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, 243 insertions, 0 deletions

diff --git a/net/sunrpc/auth_unix.c b/net/sunrpc/auth_unix.c
new file mode 100644
index 000000000..6c742a340
--- /dev/null
+++ b/net/sunrpc/auth_unix.c
@@ -0,0 +1,243 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/net/sunrpc/auth_unix.c
+ *
+ * UNIX-style authentication; no AUTH_SHORT support
+ *
+ * Copyright (C) 1996, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#include <linux/slab.h>
+#include <linux/types.h>
+#include <linux/sched.h>
+#include <linux/module.h>
+#include <linux/mempool.h>
+#include <linux/sunrpc/clnt.h>
+#include <linux/sunrpc/auth.h>
+#include <linux/user_namespace.h>
+
+
+#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
+# define RPCDBG_FACILITY	RPCDBG_AUTH
+#endif
+
+static struct rpc_auth		unix_auth;
+static const struct rpc_credops	unix_credops;
+static mempool_t		*unix_pool;
+
+static struct rpc_auth *
+unx_create(const struct rpc_auth_create_args *args, struct rpc_clnt *clnt)
+{
+	refcount_inc(&unix_auth.au_count);
+	return &unix_auth;
+}
+
+static void
+unx_destroy(struct rpc_auth *auth)
+{
+}
+
+/*
+ * Lookup AUTH_UNIX creds for current process
+ */
+static struct rpc_cred *unx_lookup_cred(struct rpc_auth *auth,
+					struct auth_cred *acred, int flags)
+{
+	struct rpc_cred *ret;
+
+	ret = kmalloc_obj(*ret, rpc_task_gfp_mask());
+	if (!ret) {
+		if (!(flags & RPCAUTH_LOOKUP_ASYNC))
+			return ERR_PTR(-ENOMEM);
+		ret = mempool_alloc(unix_pool, GFP_NOWAIT);
+		if (!ret)
+			return ERR_PTR(-ENOMEM);
+	}
+	rpcauth_init_cred(ret, acred, auth, &unix_credops);
+	ret->cr_flags = 1UL << RPCAUTH_CRED_UPTODATE;
+	return ret;
+}
+
+static void
+unx_free_cred_callback(struct rcu_head *head)
+{
+	struct rpc_cred *rpc_cred = container_of(head, struct rpc_cred, cr_rcu);
+
+	put_cred(rpc_cred->cr_cred);
+	mempool_free(rpc_cred, unix_pool);
+}
+
+static void
+unx_destroy_cred(struct rpc_cred *cred)
+{
+	call_rcu(&cred->cr_rcu, unx_free_cred_callback);
+}
+
+/*
+ * Match credentials against current the auth_cred.
+ */
+static int
+unx_match(struct auth_cred *acred, struct rpc_cred *cred, int flags)
+{
+	unsigned int groups = 0;
+	unsigned int i;
+
+	if (cred->cr_cred == acred->cred)
+		return 1;
+
+	if (!uid_eq(cred->cr_cred->fsuid, acred->cred->fsuid) || !gid_eq(cred->cr_cred->fsgid, acred->cred->fsgid))
+		return 0;
+
+	if (acred->cred->group_info != NULL)
+		groups = acred->cred->group_info->ngroups;
+	if (groups > UNX_NGROUPS)
+		groups = UNX_NGROUPS;
+	if (cred->cr_cred->group_info == NULL)
+		return groups == 0;
+	if (groups != cred->cr_cred->group_info->ngroups)
+		return 0;
+
+	for (i = 0; i < groups ; i++)
+		if (!gid_eq(cred->cr_cred->group_info->gid[i], acred->cred->group_info->gid[i]))
+			return 0;
+	return 1;
+}
+
+/*
+ * Marshal credentials.
+ * Maybe we should keep a cached credential for performance reasons.
+ */
+static int
+unx_marshal(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	struct rpc_clnt	*clnt = task->tk_client;
+	struct rpc_cred	*cred = task->tk_rqstp->rq_cred;
+	__be32		*p, *cred_len, *gidarr_len;
+	int		i;
+	struct group_info *gi = cred->cr_cred->group_info;
+	struct user_namespace *userns = clnt->cl_cred ?
