Commit ccfe29eb authored by Alexei Starovoitov's avatar Alexei Starovoitov Committed by Daniel Borkmann
Browse files

bpf: Add attach_btf_id attribute to program load 



Add attach_btf_id attribute to prog_load command.
It's similar to existing expected_attach_type attribute which is
used in several cgroup based program types.
Unfortunately expected_attach_type is ignored for
tracing programs and cannot be reused for new purpose.
Hence introduce attach_btf_id to verify bpf programs against
given in-kernel BTF type id at load time.
It is strictly checked to be valid for raw_tp programs only.
In a later patches it will become:
btf_id == 0 semantics of existing raw_tp progs.
btd_id > 0 raw_tp with BTF and additional type safety.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Signed-off-by: default avatarDaniel Borkmann <daniel@iogearbox.net>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Acked-by: default avatarMartin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20191016032505.2089704-5-ast@kernel.org
parent 8580ac94

include/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -375,6 +375,7 @@ struct bpf_prog_aux { 
	u32 id;

	u32 func_cnt; /* used by non-func prog as the number of func progs */

	u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */

	u32 attach_btf_id; /* in-kernel BTF type id to attach to */

	bool verifier_zext; /* Zero extensions has been inserted by verifier. */

	bool offload_requested;

	struct bpf_prog **func;

include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -420,6 +420,7 @@ union bpf_attr { 
		__u32		line_info_rec_size;	/* userspace bpf_line_info size */

		__aligned_u64	line_info;	/* line info */

		__u32		line_info_cnt;	/* number of bpf_line_info records */

		__u32		attach_btf_id;	/* in-kernel BTF type id to attach to */

	};



	struct { /* anonymous struct used by BPF_OBJ_* commands */

kernel/bpf/syscall.c

+14 −4
Original line number Diff line number Diff line
@@ -23,6 +23,7 @@ 
#include <linux/timekeeping.h>

#include <linux/ctype.h>

#include <linux/nospec.h>

#include <uapi/linux/btf.h>



#define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY || \

			   (map)->map_type == BPF_MAP_TYPE_PERF_EVENT_ARRAY || \
@@ -1565,8 +1566,9 @@ static void bpf_prog_load_fixup_attach_type(union bpf_attr *attr) 
}



static int

bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,

				enum bpf_attach_type expected_attach_type)

bpf_prog_load_check_attach(enum bpf_prog_type prog_type,

			   enum bpf_attach_type expected_attach_type,

			   u32 btf_id)

{

	switch (prog_type) {

	case BPF_PROG_TYPE_CGROUP_SOCK:
@@ -1608,13 +1610,19 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type, 
		default:

			return -EINVAL;

		}

	case BPF_PROG_TYPE_RAW_TRACEPOINT:

		if (btf_id > BTF_MAX_TYPE)

			return -EINVAL;

		return 0;

	default:

		if (btf_id)

			return -EINVAL;

		return 0;

	}

}



/* last field in 'union bpf_attr' used by this command */

#define	BPF_PROG_LOAD_LAST_FIELD line_info_cnt

#define	BPF_PROG_LOAD_LAST_FIELD attach_btf_id



static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr)

{
@@ -1656,7 +1664,8 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) 
		return -EPERM;



	bpf_prog_load_fixup_attach_type(attr);

	if (bpf_prog_load_check_attach_type(type, attr->expected_attach_type))

	if (bpf_prog_load_check_attach(type, attr->expected_attach_type,

				       attr->attach_btf_id))

		return -EINVAL;



	/* plain bpf_prog allocation */
@@ -1665,6 +1674,7 @@ static int bpf_prog_load(union bpf_attr *attr, union bpf_attr __user *uattr) 
		return -ENOMEM;



	prog->expected_attach_type = attr->expected_attach_type;

	prog->aux->attach_btf_id = attr->attach_btf_id;



	prog->aux->offload_requested = !!attr->prog_ifindex;

tools/include/uapi/linux/bpf.h

+1 −0
Original line number Diff line number Diff line
@@ -420,6 +420,7 @@ union bpf_attr { 
		__u32		line_info_rec_size;	/* userspace bpf_line_info size */

		__aligned_u64	line_info;	/* line info */

		__u32		line_info_cnt;	/* number of bpf_line_info records */

		__u32		attach_btf_id;	/* in-kernel BTF type id to attach to */

	};



	struct { /* anonymous struct used by BPF_OBJ_* commands */

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