src/bin/lttng-sessiond/modprobe.c

   1 /*
   2  * Copyright (C) 2011 David Goulet <dgoulet@efficios.com>
   3  * Copyright (C) 2014 Jan Glauber <jan.glauber@gmail.com>
   4  *
   5  * SPDX-License-Identifier: GPL-2.0-only
   6  *
   7  */
   8
   9 /**
  10  * @file modprobe.c
  11  *
  12  * @brief modprobe related functions.
  13  *
  14  */
  15
  16 #define _LGPL_SOURCE
  17 #include <assert.h>
  18 #include <stdio.h>
  19 #include <stdlib.h>
  20 #include <sys/wait.h>
  21
  22 #include <common/common.h>
  23 #include <common/utils.h>
  24
  25 #include "modprobe.h"
  26 #include "kern-modules.h"
  27 #include "lttng-sessiond.h"
  28
  29 #define LTTNG_MOD_REQUIRED      1
  30 #define LTTNG_MOD_OPTIONAL      0
  31
  32 /* LTTng kernel tracer mandatory core modules list */
  33 struct kern_modules_param kern_modules_control_core[] = {
  34         { (char *) "lttng-ring-buffer-client-discard" },
  35         { (char *) "lttng-ring-buffer-client-overwrite" },
  36         { (char *) "lttng-ring-buffer-metadata-client" },
  37         { (char *) "lttng-ring-buffer-client-mmap-discard" },
  38         { (char *) "lttng-ring-buffer-client-mmap-overwrite" },
  39         { (char *) "lttng-ring-buffer-metadata-mmap-client" },
  40 };
  41
  42 /* LTTng kernel tracer probe modules list */
  43 struct kern_modules_param kern_modules_probes_default[] = {
  44         { (char *) "lttng-probe-asoc" },
  45         { (char *) "lttng-probe-block" },
  46         { (char *) "lttng-probe-btrfs" },
  47         { (char *) "lttng-probe-compaction" },
  48         { (char *) "lttng-probe-ext3" },
  49         { (char *) "lttng-probe-ext4" },
  50         { (char *) "lttng-probe-gpio" },
  51         { (char *) "lttng-probe-i2c" },
  52         { (char *) "lttng-probe-irq" },
  53         { (char *) "lttng-probe-jbd" },
  54         { (char *) "lttng-probe-jbd2" },
  55         { (char *) "lttng-probe-kmem" },
  56         { (char *) "lttng-probe-kvm" },
  57         { (char *) "lttng-probe-kvm-x86" },
  58         { (char *) "lttng-probe-kvm-x86-mmu" },
  59         { (char *) "lttng-probe-lock" },
  60         { (char *) "lttng-probe-module" },
  61         { (char *) "lttng-probe-napi" },
  62         { (char *) "lttng-probe-net" },
  63         { (char *) "lttng-probe-power" },
  64         { (char *) "lttng-probe-preemptirq" },
  65         { (char *) "lttng-probe-printk" },
  66         { (char *) "lttng-probe-random" },
  67         { (char *) "lttng-probe-rcu" },
  68         { (char *) "lttng-probe-regmap" },
  69         { (char *) "lttng-probe-regulator" },
  70         { (char *) "lttng-probe-rpm" },
  71         { (char *) "lttng-probe-sched" },
  72         { (char *) "lttng-probe-scsi" },
  73         { (char *) "lttng-probe-signal" },
  74         { (char *) "lttng-probe-skb" },
  75         { (char *) "lttng-probe-sock" },
  76         { (char *) "lttng-probe-statedump" },
  77         { (char *) "lttng-probe-sunrpc" },
  78         { (char *) "lttng-probe-timer" },
  79         { (char *) "lttng-probe-udp" },
  80         { (char *) "lttng-probe-vmscan" },
  81         { (char *) "lttng-probe-v4l2" },
  82         { (char *) "lttng-probe-workqueue" },
  83         { (char *) "lttng-probe-writeback" },
  84         { (char *) "lttng-probe-x86-irq-vectors" },
  85         { (char *) "lttng-probe-x86-exceptions" },
  86 };
  87
  88 /* dynamic probe modules list */
  89 static struct kern_modules_param *probes;
  90 static int nr_probes;
  91 static int probes_capacity;
  92
  93 #if HAVE_KMOD
  94 #include <libkmod.h>
  95
  96 /**
  97  * @brief Logging function for libkmod integration.
