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 static bool grep(const char *buffer, const char *pattern)
  21 {
  22         return !!strstr(buffer, pattern);
  23 }
  24
  25 static int get_vendor_id(int ifindex)
  26 {
  27         char ifname[IF_NAMESIZE], path[64], buf[8];
  28         ssize_t len;
  29         int fd;
  30
  31         if (!if_indextoname(ifindex, ifname))
  32                 return -1;
  33
  34         snprintf(path, sizeof(path), "/sys/class/net/%s/device/vendor", ifname);
  35
  36         fd = open(path, O_RDONLY);
  37         if (fd < 0)
  38                 return -1;
  39
  40         len = read(fd, buf, sizeof(buf));
  41         close(fd);
  42         if (len < 0)
  43                 return -1;
  44         if (len >= (ssize_t)sizeof(buf))
  45                 return -1;
  46         buf[len] = '\0';
  47
  48         return strtol(buf, NULL, 0);
  49 }
  50
  51 static int get_kernel_version(void)
  52 {
  53         int version, subversion, patchlevel;
  54         struct utsname utsn;
  55
  56         /* Return 0 on failure, and attempt to probe with empty kversion */
  57         if (uname(&utsn))
  58                 return 0;
  59
  60         if (sscanf(utsn.release, "%d.%d.%d",
  61                    &version, &subversion, &patchlevel) != 3)
  62                 return 0;
  63
  64         return (version << 16) + (subversion << 8) + patchlevel;
  65 }
  66
  67 static void
  68 probe_load(enum bpf_prog_type prog_type, const struct bpf_insn *insns,
  69            size_t insns_cnt, char *buf, size_t buf_len, __u32 ifindex)
  70 {
  71         struct bpf_load_program_attr xattr = {};
  72         int fd;
  73
  74         switch (prog_type) {
  75         case BPF_PROG_TYPE_CGROUP_SOCK_ADDR:
  76                 xattr.expected_attach_type = BPF_CGROUP_INET4_CONNECT;
  77                 break;
  78         case BPF_PROG_TYPE_SK_LOOKUP:
  79                 xattr.expected_attach_type = BPF_SK_LOOKUP;
  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         case BPF_PROG_TYPE_LSM:
 112         default:
 113                 break;
 114         }
 115
 116         xattr.prog_type = prog_type;
 117         xattr.insns = insns;
 118         xattr.insns_cnt = insns_cnt;
 119         xattr.license = "GPL";
 120         xattr.prog_ifindex = ifindex;
 121
 122         fd = bpf_load_program_xattr(&xattr, buf, buf_len);
 123         if (fd >= 0)
 124                 close(fd);
 125 }
 126
 127 bool bpf_probe_prog_type(enum bpf_prog_type prog_type, __u32 ifindex)
 128 {
 129         struct bpf_insn insns[2] = {
 130                 BPF_MOV64_IMM(BPF_REG_0, 0),
 131                 BPF_EXIT_INSN()
 132         };
 133
 134         if (ifindex && prog_type == BPF_PROG_TYPE_SCHED_CLS)
 135                 /* nfp returns -EINVAL on exit(0) with TC offload */
 136                 insns[0].imm = 2;
 137
 138         errno = 0;
 139         probe_load(prog_type, insns, ARRAY_SIZE(insns), NULL, 0, ifindex);
 140
 141         return errno != EINVAL && errno != EOPNOTSUPP;
 142 }
 143
 144 int libbpf__load_raw_btf(const char *raw_types, size_t types_len,
 145                          const char *str_sec, size_t str_len)
 146 {
 147         struct btf_header hdr = {
 148                 .magic = BTF_MAGIC,
 149                 .version = BTF_VERSION,
 150                 .hdr_len = sizeof(struct btf_header),
 151                 .type_len = types_len,
 152                 .str_off = types_len,
 153                 .str_len = str_len,
 154         };
 155         int btf_fd, btf_len;
 156         __u8 *raw_btf;
 157
 158         btf_len = hdr.hdr_len + hdr.type_len + hdr.str_len;
 159         raw_btf = malloc(btf_len);
 160         if (!raw_btf)
 161                 return -ENOMEM;
 162
 163         memcpy(raw_btf, &hdr, sizeof(hdr));
