[RFC 7/9] bpf: split get_id and fd_by_id in bpf_attr

[Lorenz Bauer <lmb@cloudflare.com>]

---
 include/uapi/linux/bpf.h | 60 ++++++++++++++++++++++++++++++++--------
 kernel/bpf/syscall.c     | 18 ++++++------
 2 files changed, 58 insertions(+), 20 deletions(-)

diff --git a/include/uapi/linux/bpf.h b/include/uapi/linux/bpf.h
index d3acd12d98c1..13d126c201ce 100644
--- a/include/uapi/linux/bpf.h
+++ b/include/uapi/linux/bpf.h
@@ -1422,17 +1422,43 @@ union bpf_attr {
 		__u32		cpu;
 	} test;
 
-	struct { /* anonymous struct used by BPF_*_GET_*_ID */
-		union {
-			__u32		start_id;
-			__u32		prog_id;
-			__u32		map_id;
-			__u32		btf_id;
-			__u32		link_id;
-		};
-		__u32		next_id;
-		__u32		open_flags;
-	};
+	struct { /* used by BPF_PROG_GET_FD_BY_ID command */
+		__u32 id;
+	} prog_get_fd_by_id;
+
+	struct { /* used by BPF_MAP_GET_FD_BY_ID command */
+		__u32 id;
+		__u32 ingnored;
+		__u32 open_flags;
+	} map_get_fd_by_id;
+
+	struct { /* used by BPF_BTF_GET_FD_BY_ID command */
+		__u32 id;
+	} btf_get_fd_by_id;
+
+	struct { /* used by BPF_LINK_GET_FD_BY_ID command */
+		__u32 id;
+	} link_get_fd_by_id;
+
+	struct { /* used by BPF_PROG_GET_NEXT_ID command */
+		__u32 start_id;
+		__u32 next_id;
+	} prog_get_next_id;
+
+	struct { /* used by BPF_MAP_GET_NEXT_ID command */
+		__u32 start_id;
+		__u32 next_id;
+	} map_get_next_id;
+
+	struct { /* used by BPF_BTF_GET_NEXT_ID command */
+		__u32 start_id;
+		__u32 next_id;
+	} btf_get_next_id;
+
+	struct { /* used by BPF_LINK_GET_NEXT_ID command */
+		__u32 start_id;
+		__u32 next_id;
+	} link_get_next_id;
 
 	struct { /* anonymous struct used by BPF_OBJ_GET_INFO_BY_FD */
 		__u32		bpf_fd;
@@ -1557,6 +1583,18 @@ union bpf_attr {
 		};
 		__u64		flags;
 	};
+
+	struct { /* anonymous struct used by BPF_*_GET_*_ID */
+		union {
+			__u32		start_id;
+			__u32		prog_id;
+			__u32		map_id;
+			__u32		btf_id;
+			__u32		link_id;
+		};
+		__u32		next_id;
+		__u32		open_flags;
+	};
 } __attribute__((aligned(8)));
 
 /* The description below is an attempt at providing documentation to eBPF
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index c4aecdbb390e..234860bd05bf 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -3367,7 +3367,7 @@ struct bpf_prog *bpf_prog_get_curr_or_next(u32 *id)
 	return prog;
 }
 
-#define BPF_PROG_GET_FD_BY_ID_LAST_FIELD prog_id
+#define BPF_PROG_GET_FD_BY_ID_LAST_FIELD prog_get_fd_by_id.id
 
 struct bpf_prog *bpf_prog_by_id(u32 id)
 {
@@ -3389,7 +3389,7 @@ struct bpf_prog *bpf_prog_by_id(u32 id)
 static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
 {
 	struct bpf_prog *prog;
-	u32 id = attr->prog_id;
+	u32 id = attr->prog_get_fd_by_id.id;
 	int fd;
 
 	if (CHECK_ATTR(BPF_PROG_GET_FD_BY_ID))
@@ -3409,12 +3409,12 @@ static int bpf_prog_get_fd_by_id(const union bpf_attr *attr)
 	return fd;
 }
 
-#define BPF_MAP_GET_FD_BY_ID_LAST_FIELD open_flags
+#define BPF_MAP_GET_FD_BY_ID_LAST_FIELD map_get_fd_by_id.open_flags
 
 static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
 {
 	struct bpf_map *map;
-	u32 id = attr->map_id;
+	u32 id = attr->map_get_fd_by_id.id;
 	int f_flags;
 	int fd;
 
@@ -3425,7 +3425,7 @@ static int bpf_map_get_fd_by_id(const union bpf_attr *attr)
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	f_flags = bpf_get_file_flag(attr->open_flags);
+	f_flags = bpf_get_file_flag(attr->map_get_fd_by_id.open_flags);
 	if (f_flags < 0)
 		return f_flags;
 
@@ -3984,7 +3984,7 @@ static int bpf_btf_load(const union bpf_attr *attr, bpfptr_t uattr)
 	return btf_new_fd(attr, uattr);
 }
 
-#define BPF_BTF_GET_FD_BY_ID_LAST_FIELD btf_id
+#define BPF_BTF_GET_FD_BY_ID_LAST_FIELD btf_get_fd_by_id.id
 
 static int bpf_btf_get_fd_by_id(const union bpf_attr *attr)
 {
@@ -3994,7 +3994,7 @@ static int bpf_btf_get_fd_by_id(const union bpf_attr *attr)
 	if (!capable(CAP_SYS_ADMIN))
 		return -EPERM;
 
-	return btf_get_fd_by_id(attr->btf_id);
+	return btf_get_fd_by_id(attr->btf_get_fd_by_id.id);
 }
 
 static int bpf_task_fd_query_copy(const union bpf_attr *attr,
@@ -4369,12 +4369,12 @@ struct bpf_link *bpf_link_by_id(u32 id)
 	return link;
 }
 
-#define BPF_LINK_GET_FD_BY_ID_LAST_FIELD link_id
+#define BPF_LINK_GET_FD_BY_ID_LAST_FIELD link_get_fd_by_id.id
 
 static int bpf_link_get_fd_by_id(const union bpf_attr *attr)
 {
 	struct bpf_link *link;
-	u32 id = attr->link_id;
+	u32 id = attr->link_get_fd_by_id.id;
 	int fd;
 
 	if (CHECK_ATTR(BPF_LINK_GET_FD_BY_ID))
-- 
2.30.2