  98  */
  99 static void log_kmod(void *data, int priority, const char *file, int line,
 100                 const char *fn, const char *format, va_list args)
 101 {
 102         char *str;
 103
 104         if (vasprintf(&str, format, args) < 0) {
 105                 return;
 106         }
 107
 108         DBG("libkmod: %s", str);
 109         free(str);
 110 }
 111
 112 /**
 113  * @brief Setup the libkmod context.
 114  *
 115  * Create the context, add a custom logging function and preload the
 116  * ressources for faster operation.
 117  *
 118  * @returns     \c 0 on success
 119  *              \c < 0 on error
 120  */
 121 static int setup_kmod_ctx(struct kmod_ctx **ctx)
 122 {
 123         int ret = 0;
 124
 125         *ctx = kmod_new(NULL, NULL);
 126         if (!ctx) {
 127                 PERROR("Unable to create kmod library context");
 128                 ret = -ENOMEM;
 129                 goto error;
 130         }
 131
 132         kmod_set_log_fn(*ctx, log_kmod, NULL);
 133         ret = kmod_load_resources(*ctx);
 134         if (ret < 0) {
 135                 ERR("Failed to load kmod library resources");
 136                 goto error;
 137         }
 138
 139 error:
 140         return ret;
 141 }
 142
 143 /**
 144  * @brief Loads the kernel modules in \p modules
 145  *
 146  * @param modules       List of modules to load
 147  * @param entries       Number of modules in the list
 148  * @param required      Are the modules required or optionnal
 149  *
 150  * If the modules are required, we will return with error after the
 151  * first failed module load, otherwise we continue loading.
 152  *
 153  * @returns             \c 0 on success
 154  *                      \c < 0 on error
 155  */
 156 static int modprobe_lttng(struct kern_modules_param *modules,
 157                 int entries, int required)
 158 {
 159         int ret = 0, i;
 160         struct kmod_ctx *ctx;
 161
 162         ret = setup_kmod_ctx(&ctx);
 163         if (ret < 0) {
 164                 goto error;
 165         }
 166
 167         for (i = 0; i < entries; i++) {
 168                 struct kmod_module *mod = NULL;
 169
 170                 ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
 171                 if (ret < 0) {
 172                         PERROR("Failed to create kmod module for %s", modules[i].name);
 173                         goto error;
 174                 }
 175
 176                 ret = kmod_module_probe_insert_module(mod, 0,
 177                                 NULL, NULL, NULL, NULL);
 178                 if (ret == -EEXIST) {
 179                         DBG("Module %s is already loaded", modules[i].name);
 180                         ret = 0;
 181                 } else if (ret < 0) {
 182                         if (required) {
 183                                 ERR("Unable to load required module %s",
 184                                                 modules[i].name);
 185                                 goto error;
 186                         } else {
 187                                 DBG("Unable to load optional module %s; continuing",
 188                                                 modules[i].name);
 189                                 ret = 0;
 190                         }
 191                 } else {
 192                         DBG("Modprobe successfully %s", modules[i].name);
 193                         modules[i].loaded = true;
 194                 }
 195
 196                 kmod_module_unref(mod);
 197         }
 198
 199 error:
 200         if (ctx) {
 201                 kmod_unref(ctx);
 202         }
 203         return ret;
 204 }
 205
 206 /**
 207  * @brief Recursively unload modules.
 208  *
 209  * This function implements the same modules unloading behavior as
 210  * 'modprobe -r' or rmmod, it will recursevily go trought the \p module
 211  * dependencies and unload modules with a refcount of 0.
