selftests/bpf: Reject graph kptr use after RCU unlockgrafted

Add a sleepable verifier test that loads a graph-node local kptr in an
explicit RCU read-side critical section, then passes its node to
bpf_rbtree_remove() after the section ends.

Before the verifier fix, the stale NON_OWN_REF flag makes the node look like
a live borrowed reference and the program is accepted. After the fix, the
pointer is demoted without NON_OWN_REF and the graph kfunc argument is
rejected.

Also exercise a graph kptr loaded while a spin lock provides implicit RCU
protection. The pointer must be invalidated when the lock is released, which
guards the required ordering between non-owning-reference invalidation and
RCU demotion.

Update the existing fault-protected load test state description. The
post-unlock pointer no longer carries NON_OWN_REF, but remains readable
because the load is rewritten to use BPF_PROBE_MEM.

Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Link: https://lore.kernel.org/r/20260904084325.52250-7-memxor@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

1 files changed, 143 insertions, 0 deletions

diff --git a/fs/smb/server/oplock.h b/fs/smb/server/oplock.h
new file mode 100644
index 000000000..3f581d22b
--- /dev/null
+++ b/fs/smb/server/oplock.h
@@ -0,0 +1,143 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2016 Namjae Jeon <linkinjeon@kernel.org>
+ *   Copyright (C) 2018 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __KSMBD_OPLOCK_H
+#define __KSMBD_OPLOCK_H
+
+#include "smb_common.h"
+
+#define OPLOCK_WAIT_TIME	(35 * HZ)
+
+/* Oplock states */
+#define OPLOCK_STATE_NONE	0x00
+#define OPLOCK_ACK_WAIT		0x01
+#define OPLOCK_CLOSING		0x02
+
+#define OPLOCK_WRITE_TO_READ		0x01
+#define OPLOCK_READ_HANDLE_TO_READ	0x02
+#define OPLOCK_WRITE_TO_NONE		0x04
+#define OPLOCK_READ_TO_NONE		0x08
+
+struct lease_ctx_info {
+	__u8			lease_key[SMB2_LEASE_KEY_SIZE];
+	__le32			req_state;
+	__le32			flags;
+	__le64			duration;
+	__u8			parent_lease_key[SMB2_LEASE_KEY_SIZE];
+	__le16			epoch;
+	int			version;
+	bool			is_dir;
+};
+
+struct lease_table {
+	char			client_guid[SMB2_CLIENT_GUID_SIZE];
+	struct ksmbd_conn	*conn;
+	struct list_head	lease_list;
+	struct list_head	l_entry;
+	spinlock_t		lb_lock;
+};
+
+struct lease {
+	__u8			lease_key[SMB2_LEASE_KEY_SIZE];
+	__le32			state;
+	__le32			new_state;
+	__le32			flags;
+	__le64			duration;
+	__u8			parent_lease_key[SMB2_LEASE_KEY_SIZE];
+	int			version;
+	unsigned short		epoch;
+	bool			is_dir;
+	bool			reuse_epoch;
+	struct ksmbd_inode	*ci;
+	struct lease_table	*l_lb;
+	struct list_head	l_entry;
+	struct list_head	open_list;
+	spinlock_t		lock;
+	atomic_t		refcount;
+};
+
+struct oplock_info {
+	struct ksmbd_conn	*conn;
+	struct ksmbd_session	*sess;
+	struct ksmbd_work	*work;
+	struct ksmbd_file	*o_fp;
+	int                     level;
+	int                     op_state;
+	unsigned long		pending_break;
+	u64			fid;
+	atomic_t		breaking_cnt;
+	atomic_t		refcount;
+	__u16                   Tid;
+	bool			is_lease;
+	bool			open_trunc;	/* truncate on open */
+	struct lease		*o_lease;
+	struct list_head        op_entry;
+	struct list_head        lease_entry;
+	wait_queue_head_t	oplock_q; /* Other server threads */
+	wait_queue_head_t	oplock_brk; /* oplock breaking wait */
+	struct rcu_head		rcu;
+};
+
+struct lease_break_info {
+	__le32			curr_state;
+	__le32			new_state;
+	__le16			epoch;
+	char			lease_key[SMB2_LEASE_KEY_SIZE];
+};
+
+struct oplock_break_info {
+	int level;
+	int open_trunc;
+	int fid;
+};
+
+int smb_grant_oplock(struct ksmbd_work *work, int req_op_level,
+		     u64 pid, struct ksmbd_file *fp, __u16 tid,
+		     struct lease_ctx_info *lctx, int share_ret);
+void smb_break_all_levII_oplock(struct ksmbd_work *work,
+				struct ksmbd_file *fp, int is_trunc);
+void smb_break_all_levII_oplock_no_interim(struct ksmbd_work *work,
+					   struct ksmbd_file *fp, int is_trunc);
+void smb_break_all_levII_oplock_for_delete(struct ksmbd_work *work,
+					   struct ksmbd_file *fp);
+int opinfo_write_to_read(struct oplock_info *opinfo);
+int opinfo_read_handle_to_read(struct oplock_info *opinfo);
+int opinfo_write_to_none(struct oplock_info *opinfo);
+int opinfo_read_to_none(struct oplock_info *opinfo);
+void close_id_del_oplock(struct ksmbd_file *fp);
+void smb_break_all_oplock(struct ksmbd_work *work, struct ksmbd_file *fp);
+struct oplock_info *opinfo_get(struct ksmbd_file *fp);
+void opinfo_put(struct oplock_info *opinfo);
+
+/* Lease related functions */
+void create_lease_buf(u8 *rbuf, struct lease *lease);
+struct lease_ctx_info *parse_lease_state(void *open_req);
+__u8 smb2_map_lease_to_oplock(__le32 lease_state);
+void lease_update_oplock_levels(struct lease *lease);
+int lease_read_to_write(struct oplock_info *opinfo);
+
+/* Durable related functions */
+void create_durable_rsp_buf(char *cc);
+void create_durable_v2_rsp_buf(char *cc, struct ksmbd_file *fp);
+void create_mxac_rsp_buf(char *cc, int maximal_access);
+void create_disk_id_rsp_buf(char *cc, __u64 file_id, __u64 vol_id);
+void create_posix_rsp_buf(char *cc, struct ksmbd_file *fp);
+struct create_context *smb2_find_context_vals(void *open_req, const char *tag, int tag_len);
+struct oplock_info *lookup_lease_in_table(struct ksmbd_conn *conn,
+					  char *lease_key);
+int find_same_lease_key(struct ksmbd_conn *conn, struct ksmbd_inode *ci,
+			struct lease_ctx_info *lctx);
+void destroy_lease_table(struct ksmbd_conn *conn);
+void smb_send_parent_lease_break_noti(struct ksmbd_file *fp,
+				      struct lease_ctx_info *lctx);
+void smb_lazy_parent_lease_break_close(struct ksmbd_file *fp);
+int smb2_check_durable_oplock(struct ksmbd_conn *conn,
+			      struct ksmbd_share_config *share,
+			      struct ksmbd_file *fp,
+			      struct lease_ctx_info *lctx,
+			      struct ksmbd_user *user,
+			      char *name);
+#endif /* __KSMBD_OPLOCK_H */