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, 314 insertions, 0 deletions

diff --git a/fs/nfsd/xdr3.h b/fs/nfsd/xdr3.h
new file mode 100644
index 000000000..a7c9714b0
--- /dev/null
+++ b/fs/nfsd/xdr3.h
@@ -0,0 +1,314 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * XDR types for NFSv3 in nfsd.
+ *
+ * Copyright (C) 1996-1998, Olaf Kirch <okir@monad.swb.de>
+ */
+
+#ifndef _LINUX_NFSD_XDR3_H
+#define _LINUX_NFSD_XDR3_H
+
+#include "xdr.h"
+
+struct nfsd3_sattrargs {
+	struct svc_fh		fh;
+	struct iattr		attrs;
+	int			check_guard;
+	struct timespec64	guardtime;
+};
+
+struct nfsd3_diropargs {
+	struct svc_fh		fh;
+	char *			name;
+	unsigned int		len;
+};
+
+struct nfsd3_accessargs {
+	struct svc_fh		fh;
+	__u32			access;
+};
+
+struct nfsd3_readargs {
+	struct svc_fh		fh;
+	__u64			offset;
+	__u32			count;
+};
+
+struct nfsd3_writeargs {
+	svc_fh			fh;
+	__u64			offset;
+	__u32			count;
+	int			stable;
+	__u32			len;
+	struct xdr_buf		payload;
+};
+
+struct nfsd3_createargs {
+	struct svc_fh		fh;
+	char *			name;
+	unsigned int		len;
+	int			createmode;
+	struct iattr		attrs;
+	__be32 *		verf;
+};
+
+struct nfsd3_mknodargs {
+	struct svc_fh		fh;
+	char *			name;
+	unsigned int		len;
+	__u32			ftype;
+	__u32			major, minor;
+	struct iattr		attrs;
+};
+
+struct nfsd3_renameargs {
+	struct svc_fh		ffh;
+	char *			fname;
+	unsigned int		flen;
+	struct svc_fh		tfh;
+	char *			tname;
+	unsigned int		tlen;
+};
+
+struct nfsd3_linkargs {
+	struct svc_fh		ffh;
+	struct svc_fh		tfh;
+	char *			tname;
+	unsigned int		tlen;
+};
+
+struct nfsd3_symlinkargs {
+	struct svc_fh		ffh;
+	char *			fname;
+	unsigned int		flen;
+	char *			tname;
+	unsigned int		tlen;
+	struct iattr		attrs;
+	struct kvec		first;
+};
+
+struct nfsd3_readdirargs {
+	struct svc_fh		fh;
+	__u64			cookie;
+	__u32			count;
+	__be32 *		verf;
+};
+
+struct nfsd3_commitargs {
+	struct svc_fh		fh;
+	__u64			offset;
+	__u32			count;
+};
+
+struct nfsd3_getaclargs {
+	struct svc_fh		fh;
+	__u32			mask;
+};
+
+struct posix_acl;
+struct nfsd3_setaclargs {
+	struct svc_fh		fh;
+	__u32			mask;
+	struct posix_acl	*acl_access;
+	struct posix_acl	*acl_default;
+};
+
+struct nfsd3_attrstat {
+	__be32			status;
+	struct svc_fh		fh;
+	struct kstat            stat;
+};
+
+/* LOOKUP, CREATE, MKDIR, SYMLINK, MKNOD */
+struct nfsd3_diropres  {
+	__be32			status;
+	struct svc_fh		dirfh;
+	struct svc_fh		fh;
+};
+
+struct nfsd3_accessres {
+	__be32			status;
+	struct svc_fh		fh;
+	__u32			access;
+	struct kstat		stat;
+};
+
+struct nfsd3_readlinkres {
+	__be32			status;
+	struct svc_fh		fh;
+	__u32			len;
+	struct page		**pages;
+};
+
+struct nfsd3_readres {
+	__be32			status;
+	struct svc_fh		fh;
+	unsigned long		count;
+	__u32			eof;
+	struct page		**pages;
+};
+
+struct nfsd3_writeres {
+	__be32			status;
+	struct svc_fh		fh;
+	unsigned long		count;
+	int			committed;
+	__be32			verf[2];
+};
+
+struct nfsd3_renameres {
+	__be32			status;
+	struct svc_fh		ffh;
+	struct svc_fh		tfh;
+};
+
+struct nfsd3_linkres {
+	__be32			status;
+	struct svc_fh		tfh;
+	struct svc_fh		fh;
+};
+
+struct nfsd3_readdirres {
+	/* Components of the reply */
+	__be32			status;
+	struct svc_fh		fh;
+	__be32			verf[2];
+
+	/* Used to encode the reply's entry list */
+	struct xdr_stream	xdr;
+	struct xdr_buf		dirlist;
+	struct svc_fh		scratch;
+	struct readdir_cd	common;
+	unsigned int		cookie_offset;
+	struct svc_rqst *	rqstp;
+
+};
+
+struct nfsd3_fsstatres {
+	__be32			status;
+	struct kstatfs		stats;
+	__u32			invarsec;
+};
+
+struct nfsd3_fsinfores {
+	__be32			status;
+	__u32			f_rtmax;
+	__u32			f_rtpref;
+	__u32			f_rtmult;
+	__u32			f_wtmax;
+	__u32			f_wtpref;
+	__u32			f_wtmult;
+	__u32			f_dtpref;
+	__u64			f_maxfilesize;
+	__u32			f_properties;
+};
+
+struct nfsd3_pathconfres {
+	__be32			status;
+	__u32			p_link_max;
+	__u32			p_name_max;
+	__u32			p_no_trunc;
+	__u32			p_chown_restricted;
+	bool			p_case_insensitive;
+	bool			p_case_preserving;
+};
+
+struct nfsd3_commitres {
+	__be32			status;
+	struct svc_fh		fh;
