Commit 1f235777 authored by Hangbin Liu's avatar Hangbin Liu Committed by Andrii Nakryiko
Browse files

libbpf: Making bpf_prog_load() ignore name if kernel doesn't support 



Similar with commit 10b62d6a ("libbpf: Add names for auxiliary maps"),
let's make bpf_prog_load() also ignore name if kernel doesn't support
program name.

To achieve this, we need to call sys_bpf_prog_load() directly in
probe_kern_prog_name() to avoid circular dependency. sys_bpf_prog_load()
also need to be exported in the libbpf_internal.h file.

Signed-off-by: default avatarHangbin Liu <liuhangbin@gmail.com>
Signed-off-by: default avatarAndrii Nakryiko <andrii@kernel.org>
Acked-by: default avatarQuentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220813000936.6464-1-liuhangbin@gmail.com
parent 8308bf20

tools/lib/bpf/bpf.c

+2 −4
Original line number Diff line number Diff line
@@ -84,9 +84,7 @@ static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr, 
	return ensure_good_fd(fd);

}



#define PROG_LOAD_ATTEMPTS 5



static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)

int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)

{

	int fd;
@@ -263,7 +261,7 @@ int bpf_prog_load(enum bpf_prog_type prog_type, 
	attr.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0);

	attr.kern_version = OPTS_GET(opts, kern_version, 0);



	if (prog_name)

	if (prog_name && kernel_supports(NULL, FEAT_PROG_NAME))

		libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));

	attr.license = ptr_to_u64(license);

tools/lib/bpf/libbpf.c

+11 −2
Original line number Diff line number Diff line
@@ -4415,14 +4415,23 @@ static int probe_fd(int fd) 


static int probe_kern_prog_name(void)

{

	const size_t attr_sz = offsetofend(union bpf_attr, prog_name);

	struct bpf_insn insns[] = {

		BPF_MOV64_IMM(BPF_REG_0, 0),

		BPF_EXIT_INSN(),

	};

	int ret, insn_cnt = ARRAY_SIZE(insns);

	union bpf_attr attr;

	int ret;



	memset(&attr, 0, attr_sz);

	attr.prog_type = BPF_PROG_TYPE_SOCKET_FILTER;

	attr.license = ptr_to_u64("GPL");

	attr.insns = ptr_to_u64(insns);

	attr.insn_cnt = (__u32)ARRAY_SIZE(insns);

	libbpf_strlcpy(attr.prog_name, "libbpf_nametest", sizeof(attr.prog_name));



	/* make sure loading with name works */

	ret = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, "test", "GPL", insns, insn_cnt, NULL);

	ret = sys_bpf_prog_load(&attr, attr_sz, PROG_LOAD_ATTEMPTS);

	return probe_fd(ret);

}

tools/lib/bpf/libbpf_internal.h

+3 −0
Original line number Diff line number Diff line
@@ -573,4 +573,7 @@ static inline bool is_pow_of_2(size_t x) 
	return x && (x & (x - 1)) == 0;

}



#define PROG_LOAD_ATTEMPTS 5

int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts);



#endif /* __LIBBPF_LIBBPF_INTERNAL_H */