tools/lib/bpf/libbpf_probes.c

   1 // SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
   2 /* Copyright (c) 2019 Netronome Systems, Inc. */
   3
   4 #include <errno.h>
   5 #include <fcntl.h>
   6 #include <string.h>
   7 #include <stdlib.h>
   8 #include <unistd.h>
   9 #include <net/if.h>
  10 #include <sys/utsname.h>
  11
  12 #include <linux/btf.h>
  13 #include <linux/filter.h>
  14 #include <linux/kernel.h>
  15
  16 #include "bpf.h"
  17 #include "libbpf.h"
  18 #include "libbpf_internal.h"
  19
  20 /* make sure libbpf doesn't use kernel-only integer typedefs */
  21 #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
  22
  23 static bool grep(const char *buffer, const char *pattern)
  24 {
  25         return !!strstr(buffer, pattern);
  26 }
  27
  28 static int get_vendor_id(int ifindex)
  29 {
  30         char ifname[IF_NAMESIZE], path[64], buf[8];
  31         ssize_t len;
  32         int fd;
  33
  34         if (!if_indextoname(ifindex, ifname))
  35                 return -1;
  36
  37         snprintf(path, sizeof(path), "/sys/class/net/%s/device/vendor", ifname);
  38
  39         fd = open(path, O_RDONLY);
  40         if (fd < 0)
  41                 return -1;
  42
  43         len = read(fd, buf, sizeof(buf));
  44         close(fd);
  45         if (len < 0)
  46                 return -1;
  47         if (len >= (ssize_t)sizeof(buf))
  48                 return -1;
  49         buf[len] = '\0';
  50
  51         return strtol(buf, NULL, 0);
  52 }
  53
  54 static int get_kernel_version(void)
  55 {
  56         int version, subversion, patchlevel;
  57         struct utsname utsn;
  58
  59         /* Return 0 on failure, and attempt to probe with empty kversion */
  60         if (uname(&utsn))
  61                 return 0;
  62
  63         if (sscanf(utsn.release, "%d.%d.%d",
  64                    &version, &subversion, &patchlevel) != 3)
  65                 return 0;
  66
  67         return (version << 16) + (subversion << 8) + patchlevel;
  68 }
  69
  70 static void
  71 probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
  72            size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex)
  73 {
  74         struct bpf_load_program_attr xattr = {};
  75         int fd;
  76
  77         switch (prog_type) {
  78         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
  79                 xattr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
  80                 break;
  81         case BPF_PROG_TYPE_KPROBE:
  82                 xattr.kern_version = get_kernel_version();
  83                 break;
  84         case BPF_PROG_TYPE_UNSPEC:
  85         case BPF_PROG_TYPE_SOCKET_FILTER:
  86         case BPF_PROG_TYPE_SCHED_CLS:
  87         case BPF_PROG_TYPE_SCHED_ACT:
  88         case BPF_PROG_TYPE_TRACEPOINT:
  89         case BPF_PROG_TYPE_XDP:
  90         case BPF_PROG_TYPE_PERF_EVENT:
  91         case BPF_PROG_TYPE_CGROUP_SKB:
  92         case BPF_PROG_TYPE_CGROUP_SOCK:
  93         case BPF_PROG_TYPE_LWT_IN:
  94         case BPF_PROG_TYPE_LWT_OUT:
  95         case BPF_PROG_TYPE_LWT_XMIT:
  96         case BPF_PROG_TYPE_SOCK_OPS:
  97         case BPF_PROG_TYPE_SK_SKB:
  98         case BPF_PROG_TYPE_CGROUP_DEVICE:
  99         case BPF_PROG_TYPE_SK_MSG:
 100         case BPF_PROG_TYPE_RAW_TRACEPOINT:
 101         case BPF_PROG_TYPE_RAW_TRACEPOINT_WRITABLE:
 102         case BPF_PROG_TYPE_LWT_SEG6LOCAL:
 103         case BPF_PROG_TYPE_LIRC_MODE2:
 104         case BPF_PROG_TYPE_SK_REUSEPORT:
 105         case BPF_PROG_TYPE_FLOW_DISSECTOR:
 106         case BPF_PROG_TYPE_CGROUP_SYSCTL:
 107         case BPF_PROG_TYPE_CGROUP_SOCKOPT:
 108         case BPF_PROG_TYPE_TRACING:
 109         case BPF_PROG_TYPE_STRUCT_OPS:
 110         case BPF_PROG_TYPE_EXT:
 111         default:
 112                 break;
 113         }
 114
 115         xattr.prog_type = prog_type;
 116         xattr.insns = insns;
 117         xattr.insns_cnt = insns_cnt;
 118         xattr.license = "GPL";
 119         xattr.prog_ifindex = ifindex;
 120
 121         fd = bpf_load_program_xattr(&xattr, buf, buf_len);
 122         if (fd >= 0)
 123                 close(fd);
 124 }
 125
 126 bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
 127 {
 128         struct bpf_insn insns[2] = {
 129                 BPF_MOV64_IMM(BPF_REG_0, 0),