+		clnt->cl_cred->user_ns : &init_user_ns;
+
+	/* Credential */
+
+	p = xdr_reserve_space(xdr, 3 * sizeof(*p));
+	if (!p)
+		goto marshal_failed;
+	*p++ = rpc_auth_unix;
+	cred_len = p++;
+	*p++ = xdr_zero;	/* stamp */
+	if (xdr_stream_encode_opaque(xdr, clnt->cl_nodename,
+				     clnt->cl_nodelen) < 0)
+		goto marshal_failed;
+	p = xdr_reserve_space(xdr, 3 * sizeof(*p));
+	if (!p)
+		goto marshal_failed;
+	*p++ = cpu_to_be32(from_kuid_munged(userns, cred->cr_cred->fsuid));
+	*p++ = cpu_to_be32(from_kgid_munged(userns, cred->cr_cred->fsgid));
+
+	gidarr_len = p++;
+	if (gi)
+		for (i = 0; i < UNX_NGROUPS && i < gi->ngroups; i++)
+			*p++ = cpu_to_be32(from_kgid_munged(userns, gi->gid[i]));
+	*gidarr_len = cpu_to_be32(p - gidarr_len - 1);
+	*cred_len = cpu_to_be32((p - cred_len - 1) << 2);
+	p = xdr_reserve_space(xdr, (p - gidarr_len - 1) << 2);
+	if (!p)
+		goto marshal_failed;
+
+	/* Verifier */
+
+	p = xdr_reserve_space(xdr, 2 * sizeof(*p));
+	if (!p)
+		goto marshal_failed;
+	*p++ = rpc_auth_null;
+	*p   = xdr_zero;
+
+	return 0;
+
+marshal_failed:
+	return -EMSGSIZE;
+}
+
+/*
+ * Refresh credentials. This is a no-op for AUTH_UNIX
+ */
+static int
+unx_refresh(struct rpc_task *task)
+{
+	set_bit(RPCAUTH_CRED_UPTODATE, &task->tk_rqstp->rq_cred->cr_flags);
+	return 0;
+}
+
+static int
+unx_validate(struct rpc_task *task, struct xdr_stream *xdr)
+{
+	struct rpc_auth *auth = task->tk_rqstp->rq_cred->cr_auth;
+	__be32 *p;
+	u32 size;
+
+	p = xdr_inline_decode(xdr, 2 * sizeof(*p));
+	if (!p)
+		return -EIO;
+	switch (*p++) {
+	case rpc_auth_null:
+	case rpc_auth_unix:
+	case rpc_auth_short:
+		break;
+	default:
+		return -EIO;
+	}
+	size = be32_to_cpup(p);
+	if (size > RPC_MAX_AUTH_SIZE)
+		return -EIO;
+	p = xdr_inline_decode(xdr, size);
+	if (!p)
+		return -EIO;
+
+	auth->au_verfsize = XDR_QUADLEN(size) + 2;
+	auth->au_rslack = XDR_QUADLEN(size) + 2;
+	auth->au_ralign = XDR_QUADLEN(size) + 2;
+	return 0;
+}
+
+int __init rpc_init_authunix(void)
+{
+	unix_pool = mempool_create_kmalloc_pool(16, sizeof(struct rpc_cred));
+	return unix_pool ? 0 : -ENOMEM;
+}
+
+void rpc_destroy_authunix(void)
+{
+	mempool_destroy(unix_pool);
+}
+
+const struct rpc_authops authunix_ops = {
+	.owner		= THIS_MODULE,
+	.au_flavor	= RPC_AUTH_UNIX,
+	.au_name	= "UNIX",
+	.create		= unx_create,
+	.destroy	= unx_destroy,
+	.lookup_cred	= unx_lookup_cred,
+};
+
+static
+struct rpc_auth		unix_auth = {
+	.au_cslack	= UNX_CALLSLACK,
+	.au_rslack	= NUL_REPLYSLACK,
+	.au_verfsize	= NUL_REPLYSLACK,
+	.au_ops		= &authunix_ops,
+	.au_flavor	= RPC_AUTH_UNIX,
+	.au_count	= REFCOUNT_INIT(1),
+};
+
+static
+const struct rpc_credops unix_credops = {
+	.cr_name	= "AUTH_UNIX",
+	.crdestroy	= unx_destroy_cred,
+	.crmatch	= unx_match,
+	.crmarshal	= unx_marshal,
+	.crwrap_req	= rpcauth_wrap_req_encode,
+	.crrefresh	= unx_refresh,
+	.crvalidate	= unx_validate,
+	.crunwrap_resp	= rpcauth_unwrap_resp_decode,
+};