[PATCH 03/26] fuse-bpf: Update uapi for fuse-bpf

[Daniel Rosenberg <drosen@google.com>]

This adds the bpf prog type for fuse-bpf, and the associated structures.

Signed-off-by: Daniel Rosenberg <drosen@google.com>
Signed-off-by: Paul Lawrence <paullawrence@google.com>
---
 include/linux/bpf_fuse.h  | 50 +++++++++++++++++++++++++++++++++++++++
 include/linux/bpf_types.h |  4 ++++
 include/uapi/linux/bpf.h  | 31 ++++++++++++++++++++++++
 include/uapi/linux/fuse.h | 13 +++++++++-
 4 files changed, 97 insertions(+), 1 deletion(-)

diff --git a/include/linux/bpf_fuse.h b/include/linux/bpf_fuse.h
index 18e2ec5bf453..9d22205c9ae0 100644
--- a/include/linux/bpf_fuse.h
+++ b/include/linux/bpf_fuse.h
@@ -6,6 +6,56 @@
 #ifndef _BPF_FUSE_H
 #define _BPF_FUSE_H
 
+/*
+ * Fuse BPF Args
+ *
+ * Used to communicate with bpf programs to allow checking or altering certain values.
+ * The end_offset allows the bpf verifier to check boundaries statically. This reflects
+ * the ends of the buffer. size shows the length that was actually used.
+ *
+ * In order to write to the output args, you must use the pointer returned by
+ * bpf_fuse_get_writeable.
+ *
+ */
+
+#define FUSE_MAX_ARGS_IN 3
+#define FUSE_MAX_ARGS_OUT 2
+
+struct bpf_fuse_arg {
+	void *value;		// Start of the buffer
+	void *end_offset;	// End of the buffer
+	uint32_t size;		// Used size of the buffer
+	uint32_t max_size;	// Max permitted size, if buffer is resizable. Otherwise 0
+	uint32_t flags;		// Flags indicating buffer status
+};
+
+#define FUSE_BPF_FORCE (1 << 0)
+#define FUSE_BPF_OUT_ARGVAR (1 << 6)
+
+struct bpf_fuse_args {
+	uint64_t nodeid;
+	uint32_t opcode;
+	uint32_t error_in;
+	uint32_t in_numargs;
+	uint32_t out_numargs;
+	uint32_t flags;
+	struct bpf_fuse_arg in_args[FUSE_MAX_ARGS_IN];
+	struct bpf_fuse_arg out_args[FUSE_MAX_ARGS_OUT];
+};
+
+/* These flags are used internally to track information about the fuse buffers.
+ * Fuse sets some of the flags in init. The helper functions sets others, depending on what
+ * was requested by the bpf program.
+ */
+// Flags set by FUSE
+#define BPF_FUSE_IMMUTABLE	(1 << 0) // Buffer may not be written to
+#define BPF_FUSE_VARIABLE_SIZE	(1 << 1) // Buffer length may be changed (growth requires alloc)
+#define BPF_FUSE_MUST_ALLOCATE	(1 << 2) // Buffer must be re allocated before allowing writes
+
+// Flags set by helper function
+#define BPF_FUSE_MODIFIED	(1 << 3) // The helper function allowed writes to the buffer
+#define BPF_FUSE_ALLOCATED	(1 << 4) // The helper function allocated the buffer
+
 bool bpf_helper_changes_one_pkt_data(void *func);
 
 #endif /* _BPF_FUSE_H */
diff --git a/include/linux/bpf_types.h b/include/linux/bpf_types.h
index 2b9112b80171..80c7f7d69794 100644
--- a/include/linux/bpf_types.h
+++ b/include/linux/bpf_types.h
@@ -79,6 +79,10 @@ BPF_PROG_TYPE(BPF_PROG_TYPE_LSM, lsm,
 #endif
 BPF_PROG_TYPE(BPF_PROG_TYPE_SYSCALL, bpf_syscall,
 	      void *, void *)
+#ifdef CONFIG_FUSE_BPF
+BPF_PROG_TYPE(BPF_PROG_TYPE_FUSE, fuse,
+	      struct __bpf_fuse_args, struct bpf_fuse_args)
+#endif
 
 BPF_MAP_TYPE(BPF_MAP_TYPE_ARRAY, array_map_ops)
 BPF_MAP_TYPE(BPF_MAP_TYPE_PERCPU_ARRAY, percpu_array_map_ops)
diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index 59a217ca2dfd..ac81763f002b 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -952,6 +952,7 @@ enum bpf_prog_type {
 	BPF_PROG_TYPE_LSM,
 	BPF_PROG_TYPE_SK_LOOKUP,
 	BPF_PROG_TYPE_SYSCALL, /* a program that can execute syscalls */
+	BPF_PROG_TYPE_FUSE,
 };
 
 enum bpf_attach_type {
@@ -6848,4 +6849,34 @@ struct bpf_core_relo {
 	enum bpf_core_relo_kind kind;
 };
 
+struct __bpf_fuse_arg {
+	__u64 value;
+	__u64 end_offset;
+	__u32 size;
+	__u32 max_size;
+};
+
+struct __bpf_fuse_args {
+	__u64 nodeid;
+	__u32 opcode;
+	__u32 error_in;
+	__u32 in_numargs;
+	__u32 out_numargs;
+	__u32 flags;
+	struct __bpf_fuse_arg in_args[3];
+	struct __bpf_fuse_arg out_args[2];
+};
+
+/* Return Codes for Fuse BPF programs */
+#define BPF_FUSE_CONTINUE		0
+#define BPF_FUSE_USER			1
+#define BPF_FUSE_USER_PREFILTER		2
+#define BPF_FUSE_POSTFILTER		3
+#define BPF_FUSE_USER_POSTFILTER	4
+
+/* Op Code Filter values for BPF Programs */
+#define FUSE_OPCODE_FILTER	0x0ffff
+#define FUSE_PREFILTER		0x10000
+#define FUSE_POSTFILTER		0x20000
+
 #endif /* _UAPI__LINUX_BPF_H__ */
diff --git a/include/uapi/linux/fuse.h b/include/uapi/linux/fuse.h
index d6ccee961891..8c80c146e69b 100644
--- a/include/uapi/linux/fuse.h
+++ b/include/uapi/linux/fuse.h
@@ -572,6 +572,17 @@ struct fuse_entry_out {
 	struct fuse_attr attr;
 };
 
+#define FUSE_ACTION_KEEP	0
+#define FUSE_ACTION_REMOVE	1
+#define FUSE_ACTION_REPLACE	2
+
+struct fuse_entry_bpf_out {
+	uint64_t	backing_action;
+	uint64_t	backing_fd;
+	uint64_t	bpf_action;
+	uint64_t	bpf_fd;
+};
+
 struct fuse_forget_in {
 	uint64_t	nlookup;
 };
@@ -870,7 +881,7 @@ struct fuse_in_header {
 	uint32_t	uid;
 	uint32_t	gid;
 	uint32_t	pid;
-	uint32_t	padding;
+	uint32_t	error_in;
 };
 
 struct fuse_out_header {
-- 
2.37.3.998.g577e59143f-goog