 130                 BPF_EXIT_INSN()
 131         };
 132
 133         if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
 134                 /* nfp returns -EINVAL on exit(0) with TC offload */
 135                 insns[0].imm = 2;
 136
 137         errno = 0;
 138         probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
 139
 140         return errno != EINVAL && errno != EOPNOTSUPP;
 141 }
 142
 143 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
 144                          const char *str_sec, size_t str_len)
 145 {
 146         struct btf_header hdr = {
 147                 .magic = BTF_MAGIC,
 148                 .version = BTF_VERSION,
 149                 .hdr_len = sizeof(struct btf_header),
 150                 .type_len = types_len,
 151                 .str_off = types_len,
 152                 .str_len = str_len,
 153         };
 154         int btf_fd, btf_len;
 155         __u8 *raw_btf;
 156
 157         btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
 158         raw_btf = malloc(btf_len);
 159         if (!raw_btf)
 160                 return -ENOMEM;
 161
 162         memcpy(raw_btf, &hdr, sizeof(hdr));
 163         memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
 164         memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
 165
 166         btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false);
 167
 168         free(raw_btf);
 169         return btf_fd;
 170 }
 171
 172 static int load_sk_storage_btf(void)
 173 {
 174         const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
 175         /* struct bpf_spin_lock {
 176          *   int val;
 177          * };
 178          * struct val {
 179          *   int cnt;
 180          *   struct bpf_spin_lock l;
 181          * };
 182          */
 183         __u32 types[] = {
 184                 /* int */
 185                 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
 186                 /* struct bpf_spin_lock */                      /* [2] */
 187                 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
 188                 BTF_MEMBER_ENC(15, 1, 0), /* int val; */
 189                 /* struct val */                                /* [3] */
 190                 BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
 191                 BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
 192                 BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
 193         };
 194
 195         return libbpf__load_raw_btf((char *)types, sizeof(types),
 196                                      strs, sizeof(strs));
 197 }
 198
 199 bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
 200 {
 201         int key_size, value_size, max_entries, map_flags;
 202         __u32 btf_key_type_id = 0, btf_value_type_id = 0;
 203         struct bpf_create_map_attr attr = {};
 204         int fd = -1, btf_fd = -1, fd_inner;
 205
 206         key_size        = sizeof(__u32);
 207         value_size      = sizeof(__u32);
 208         max_entries     = 1;
 209         map_flags       = 0;
 210
 211         switch (map_type) {
 212         case BPF_MAP_TYPE_STACK_TRACE:
 213                 value_size      = sizeof(__u64);
 214                 break;
 215         case BPF_MAP_TYPE_LPM_TRIE:
 216                 key_size        = sizeof(__u64);
 217                 value_size      = sizeof(__u64);
 218                 map_flags       = BPF_F_NO_PREALLOC;
 219                 break;
 220         case BPF_MAP_TYPE_CGROUP_STORAGE:
 221         case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
 222                 key_size        = sizeof(struct bpf_cgroup_storage_key);
 223                 value_size      = sizeof(__u64);
 224                 max_entries     = 0;
 225                 break;
 226         case BPF_MAP_TYPE_QUEUE:
 227         case BPF_MAP_TYPE_STACK:
 228                 key_size        = 0;
 229                 break;
 230         case BPF_MAP_TYPE_SK_STORAGE:
 231                 btf_key_type_id = 1;
 232                 btf_value_type_id = 3;
 233                 value_size = 8;
 234                 max_entries = 0;
 235                 map_flags = BPF_F_NO_PREALLOC;
 236                 btf_fd = load_sk_storage_btf();
 237                 if (btf_fd < 0)
 238                         return false;
