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, 235 insertions, 0 deletions

diff --git a/security/selinux/ibpkey.c b/security/selinux/ibpkey.c
new file mode 100644
index 000000000..ae09d59aa
--- /dev/null
+++ b/security/selinux/ibpkey.c
@@ -0,0 +1,235 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Pkey table
+ *
+ * SELinux must keep a mapping of Infiniband PKEYs to labels/SIDs.  This
+ * mapping is maintained as part of the normal policy but a fast cache is
+ * needed to reduce the lookup overhead.
+ *
+ * This code is heavily based on the "netif" and "netport" concept originally
+ * developed by
+ * James Morris <jmorris@redhat.com> and
+ * Paul Moore <paul@paul-moore.com>
+ *   (see security/selinux/netif.c and security/selinux/netport.c for more
+ *   information)
+ */
+
+/*
+ * (c) Mellanox Technologies, 2016
+ */
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+
+#include "initcalls.h"
+#include "ibpkey.h"
+#include "objsec.h"
+
+#define SEL_PKEY_HASH_SIZE       256
+#define SEL_PKEY_HASH_BKT_LIMIT   16
+
+struct sel_ib_pkey_bkt {
+	int size;
+	struct list_head list;
+};
+
+struct sel_ib_pkey {
+	struct pkey_security_struct psec;
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
+static DEFINE_SPINLOCK(sel_ib_pkey_lock);
+static struct sel_ib_pkey_bkt sel_ib_pkey_hash[SEL_PKEY_HASH_SIZE];
+
+/**
+ * sel_ib_pkey_hashfn - Hashing function for the pkey table
+ * @pkey: pkey number
+ *
+ * Description:
+ * This is the hashing function for the pkey table, it returns the bucket
+ * number for the given pkey.
+ *
+ */
+static unsigned int sel_ib_pkey_hashfn(u16 pkey)
+{
+	return (pkey & (SEL_PKEY_HASH_SIZE - 1));
+}
+
+/**
+ * sel_ib_pkey_find - Search for a pkey record
+ * @subnet_prefix: subnet_prefix
+ * @pkey_num: pkey_num
+ *
+ * Description:
+ * Search the pkey table and return the matching record.  If an entry
+ * can not be found in the table return NULL.
+ *
+ */
+static struct sel_ib_pkey *sel_ib_pkey_find(u64 subnet_prefix, u16 pkey_num)
+{
+	unsigned int idx;
+	struct sel_ib_pkey *pkey;
+
+	idx = sel_ib_pkey_hashfn(pkey_num);
+	list_for_each_entry_rcu(pkey, &sel_ib_pkey_hash[idx].list, list) {
+		if (pkey->psec.pkey == pkey_num &&
+		    pkey->psec.subnet_prefix == subnet_prefix)
+			return pkey;
+	}
+
+	return NULL;
+}
+
+/**
+ * sel_ib_pkey_insert - Insert a new pkey into the table
+ * @pkey: the new pkey record
+ *
+ * Description:
+ * Add a new pkey record to the hash table.
+ *
+ */
+static void sel_ib_pkey_insert(struct sel_ib_pkey *pkey)
+{
+	unsigned int idx;
+
+	/* we need to impose a limit on the growth of the hash table so check
+	 * this bucket to make sure it is within the specified bounds
+	 */
+	idx = sel_ib_pkey_hashfn(pkey->psec.pkey);
+	list_add_rcu(&pkey->list, &sel_ib_pkey_hash[idx].list);
+	if (sel_ib_pkey_hash[idx].size == SEL_PKEY_HASH_BKT_LIMIT) {
+		struct sel_ib_pkey *tail;
+
+		tail = list_entry(
+			rcu_dereference_protected(
+				list_tail_rcu(&sel_ib_pkey_hash[idx].list),
+				lockdep_is_held(&sel_ib_pkey_lock)),
+			struct sel_ib_pkey, list);
+		list_del_rcu(&tail->list);
+		kfree_rcu(tail, rcu);
+	} else {
+		sel_ib_pkey_hash[idx].size++;
+	}
+}
+
+/**
+ * sel_ib_pkey_sid_slow - Lookup the SID of a pkey using the policy
+ * @subnet_prefix: subnet prefix
+ * @pkey_num: pkey number
+ * @sid: pkey SID
+ *
+ * Description:
+ * This function determines the SID of a pkey by querying the security
+ * policy.  The result is added to the pkey table to speedup future
+ * queries.  Returns zero on success, negative values on failure.
