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, 286 insertions, 0 deletions

diff --git a/fs/nfsd/nfs3acl.c b/fs/nfsd/nfs3acl.c
new file mode 100644
index 000000000..e87731380
--- /dev/null
+++ b/fs/nfsd/nfs3acl.c
@@ -0,0 +1,286 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Process version 3 NFSACL requests.
+ *
+ * Copyright (C) 2002-2003 Andreas Gruenbacher <agruen@suse.de>
+ */
+
+#include "nfsd.h"
+/* FIXME: nfsacl.h is a broken header */
+#include <linux/nfsacl.h>
+#include <linux/gfp.h>
+#include "cache.h"
+#include "xdr3.h"
+#include "vfs.h"
+
+/*
+ * NULL call.
+ */
+static __be32
+nfsd3_proc_null(struct svc_rqst *rqstp)
+{
+	return rpc_success;
+}
+
+/*
+ * Get the Access and/or Default ACL of a file.
+ */
+static __be32 nfsd3_proc_getacl(struct svc_rqst *rqstp)
+{
+	struct nfsd3_getaclargs *argp = rqstp->rq_argp;
+	struct nfsd3_getaclres *resp = rqstp->rq_resp;
+	struct posix_acl *acl;
+	struct inode *inode;
+	svc_fh *fh;
+
+	fh = fh_copy(&resp->fh, &argp->fh);
+	resp->status = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_NOP);
+	if (resp->status != nfs_ok)
+		goto out;
+
+	inode = d_inode(fh->fh_dentry);
+
+	if (argp->mask & ~NFS_ACL_MASK) {
+		resp->status = nfserr_inval;
+		goto out;
+	}
+	resp->mask = argp->mask;
+
+	if (resp->mask & (NFS_ACL|NFS_ACLCNT)) {
+		acl = get_inode_acl(inode, ACL_TYPE_ACCESS);
+		if (acl == NULL) {
+			/* Solaris returns the inode's minimum ACL. */
+			acl = posix_acl_from_mode(inode->i_mode, GFP_KERNEL);
+		}
+		if (IS_ERR(acl)) {
+			resp->status = nfserrno(PTR_ERR(acl));
+			goto fail;
+		}
+		resp->acl_access = acl;
+	}
+	if (resp->mask & (NFS_DFACL|NFS_DFACLCNT)) {
+		/* Check how Solaris handles requests for the Default ACL
+		   of a non-directory! */
+		acl = get_inode_acl(inode, ACL_TYPE_DEFAULT);
+		if (IS_ERR(acl)) {
+			resp->status = nfserrno(PTR_ERR(acl));
+			goto fail;
+		}
+		resp->acl_default = acl;
+	}
+
+	/* resp->acl_{access,default} are released in nfs3svc_release_getacl. */
+out:
+	return rpc_success;
+
+fail:
+	posix_acl_release(resp->acl_access);
+	posix_acl_release(resp->acl_default);
+	resp->acl_access = NULL;
+	resp->acl_default = NULL;
+	goto out;
+}
+
+/*
+ * Set the Access and/or Default ACL of a file.
+ */
+static __be32 nfsd3_proc_setacl(struct svc_rqst *rqstp)
+{
+	struct nfsd3_setaclargs *argp = rqstp->rq_argp;
+	struct nfsd3_attrstat *resp = rqstp->rq_resp;
+	struct inode *inode;
+	svc_fh *fh;
+	int error;
+
+	fh = fh_copy(&resp->fh, &argp->fh);
+	resp->status = fh_verify(rqstp, &resp->fh, 0, NFSD_MAY_SATTR);
+	if (resp->status != nfs_ok)
+		goto out;
+
+	inode = d_inode(fh->fh_dentry);
+
+	error = fh_want_write(fh);
+	if (error)
+		goto out_errno;
+
+	inode_lock(inode);
+
+	error = set_posix_acl(&nop_mnt_idmap, fh->fh_dentry, ACL_TYPE_ACCESS,
+			      argp->acl_access);
+	if (error)
+		goto out_drop_lock;
+	error = set_posix_acl(&nop_mnt_idmap, fh->fh_dentry, ACL_TYPE_DEFAULT,
+			      argp->acl_default);
+
+out_drop_lock:
+	inode_unlock(inode);
+	fh_drop_write(fh);
+out_errno:
+	resp->status = nfserrno(error);
+out:
+	/* argp->acl_{access,default} are released in nfs3svc_release_setacl. */
+	return rpc_success;
+}
+
+/*
+ * XDR decode functions
+ */
+
+static bool
+nfs3svc_decode_getaclargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
+{
+	struct nfsd3_getaclargs *args = rqstp->rq_argp;
+
+	if (!svcxdr_decode_nfs_fh3(xdr, &args->fh))
+		return false;
+	if (xdr_stream_decode_u32(xdr, &args->mask) < 0)
+		return false;
+
+	return true;
+}
+
+static bool
+nfs3svc_decode_setaclargs(struct svc_rqst *rqstp, struct xdr_stream *xdr)
+{
+	struct nfsd3_setaclargs *argp = rqstp->rq_argp;
+
+	if (!svcxdr_decode_nfs_fh3(xdr, &argp->fh))
+		return false;
+	if (xdr_stream_decode_u32(xdr, &argp->mask) < 0)
+		return false;
+	if (argp->mask & ~NFS_ACL_MASK)
+		return false;
+	if (!nfs_stream_decode_acl(xdr, NULL, (argp->mask & NFS_ACL) ?