 164         memcpy(raw_btf + hdr.hdr_len, raw_types, hdr.type_len);
 165         memcpy(raw_btf + hdr.hdr_len + hdr.type_len, str_sec, hdr.str_len);
 166
 167         btf_fd = bpf_load_btf(raw_btf, btf_len, NULL, 0, false);
 168
 169         free(raw_btf);
 170         return btf_fd;
 171 }
 172
 173 static int load_local_storage_btf(void)
 174 {
 175         const char strs[] = "\0bpf_spin_lock\0val\0cnt\0l";
 176         /* struct bpf_spin_lock {
 177          *   int val;
 178          * };
 179          * struct val {
 180          *   int cnt;
 181          *   struct bpf_spin_lock l;
 182          * };
 183          */
 184         __u32 types[] = {
 185                 /* int */
 186                 BTF_TYPE_INT_ENC(0, BTF_INT_SIGNED, 0, 32, 4),  /* [1] */
 187                 /* struct bpf_spin_lock */                      /* [2] */
 188                 BTF_TYPE_ENC(1, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 1), 4),
 189                 BTF_MEMBER_ENC(15, 1, 0), /* int val; */
 190                 /* struct val */                                /* [3] */
 191                 BTF_TYPE_ENC(15, BTF_INFO_ENC(BTF_KIND_STRUCT, 0, 2), 8),
 192                 BTF_MEMBER_ENC(19, 1, 0), /* int cnt; */
 193                 BTF_MEMBER_ENC(23, 2, 32),/* struct bpf_spin_lock l; */
 194         };
 195
 196         return libbpf__load_raw_btf((char *)types, sizeof(types),
 197                                      strs, sizeof(strs));
 198 }
 199
 200 bool bpf_probe_map_type(enum bpf_map_type map_type, __u32 ifindex)
 201 {
 202         int key_size, value_size, max_entries, map_flags;
 203         __u32 btf_key_type_id = 0, btf_value_type_id = 0;
 204         struct bpf_create_map_attr attr = {};
 205         int fd = -1, btf_fd = -1, fd_inner;
 206
 207         key_size        = sizeof(__u32);
 208         value_size      = sizeof(__u32);
 209         max_entries     = 1;
 210         map_flags       = 0;
 211
 212         switch (map_type) {
 213         case BPF_MAP_TYPE_STACK_TRACE:
 214                 value_size      = sizeof(__u64);
 215                 break;
 216         case BPF_MAP_TYPE_LPM_TRIE:
 217                 key_size        = sizeof(__u64);
 218                 value_size      = sizeof(__u64);
 219                 map_flags       = BPF_F_NO_PREALLOC;
 220                 break;
 221         case BPF_MAP_TYPE_CGROUP_STORAGE:
 222         case BPF_MAP_TYPE_PERCPU_CGROUP_STORAGE:
 223                 key_size        = sizeof(struct bpf_cgroup_storage_key);
 224                 value_size      = sizeof(__u64);
 225                 max_entries     = 0;
 226                 break;
 227         case BPF_MAP_TYPE_QUEUE:
 228         case BPF_MAP_TYPE_STACK:
 229                 key_size        = 0;
 230                 break;
 231         case BPF_MAP_TYPE_SK_STORAGE:
 232         case BPF_MAP_TYPE_INODE_STORAGE:
 233         case BPF_MAP_TYPE_TASK_STORAGE:
 234                 btf_key_type_id = 1;
 235                 btf_value_type_id = 3;
 236                 value_size = 8;
 237                 max_entries = 0;
 238                 map_flags = BPF_F_NO_PREALLOC;
 239                 btf_fd = load_local_storage_btf();
 240                 if (btf_fd < 0)
 241                         return false;
 242                 break;
 243         case BPF_MAP_TYPE_RINGBUF:
 244                 key_size = 0;
 245                 value_size = 0;
 246                 max_entries = 4096;
 247                 break;
 248         case BPF_MAP_TYPE_UNSPEC:
 249         case BPF_MAP_TYPE_HASH:
 250         case BPF_MAP_TYPE_ARRAY:
 251         case BPF_MAP_TYPE_PROG_ARRAY:
 252         case BPF_MAP_TYPE_PERF_EVENT_ARRAY:
 253         case BPF_MAP_TYPE_PERCPU_HASH:
 254         case BPF_MAP_TYPE_PERCPU_ARRAY:
 255         case BPF_MAP_TYPE_CGROUP_ARRAY:
 256         case BPF_MAP_TYPE_LRU_HASH:
 257         case BPF_MAP_TYPE_LRU_PERCPU_HASH:
 258         case BPF_MAP_TYPE_ARRAY_OF_MAPS:
 259         case BPF_MAP_TYPE_HASH_OF_MAPS:
 260         case BPF_MAP_TYPE_DEVMAP:
 261         case BPF_MAP_TYPE_DEVMAP_HASH:
 262         case BPF_MAP_TYPE_SOCKMAP:
 263         case BPF_MAP_TYPE_CPUMAP:
 264         case BPF_MAP_TYPE_XSKMAP:
 265         case BPF_MAP_TYPE_SOCKHASH:
 266         case BPF_MAP_TYPE_REUSEPORT_SOCKARRAY:
 267         case BPF_MAP_TYPE_STRUCT_OPS:
 268         default:
 269                 break;
 270         }
 271
 272         if (map_type == BPF_MAP_TYPE_ARRAY_OF_MAPS ||
 273             map_type == BPF_MAP_TYPE_HASH_OF_MAPS) {
 274                 /* TODO: probe for device, once libbpf has a function to create
 275                  * map-in-map for offload
 276                  */
 277                 if (ifindex)
 278                         return false;
 279
 280                 fd_inner = bpf_create_map(BPF_MAP_TYPE_HASH,
 281                                           sizeof(__u32), sizeof(__u32), 1, 0);
 282                 if (fd_inner < 0)
 283                         return false;
 284                 fd = bpf_create_map_in_map(map_type, NULL, sizeof(__u32),
 285                                            fd_inner, 1, 0);
 286                 close(fd_inner);
 287         } else {
 288                 /* Note: No other restriction on map type probes for offload */
 289                 attr.map_type = map_type;
 290                 attr.key_size = key_size;
 291                 attr.value_size = value_size;
 292                 attr.max_entries = max_entries;
 293                 attr.map_flags = map_flags;
 294                 attr.map_ifindex = ifindex;
 295                 if (btf_fd >= 0) {
 296                         attr.btf_fd = btf_fd;
 297                         attr.btf_key_type_id = btf_key_type_id;
 298                         attr.btf_value_type_id = btf_value_type_id;
 299                 }
 300
 301                 fd = bpf_create_map_xattr(&attr);
 302         }
 303         if (fd >= 0)
 304                 close(fd);
 305         if (btf_fd >= 0)
 306                 close(btf_fd);
 307
 308         return fd >= 0;
 309 }
 310
 311 bool bpf_probe_helper(enum bpf_func_id id, enum bpf_prog_type prog_type,
 312                       __u32 ifindex)
 313 {
 314         struct bpf_insn insns[2] = {
 315                 BPF_EMIT_CALL(id),
 316                 BPF_EXIT_INSN()
 317         };
 318         char buf[4096] = {};
 319         bool res;
 320
 321         probe_load(prog_type, insns, ARRAY_SIZE(insns), buf, sizeof(buf),
 322                    ifindex);
 323         res = !grep(buf, "invalid func ") && !grep(buf, "unknown func ");
 324
 325         if (ifindex) {
 326                 switch (get_vendor_id(ifindex)) {
 327                 case 0x19ee: /* Netronome specific */
 328                         res = res && !grep(buf, "not supported by FW") &&
 329                                 !grep(buf, "unsupported function id");
 330                         break;
 331                 default:
 332                         break;
 333                 }
 334         }
 335
 336         return res;
 337 }
 338
 339 /*
 340  * Probe for availability of kernel commit (5.3):
 341  *
 342  * c04c0d2b968a ("bpf: increase complexity limit and maximum program size")
 343  */
 344 bool bpf_probe_large_insn_limit(__u32 ifindex)
 345 {
 346         struct bpf_insn insns[BPF_MAXINSNS + 1];
 347         int i;
 348
 349         for (i = 0; i < BPF_MAXINSNS; i++)
 350                 insns[i] = BPF_MOV64_IMM(BPF_REG_0, 1);
 351         insns[BPF_MAXINSNS] = BPF_EXIT_INSN();
 352
 353         errno = 0;
 354         probe_load(BPF_PROG_TYPE_SCHED_CLS, insns, ARRAY_SIZE(insns), NULL, 0,
 355                    ifindex);
 356
 357         return errno != E2BIG && errno != EINVAL;
 358 }