Commit eae2e83e authored by Jiri Olsa's avatar Jiri Olsa Committed by Alexei Starovoitov
Browse files

bpf: Add BTF_SET_START/END macros 



Adding support to define sorted set of BTF ID values.

Following defines sorted set of BTF ID values:

  BTF_SET_START(btf_allowlist_d_path)
  BTF_ID(func, vfs_truncate)
  BTF_ID(func, vfs_fallocate)
  BTF_ID(func, dentry_open)
  BTF_ID(func, vfs_getattr)
  BTF_ID(func, filp_close)
  BTF_SET_END(btf_allowlist_d_path)

It defines following 'struct btf_id_set' variable to access
values and count:

  struct btf_id_set btf_allowlist_d_path;

Adding 'allowed' callback to struct bpf_func_proto, to allow
verifier the check on allowed callers.

Adding btf_id_set_contains function, which will be used by
allowed callbacks to verify the caller's BTF ID value is
within allowed set.

Also removing extra '\' in __BTF_ID_LIST macro.

Added BTF_SET_START_GLOBAL macro for global sets.

Signed-off-by: default avatarJiri Olsa <jolsa@kernel.org>
Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Acked-by: default avatarAndrii Nakryiko <andriin@fb.com>
Link: https://lore.kernel.org/bpf/20200825192124.710397-10-jolsa@kernel.org
parent faaf4a79

include/linux/bpf.h

+4 −0
Original line number Diff line number Diff line
@@ -317,6 +317,7 @@ struct bpf_func_proto { 
						    * for this argument.

						    */

	int *ret_btf_id; /* return value btf_id */

	bool (*allowed)(const struct bpf_prog *prog);

};



/* bpf_context is intentionally undefined structure. Pointer to bpf_context is
@@ -1878,4 +1879,7 @@ enum bpf_text_poke_type { 
int bpf_arch_text_poke(void *ip, enum bpf_text_poke_type t,

		       void *addr1, void *addr2);



struct btf_id_set;

bool btf_id_set_contains(struct btf_id_set *set, u32 id);



#endif /* _LINUX_BPF_H */

include/linux/btf_ids.h

+50 −1
Original line number Diff line number Diff line
@@ -3,6 +3,11 @@ 
#ifndef _LINUX_BTF_IDS_H

#define _LINUX_BTF_IDS_H



struct btf_id_set {

	u32 cnt;

	u32 ids[];

};



#ifdef CONFIG_DEBUG_INFO_BTF



#include <linux/compiler.h> /* for __PASTE */
@@ -62,7 +67,7 @@ asm( \ 
".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\

"." #scope " " #name ";                        \n"	\

#name ":;                                      \n"	\

".popsection;                                  \n");	\

".popsection;                                  \n");



#define BTF_ID_LIST(name)				\

__BTF_ID_LIST(name, local)				\
@@ -88,12 +93,56 @@ asm( \ 
".zero 4                                       \n"	\

".popsection;                                  \n");



/*

 * The BTF_SET_START/END macros pair defines sorted list of

 * BTF IDs plus its members count, with following layout:

 *

 * BTF_SET_START(list)

 * BTF_ID(type1, name1)

 * BTF_ID(type2, name2)

 * BTF_SET_END(list)

 *

 * __BTF_ID__set__list:

 * .zero 4

 * list:

 * __BTF_ID__type1__name1__3:

 * .zero 4

 * __BTF_ID__type2__name2__4:

 * .zero 4

 *

 */

#define __BTF_SET_START(name, scope)			\

asm(							\

".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\

"." #scope " __BTF_ID__set__" #name ";         \n"	\

"__BTF_ID__set__" #name ":;                    \n"	\

".zero 4                                       \n"	\

".popsection;                                  \n");



#define BTF_SET_START(name)				\

__BTF_ID_LIST(name, local)				\

__BTF_SET_START(name, local)



#define BTF_SET_START_GLOBAL(name)			\

__BTF_ID_LIST(name, globl)				\

__BTF_SET_START(name, globl)



#define BTF_SET_END(name)				\

asm(							\

".pushsection " BTF_IDS_SECTION ",\"a\";      \n"	\

".size __BTF_ID__set__" #name ", .-" #name "  \n"	\

".popsection;                                 \n");	\

extern struct btf_id_set name;



#else



#define BTF_ID_LIST(name) static u32 name[5];

#define BTF_ID(prefix, name)

#define BTF_ID_UNUSED

#define BTF_ID_LIST_GLOBAL(name) u32 name[1];

