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, 171 insertions, 0 deletions

diff --git a/net/nfc/digital.h b/net/nfc/digital.h
new file mode 100644
index 000000000..c33b2f7e1
--- /dev/null
+++ b/net/nfc/digital.h
@@ -0,0 +1,171 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * NFC Digital Protocol stack
+ * Copyright (c) 2013, Intel Corporation.
+ */
+
+#ifndef __DIGITAL_H
+#define __DIGITAL_H
+
+#include <net/nfc/nfc.h>
+#include <net/nfc/digital.h>
+
+#include <linux/crc-ccitt.h>
+#include <linux/crc-itu-t.h>
+
+#define PROTOCOL_ERR(req) pr_err("%d: NFC Digital Protocol error: %s\n", \
+				 __LINE__, req)
+
+#define DIGITAL_CMD_IN_SEND        0
+#define DIGITAL_CMD_TG_SEND        1
+#define DIGITAL_CMD_TG_LISTEN      2
+#define DIGITAL_CMD_TG_LISTEN_MDAA 3
+#define DIGITAL_CMD_TG_LISTEN_MD   4
+
+#define DIGITAL_MAX_HEADER_LEN 7
+#define DIGITAL_CRC_LEN        2
+
+#define DIGITAL_SENSF_NFCID2_NFC_DEP_B1 0x01
+#define DIGITAL_SENSF_NFCID2_NFC_DEP_B2 0xFE
+
+#define DIGITAL_SENS_RES_NFC_DEP 0x0100
+#define DIGITAL_SEL_RES_NFC_DEP  0x40
+#define DIGITAL_SENSF_FELICA_SC  0xFFFF
+
+#define DIGITAL_DRV_CAPS_IN_CRC(ddev) \
+	((ddev)->driver_capabilities & NFC_DIGITAL_DRV_CAPS_IN_CRC)
+#define DIGITAL_DRV_CAPS_TG_CRC(ddev) \
+	((ddev)->driver_capabilities & NFC_DIGITAL_DRV_CAPS_TG_CRC)
+
+struct digital_data_exch {
+	data_exchange_cb_t cb;
+	void *cb_context;
+};
+
+struct sk_buff *digital_skb_alloc(struct nfc_digital_dev *ddev,
+				  unsigned int len);
+
+int digital_send_cmd(struct nfc_digital_dev *ddev, u8 cmd_type,
+		     struct sk_buff *skb, struct digital_tg_mdaa_params *params,
+		     u16 timeout, nfc_digital_cmd_complete_t cmd_cb,
+		     void *cb_context);
+
+int digital_in_configure_hw(struct nfc_digital_dev *ddev, int type, int param);
+static inline int digital_in_send_cmd(struct nfc_digital_dev *ddev,
+				      struct sk_buff *skb, u16 timeout,
+				      nfc_digital_cmd_complete_t cmd_cb,
+				      void *cb_context)
+{
+	return digital_send_cmd(ddev, DIGITAL_CMD_IN_SEND, skb, NULL, timeout,
+				cmd_cb, cb_context);
+}
+
+void digital_poll_next_tech(struct nfc_digital_dev *ddev);
+
+int digital_in_send_sens_req(struct nfc_digital_dev *ddev, u8 rf_tech);
+int digital_in_send_sensb_req(struct nfc_digital_dev *ddev, u8 rf_tech);
+int digital_in_send_sensf_req(struct nfc_digital_dev *ddev, u8 rf_tech);
+int digital_in_send_iso15693_inv_req(struct nfc_digital_dev *ddev, u8 rf_tech);
+
+int digital_in_iso_dep_pull_sod(struct nfc_digital_dev *ddev,
+				struct sk_buff *skb);
+int digital_in_iso_dep_push_sod(struct nfc_digital_dev *ddev,
+				struct sk_buff *skb);
+
+int digital_target_found(struct nfc_digital_dev *ddev,
+			 struct nfc_target *target, u8 protocol);
+
+int digital_in_recv_mifare_res(struct sk_buff *resp);
+
+int digital_in_send_atr_req(struct nfc_digital_dev *ddev,
