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, 122 insertions, 0 deletions

diff --git a/fs/smb/server/xattr.h b/fs/smb/server/xattr.h
new file mode 100644
index 000000000..505101a81
--- /dev/null
+++ b/fs/smb/server/xattr.h
@@ -0,0 +1,122 @@
+/* SPDX-License-Identifier: GPL-2.0-or-later */
+/*
+ *   Copyright (C) 2021 Samsung Electronics Co., Ltd.
+ */
+
+#ifndef __XATTR_H__
+#define __XATTR_H__
+
+/*
+ * These are on-disk structures to store additional metadata into xattr to
+ * reproduce windows filesystem semantics. And they are encoded with NDR to
+ * compatible with samba's xattr meta format. The compatibility with samba
+ * is important because it can lose the information(file attribute,
+ * creation time, acls) about the existing files when switching between
+ * ksmbd and samba.
+ */
+
+/*
+ * Dos attribute flags used for what variable is valid.
+ */
+enum {
+	XATTR_DOSINFO_ATTRIB		= 0x00000001,
+	XATTR_DOSINFO_EA_SIZE		= 0x00000002,
+	XATTR_DOSINFO_SIZE		= 0x00000004,
+	XATTR_DOSINFO_ALLOC_SIZE	= 0x00000008,
+	XATTR_DOSINFO_CREATE_TIME	= 0x00000010,
+	XATTR_DOSINFO_CHANGE_TIME	= 0x00000020,
+	XATTR_DOSINFO_ITIME		= 0x00000040
+};
+
+/*
+ * Dos attribute structure which is compatible with samba's one.
+ * Storing it into the xattr named "DOSATTRIB" separately from inode
+ * allows ksmbd to faithfully reproduce windows filesystem semantics
+ * on top of a POSIX filesystem.
+ */
+struct xattr_dos_attrib {
+	__u16	version;	/* version 3 or version 4 */
+	__u32	flags;		/* valid flags */
+	__u32	attr;		/* Dos attribute */
+	__u32	ea_size;	/* EA size */
+	__u64	size;
+	__u64	alloc_size;
+	__u64	create_time;	/* File creation time */
+	__u64	change_time;	/* File change time */
+	__u64	itime;		/* Invented/Initial time */
+};
+
+/*
+ * Enumeration is used for computing posix acl hash.
+ */
+enum {
+	SMB_ACL_TAG_INVALID = 0,
+	SMB_ACL_USER,
+	SMB_ACL_USER_OBJ,
+	SMB_ACL_GROUP,
+	SMB_ACL_GROUP_OBJ,
+	SMB_ACL_OTHER,
+	SMB_ACL_MASK
+};
+
+#define SMB_ACL_READ			4
+#define SMB_ACL_WRITE			2
+#define SMB_ACL_EXECUTE			1
+
+struct xattr_acl_entry {
+	int type;
+	uid_t uid;
+	gid_t gid;
+	mode_t perm;
+};
+
+/*
+ * xattr_smb_acl structure is used for computing posix acl hash.
+ */
+struct xattr_smb_acl {
+	int count;
+	int next;
+	struct xattr_acl_entry entries[] __counted_by(count);
+};
+
+/* 64bytes hash in xattr_ntacl is computed with sha256 */
+#define XATTR_SD_HASH_TYPE_SHA256	0x1
+#define XATTR_SD_HASH_SIZE		64
+
+/*
+ * xattr_ntacl is used for storing ntacl and hashes.
+ * Hash is used for checking valid posix acl and ntacl in xattr.
+ */
+struct xattr_ntacl {
+	__u16	version; /* version 4*/
+	void	*sd_buf;
+	__u32	sd_size;
+	__u16	hash_type; /* hash type */
+	__u8	desc[10]; /* posix_acl description */
+	__u16	desc_len;
+	__u64	current_time;
+	__u8	hash[XATTR_SD_HASH_SIZE]; /* 64bytes hash for ntacl */
+	__u8	posix_acl_hash[XATTR_SD_HASH_SIZE]; /* 64bytes hash for posix acl */
+};
+
+/* DOS ATTRIBUTE XATTR PREFIX */
+#define DOS_ATTRIBUTE_PREFIX		"DOSATTRIB"
+#define DOS_ATTRIBUTE_PREFIX_LEN	(sizeof(DOS_ATTRIBUTE_PREFIX) - 1)
+#define XATTR_NAME_DOS_ATTRIBUTE	(XATTR_USER_PREFIX DOS_ATTRIBUTE_PREFIX)
+#define XATTR_NAME_DOS_ATTRIBUTE_LEN	\
+		(sizeof(XATTR_USER_PREFIX DOS_ATTRIBUTE_PREFIX) - 1)
+
+/* STREAM XATTR PREFIX */
+#define STREAM_PREFIX			"DosStream."
+#define STREAM_PREFIX_LEN		(sizeof(STREAM_PREFIX) - 1)
+#define XATTR_NAME_STREAM		(XATTR_USER_PREFIX STREAM_PREFIX)
+#define XATTR_NAME_STREAM_LEN		(sizeof(XATTR_NAME_STREAM) - 1)
+
+/* SECURITY DESCRIPTOR(NTACL) XATTR PREFIX */
+#define SD_PREFIX			"NTACL"
+#define SD_PREFIX_LEN	(sizeof(SD_PREFIX) - 1)
+#define XATTR_NAME_SD	(XATTR_SECURITY_PREFIX SD_PREFIX)
+#define XATTR_NAME_SD_LEN	\
+		(sizeof(XATTR_SECURITY_PREFIX SD_PREFIX) - 1)
+
+#endif /* __XATTR_H__ */