#define BTF_SET_START(name) static struct btf_id_set name = { 0 };

#define BTF_SET_START_GLOBAL(name) static struct btf_id_set name = { 0 };

#define BTF_SET_END(name)



#endif /* CONFIG_DEBUG_INFO_BTF */

kernel/bpf/btf.c

+14 −0
Original line number Diff line number Diff line
@@ -21,6 +21,8 @@ 
#include <linux/btf_ids.h>

#include <linux/skmsg.h>

#include <linux/perf_event.h>

#include <linux/bsearch.h>

#include <linux/btf_ids.h>

#include <net/sock.h>



/* BTF (BPF Type Format) is the meta data format which describes
@@ -4762,3 +4764,15 @@ u32 btf_id(const struct btf *btf) 
{

	return btf->id;

}



static int btf_id_cmp_func(const void *a, const void *b)

{

	const int *pa = a, *pb = b;



	return *pa - *pb;

}



bool btf_id_set_contains(struct btf_id_set *set, u32 id)

{

	return bsearch(&id, set->ids, set->cnt, sizeof(u32), btf_id_cmp_func) != NULL;

}

kernel/bpf/verifier.c

+5 −0
Original line number Diff line number Diff line
@@ -4859,6 +4859,11 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn 
		return -EINVAL;

	}



	if (fn->allowed && !fn->allowed(env->prog)) {

		verbose(env, "helper call is not allowed in probe\n");

		return -EINVAL;

	}



	/* With LD_ABS/IND some JITs save/restore skb from r1. */

	changes_data = bpf_helper_changes_pkt_data(fn->func);

	if (changes_data && fn->arg1_type != ARG_PTR_TO_CTX) {

tools/include/linux/btf_ids.h

+50 −1
Original line number Diff line number Diff line
@@ -3,6 +3,11 @@ 
#ifndef _LINUX_BTF_IDS_H

#define _LINUX_BTF_IDS_H



struct btf_id_set {

	u32 cnt;

	u32 ids[];

};



#ifdef CONFIG_DEBUG_INFO_BTF



#include <linux/compiler.h> /* for __PASTE */
@@ -62,7 +67,7 @@ asm( \ 
".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\

"." #scope " " #name ";                        \n"	\

#name ":;                                      \n"	\

".popsection;                                  \n");	\

".popsection;                                  \n");



#define BTF_ID_LIST(name)				\

__BTF_ID_LIST(name, local)				\
@@ -88,12 +93,56 @@ asm( \ 
".zero 4                                       \n"	\

".popsection;                                  \n");



/*

 * The BTF_SET_START/END macros pair defines sorted list of

 * BTF IDs plus its members count, with following layout:

 *

 * BTF_SET_START(list)

 * BTF_ID(type1, name1)

 * BTF_ID(type2, name2)

 * BTF_SET_END(list)

 *

 * __BTF_ID__set__list:

 * .zero 4

 * list:

 * __BTF_ID__type1__name1__3:

 * .zero 4

 * __BTF_ID__type2__name2__4:

 * .zero 4

 *

 */

#define __BTF_SET_START(name, scope)			\

asm(							\

".pushsection " BTF_IDS_SECTION ",\"a\";       \n"	\

"." #scope " __BTF_ID__set__" #name ";         \n"	\

"__BTF_ID__set__" #name ":;                    \n"	\

".zero 4                                       \n"	\

".popsection;                                  \n");



#define BTF_SET_START(name)				\

__BTF_ID_LIST(name, local)				\

__BTF_SET_START(name, local)



#define BTF_SET_START_GLOBAL(name)			\

__BTF_ID_LIST(name, globl)				\

__BTF_SET_START(name, globl)



#define BTF_SET_END(name)				\

asm(							\

".pushsection " BTF_IDS_SECTION ",\"a\";      \n"	\

".size __BTF_ID__set__" #name ", .-" #name "  \n"	\

".popsection;                                 \n");	\

extern struct btf_id_set name;



#else



#define BTF_ID_LIST(name) static u32 name[5];

#define BTF_ID(prefix, name)

#define BTF_ID_UNUSED

#define BTF_ID_LIST_GLOBAL(name) u32 name[1];

#define BTF_SET_START(name) static struct btf_id_set name = { 0 };

#define BTF_SET_START_GLOBAL(name) static struct btf_id_set name = { 0 };

#define BTF_SET_END(name)



#endif /* CONFIG_DEBUG_INFO_BTF */

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