liblttng-ust-dl/lttng-ust-dl.c

   1 /*
   2  * SPDX-License-Identifier: LGPL-2.1-only
   3  *
   4  * Copyright (C) 2013 Paul Woegerer <paul.woegerer@mentor.com>
   5  * Copyright (C) 2015 Antoine Busque <abusque@efficios.com>
   6  * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  */
   8
   9 #define _LGPL_SOURCE
  10 #include <limits.h>
  11 #include <stdio.h>
  12 #include <stdint.h>
  13 #include <sys/types.h>
  14 #include <unistd.h>
  15
  16 #include <ust-dlfcn.h>
  17 #include <ust-elf.h>
  18 #include <lttng/ust-events.h>
  19 #include <ust-helper.h>
  20 #include "usterr-signal-safe.h"
  21
  22 #include "../liblttng-ust/ust-events-internal.h"
  23
  24 /* Include link.h last else it conflicts with ust-dlfcn. */
  25 #include <link.h>
  26
  27 #define TRACEPOINT_DEFINE
  28 #include "ust_dl.h"
  29
  30 static void *(*__lttng_ust_plibc_dlopen)(const char *filename, int flags);
  31 #ifdef HAVE_DLMOPEN
  32 static void *(*__lttng_ust_plibc_dlmopen)(Lmid_t nsid, const char *filename,
  33                 int flags);
  34 #endif
  35 static int (*__lttng_ust_plibc_dlclose)(void *handle);
  36
  37 static __attribute__((constructor))
  38 void _lttng_ust_dl_init(void)
  39 {
  40         ust_err_init();
  41 }
  42
  43 static
  44 void *_lttng_ust_dl_libc_dlopen(const char *filename, int flags)
  45 {
  46         if (!__lttng_ust_plibc_dlopen) {
  47                 __lttng_ust_plibc_dlopen = dlsym(RTLD_NEXT, "dlopen");
  48                 if (!__lttng_ust_plibc_dlopen) {
  49                         fprintf(stderr, "%s\n", dlerror());
  50                         return NULL;
  51                 }
  52         }
  53         return __lttng_ust_plibc_dlopen(filename, flags);
  54 }
  55
  56 #ifdef HAVE_DLMOPEN
  57 static
  58 void *_lttng_ust_dl_libc_dlmopen(Lmid_t nsid, const char *filename,
  59                 int flags)
  60 {
  61         if (!__lttng_ust_plibc_dlmopen) {
  62                 __lttng_ust_plibc_dlmopen = dlsym(RTLD_NEXT, "dlmopen");
  63                 if (!__lttng_ust_plibc_dlmopen) {
  64                         fprintf(stderr, "%s\n", dlerror());
  65                         return NULL;
  66                 }
  67         }
  68         return __lttng_ust_plibc_dlmopen(nsid, filename, flags);
  69 }
  70 #endif
  71
  72 static
  73 int _lttng_ust_dl_libc_dlclose(void *handle)
  74 {
  75         if (!__lttng_ust_plibc_dlclose) {
  76                 __lttng_ust_plibc_dlclose = dlsym(RTLD_NEXT, "dlclose");
  77                 if (!__lttng_ust_plibc_dlclose) {
  78                         fprintf(stderr, "%s\n", dlerror());
  79                         return -1;
  80                 }
  81         }
  82         return __lttng_ust_plibc_dlclose(handle);
  83 }
  84
  85 static
  86 void lttng_ust_dl_dlopen(void *so_base, const char *so_name,
  87                 int flags, void *ip)
  88 {
  89         char resolved_path[PATH_MAX];
  90         struct lttng_ust_elf *elf;
  91         uint64_t memsz;
  92         uint8_t *build_id = NULL;
  93         size_t build_id_len;
  94         char *dbg_file = NULL;
  95         uint32_t crc;
  96         int has_build_id = 0, has_debug_link = 0;
  97         int ret;
  98
  99         if (!realpath(so_name, resolved_path)) {
 100                 ERR("could not resolve path '%s'", so_name);
 101                 return;
 102         }
 103
 104         elf = lttng_ust_elf_create(resolved_path);
 105         if (!elf) {
 106                 ERR("could not access file %s", resolved_path);
 107                 return;
 108         }
 109
 110         ret = lttng_ust_elf_get_memsz(elf, &memsz);
 111         if (ret) {
 112                 goto end;
 113         }
 114         ret = lttng_ust_elf_get_build_id(
 115                 elf, &build_id, &build_id_len, &has_build_id);
 116         if (ret) {
 117                 goto end;
 118         }
 119         ret = lttng_ust_elf_get_debug_link(
 120                 elf, &dbg_file, &crc, &has_debug_link);
 121         if (ret) {
 122                 goto end;
 123         }
 124
 125         tracepoint(lttng_ust_dl, dlopen,
 126                 ip, so_base, resolved_path, flags, memsz,
 127                 has_build_id, has_debug_link);
 128
 129         if (has_build_id) {
 130                 tracepoint(lttng_ust_dl, build_id,
 131                         ip, so_base, build_id, build_id_len);
 132         }
 133
 134         if (has_debug_link) {
 135                 tracepoint(lttng_ust_dl, debug_link,