 212  *
 213  * @param mod           The module to unload
 214  *
 215  * @returns             \c 0 on success
 216  *                      \c < 0 on error
 217  */
 218 static int rmmod_recurse(struct kmod_module *mod) {
 219         int ret = 0;
 220         struct kmod_list *deps, *itr;
 221
 222         if (kmod_module_get_initstate(mod) == KMOD_MODULE_BUILTIN) {
 223                 DBG("Module %s is builtin", kmod_module_get_name(mod));
 224                 return ret;
 225         }
 226
 227         ret = kmod_module_remove_module(mod, 0);
 228
 229         deps = kmod_module_get_dependencies(mod);
 230         if (deps != NULL) {
 231                 kmod_list_foreach(itr, deps) {
 232                         struct kmod_module *dep = kmod_module_get_module(itr);
 233                         if (kmod_module_get_refcnt(dep) == 0) {
 234                                 DBG("Recursive remove module %s",
 235                                                 kmod_module_get_name(dep));
 236                                 rmmod_recurse(dep);
 237                         }
 238                         kmod_module_unref(dep);
 239                 }
 240                 kmod_module_unref_list(deps);
 241         }
 242
 243         return ret;
 244 }
 245
 246 /**
 247  * @brief Unloads the kernel modules in \p modules
 248  *
 249  * @param modules       List of modules to unload
 250  * @param entries       Number of modules in the list
 251  * @param required      Are the modules required or optionnal
 252  *
 253  */
 254 static void modprobe_remove_lttng(const struct kern_modules_param *modules,
 255                 int entries, int required)
 256 {
 257         int ret = 0, i;
 258         struct kmod_ctx *ctx;
 259
 260         ret = setup_kmod_ctx(&ctx);
 261         if (ret < 0) {
 262                 goto error;
 263         }
 264
 265         for (i = entries - 1; i >= 0; i--) {
 266                 struct kmod_module *mod = NULL;
 267
 268                 if (!modules[i].loaded) {
 269                         continue;
 270                 }
 271
 272                 ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
 273                 if (ret < 0) {
 274                         PERROR("Failed to create kmod module for %s", modules[i].name);
 275                         goto error;
 276                 }
 277
 278                 ret = rmmod_recurse(mod);
 279                 if (ret == -EEXIST) {
 280                         DBG("Module %s is not in kernel.", modules[i].name);
 281                 } else if (required && ret < 0) {
 282                         ERR("Unable to remove module %s", modules[i].name);
 283                 } else {
 284                         DBG("Modprobe removal successful %s",
 285                                 modules[i].name);
 286                 }
 287
 288                 kmod_module_unref(mod);
 289         }
 290
 291 error:
 292         if (ctx) {
 293                 kmod_unref(ctx);
 294         }
 295 }
 296
 297 #else /* HAVE_KMOD */
 298
 299 static int modprobe_lttng(struct kern_modules_param *modules,
 300                 int entries, int required)
 301 {
 302         int ret = 0, i;
 303         char modprobe[256];
 304
 305         for (i = 0; i < entries; i++) {
 306                 ret = snprintf(modprobe, sizeof(modprobe),
 307                                 "/sbin/modprobe %s%s",
 308                                 required ? "" : "-q ",
 309                                 modules[i].name);
 310                 if (ret < 0) {
 311                         PERROR("snprintf modprobe");
 312                         goto error;
 313                 }
 314                 modprobe[sizeof(modprobe) - 1] = '\0';
 315                 ret = system(modprobe);
 316                 if (ret == -1) {
 317                         if (required) {
 318                                 ERR("Unable to launch modprobe for required module %s",
 319                                                 modules[i].name);
 320                                 goto error;
 321                         } else {
 322                                 DBG("Unable to launch modprobe for optional module %s; continuing",
 323                                                 modules[i].name);
 324                                 ret = 0;
 325                         }
 326                 } else if (WEXITSTATUS(ret) != 0) {
 327                         if (required) {
 328                                 ERR("Unable to load required module %s",
 329                                                 modules[i].name);
 330                                 goto error;
 331                         } else {
 332                                 DBG("Unable to load optional module %s; continuing",