+			    struct nfc_target *target, __u8 comm_mode, __u8 *gb,
+			    size_t gb_len);
+int digital_in_send_dep_req(struct nfc_digital_dev *ddev,
+			    struct nfc_target *target, struct sk_buff *skb,
+			    struct digital_data_exch *data_exch);
+
+int digital_tg_configure_hw(struct nfc_digital_dev *ddev, int type, int param);
+static inline int digital_tg_send_cmd(struct nfc_digital_dev *ddev,
+			struct sk_buff *skb, u16 timeout,
+			nfc_digital_cmd_complete_t cmd_cb, void *cb_context)
+{
+	return digital_send_cmd(ddev, DIGITAL_CMD_TG_SEND, skb, NULL, timeout,
+				cmd_cb, cb_context);
+}
+
+void digital_tg_recv_sens_req(struct nfc_digital_dev *ddev, void *arg,
+			      struct sk_buff *resp);
+
+void digital_tg_recv_sensf_req(struct nfc_digital_dev *ddev, void *arg,
+			       struct sk_buff *resp);
+
+static inline int digital_tg_listen(struct nfc_digital_dev *ddev, u16 timeout,
+				    nfc_digital_cmd_complete_t cb, void *arg)
+{
+	return digital_send_cmd(ddev, DIGITAL_CMD_TG_LISTEN, NULL, NULL,
+				timeout, cb, arg);
+}
+
+void digital_tg_recv_atr_req(struct nfc_digital_dev *ddev, void *arg,
+			     struct sk_buff *resp);
+
+int digital_tg_send_dep_res(struct nfc_digital_dev *ddev, struct sk_buff *skb);
+
+int digital_tg_listen_nfca(struct nfc_digital_dev *ddev, u8 rf_tech);
+int digital_tg_listen_nfcf(struct nfc_digital_dev *ddev, u8 rf_tech);
+void digital_tg_recv_md_req(struct nfc_digital_dev *ddev, void *arg,
+			    struct sk_buff *resp);
+
+typedef u16 (*crc_func_t)(u16, const u8 *, size_t);
+
+#define CRC_A_INIT 0x6363
+#define CRC_B_INIT 0xFFFF
+#define CRC_F_INIT 0x0000
+
+void digital_skb_add_crc(struct sk_buff *skb, crc_func_t crc_func, u16 init,
+			 u8 bitwise_inv, u8 msb_first);
+
+static inline void digital_skb_add_crc_a(struct sk_buff *skb)
+{
+	digital_skb_add_crc(skb, crc_ccitt, CRC_A_INIT, 0, 0);
+}
+
+static inline void digital_skb_add_crc_b(struct sk_buff *skb)
+{
+	digital_skb_add_crc(skb, crc_ccitt, CRC_B_INIT, 1, 0);
+}
+
+static inline void digital_skb_add_crc_f(struct sk_buff *skb)
+{
+	digital_skb_add_crc(skb, crc_itu_t, CRC_F_INIT, 0, 1);
+}
+
+static inline void digital_skb_add_crc_none(struct sk_buff *skb)
+{
+	return;
+}
+
+int digital_skb_check_crc(struct sk_buff *skb, crc_func_t crc_func,
+			  u16 crc_init, u8 bitwise_inv, u8 msb_first);
+
+static inline int digital_skb_check_crc_a(struct sk_buff *skb)
+{
+	return digital_skb_check_crc(skb, crc_ccitt, CRC_A_INIT, 0, 0);
+}
+
+static inline int digital_skb_check_crc_b(struct sk_buff *skb)
+{
+	return digital_skb_check_crc(skb, crc_ccitt, CRC_B_INIT, 1, 0);
+}
+
+static inline int digital_skb_check_crc_f(struct sk_buff *skb)
+{
+	return digital_skb_check_crc(skb, crc_itu_t, CRC_F_INIT, 0, 1);
+}
+
+static inline int digital_skb_check_crc_none(struct sk_buff *skb)
+{
+	return 0;
+}
+
+#endif /* __DIGITAL_H */