+	__be32			verf[2];
+};
+
+struct nfsd3_getaclres {
+	__be32			status;
+	struct svc_fh		fh;
+	int			mask;
+	struct posix_acl	*acl_access;
+	struct posix_acl	*acl_default;
+	struct kstat		stat;
+};
+
+/* dummy type for release */
+struct nfsd3_fhandle_pair {
+	__u32			dummy;
+	struct svc_fh		fh1;
+	struct svc_fh		fh2;
+};
+
+/*
+ * Storage requirements for XDR arguments and results.
+ */
+union nfsd3_xdrstore {
+	struct nfsd3_sattrargs		sattrargs;
+	struct nfsd3_diropargs		diropargs;
+	struct nfsd3_readargs		readargs;
+	struct nfsd3_writeargs		writeargs;
+	struct nfsd3_createargs		createargs;
+	struct nfsd3_renameargs		renameargs;
+	struct nfsd3_linkargs		linkargs;
+	struct nfsd3_symlinkargs	symlinkargs;
+	struct nfsd3_readdirargs	readdirargs;
+	struct nfsd3_diropres 		diropres;
+	struct nfsd3_accessres		accessres;
+	struct nfsd3_readlinkres	readlinkres;
+	struct nfsd3_readres		readres;
+	struct nfsd3_writeres		writeres;
+	struct nfsd3_renameres		renameres;
+	struct nfsd3_linkres		linkres;
+	struct nfsd3_readdirres		readdirres;
+	struct nfsd3_fsstatres		fsstatres;
+	struct nfsd3_fsinfores		fsinfores;
+	struct nfsd3_pathconfres	pathconfres;
+	struct nfsd3_commitres		commitres;
+	struct nfsd3_getaclres		getaclres;
+};
+
+#define NFS3_SVC_XDRSIZE		sizeof(union nfsd3_xdrstore)
+
+bool nfs3svc_decode_fhandleargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_sattrargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_diropargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_accessargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_readargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_writeargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_createargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_mkdirargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_mknodargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_renameargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_linkargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_symlinkargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_readdirargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_readdirplusargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_decode_commitargs(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+
+bool nfs3svc_encode_getattrres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_wccstat(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_lookupres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_accessres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_readlinkres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_readres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_writeres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_createres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_renameres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_linkres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_readdirres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_fsstatres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_fsinfores(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_pathconfres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+bool nfs3svc_encode_commitres(struct svc_rqst *rqstp, struct xdr_stream *xdr);
+
+void nfs3svc_release_fhandle(struct svc_rqst *);
+void nfs3svc_release_fhandle2(struct svc_rqst *);
+
+void nfs3svc_encode_cookie3(struct nfsd3_readdirres *resp, u64 offset);
+int nfs3svc_encode_entry3(void *data, const char *name, int namlen,
+			  loff_t offset, u64 ino, unsigned int d_type);
+int nfs3svc_encode_entryplus3(void *data, const char *name, int namlen,
+			      loff_t offset, u64 ino, unsigned int d_type);
+/* Helper functions for NFSv3 ACL code */
+bool svcxdr_decode_nfs_fh3(struct xdr_stream *xdr, struct svc_fh *fhp);
+bool svcxdr_encode_nfsstat3(struct xdr_stream *xdr, __be32 status);
+bool svcxdr_encode_post_op_attr(struct svc_rqst *rqstp, struct xdr_stream *xdr,
+				const struct svc_fh *fhp);
+
+#endif /* _LINUX_NFSD_XDR3_H */