 333                                                 modules[i].name);
 334                                 ret = 0;
 335                         }
 336                 } else {
 337                         DBG("Modprobe successfully %s", modules[i].name);
 338                         modules[i].loaded = true;
 339                 }
 340         }
 341
 342 error:
 343         return ret;
 344 }
 345
 346 static void modprobe_remove_lttng(const struct kern_modules_param *modules,
 347                 int entries, int required)
 348 {
 349         int ret = 0, i;
 350         char modprobe[256];
 351
 352         for (i = entries - 1; i >= 0; i--) {
 353                 if (!modules[i].loaded) {
 354                         continue;
 355                 }
 356                 ret = snprintf(modprobe, sizeof(modprobe),
 357                                 "/sbin/modprobe -r -q %s",
 358                                 modules[i].name);
 359                 if (ret < 0) {
 360                         PERROR("snprintf modprobe -r");
 361                         return;
 362                 }
 363                 modprobe[sizeof(modprobe) - 1] = '\0';
 364                 ret = system(modprobe);
 365                 if (ret == -1) {
 366                         ERR("Unable to launch modprobe -r for module %s",
 367                                         modules[i].name);
 368                 } else if (required && WEXITSTATUS(ret) != 0) {
 369                         ERR("Unable to remove module %s",
 370                                         modules[i].name);
 371                 } else {
 372                         DBG("Modprobe removal successful %s",
 373                                         modules[i].name);
 374                 }
 375         }
 376 }
 377
 378 #endif /* HAVE_KMOD */
 379
 380 /*
 381  * Remove control kernel module(s) in reverse load order.
 382  */
 383 void modprobe_remove_lttng_control(void)
 384 {
 385         modprobe_remove_lttng(kern_modules_control_core,
 386                               ARRAY_SIZE(kern_modules_control_core),
 387                               LTTNG_MOD_REQUIRED);
 388 }
 389
 390 static void free_probes(void)
 391 {
 392         int i;
 393
 394         if (!probes) {
 395                 return;
 396         }
 397         for (i = 0; i < nr_probes; ++i) {
 398                 free(probes[i].name);
 399         }
 400         free(probes);
 401         probes = NULL;
 402         nr_probes = 0;
 403 }
 404
 405 /*
 406  * Remove data kernel modules in reverse load order.
 407  */
 408 void modprobe_remove_lttng_data(void)
 409 {
 410         if (!probes) {
 411                 return;
 412         }
 413         modprobe_remove_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 414         free_probes();
 415 }
 416
 417 /*
 418  * Remove all kernel modules in reverse order.
 419  */
 420 void modprobe_remove_lttng_all(void)
 421 {
 422         modprobe_remove_lttng_data();
 423         modprobe_remove_lttng_control();
 424 }
 425
 426 /*
 427  * Load control kernel module(s).
 428  */
 429 int modprobe_lttng_control(void)
 430 {
 431         int ret;
 432
 433         ret = modprobe_lttng(kern_modules_control_core,
 434                              ARRAY_SIZE(kern_modules_control_core),
 435                              LTTNG_MOD_REQUIRED);
 436         return ret;
 437 }
 438
 439 /**
 440  * Grow global list of probes (double capacity or set it to 1 if
 441  * currently 0 and copy existing data).
 442  */
 443 static int grow_probes(void)
 444 {
 445         int i;
 446         struct kern_modules_param *tmp_probes;
 447
 448         /* Initialize capacity to 1 if 0. */
 449         if (probes_capacity == 0) {
 450                 probes = zmalloc(sizeof(*probes));
 451                 if (!probes) {
 452                         PERROR("malloc probe list");
 453                         return -ENOMEM;
 454                 }
 455
 456                 probes_capacity = 1;
 457                 return 0;
 458         }
 459
 460         /* Double size. */
 461         probes_capacity *= 2;
 462
 463         tmp_probes = zmalloc(sizeof(*tmp_probes) * probes_capacity);
 464         if (!tmp_probes) {
 465                 PERROR("malloc probe list");
 466                 return -ENOMEM;
 467         }
 468
 469         for (i = 0; i < nr_probes; ++i) {
 470                 /* Move name pointer. */
 471                 tmp_probes[i].name = probes[i].name;
 472         }
 473
 474         /* Replace probes with larger copy. */
 475         free(probes);
 476         probes = tmp_probes;
 477
 478         return 0;
 479 }
 480
 481 /*
 482  * Appends a comma-separated list of probes to the global list
 483  * of probes.
