From e5659e4e19e49f1eac58bb07ce8bc2d78a89fe65 Mon Sep 17 00:00:00 2001 From: Rong Tao Date: Sat, 5 Nov 2022 14:48:00 +0800 Subject: samples/bpf: Fix sockex3 error: Missing BPF prog type since commit 450b167fb9be("libbpf: clean up SEC() handling"), sec_def_matches() does not recognize "socket/xxx" as "socket", therefore, the BPF program type is not recognized. Instead of sockex3_user.c parsing section names to get the BPF program fd. We use the program array map to assign a static index to each BPF program (get inspired by selftests/bpf progs/test_prog_array_init.c). Therefore, use SEC("socket") as section name instead of SEC("socket/xxx"), so that the BPF program is parsed to SOCKET_FILTER type. The "missing BPF prog type" problem is solved. How to reproduce this error: $ cd samples/bpf $ sudo ./sockex3 libbpf: prog 'bpf_func_PARSE_IP': missing BPF prog type, check ELF section name 'socket/3' libbpf: prog 'bpf_func_PARSE_IP': failed to load: -22 libbpf: failed to load object './sockex3_kern.o' ERROR: loading BPF object file failed Signed-off-by: Rong Tao Signed-off-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/tencent_EBA3C18864069E42175946973C2ACBAF5408@qq.com --- samples/bpf/sockex3_kern.c | 95 ++++++++++++++++++++++++++-------------------- samples/bpf/sockex3_user.c | 23 +++++------ 2 files changed, 63 insertions(+), 55 deletions(-) (limited to 'samples') diff --git a/samples/bpf/sockex3_kern.c b/samples/bpf/sockex3_kern.c index b363503357e5..822c13242251 100644 --- a/samples/bpf/sockex3_kern.c +++ b/samples/bpf/sockex3_kern.c @@ -17,48 +17,11 @@ #define IP_MF 0x2000 #define IP_OFFSET 0x1FFF -#define PROG(F) SEC("socket/"__stringify(F)) int bpf_func_##F - -struct { - __uint(type, BPF_MAP_TYPE_PROG_ARRAY); - __uint(key_size, sizeof(u32)); - __uint(value_size, sizeof(u32)); - __uint(max_entries, 8); -} jmp_table SEC(".maps"); - #define PARSE_VLAN 1 #define PARSE_MPLS 2 #define PARSE_IP 3 #define PARSE_IPV6 4 -/* Protocol dispatch routine. It tail-calls next BPF program depending - * on eth proto. Note, we could have used ... - * - * bpf_tail_call(skb, &jmp_table, proto); - * - * ... but it would need large prog_array and cannot be optimised given - * the map key is not static. - */ -static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto) -{ - switch (proto) { - case ETH_P_8021Q: - case ETH_P_8021AD: - bpf_tail_call(skb, &jmp_table, PARSE_VLAN); - break; - case ETH_P_MPLS_UC: - case ETH_P_MPLS_MC: - bpf_tail_call(skb, &jmp_table, PARSE_MPLS); - break; - case ETH_P_IP: - bpf_tail_call(skb, &jmp_table, PARSE_IP); - break; - case ETH_P_IPV6: - bpf_tail_call(skb, &jmp_table, PARSE_IPV6); - break; - } -} - struct vlan_hdr { __be16 h_vlan_TCI; __be16 h_vlan_encapsulated_proto; @@ -74,6 +37,8 @@ struct flow_key_record { __u32 ip_proto; }; +static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto); + static inline int ip_is_fragment(struct __sk_buff *ctx, __u64 nhoff) { return load_half(ctx, nhoff + offsetof(struct iphdr, frag_off)) @@ -189,7 +154,8 @@ static __always_inline void parse_ip_proto(struct __sk_buff *skb, } } -PROG(PARSE_IP)(struct __sk_buff *skb) +SEC("socket") +int bpf_func_ip(struct __sk_buff *skb) { struct globals *g = this_cpu_globals(); __u32 nhoff, verlen, ip_proto; @@ -217,7 +183,8 @@ PROG(PARSE_IP)(struct __sk_buff *skb) return 0; } -PROG(PARSE_IPV6)(struct __sk_buff *skb) +SEC("socket") +int bpf_func_ipv6(struct __sk_buff *skb) { struct globals *g = this_cpu_globals(); __u32 nhoff, ip_proto; @@ -240,7 +207,8 @@ PROG(PARSE_IPV6)(struct __sk_buff *skb) return 0; } -PROG(PARSE_VLAN)(struct __sk_buff *skb) +SEC("socket") +int bpf_func_vlan(struct __sk_buff *skb) { __u32 nhoff, proto; @@ -256,7 +224,8 @@ PROG(PARSE_VLAN)(struct __sk_buff *skb) return 0; } -PROG(PARSE_MPLS)(struct __sk_buff *skb) +SEC("socket") +int bpf_func_mpls(struct __sk_buff *skb) { __u32 nhoff, label; @@ -279,7 +248,49 @@ PROG(PARSE_MPLS)(struct __sk_buff *skb) return 0; } -SEC("socket/0") +struct { + __uint(type, BPF_MAP_TYPE_PROG_ARRAY); + __uint(key_size, sizeof(u32)); + __uint(max_entries, 8); + __array(values, u32 (void *)); +} prog_array_init SEC(".maps") = { + .values = { + [PARSE_VLAN] = (void *)&bpf_func_vlan, + [PARSE_IP] = (void *)&bpf_func_ip, + [PARSE_IPV6] = (void *)&bpf_func_ipv6, + [PARSE_MPLS] = (void *)&bpf_func_mpls, + }, +}; + +/* Protocol dispatch routine. It tail-calls next BPF program depending + * on eth proto. Note, we could have used ... + * + * bpf_tail_call(skb, &prog_array_init, proto); + * + * ... but it would need large prog_array and cannot be optimised given + * the map key is not static. + */ +static inline void parse_eth_proto(struct __sk_buff *skb, u32 proto) +{ + switch (proto) { + case ETH_P_8021Q: + case ETH_P_8021AD: + bpf_tail_call(skb, &prog_array_init, PARSE_VLAN); + break; + case ETH_P_MPLS_UC: + case ETH_P_MPLS_MC: + bpf_tail_call(skb, &prog_array_init, PARSE_MPLS); + break; + case ETH_P_IP: + bpf_tail_call(skb, &prog_array_init, PARSE_IP); + break; + case ETH_P_IPV6: + bpf_tail_call(skb, &prog_array_init, PARSE_IPV6); + break; + } +} + +SEC("socket") int main_prog(struct __sk_buff *skb) { __u32 nhoff = ETH_HLEN; diff --git a/samples/bpf/sockex3_user.c b/samples/bpf/sockex3_user.c index cd6fa79df900..56044acbd25d 100644 --- a/samples/bpf/sockex3_user.c +++ b/samples/bpf/sockex3_user.c @@ -24,10 +24,9 @@ struct pair { int main(int argc, char **argv) { - int i, sock, key, fd, main_prog_fd, jmp_table_fd, hash_map_fd; + int i, sock, fd, main_prog_fd, hash_map_fd; struct bpf_program *prog; struct bpf_object *obj; - const char *section; char filename[256]; FILE *f; @@ -45,26 +44,24 @@ int main(int argc, char **argv) goto cleanup; } - jmp_table_fd = bpf_object__find_map_fd_by_name(obj, "jmp_table"); hash_map_fd = bpf_object__find_map_fd_by_name(obj, "hash_map"); - if (jmp_table_fd < 0 || hash_map_fd < 0) { + if (hash_map_fd < 0) { fprintf(stderr, "ERROR: finding a map in obj file failed\n"); goto cleanup; } + /* find BPF main program */ + main_prog_fd = 0; bpf_object__for_each_program(prog, obj) { fd = bpf_program__fd(prog); - section = bpf_program__section_name(prog); - if (sscanf(section, "socket/%d", &key) != 1) { - fprintf(stderr, "ERROR: finding prog failed\n"); - goto cleanup; - } - - if (key == 0) + if (!strcmp(bpf_program__name(prog), "main_prog")) main_prog_fd = fd; - else - bpf_map_update_elem(jmp_table_fd, &key, &fd, BPF_ANY); + } + + if (main_prog_fd == 0) { + fprintf(stderr, "ERROR: can't find main_prog\n"); + goto cleanup; } sock = open_raw_sock("lo"); -- cgit v1.2.3