 239                 break;
 240         case BPF_MAP_TYPE_UNSPEC:
 241         case BPF_MAP_TYPE_HASH:
 242         case BPF_MAP_TYPE_ARRAY:
 243         case BPF_MAP_TYPE_PROG_ARRAY:
 244         case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
 245         case BPF_MAP_TYPE_PERCPU_HASH:
 246         case BPF_MAP_TYPE_PERCPU_ARRAY:
 247         case BPF_MAP_TYPE_CGROUP_ARRAY:
 248         case BPF_MAP_TYPE_LRU_HASH:
 249         case BPF_MAP_TYPE_LRU_PERCPU_HASH:
 250         case BPF_MAP_TYPE_ARRAY_OF_MAPS:
 251         case BPF_MAP_TYPE_HASH_OF_MAPS:
 252         case BPF_MAP_TYPE_DEVMAP:
 253         case BPF_MAP_TYPE_DEVMAP_HASH:
 254         case BPF_MAP_TYPE_SOCKMAP:
 255         case BPF_MAP_TYPE_CPUMAP:
 256         case BPF_MAP_TYPE_XSKMAP:
 257         case BPF_MAP_TYPE_SOCKHASH:
 258         case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
 259         case BPF_MAP_TYPE_STRUCT_OPS:
 260         default:
 261                 break;
 262         }
 263
 264         if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
 265             map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
 266                 /* TODO: probe for device, once libbpf has a function to create
 267                  * map-in-map for offload
 268                  */
 269                 if (ifindex)
 270                         return false;
 271
 272                 fd_inner = bpf_create_map(BPF_MAP_TYPE_HASH,
 273                                           sizeof(__u32), sizeof(__u32), 1, 0);
 274                 if (fd_inner < 0)
 275                         return false;
 276                 fd = bpf_create_map_in_map(map_type, NULL, sizeof(__u32),
 277                                            fd_inner, 1, 0);
 278                 close(fd_inner);
 279         } else {
 280                 /* Note: No other restriction on map type probes for offload */
 281                 attr.map_type = map_type;
 282                 attr.key_size = key_size;
 283                 attr.value_size = value_size;
 284                 attr.max_entries = max_entries;
 285                 attr.map_flags = map_flags;
 286                 attr.map_ifindex = ifindex;
 287                 if (btf_fd >= 0) {
 288                         attr.btf_fd = btf_fd;
 289                         attr.btf_key_type_id = btf_key_type_id;
 290                         attr.btf_value_type_id = btf_value_type_id;
 291                 }
 292
 293                 fd = bpf_create_map_xattr(&attr);
 294         }
 295         if (fd >= 0)
 296                 close(fd);
 297         if (btf_fd >= 0)
 298                 close(btf_fd);
 299
 300         return fd >= 0;
 301 }
 302
 303 bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
 304                       __u32 ifindex)
 305 {
 306         struct bpf_insn insns[2] = {
 307                 BPF_EMIT_CALL(id),
 308                 BPF_EXIT_INSN()
 309         };
 310         char buf[4096] = {};
 311         bool res;
 312
 313         probe_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf),
 314                    ifindex);
 315         res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ");
 316
 317         if (ifindex) {
 318                 switch (get_vendor_id(ifindex)) {
 319                 case 0x19ee: /* Netronome specific */
 320                         res = res && !grep(buf, "not supported by FW") &&
 321                                 !grep(buf, "unsupported function id");
 322                         break;
 323                 default:
 324                         break;
 325                 }
 326         }
 327
 328         return res;
 329 }
 330
 331 /*
 332  * Probe for availability of kernel commit (5.3):
 333  *
 334  * c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
 335  */
 336 bool bpf_probe_large_insn_limit(__u32 ifindex)
 337 {
 338         struct bpf_insn insns[BPF_MAXINSNS + 1];
 339         int i;
 340
 341         for (i = 0; i < BPF_MAXINSNS; i++)
 342                 insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
 343         insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
 344
 345         errno = 0;
 346         probe_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0,
 347                    ifindex);
 348
 349         return errno != E2BIG && errno != EINVAL;
 350 }