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 /* TODO: the new trigger client might not be present in previous lttng-modules
  34  * should it be optional?
  35  * Can we reuse this to also know of the trigger feature is supported?
  36  */
  37 struct kern_modules_param kern_modules_control_core[] = {
  38         { (char *) "lttng-ring-buffer-client-discard" },
  39         { (char *) "lttng-ring-buffer-client-overwrite" },
  40         { (char *) "lttng-ring-buffer-metadata-client" },
  41         { (char *) "lttng-ring-buffer-client-mmap-discard" },
  42         { (char *) "lttng-ring-buffer-client-mmap-overwrite" },
  43         { (char *) "lttng-ring-buffer-metadata-mmap-client" },
  44         { (char *) "lttng-ring-buffer-trigger-client" },
  45 };
  46
  47 /* LTTng kernel tracer probe modules list */
  48 struct kern_modules_param kern_modules_probes_default[] = {
  49         { (char *) "lttng-probe-asoc" },
  50         { (char *) "lttng-probe-block" },
  51         { (char *) "lttng-probe-btrfs" },
  52         { (char *) "lttng-probe-compaction" },
  53         { (char *) "lttng-probe-ext3" },
  54         { (char *) "lttng-probe-ext4" },
  55         { (char *) "lttng-probe-gpio" },
  56         { (char *) "lttng-probe-i2c" },
  57         { (char *) "lttng-probe-irq" },
  58         { (char *) "lttng-probe-jbd" },
  59         { (char *) "lttng-probe-jbd2" },
  60         { (char *) "lttng-probe-kmem" },
  61         { (char *) "lttng-probe-kvm" },
  62         { (char *) "lttng-probe-kvm-x86" },
  63         { (char *) "lttng-probe-kvm-x86-mmu" },
  64         { (char *) "lttng-probe-lock" },
  65         { (char *) "lttng-probe-module" },
  66         { (char *) "lttng-probe-napi" },
  67         { (char *) "lttng-probe-net" },
  68         { (char *) "lttng-probe-power" },
  69         { (char *) "lttng-probe-preemptirq" },
  70         { (char *) "lttng-probe-printk" },
  71         { (char *) "lttng-probe-random" },
  72         { (char *) "lttng-probe-rcu" },
  73         { (char *) "lttng-probe-regmap" },
  74         { (char *) "lttng-probe-regulator" },
  75         { (char *) "lttng-probe-rpm" },
  76         { (char *) "lttng-probe-sched" },
  77         { (char *) "lttng-probe-scsi" },
  78         { (char *) "lttng-probe-signal" },
  79         { (char *) "lttng-probe-skb" },
  80         { (char *) "lttng-probe-sock" },
  81         { (char *) "lttng-probe-statedump" },
  82         { (char *) "lttng-probe-sunrpc" },
  83         { (char *) "lttng-probe-timer" },
  84         { (char *) "lttng-probe-udp" },
  85         { (char *) "lttng-probe-vmscan" },
  86         { (char *) "lttng-probe-v4l2" },
  87         { (char *) "lttng-probe-workqueue" },
  88         { (char *) "lttng-probe-writeback" },
  89         { (char *) "lttng-probe-x86-irq-vectors" },
  90         { (char *) "lttng-probe-x86-exceptions" },
  91 };
  92
  93 /* dynamic probe modules list */
  94 static struct kern_modules_param *probes;
  95 static int nr_probes;
  96 static int probes_capacity;
  97
  98 #if HAVE_KMOD
  99 #include <libkmod.h>
 100
 101 /**
 102  * @brief Logging function for libkmod integration.
 103  */
 104 static void log_kmod(void *data, int priority, const char *file, int line,
 105                 const char *fn, const char *format, va_list args)
 106 {
 107         char *str;
 108
 109         if (vasprintf(&str, format, args) < 0) {
 110                 return;
 111         }
 112
 113         DBG("libkmod: %s", str);
 114         free(str);
 115 }
 116
 117 /**
 118  * @brief Setup the libkmod context.
 119  *
 120  * Create the context, add a custom logging function and preload the
 121  * ressources for faster operation.
 122  *
 123  * @returns     \c 0 on success
 124  *              \c < 0 on error
 125  */
 126 static int setup_kmod_ctx(struct kmod_ctx **ctx)
 127 {
 128         int ret = 0;
 129
 130         *ctx = kmod_new(NULL, NULL);
 131         if (!ctx) {
 132                 PERROR("Unable to create kmod library context");
 133                 ret = -ENOMEM;
 134                 goto error;
 135         }
 136
 137         kmod_set_log_fn(*ctx, log_kmod, NULL);
 138         ret = kmod_load_resources(*ctx);
 139         if (ret < 0) {
 140                 ERR("Failed to load kmod library resources");
 141                 goto error;
 142         }
 143
 144 error:
 145         return ret;
 146 }
 147
 148 /**
 149  * @brief Loads the kernel modules in \p modules
 150  *
 151  * @param modules       List of modules to load
 152  * @param entries       Number of modules in the list
 153  * @param required      Are the modules required or optionnal
 154  *
 155  * If the modules are required, we will return with error after the
 156  * first failed module load, otherwise we continue loading.