 136                         ip, so_base, dbg_file, crc);
 137         }
 138
 139 end:
 140         free(dbg_file);
 141         free(build_id);
 142         lttng_ust_elf_destroy(elf);
 143         return;
 144 }
 145
 146 #ifdef HAVE_DLMOPEN
 147 static
 148 void lttng_ust_dl_dlmopen(void *so_base, Lmid_t nsid, const char *so_name,
 149                 int flags, void *ip)
 150 {
 151         char resolved_path[PATH_MAX];
 152         struct lttng_ust_elf *elf;
 153         uint64_t memsz;
 154         uint8_t *build_id = NULL;
 155         size_t build_id_len;
 156         char *dbg_file = NULL;
 157         uint32_t crc;
 158         int has_build_id = 0, has_debug_link = 0;
 159         int ret;
 160
 161         if (!realpath(so_name, resolved_path)) {
 162                 ERR("could not resolve path '%s'", so_name);
 163                 return;
 164         }
 165
 166         elf = lttng_ust_elf_create(resolved_path);
 167         if (!elf) {
 168                 ERR("could not access file %s", resolved_path);
 169                 return;
 170         }
 171
 172         ret = lttng_ust_elf_get_memsz(elf, &memsz);
 173         if (ret) {
 174                 goto end;
 175         }
 176         ret = lttng_ust_elf_get_build_id(
 177                 elf, &build_id, &build_id_len, &has_build_id);
 178         if (ret) {
 179                 goto end;
 180         }
 181         ret = lttng_ust_elf_get_debug_link(
 182                 elf, &dbg_file, &crc, &has_debug_link);
 183         if (ret) {
 184                 goto end;
 185         }
 186
 187         tracepoint(lttng_ust_dl, dlmopen,
 188                 ip, so_base, nsid, resolved_path, flags, memsz,
 189                 has_build_id, has_debug_link);
 190
 191         if (has_build_id) {
 192                 tracepoint(lttng_ust_dl, build_id,
 193                         ip, so_base, build_id, build_id_len);
 194         }
 195
 196         if (has_debug_link) {
 197                 tracepoint(lttng_ust_dl, debug_link,
 198                         ip, so_base, dbg_file, crc);
 199         }
 200
 201 end:
 202         free(dbg_file);
 203         free(build_id);
 204         lttng_ust_elf_destroy(elf);
 205         return;
 206 }
 207 #endif
 208
 209 void *dlopen(const char *filename, int flags)
 210 {
 211         void *handle;
 212
 213         handle = _lttng_ust_dl_libc_dlopen(filename, flags);
 214         if (__tracepoint_ptrs_registered && handle) {
 215                 struct link_map *p = NULL;
 216                 int ret;
 217
 218                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 219                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 220                         lttng_ust_dl_dlopen((void *) p->l_addr,
 221                                 p->l_name, flags, LTTNG_UST_CALLER_IP());
 222                 }
 223         }
 224         lttng_ust_dl_update(LTTNG_UST_CALLER_IP());
 225         return handle;
 226 }
 227
 228 #ifdef HAVE_DLMOPEN
 229 void *dlmopen(Lmid_t nsid, const char *filename, int flags)
 230 {
 231         void *handle;
 232
 233         handle = _lttng_ust_dl_libc_dlmopen(nsid, filename, flags);
 234         if (__tracepoint_ptrs_registered && handle) {
 235                 struct link_map *p = NULL;
 236                 int ret;
 237
 238                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 239                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 240                         lttng_ust_dl_dlmopen((void *) p->l_addr,
 241                                 nsid, p->l_name, flags,
 242                                 LTTNG_UST_CALLER_IP());
 243                 }
 244         }
 245         lttng_ust_dl_update(LTTNG_UST_CALLER_IP());
 246         return handle;
 247
 248 }
 249 #endif
 250
 251 int dlclose(void *handle)
 252 {
 253         int ret;
 254
 255         if (__tracepoint_ptrs_registered) {
 256                 struct link_map *p = NULL;
 257
 258                 ret = dlinfo(handle, RTLD_DI_LINKMAP, &p);
 259                 if (ret != -1 && p != NULL && p->l_addr != 0) {
 260                         tracepoint(lttng_ust_dl, dlclose,
 261                                 LTTNG_UST_CALLER_IP(),
 262                                 (void *) p->l_addr);
 263                 }
 264         }
 265         ret = _lttng_ust_dl_libc_dlclose(handle);
 266         lttng_ust_dl_update(LTTNG_UST_CALLER_IP());
 267         return ret;
 268 }