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, 121 insertions, 0 deletions

diff --git a/security/selinux/ima.c b/security/selinux/ima.c
new file mode 100644
index 000000000..cda68122e
--- /dev/null
+++ b/security/selinux/ima.c
@@ -0,0 +1,121 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Copyright (C) 2021 Microsoft Corporation
+ *
+ * Author: Lakshmi Ramasubramanian (nramas@linux.microsoft.com)
+ *
+ * Measure critical data structures maintained by SELinux
+ * using IMA subsystem.
+ */
+#include <linux/vmalloc.h>
+#include <linux/ima.h>
+#include <linux/seq_buf.h>
+#include "security.h"
+#include "ima.h"
+
+static int selinux_ima_config_len __ro_after_init;
+
+/*
+ * selinux_ima_config_len_init - Compute the configuration settings string length
+ *
+ * The string is fixed text plus one digit per setting, so its length
+ * is known at boot.
+ */
+void __init selinux_ima_config_len_init(void)
+{
+	int buf_len, suffix_len, i;
+
+	buf_len = strlen("initialized=0;enforcing=0;checkreqprot=0;") + 1;
+	suffix_len = strlen("=0;");
+
+	for (i = 0; i < __POLICYDB_CAP_MAX; i++)
+		buf_len += strlen(selinux_policycap_names[i]) + suffix_len;
+
+	selinux_ima_config_len = buf_len;
+}
+
+/*
+ * selinux_ima_collect_state - Read selinux configuration settings
+ *
+ * On success returns the configuration settings string.
+ * On error, returns NULL.
+ */
+static char *selinux_ima_collect_state(void)
+{
+	struct seq_buf s;
+	char *buf;
+	int i;
+
+	buf = kzalloc(selinux_ima_config_len, GFP_KERNEL);
+	if (!buf)
+		return NULL;
+
+	seq_buf_init(&s, buf, selinux_ima_config_len);
+
+	seq_buf_printf(&s, "initialized=%d;enforcing=%d;checkreqprot=%d;",
+		       selinux_initialized(), enforcing_enabled(),
+		       checkreqprot_get());
+
+	for (i = 0; i < __POLICYDB_CAP_MAX; i++)
+		seq_buf_printf(&s, "%s=%d;", selinux_policycap_names[i],
+			       selinux_state.policycap[i]);
+
+	WARN_ON(seq_buf_has_overflowed(&s));
+
+	return buf;
+}
+
+/*
+ * selinux_ima_measure_state_locked - Measure SELinux state and hash of policy
+ */
+void selinux_ima_measure_state_locked(void)
+{
+	char *state_str = NULL;
+	void *policy = NULL;
+	size_t policy_len;
+	int rc = 0;
+
+	lockdep_assert_held(&selinux_state.policy_mutex);
+
+	state_str = selinux_ima_collect_state();
+	if (!state_str) {
+		pr_err("SELinux: %s: failed to read state.\n", __func__);
+		return;
+	}
+
+	ima_measure_critical_data("selinux", "selinux-state",
+				  state_str, strlen(state_str), false,
+				  NULL, 0);
+
+	kfree(state_str);
+
+	/*
+	 * Measure SELinux policy only after initialization is completed.
+	 */
+	if (!selinux_initialized())
+		return;
+
+	rc = security_read_state_kernel(&policy, &policy_len);
+	if (rc) {
+		pr_err("SELinux: %s: failed to read policy %d.\n", __func__, rc);
+		return;
+	}
+
+	ima_measure_critical_data("selinux", "selinux-policy-hash",
+				  policy, policy_len, true,
+				  NULL, 0);
+
+	vfree(policy);
+}
+
+/*
+ * selinux_ima_measure_state - Measure SELinux state and hash of policy
+ */
+void selinux_ima_measure_state(void)
+{
+	lockdep_assert_not_held(&selinux_state.policy_mutex);
+
+	mutex_lock(&selinux_state.policy_mutex);
+	selinux_ima_measure_state_locked();
+	mutex_unlock(&selinux_state.policy_mutex);
+}