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, 33 insertions, 0 deletions

diff --git a/fs/xfs/xfs_handle.h b/fs/xfs/xfs_handle.h
new file mode 100644
index 000000000..6799a86d8
--- /dev/null
+++ b/fs/xfs/xfs_handle.h
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2000-2005 Silicon Graphics, Inc.
+ * Copyright (c) 2022-2024 Oracle.
+ * All rights reserved.
+ */
+#ifndef	__XFS_HANDLE_H__
+#define	__XFS_HANDLE_H__
+
+int xfs_attrlist_by_handle(struct file *parfilp,
+		struct xfs_fsop_attrlist_handlereq __user *p);
+int xfs_attrmulti_by_handle(struct file *parfilp, void __user *arg);
+
+int xfs_find_handle(unsigned int cmd, struct xfs_fsop_handlereq *hreq);
+int xfs_open_by_handle(struct file *parfilp, struct xfs_fsop_handlereq *hreq);
+int xfs_readlink_by_handle(struct file *parfilp,
+		struct xfs_fsop_handlereq *hreq);
+
+int xfs_ioc_attrmulti_one(struct file *parfilp, struct inode *inode,
+		uint32_t opcode, void __user *uname, void __user *value,
+		uint32_t *len, uint32_t flags);
+int xfs_ioc_attr_list(struct xfs_inode *dp, void __user *ubuf,
+		      size_t bufsize, int flags,
+		      struct xfs_attrlist_cursor __user *ucursor);
+
+struct dentry *xfs_handle_to_dentry(struct file *parfilp, void __user *uhandle,
+		u32 hlen);
+
+int xfs_ioc_getparents(struct file *file, struct xfs_getparents __user *arg);
+int xfs_ioc_getparents_by_handle(struct file *file,
+		struct xfs_getparents_by_handle __user *arg);
+
+#endif	/* __XFS_HANDLE_H__ */