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, 246 insertions, 0 deletions

diff --git a/security/ipe/fs.c b/security/ipe/fs.c
new file mode 100644
index 000000000..076c111c8
--- /dev/null
+++ b/security/ipe/fs.c
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2020-2024 Microsoft Corporation. All rights reserved.
+ */
+
+#include <linux/dcache.h>
+#include <linux/security.h>
+
+#include "ipe.h"
+#include "fs.h"
+#include "eval.h"
+#include "policy.h"
+#include "audit.h"
+
+static struct dentry *root __ro_after_init;
+struct dentry *policy_root __ro_after_init;
+
+/**
+ * setaudit() - Write handler for the securityfs node, "ipe/success_audit"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the write syscall.
+ * @len: Supplies the length of @data.
+ * @offset: unused.
+ *
+ * Return:
+ * * Length of buffer written	- Success
+ * * %-EPERM			- Insufficient permission
+ */
+static ssize_t setaudit(struct file *f, const char __user *data,
+			size_t len, loff_t *offset)
+{
+	int rc = 0;
+	bool value;
+
+	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
+		return -EPERM;
+
+	rc = kstrtobool_from_user(data, len, &value);
+	if (rc)
+		return rc;
+
+	WRITE_ONCE(success_audit, value);
+
+	return len;
+}
+
+/**
+ * getaudit() - Read handler for the securityfs node, "ipe/success_audit"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the read syscall.
+ * @len: Supplies the length of @data.
+ * @offset: unused.
+ *
+ * Return: Length of buffer written
+ */
+static ssize_t getaudit(struct file *f, char __user *data,
+			size_t len, loff_t *offset)
+{
+	const char *result;
+
+	result = ((READ_ONCE(success_audit)) ? "1" : "0");
+
+	return simple_read_from_buffer(data, len, offset, result, 1);
+}
+
+/**
+ * setenforce() - Write handler for the securityfs node, "ipe/enforce"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the write syscall.
+ * @len: Supplies the length of @data.
+ * @offset: unused.
+ *
+ * Return:
+ * * Length of buffer written	- Success
+ * * %-EPERM			- Insufficient permission
+ */
+static ssize_t setenforce(struct file *f, const char __user *data,
+			  size_t len, loff_t *offset)
+{
+	int rc = 0;
+	bool new_value, old_value;
+
+	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN))
+		return -EPERM;
+
+	old_value = READ_ONCE(enforce);
+	rc = kstrtobool_from_user(data, len, &new_value);
+	if (rc)
+		return rc;
+
+	if (new_value != old_value) {
+		ipe_audit_enforce(new_value, old_value);
+		WRITE_ONCE(enforce, new_value);
+	}
+
+	return len;
+}
+
+/**
+ * getenforce() - Read handler for the securityfs node, "ipe/enforce"
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the read syscall.
+ * @len: Supplies the length of @data.
+ * @offset: unused.
+ *
+ * Return: Length of buffer written
+ */
+static ssize_t getenforce(struct file *f, char __user *data,
+			  size_t len, loff_t *offset)
+{
+	const char *result;
+
+	result = ((READ_ONCE(enforce)) ? "1" : "0");
+
+	return simple_read_from_buffer(data, len, offset, result, 1);
+}
+
+/**
+ * new_policy() - Write handler for the securityfs node, "ipe/new_policy".
+ * @f: Supplies a file structure representing the securityfs node.
+ * @data: Supplies a buffer passed to the write syscall.
+ * @len: Supplies the length of @data.
+ * @offset: unused.
+ *
+ * Return:
+ * * Length of buffer written	- Success
+ * * %-EPERM			- Insufficient permission
+ * * %-ENOMEM			- Out of memory (OOM)
+ * * %-EBADMSG			- Policy is invalid
+ * * %-ERANGE			- Policy version number overflow
+ * * %-EINVAL			- Policy version parsing error
+ * * %-EEXIST			- Same name policy already deployed
+ * * %-ENOKEY			- Policy signing key not found
+ * * %-EKEYREJECTED		- Policy signature verification failed
+ */
+static ssize_t new_policy(struct file *f, const char __user *data,
+			  size_t len, loff_t *offset)
+{
+	struct ipe_policy *p = NULL;
+	char *copy = NULL;
+	int rc = 0;
+
+	if (!file_ns_capable(f, &init_user_ns, CAP_MAC_ADMIN)) {
+		rc = -EPERM;
+		goto out;
+	}
+
+	copy = memdup_user_nul(data, len);
+	if (IS_ERR(copy)) {
+		rc = PTR_ERR(copy);
+		copy = NULL;
+		goto out;
+	}
+
+	p = ipe_new_policy(NULL, 0, copy, len);
+	if (IS_ERR(p)) {
+		rc = PTR_ERR(p);
+		goto out;
+	}
+
+	rc = ipe_new_policyfs_node(p);
+	if (rc)
+		goto out;
+
+out:
+	kfree(copy);
+	if (rc < 0) {
+		ipe_free_policy(p);
+		ipe_audit_policy_load(ERR_PTR(rc));
+	} else {
+		ipe_audit_policy_load(p);
+	}
+	return (rc < 0) ? rc : len;
+}
+
+static const struct file_operations np_fops = {
+	.write = new_policy,
+};
+
+static const struct file_operations audit_fops = {
+	.write = setaudit,
+	.read = getaudit,
+};
+
+static const struct file_operations enforce_fops = {
+	.write = setenforce,
+	.read = getenforce,
+};
+
+/**
+ * ipe_init_securityfs() - Initialize IPE's securityfs tree at fsinit.
+ *
+ * Return: %0 on success. If an error occurs, the function will return
+ * the -errno.
+ */
+int __init ipe_init_securityfs(void)
+{
+	int rc = 0;
+	struct ipe_policy *ap;
+	struct dentry *dentry;
+
+	if (!ipe_enabled)
+		return -EOPNOTSUPP;
+
+	root = securityfs_create_dir("ipe", NULL);
+	if (IS_ERR(root))
+		return PTR_ERR(root);
+
+	dentry = securityfs_create_file("success_audit", 0600, root,
+					    NULL, &audit_fops);
+	if (IS_ERR(dentry)) {
+		rc = PTR_ERR(dentry);
+		goto err;
+	}
+
+	dentry = securityfs_create_file("enforce", 0600, root, NULL,
+					      &enforce_fops);
+	if (IS_ERR(dentry)) {
+		rc = PTR_ERR(dentry);
+		goto err;
+	}
+
+	policy_root = securityfs_create_dir("policies", root);
+	if (IS_ERR(policy_root)) {
+		rc = PTR_ERR(policy_root);
+		goto err;
+	}
+
+	ap = rcu_access_pointer(ipe_active_policy);
+	if (ap) {
+		rc = ipe_new_policyfs_node(ap);
+		if (rc)
+			goto err;
+	}
+
+	dentry = securityfs_create_file("new_policy", 0200, root, NULL, &np_fops);
+	if (IS_ERR(dentry)) {
+		rc = PTR_ERR(dentry);
+		goto err;
+	}
+
+	return 0;
+err:
+	securityfs_remove(root);
+	return rc;
+}