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.

Alexei Starovoitov committed 7 years ago

Commit ccfe29e1 parent 8580ac94 files · +17 −4Browse files

Unified · Split

4 files

include/linux/bpf.h +1 −0
include/uapi/linux/bpf.h +1 −0
kernel/bpf/syscall.c +14 −4
tools/include/uapi/linux/bpf.h +1 −0

include/linux/bpf.h+1−0

@@ -375,6 +375,7 @@ struct bpf_prog_aux { · 374 unmodified lines
375	375	u32 id;
376	376	u32 func_cnt; /* used by non-func prog as the number of func progs */
377	377	u32 func_idx; /* 0 for non-func prog, the index in func array for func prog */
	378	+ u32 attach_btf_id; /* in-kernel BTF type id to attach to */
378	379	bool verifier_zext; /* Zero extensions has been inserted by verifier. */
379	380	bool offload_requested;
380	381	struct bpf_prog **func;

include/uapi/linux/bpf.h+1−0

@@ -420,6 +420,7 @@ union bpf_attr { · 419 unmodified lines
420	420	__u32 line_info_rec_size; /* userspace bpf_line_info size */
421	421	__aligned_u64 line_info; /* line info */
422	422	__u32 line_info_cnt; /* number of bpf_line_info records */
	423	+ __u32 attach_btf_id; /* in-kernel BTF type id to attach to */
423	424	};
424	425
425	426	struct { /* anonymous struct used by BPF_OBJ_* commands */

kernel/bpf/syscall.c+14−4

@@ -23,6 +23,7 @@ · 22 unmodified lines
23	23	#include <linux/timekeeping.h>
24	24	#include <linux/ctype.h>
25	25	#include <linux/nospec.h>
	26	+#include <uapi/linux/btf.h>
26	27
27	28	#define IS_FD_ARRAY(map) ((map)->map_type == BPF_MAP_TYPE_PROG_ARRAY \|\| \
28	29	(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) · 1536 unmodified lines
1565	1566	}
1566	1567
1567	1568	static int
1568		−bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type,
1569		− enum bpf_attach_type expected_attach_type)
	1569	+bpf_prog_load_check_attach(enum bpf_prog_type prog_type,
	1570	+ enum bpf_attach_type expected_attach_type,
	1571	+ u32 btf_id)
1570	1572	{
1571	1573	switch (prog_type) {
1572	1574	case BPF_PROG_TYPE_CGROUP_SOCK:
@@ -1608,13 +1610,19 @@ bpf_prog_load_check_attach_type(enum bpf_prog_type prog_type, · 35 unmodified lines
1608	1610	default:
1609	1611	return -EINVAL;
1610	1612	}
	1613	+ case BPF_PROG_TYPE_RAW_TRACEPOINT:
	1614	+ if (btf_id > BTF_MAX_TYPE)
	1615	+ return -EINVAL;
	1616	+ return 0;
1611	1617	default:
	1618	+ if (btf_id)
	1619	+ return -EINVAL;
1612	1620	return 0;
1613	1621	}
1614	1622	}
1615	1623
1616	1624	/* last field in 'union bpf_attr' used by this command */
1617		−#define BPF_PROG_LOAD_LAST_FIELD line_info_cnt
	1625	+#define BPF_PROG_LOAD_LAST_FIELD attach_btf_id
1618	1626
1619	1627	static int bpf_prog_load(union bpf_attr attr, union bpf_attr __user uattr)
1620	1628	{
@@ -1656,7 +1664,8 @@ static int bpf_prog_load(union bpf_attr attr, union bpf_attr __user uattr) · 35 unmodified lines
1656	1664	return -EPERM;
1657	1665
1658	1666	bpf_prog_load_fixup_attach_type(attr);
1659		− if (bpf_prog_load_check_attach_type(type, attr->expected_attach_type))
	1667	+ if (bpf_prog_load_check_attach(type, attr->expected_attach_type,
	1668	+ attr->attach_btf_id))
1660	1669	return -EINVAL;
1661	1670
1662	1671	/* plain bpf_prog allocation */
@@ -1665,6 +1674,7 @@ static int bpf_prog_load(union bpf_attr attr, union bpf_attr __user uattr) · 2 unmodified lines
1665	1674	return -ENOMEM;
1666	1675
1667	1676	prog->expected_attach_type = attr->expected_attach_type;
	1677	+ prog->aux->attach_btf_id = attr->attach_btf_id;
1668	1678
1669	1679	prog->aux->offload_requested = !!attr->prog_ifindex;
1670	1680

tools/include/uapi/linux/bpf.h+1−0

@@ -420,6 +420,7 @@ union bpf_attr { · 419 unmodified lines
420	420	__u32 line_info_rec_size; /* userspace bpf_line_info size */
421	421	__aligned_u64 line_info; /* line info */
422	422	__u32 line_info_cnt; /* number of bpf_line_info records */
	423	+ __u32 attach_btf_id; /* in-kernel BTF type id to attach to */
423	424	};
424	425
425	426	struct { /* anonymous struct used by BPF_OBJ_* commands */