ftrace: Synchronize the initialization of ftrace_opsgrafted

There's some internal state that ftrace_ops needs to have set, but since
it can be declared outside of the ftrace.c code, it calls
ftrace_ops_init() on the ops in every global function. The issue is that
if two tasks call it on the same ops at the same time it is possible to
have the initialization of one corrupt the initialization of the other
call.

Create a ops_mutex to use to synchronize every initialization of the
ftrace_ops. The mutex is taken within checking the ftrace_ops flag that
states it was initializied but the flag is checked again after the mutex
has been taken. Checking first outside the mutex allows it to shortcut
having to take the mutex. But then the check needs to be done again after
the mute is taken in case of races.

Cc: stable@vger.kernel.org
Link: https://patch.msgid.link/20260902095501.6b59af20@gandalf.local.home
Fixes: f04f24fb7e48d ("ftrace, kprobes: Fix a deadlock on ftrace_regex_lock")
Reported-by: sashiko-bot@kernel.org
Close: https://lore.kernel.org/all/20260829025528.49A831F000E9@smtp.kernel.org/
Signed-off-by: Steven Rostedt <rostedt@goodmis.org>

1 files changed, 116 insertions, 0 deletions

diff --git a/security/apparmor/ipc.c b/security/apparmor/ipc.c
new file mode 100644
index 000000000..df5712cea
--- /dev/null
+++ b/security/apparmor/ipc.c
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * AppArmor security module
+ *
+ * This file contains AppArmor ipc mediation
+ *
+ * Copyright (C) 1998-2008 Novell/SUSE
+ * Copyright 2009-2017 Canonical Ltd.
+ */
+
+#include <linux/gfp.h>
+
+#include "include/audit.h"
+#include "include/capability.h"
+#include "include/cred.h"
+#include "include/policy.h"
+#include "include/ipc.h"
+#include "include/sig_names.h"
+
+
+static inline int map_signal_num(int sig)
+{
+	if (sig > SIGRTMAX)
+		return SIGUNKNOWN;
+	else if (sig >= SIGRTMIN)
+		return sig - SIGRTMIN + SIGRT_BASE;
+	else if (sig < MAXMAPPED_SIG)
+		return sig_map[sig];
+	return SIGUNKNOWN;
+}
+
+/**
+ * audit_signal_mask - convert mask to permission string
+ * @mask: permission mask to convert
+ *
+ * Returns: pointer to static string
+ */
+static const char *audit_signal_mask(u32 mask)
+{
+	if (mask & MAY_READ)
+		return "receive";
+	if (mask & MAY_WRITE)
+		return "send";
+	return "";
+}
+
+/**
+ * audit_signal_cb() - call back for signal specific audit fields
+ * @ab: audit_buffer  (NOT NULL)
+ * @va: audit struct to audit values of  (NOT NULL)
+ */
+static void audit_signal_cb(struct audit_buffer *ab, void *va)
+{
+	struct common_audit_data *sa = va;
+	struct apparmor_audit_data *ad = aad(sa);
+
+	if (ad->request & AA_SIGNAL_PERM_MASK) {
+		audit_log_format(ab, " requested_mask=\"%s\"",
+				 audit_signal_mask(ad->request));
+		if (ad->denied & AA_SIGNAL_PERM_MASK) {
+			audit_log_format(ab, " denied_mask=\"%s\"",
+					 audit_signal_mask(ad->denied));
+		}
+	}
+	if (ad->signal == SIGUNKNOWN)
+		audit_log_format(ab, "signal=unknown(%d)",
+				 ad->unmappedsig);
+	else if (ad->signal < MAXMAPPED_SIGNAME)
+		audit_log_format(ab, " signal=%s", sig_names[ad->signal]);
+	else
+		audit_log_format(ab, " signal=rtmin+%d",
+				 ad->signal - SIGRT_BASE);
+	audit_log_format(ab, " peer=");
+	aa_label_xaudit(ab, labels_ns(ad->subj_label), ad->peer,
+			FLAGS_NONE, GFP_ATOMIC);
+}
+
+static int profile_signal_perm(const struct cred *cred,
+			       struct aa_profile *profile,
+			       struct aa_label *peer, u32 request,
+			       struct apparmor_audit_data *ad)
+{
+	struct aa_ruleset *rules = profile->label.rules[0];
+	struct aa_perms perms;
+	aa_state_t state;
+
+	if (profile_unconfined(profile))
+		return 0;
+
+	ad->subj_cred = cred;
+	ad->peer = peer;
+	/* TODO: secondary cache check <profile, profile, perm> */
+	state = RULE_MEDIATES(rules, AA_CLASS_SIGNAL);
+	if (!state)
+		return 0;
+	state = aa_dfa_next(rules->policy->dfa, state, ad->signal);
+	aa_label_match(profile, rules, peer, state, false, request, &perms);
+	aa_apply_modes_to_perms(profile, &perms);
+	return aa_check_perms(profile, &perms, request, ad, audit_signal_cb);
+}
+
+int aa_may_signal(const struct cred *subj_cred, struct aa_label *sender,
+		  const struct cred *target_cred, struct aa_label *target,
+		  int sig)
+{
+	struct aa_profile *profile;
+	DEFINE_AUDIT_DATA(ad, LSM_AUDIT_DATA_NONE, AA_CLASS_SIGNAL, OP_SIGNAL);
+
+	ad.signal = map_signal_num(sig);
+	ad.unmappedsig = sig;
+	return xcheck_labels(sender, target, profile,
+			     profile_signal_perm(subj_cred, profile, target,
+						 MAY_WRITE, &ad),
+			     profile_signal_perm(target_cred, profile, sender,
+						 MAY_READ, &ad));
+}