 157  *
 158  * @returns             \c 0 on success
 159  *                      \c < 0 on error
 160  */
 161 static int modprobe_lttng(struct kern_modules_param *modules,
 162                 int entries, int required)
 163 {
 164         int ret = 0, i;
 165         struct kmod_ctx *ctx;
 166
 167         ret = setup_kmod_ctx(&ctx);
 168         if (ret < 0) {
 169                 goto error;
 170         }
 171
 172         for (i = 0; i < entries; i++) {
 173                 struct kmod_module *mod = NULL;
 174
 175                 ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
 176                 if (ret < 0) {
 177                         PERROR("Failed to create kmod module for %s", modules[i].name);
 178                         goto error;
 179                 }
 180
 181                 ret = kmod_module_probe_insert_module(mod, 0,
 182                                 NULL, NULL, NULL, NULL);
 183                 if (ret == -EEXIST) {
 184                         DBG("Module %s is already loaded", modules[i].name);
 185                         ret = 0;
 186                 } else if (ret < 0) {
 187                         if (required) {
 188                                 ERR("Unable to load required module %s",
 189                                                 modules[i].name);
 190                                 goto error;
 191                         } else {
 192                                 DBG("Unable to load optional module %s; continuing",
 193                                                 modules[i].name);
 194                                 ret = 0;
 195                         }
 196                 } else {
 197                         DBG("Modprobe successfully %s", modules[i].name);
 198                         modules[i].loaded = true;
 199                 }
 200
 201                 kmod_module_unref(mod);
 202         }
 203
 204 error:
 205         if (ctx) {
 206                 kmod_unref(ctx);
 207         }
 208         return ret;
 209 }
 210
 211 /**
 212  * @brief Recursively unload modules.
 213  *
 214  * This function implements the same modules unloading behavior as
 215  * 'modprobe -r' or rmmod, it will recursevily go trought the \p module
 216  * dependencies and unload modules with a refcount of 0.
 217  *
 218  * @param mod           The module to unload
 219  *
 220  * @returns             \c 0 on success
 221  *                      \c < 0 on error
 222  */
 223 static int rmmod_recurse(struct kmod_module *mod) {
 224         int ret = 0;
 225         struct kmod_list *deps, *itr;
 226
 227         if (kmod_module_get_initstate(mod) == KMOD_MODULE_BUILTIN) {
 228                 DBG("Module %s is builtin", kmod_module_get_name(mod));
 229                 return ret;
 230         }
 231
 232         ret = kmod_module_remove_module(mod, 0);
 233
 234         deps = kmod_module_get_dependencies(mod);
 235         if (deps != NULL) {
 236                 kmod_list_foreach(itr, deps) {
 237                         struct kmod_module *dep = kmod_module_get_module(itr);
 238                         if (kmod_module_get_refcnt(dep) == 0) {
 239                                 DBG("Recursive remove module %s",
 240                                                 kmod_module_get_name(dep));
 241                                 rmmod_recurse(dep);
 242                         }
 243                         kmod_module_unref(dep);
 244                 }
 245                 kmod_module_unref_list(deps);
 246         }
 247
 248         return ret;
 249 }
 250
 251 /**
 252  * @brief Unloads the kernel modules in \p modules
 253  *
 254  * @param modules       List of modules to unload
 255  * @param entries       Number of modules in the list
 256  * @param required      Are the modules required or optionnal
 257  *
 258  */
 259 static void modprobe_remove_lttng(const struct kern_modules_param *modules,
 260                 int entries, int required)
 261 {
 262         int ret = 0, i;
 263         struct kmod_ctx *ctx;
 264
 265         ret = setup_kmod_ctx(&ctx);
 266         if (ret < 0) {
 267                 goto error;
 268         }
 269
 270         for (i = entries - 1; i >= 0; i--) {
 271                 struct kmod_module *mod = NULL;
 272
 273                 if (!modules[i].loaded) {
 274                         continue;
 275                 }
 276
 277                 ret = kmod_module_new_from_name(ctx, modules[i].name, &mod);
 278                 if (ret < 0) {
 279                         PERROR("Failed to create kmod module for %s", modules[i].name);
 280                         goto error;
 281                 }
 282
 283                 ret = rmmod_recurse(mod);
 284                 if (ret == -EEXIST) {
 285                         DBG("Module %s is not in kernel.", modules[i].name);
 286                 } else if (required && ret < 0) {
 287                         ERR("Unable to remove module %s", modules[i].name);
 288                 } else {
 289                         DBG("Modprobe removal successful %s",
 290                                 modules[i].name);
 291                 }
 292
 293                 kmod_module_unref(mod);
 294         }
 295
 296 error:
 297         if (ctx) {
 298                 kmod_unref(ctx);