+				   &argp->acl_access : NULL))
+		return false;
+	if (!nfs_stream_decode_acl(xdr, NULL, (argp->mask & NFS_DFACL) ?
+				   &argp->acl_default : NULL))
+		return false;
+
+	return true;
+}
+
+/*
+ * XDR encode functions
+ */
+
+/* GETACL */
+static bool
+nfs3svc_encode_getaclres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
+{
+	struct nfsd3_getaclres *resp = rqstp->rq_resp;
+	struct dentry *dentry = resp->fh.fh_dentry;
+	struct inode *inode;
+
+	if (!svcxdr_encode_nfsstat3(xdr, resp->status))
+		return false;
+	switch (resp->status) {
+	case nfs_ok:
+		inode = d_inode(dentry);
+		if (!svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh))
+			return false;
+		if (xdr_stream_encode_u32(xdr, resp->mask) < 0)
+			return false;
+
+		if (!nfs_stream_encode_acl(xdr, inode, resp->acl_access,
+					   resp->mask & NFS_ACL, 0))
+			return false;
+		if (!nfs_stream_encode_acl(xdr, inode, resp->acl_default,
+					   resp->mask & NFS_DFACL,
+					   NFS_ACL_DEFAULT))
+			return false;
+		break;
+	default:
+		if (!svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh))
+			return false;
+	}
+
+	return true;
+}
+
+/* SETACL */
+static bool
+nfs3svc_encode_setaclres(struct svc_rqst *rqstp, struct xdr_stream *xdr)
+{
+	struct nfsd3_attrstat *resp = rqstp->rq_resp;
+
+	return svcxdr_encode_nfsstat3(xdr, resp->status) &&
+		svcxdr_encode_post_op_attr(rqstp, xdr, &resp->fh);
+}
+
+/*
+ * XDR release functions
+ */
+static void nfs3svc_release_getacl(struct svc_rqst *rqstp)
+{
+	struct nfsd3_getaclres *resp = rqstp->rq_resp;
+
+	fh_put(&resp->fh);
+	posix_acl_release(resp->acl_access);
+	posix_acl_release(resp->acl_default);
+}
+
+static void nfs3svc_release_setacl(struct svc_rqst *rqstp)
+{
+	struct nfsd3_setaclargs *argp = rqstp->rq_argp;
+	struct nfsd3_attrstat *resp = rqstp->rq_resp;
+
+	fh_put(&resp->fh);
+	posix_acl_release(argp->acl_access);
+	posix_acl_release(argp->acl_default);
+}
+
+#define ST 1		/* status*/
+#define AT 21		/* attributes */
+#define pAT (1+AT)	/* post attributes - conditional */
+#define ACL (1+NFS_ACL_MAX_ENTRIES*3)  /* Access Control List */
+
+static const struct svc_procedure nfsd_acl_procedures3[3] = {
+	[ACLPROC3_NULL] = {
+		.pc_func = nfsd3_proc_null,
+		.pc_decode = nfssvc_decode_voidarg,
+		.pc_encode = nfssvc_encode_voidres,
+		.pc_argsize = sizeof(struct nfsd_voidargs),
+		.pc_argzero = sizeof(struct nfsd_voidargs),
+		.pc_ressize = sizeof(struct nfsd_voidres),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_xdrressize = ST,
+		.pc_name = "NULL",
+	},
+	[ACLPROC3_GETACL] = {
+		.pc_func = nfsd3_proc_getacl,
+		.pc_decode = nfs3svc_decode_getaclargs,
+		.pc_encode = nfs3svc_encode_getaclres,
+		.pc_release = nfs3svc_release_getacl,
+		.pc_argsize = sizeof(struct nfsd3_getaclargs),
+		.pc_argzero = sizeof(struct nfsd3_getaclargs),
+		.pc_ressize = sizeof(struct nfsd3_getaclres),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_xdrressize = ST+1+2*(1+ACL),
+		.pc_name = "GETACL",
+	},
+	[ACLPROC3_SETACL] = {
+		.pc_func = nfsd3_proc_setacl,
+		.pc_decode = nfs3svc_decode_setaclargs,
+		.pc_encode = nfs3svc_encode_setaclres,
+		.pc_release = nfs3svc_release_setacl,
+		.pc_argsize = sizeof(struct nfsd3_setaclargs),
+		.pc_argzero = sizeof(struct nfsd3_setaclargs),
+		.pc_ressize = sizeof(struct nfsd3_attrstat),
+		.pc_cachetype = RC_NOCACHE,
+		.pc_xdrressize = ST+pAT,
+		.pc_name = "SETACL",
+	},
+};
+
+static DEFINE_PER_CPU_ALIGNED(unsigned long,
+			      nfsd_acl_count3[ARRAY_SIZE(nfsd_acl_procedures3)]);
+const struct svc_version nfsd_acl_version3 = {
+	.vs_vers	= 3,
+	.vs_nproc	= ARRAY_SIZE(nfsd_acl_procedures3),
+	.vs_proc	= nfsd_acl_procedures3,
+	.vs_count	= nfsd_acl_count3,
+	.vs_dispatch	= nfsd_dispatch,
+	.vs_xdrsize	= NFS3_SVC_XDRSIZE,
+};
+