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

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Similar with commit 10b62d6a38f7 ("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: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Quentin Monnet <quentin@isovalent.com>
Link: https://lore.kernel.org/bpf/20220813000936.6464-1-liuhangbin@gmail.com
This commit is contained in:
Hangbin Liu
2022-08-13 08:09:36 +08:00
committed by Andrii Nakryiko
parent 8be13ee80b
commit 079bc8536d
3 changed files with 16 additions and 6 deletions
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6
src/bpf.c
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@@ -84,9 +84,7 @@ static inline int sys_bpf_fd(enum bpf_cmd cmd, union bpf_attr *attr,
return ensure_good_fd(fd); return ensure_good_fd(fd);
} }
#define PROG_LOAD_ATTEMPTS 5 int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
static inline int sys_bpf_prog_load(union bpf_attr *attr, unsigned int size, int attempts)
{ {
int fd; 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.prog_ifindex = OPTS_GET(opts, prog_ifindex, 0);
attr.kern_version = OPTS_GET(opts, kern_version, 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)); libbpf_strlcpy(attr.prog_name, prog_name, sizeof(attr.prog_name));
attr.license = ptr_to_u64(license); attr.license = ptr_to_u64(license);

13
src/libbpf.c
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@@ -4415,14 +4415,23 @@ static int probe_fd(int fd)
static int probe_kern_prog_name(void) static int probe_kern_prog_name(void)
{ {
const size_t attr_sz = offsetofend(union bpf_attr, prog_name);
struct bpf_insn insns[] = { struct bpf_insn insns[] = {
BPF_MOV64_IMM(BPF_REG_0, 0), BPF_MOV64_IMM(BPF_REG_0, 0),
BPF_EXIT_INSN(), 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 */ /* 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); return probe_fd(ret);
} }

3
src/libbpf_internal.h
View File

@@ -573,4 +573,7 @@ static inline bool is_pow_of_2(size_t x)
return x && (x & (x - 1)) == 0; 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 */ #endif /* __LIBBPF_LIBBPF_INTERNAL_H */