
+			audit_log_format(ab, " error=%d", ad->error);
+	}
+
+	if (ad->subj_label) {
+		struct aa_label *label = ad->subj_label;
+
+		if (label_isprofile(label)) {
+			struct aa_profile *profile = labels_profile(label);
+
+			if (profile->ns != root_ns) {
+				audit_log_format(ab, " namespace=");
+				audit_log_untrustedstring(ab,
+						       profile->ns->base.hname);
+			}
+			audit_log_format(ab, " profile=");
+			audit_log_untrustedstring(ab, profile->base.hname);
+		} else {
+			audit_log_format(ab, " label=");
+			aa_label_xaudit(ab, root_ns, label, FLAG_VIEW_SUBNS,
+					GFP_ATOMIC);
+		}
+	}
+
+	if (ad->name) {
+		audit_log_format(ab, " name=");
+		audit_log_untrustedstring(ab, ad->name);
+	}
+}
+
+/**
+ * aa_audit_msg - Log a message to the audit subsystem
+ * @type: audit type for the message
+ * @ad: audit event structure (NOT NULL)
+ * @cb: optional callback fn for type specific fields (MAYBE NULL)
+ */
+void aa_audit_msg(int type, struct apparmor_audit_data *ad,
+		  void (*cb) (struct audit_buffer *, void *))
+{
+	ad->type = type;
+	common_lsm_audit(&ad->common, audit_pre, cb);
+}
+
+/**
+ * aa_audit - Log a profile based audit event to the audit subsystem
+ * @type: audit type for the message
+ * @profile: profile to check against (NOT NULL)
+ * @ad: audit event (NOT NULL)
+ * @cb: optional callback fn for type specific fields (MAYBE NULL)
+ *
+ * Handle default message switching based off of audit mode flags
+ *
+ * Returns: error on failure
+ */
+int aa_audit(int type, struct aa_profile *profile,
+	     struct apparmor_audit_data *ad,
+	     void (*cb) (struct audit_buffer *, void *))
+{
+	AA_BUG(!profile);
+
+	if (type == AUDIT_APPARMOR_AUTO) {
+		if (likely(!ad->error)) {
+			if (AUDIT_MODE(profile) != AUDIT_ALL)
+				return 0;
+			type = AUDIT_APPARMOR_AUDIT;
+		} else if (COMPLAIN_MODE(profile))
+			type = AUDIT_APPARMOR_ALLOWED;
+		else
+			type = AUDIT_APPARMOR_DENIED;
+	}
+	if (AUDIT_MODE(profile) == AUDIT_QUIET ||
+	    (type == AUDIT_APPARMOR_DENIED &&
+	     AUDIT_MODE(profile) == AUDIT_QUIET_DENIED))
+		return ad->error;
+
+	if (KILL_MODE(profile) && type == AUDIT_APPARMOR_DENIED)
+		type = AUDIT_APPARMOR_KILL;
+
+	ad->subj_label = &profile->label;
+
+	aa_audit_msg(type, ad, cb);
+
+	if (ad->type == AUDIT_APPARMOR_KILL)
+		(void)send_sig_info(profile->signal, NULL,
+			ad->common.type == LSM_AUDIT_DATA_TASK &&
+			ad->common.u.tsk ? ad->common.u.tsk : current);
+
+	if (ad->type == AUDIT_APPARMOR_ALLOWED)
+		return complain_error(ad->error);
+
+	return ad->error;
+}
+
+struct aa_audit_rule {
+	struct aa_label *label;
+};
+
+void aa_audit_rule_free(void *vrule)
+{
+	struct aa_audit_rule *rule = vrule;
+
+	if (rule) {
+		if (!IS_ERR(rule->label))
+			aa_put_label(rule->label);
+		kfree(rule);
+	}
+}
+
+int aa_audit_rule_init(u32 field, u32 op, char *rulestr, void **vrule, gfp_t gfp)
+{
+	struct aa_audit_rule *rule;
+
+	switch (field) {
+	case AUDIT_SUBJ_ROLE:
+		if (op != Audit_equal && op != Audit_not_equal)
+			return -EINVAL;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	rule = kzalloc_obj(struct aa_audit_rule, gfp);
+
+	if (!rule)
+		return -ENOMEM;
+
+	/* Currently rules are treated as coming from the root ns */
+	rule->label = aa_label_parse(&root_ns->unconfined->label, rulestr,
+				     gfp, true, false);
+	if (IS_ERR(rule->label)) {
+		int err = PTR_ERR(rule->label);
+		aa_audit_rule_free(rule);
+		return err;
+	}
+
+	*vrule = rule;
+	return 0;
+}
+
+int aa_audit_rule_known(struct audit_krule *rule)
+{
+	int i;
+
+	for (i = 0; i < rule->field_count; i++) {
+		struct audit_field *f = &rule->fields[i];
+
+		switch (f->type) {
+		case AUDIT_SUBJ_ROLE:
+			return 1;
+		}
+	}
+
+	return 0;
+}
+
+int aa_audit_rule_match(struct lsm_prop *prop, u32 field, u32 op, void *vrule)
+{
+	struct aa_audit_rule *rule = vrule;
+	struct aa_label *label;
+	int found = 0;
+
+	label = prop->apparmor.label;
+
+	if (!label)
+		return -ENOENT;
+
+	if (aa_label_is_subset(label, rule->label))
+		found = 1;
+
+	switch (field) {
+	case AUDIT_SUBJ_ROLE:
+		switch (op) {
+		case Audit_equal:
+			return found;
+		case Audit_not_equal:
+			return !found;
+		}
+	}
+	return 0;
+}