+ *
+ */
+static int sel_ib_pkey_sid_slow(u64 subnet_prefix, u16 pkey_num, u32 *sid)
+{
+	int ret;
+	struct sel_ib_pkey *pkey;
+	struct sel_ib_pkey *new;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sel_ib_pkey_lock, flags);
+	pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
+	if (pkey) {
+		*sid = pkey->psec.sid;
+		spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
+		return 0;
+	}
+
+	ret = security_ib_pkey_sid(subnet_prefix, pkey_num,
+				   sid);
+	if (ret)
+		goto out;
+
+	new = kmalloc_obj(*new, GFP_ATOMIC);
+	if (!new) {
+		/* If this memory allocation fails still return 0. The SID
+		 * is valid, it just won't be added to the cache.
+		 */
+		goto out;
+	}
+
+	new->psec.subnet_prefix = subnet_prefix;
+	new->psec.pkey = pkey_num;
+	new->psec.sid = *sid;
+	sel_ib_pkey_insert(new);
+
+out:
+	spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
+	return ret;
+}
+
+/**
+ * sel_ib_pkey_sid - Lookup the SID of a PKEY
+ * @subnet_prefix: subnet_prefix
+ * @pkey_num: pkey number
+ * @sid: pkey SID
+ *
+ * Description:
+ * This function determines the SID of a PKEY using the fastest method
+ * possible.  First the pkey table is queried, but if an entry can't be found
+ * then the policy is queried and the result is added to the table to speedup
+ * future queries.  Returns zero on success, negative values on failure.
+ *
+ */
+int sel_ib_pkey_sid(u64 subnet_prefix, u16 pkey_num, u32 *sid)
+{
+	struct sel_ib_pkey *pkey;
+
+	rcu_read_lock();
+	pkey = sel_ib_pkey_find(subnet_prefix, pkey_num);
+	if (likely(pkey)) {
+		*sid = pkey->psec.sid;
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	return sel_ib_pkey_sid_slow(subnet_prefix, pkey_num, sid);
+}
+
+/**
+ * sel_ib_pkey_flush - Flush the entire pkey table
+ *
+ * Description:
+ * Remove all entries from the pkey table
+ *
+ */
+void sel_ib_pkey_flush(void)
+{
+	unsigned int idx;
+	struct sel_ib_pkey *pkey, *pkey_tmp;
+	unsigned long flags;
+
+	spin_lock_irqsave(&sel_ib_pkey_lock, flags);
+	for (idx = 0; idx < SEL_PKEY_HASH_SIZE; idx++) {
+		list_for_each_entry_safe(pkey, pkey_tmp,
+					 &sel_ib_pkey_hash[idx].list, list) {
+			list_del_rcu(&pkey->list);
+			kfree_rcu(pkey, rcu);
+		}
+		sel_ib_pkey_hash[idx].size = 0;
+	}
+	spin_unlock_irqrestore(&sel_ib_pkey_lock, flags);
+}
+
+int __init sel_ib_pkey_init(void)
+{
+	int iter;
+
+	if (!selinux_enabled_boot)
+		return 0;
+
+	for (iter = 0; iter < SEL_PKEY_HASH_SIZE; iter++) {
+		INIT_LIST_HEAD(&sel_ib_pkey_hash[iter].list);
+		sel_ib_pkey_hash[iter].size = 0;
+	}
+
+	return 0;
+}