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, 204 insertions, 0 deletions

diff --git a/security/selinux/ss/context.h b/security/selinux/ss/context.h
new file mode 100644
index 000000000..dd3b9b5b5
--- /dev/null
+++ b/security/selinux/ss/context.h
@@ -0,0 +1,204 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * A security context is a set of security attributes
+ * associated with each subject and object controlled
+ * by the security policy.  Security contexts are
+  * externally represented as variable-length strings
+ * that can be interpreted by a user or application
+ * with an understanding of the security policy.
+ * Internally, the security server uses a simple
+ * structure.  This structure is private to the
+ * security server and can be changed without affecting
+ * clients of the security server.
+ *
+ * Author : Stephen Smalley, <stephen.smalley.work@gmail.com>
+ */
+
+#ifndef _SS_CONTEXT_H_
+#define _SS_CONTEXT_H_
+
+#include "ebitmap.h"
+#include "mls_types.h"
+#include "security.h"
+
+/*
+ * A security context consists of an authenticated user
+ * identity, a role, a type and a MLS range.
+ */
+struct context {
+	u32 user;
+	u32 role;
+	u32 type;
+	u32 len; /* length of string in bytes */
+	struct mls_range range;
+	char *str; /* string representation if context cannot be mapped. */
+};
+
+static inline void mls_context_init(struct context *c)
+{
+	memset(&c->range, 0, sizeof(c->range));
+}
+
+static inline int mls_context_cpy(struct context *dst,
+				  const struct context *src)
+{
+	int rc;
+
+	dst->range.level[0].sens = src->range.level[0].sens;
+	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
+	if (rc)
+		goto out;
+
+	dst->range.level[1].sens = src->range.level[1].sens;
+	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
+	if (rc)
+		ebitmap_destroy(&dst->range.level[0].cat);
+out:
+	return rc;
+}
+
+/*
+ * Sets both levels in the MLS range of 'dst' to the low level of 'src'.
+ */
+static inline int mls_context_cpy_low(struct context *dst,
+				      const struct context *src)
+{
+	int rc;
+
+	dst->range.level[0].sens = src->range.level[0].sens;
+	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[0].cat);
+	if (rc)
+		goto out;
+
+	dst->range.level[1].sens = src->range.level[0].sens;
+	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[0].cat);
+	if (rc)
+		ebitmap_destroy(&dst->range.level[0].cat);
+out:
+	return rc;
+}
+
+/*
+ * Sets both levels in the MLS range of 'dst' to the high level of 'src'.
+ */
+static inline int mls_context_cpy_high(struct context *dst,
+				       const struct context *src)
+{
+	int rc;
+
+	dst->range.level[0].sens = src->range.level[1].sens;
+	rc = ebitmap_cpy(&dst->range.level[0].cat, &src->range.level[1].cat);
+	if (rc)
+		goto out;
+
+	dst->range.level[1].sens = src->range.level[1].sens;
+	rc = ebitmap_cpy(&dst->range.level[1].cat, &src->range.level[1].cat);
+	if (rc)
+		ebitmap_destroy(&dst->range.level[0].cat);
+out:
+	return rc;
+}
+
+static inline int mls_context_glblub(struct context *dst,
+				     const struct context *c1,
+				     const struct context *c2)
+{
+	struct mls_range *dr = &dst->range;
+	const struct mls_range *r1 = &c1->range, *r2 = &c2->range;
+	int rc = 0;
+
+	if (r1->level[1].sens < r2->level[0].sens ||
+	    r2->level[1].sens < r1->level[0].sens)
+		/* These ranges have no common sensitivities */
+		return -EINVAL;
+
+	/* Take the greatest of the low */
+	dr->level[0].sens = max(r1->level[0].sens, r2->level[0].sens);
+
+	/* Take the least of the high */
+	dr->level[1].sens = min(r1->level[1].sens, r2->level[1].sens);
+
+	rc = ebitmap_and(&dr->level[0].cat, &r1->level[0].cat,
+			 &r2->level[0].cat);
+	if (rc)
+		goto out;
+
+	rc = ebitmap_and(&dr->level[1].cat, &r1->level[1].cat,
+			 &r2->level[1].cat);
+	if (rc)
+		goto out;
+
+out:
+	return rc;
+}
+
+static inline bool mls_context_equal(const struct context *c1,
+				     const struct context *c2)
+{
+	return ((c1->range.level[0].sens == c2->range.level[0].sens) &&
+		ebitmap_equal(&c1->range.level[0].cat, &c2->range.level[0].cat) &&
+		(c1->range.level[1].sens == c2->range.level[1].sens) &&
+		ebitmap_equal(&c1->range.level[1].cat, &c2->range.level[1].cat));
+}
+
+static inline void mls_context_destroy(struct context *c)
+{
+	ebitmap_destroy(&c->range.level[0].cat);
+	ebitmap_destroy(&c->range.level[1].cat);
+	mls_context_init(c);
+}
+
+static inline void context_init(struct context *c)
+{
+	memset(c, 0, sizeof(*c));
+}
+
+static inline int context_cpy(struct context *dst, const struct context *src)
+{
+	int rc;
+
+	dst->user = src->user;
+	dst->role = src->role;
+	dst->type = src->type;
+	if (src->str) {
+		dst->str = kstrdup(src->str, GFP_ATOMIC);
+		if (!dst->str)
+			return -ENOMEM;
+		dst->len = src->len;
+	} else {
+		dst->str = NULL;
+		dst->len = 0;
+	}
+	rc = mls_context_cpy(dst, src);
+	if (rc) {
+		kfree(dst->str);
+		dst->str = NULL;
+		dst->len = 0;
+		return rc;
+	}
+	return 0;
+}
+
+static inline void context_destroy(struct context *c)
+{
+	c->user = c->role = c->type = 0;
+	kfree(c->str);
+	c->str = NULL;
+	c->len = 0;
+	mls_context_destroy(c);
+}
+
+static inline bool context_equal(const struct context *c1,
+				 const struct context *c2)
+{
+	if (c1->len && c2->len)
+		return (c1->len == c2->len && !strcmp(c1->str, c2->str));
+	if (c1->len || c2->len)
+		return 0;
+	return ((c1->user == c2->user) && (c1->role == c2->role) &&
+		(c1->type == c2->type) && mls_context_equal(c1, c2));
+}
+
+u32 context_compute_hash(const struct context *c);
+
+#endif /* _SS_CONTEXT_H_ */