 484  */
 485 static int append_list_to_probes(const char *list)
 486 {
 487         char *next;
 488         int ret;
 489         char *tmp_list, *cur_list;
 490
 491         assert(list);
 492
 493         cur_list = tmp_list = strdup(list);
 494         if (!tmp_list) {
 495                 PERROR("strdup temp list");
 496                 return -ENOMEM;
 497         }
 498
 499         for (;;) {
 500                 size_t name_len;
 501                 struct kern_modules_param *cur_mod;
 502
 503                 next = strtok(cur_list, ",");
 504                 if (!next) {
 505                         break;
 506                 }
 507                 cur_list = NULL;
 508
 509                 /* filter leading spaces */
 510                 while (*next == ' ') {
 511                         next++;
 512                 }
 513
 514                 if (probes_capacity <= nr_probes) {
 515                         ret = grow_probes();
 516                         if (ret) {
 517                                 goto error;
 518                         }
 519                 }
 520
 521                 /* Length 13 is "lttng-probe-" + \0 */
 522                 name_len = strlen(next) + 13;
 523
 524                 cur_mod = &probes[nr_probes];
 525                 cur_mod->name = zmalloc(name_len);
 526                 if (!cur_mod->name) {
 527                         PERROR("malloc probe list");
 528                         ret = -ENOMEM;
 529                         goto error;
 530                 }
 531
 532                 ret = snprintf(cur_mod->name, name_len, "lttng-probe-%s", next);
 533                 if (ret < 0) {
 534                         PERROR("snprintf modprobe name");
 535                         ret = -ENOMEM;
 536                         goto error;
 537                 }
 538
 539                 nr_probes++;
 540         }
 541
 542         free(tmp_list);
 543         return 0;
 544
 545 error:
 546         free(tmp_list);
 547         free_probes();
 548         return ret;
 549 }
 550
 551 /*
 552  * Load data kernel module(s).
 553  */
 554 int modprobe_lttng_data(void)
 555 {
 556         int ret, i;
 557         char *list;
 558
 559         /*
 560          * Base probes: either from command line option, environment
 561          * variable or default list.
 562          */
 563         list = config.kmod_probes_list.value;
 564         if (list) {
 565                 /* User-specified probes. */
 566                 ret = append_list_to_probes(list);
 567                 if (ret) {
 568                         return ret;
 569                 }
 570         } else {
 571                 /* Default probes. */
 572                 int def_len = ARRAY_SIZE(kern_modules_probes_default);
 573
 574                 probes = zmalloc(sizeof(*probes) * def_len);
 575                 if (!probes) {
 576                         PERROR("malloc probe list");
 577                         return -ENOMEM;
 578                 }
 579
 580                 nr_probes = probes_capacity = def_len;
 581
 582                 for (i = 0; i < def_len; ++i) {
 583                         char* name = strdup(kern_modules_probes_default[i].name);
 584
 585                         if (!name) {
 586                                 PERROR("strdup probe item");
 587                                 ret = -ENOMEM;
 588                                 goto error;
 589                         }
 590
 591                         probes[i].name = name;
 592                 }
 593         }
 594
 595         /*
 596          * Extra modules? Append them to current probes list.
 597          */
 598         list = config.kmod_extra_probes_list.value;
 599         if (list) {
 600                 ret = append_list_to_probes(list);
 601                 if (ret) {
 602                         goto error;
 603                 }
 604         }
 605
 606         /*
 607          * Load probes modules now.
 608          */
 609         ret = modprobe_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 610         if (ret) {
 611                 goto error;
 612         }
 613         return ret;
 614
 615 error:
 616         free_probes();
 617         return ret;
 618 }