 299         }
 300 }
 301
 302 #else /* HAVE_KMOD */
 303
 304 static int modprobe_lttng(struct kern_modules_param *modules,
 305                 int entries, int required)
 306 {
 307         int ret = 0, i;
 308         char modprobe[256];
 309
 310         for (i = 0; i < entries; i++) {
 311                 ret = snprintf(modprobe, sizeof(modprobe),
 312                                 "/sbin/modprobe %s%s",
 313                                 required ? "" : "-q ",
 314                                 modules[i].name);
 315                 if (ret < 0) {
 316                         PERROR("snprintf modprobe");
 317                         goto error;
 318                 }
 319                 modprobe[sizeof(modprobe) - 1] = '\0';
 320                 ret = system(modprobe);
 321                 if (ret == -1) {
 322                         if (required) {
 323                                 ERR("Unable to launch modprobe for required module %s",
 324                                                 modules[i].name);
 325                                 goto error;
 326                         } else {
 327                                 DBG("Unable to launch modprobe for optional module %s; continuing",
 328                                                 modules[i].name);
 329                                 ret = 0;
 330                         }
 331                 } else if (WEXITSTATUS(ret) != 0) {
 332                         if (required) {
 333                                 ERR("Unable to load required module %s",
 334                                                 modules[i].name);
 335                                 goto error;
 336                         } else {
 337                                 DBG("Unable to load optional module %s; continuing",
 338                                                 modules[i].name);
 339                                 ret = 0;
 340                         }
 341                 } else {
 342                         DBG("Modprobe successfully %s", modules[i].name);
 343                         modules[i].loaded = true;
 344                 }
 345         }
 346
 347 error:
 348         return ret;
 349 }
 350
 351 static void modprobe_remove_lttng(const struct kern_modules_param *modules,
 352                 int entries, int required)
 353 {
 354         int ret = 0, i;
 355         char modprobe[256];
 356
 357         for (i = entries - 1; i >= 0; i--) {
 358                 if (!modules[i].loaded) {
 359                         continue;
 360                 }
 361                 ret = snprintf(modprobe, sizeof(modprobe),
 362                                 "/sbin/modprobe -r -q %s",
 363                                 modules[i].name);
 364                 if (ret < 0) {
 365                         PERROR("snprintf modprobe -r");
 366                         return;
 367                 }
 368                 modprobe[sizeof(modprobe) - 1] = '\0';
 369                 ret = system(modprobe);
 370                 if (ret == -1) {
 371                         ERR("Unable to launch modprobe -r for module %s",
 372                                         modules[i].name);
 373                 } else if (required && WEXITSTATUS(ret) != 0) {
 374                         ERR("Unable to remove module %s",
 375                                         modules[i].name);
 376                 } else {
 377                         DBG("Modprobe removal successful %s",
 378                                         modules[i].name);
 379                 }
 380         }
 381 }
 382
 383 #endif /* HAVE_KMOD */
 384
 385 /*
 386  * Remove control kernel module(s) in reverse load order.
 387  */
 388 void modprobe_remove_lttng_control(void)
 389 {
 390         modprobe_remove_lttng(kern_modules_control_core,
 391                               ARRAY_SIZE(kern_modules_control_core),
 392                               LTTNG_MOD_REQUIRED);
 393 }
 394
 395 static void free_probes(void)
 396 {
 397         int i;
 398
 399         if (!probes) {
 400                 return;
 401         }
 402         for (i = 0; i < nr_probes; ++i) {
 403                 free(probes[i].name);
 404         }
 405         free(probes);
 406         probes = NULL;
 407         nr_probes = 0;
 408 }
 409
 410 /*
 411  * Remove data kernel modules in reverse load order.
 412  */
 413 void modprobe_remove_lttng_data(void)
 414 {
 415         if (!probes) {
 416                 return;
 417         }
 418         modprobe_remove_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 419         free_probes();
 420 }
 421
 422 /*
 423  * Remove all kernel modules in reverse order.
 424  */
 425 void modprobe_remove_lttng_all(void)
 426 {
 427         modprobe_remove_lttng_data();
 428         modprobe_remove_lttng_control();
 429 }
 430
 431 /*
 432  * Load control kernel module(s).
 433  */
 434 int modprobe_lttng_control(void)
 435 {
 436         int ret;
 437
 438         ret = modprobe_lttng(kern_modules_control_core,
 439                              ARRAY_SIZE(kern_modules_control_core),
 440                              LTTNG_MOD_REQUIRED);
 441         return ret;
 442 }
 443
 444 /**
 445  * Grow global list of probes (double capacity or set it to 1 if
 446  * currently 0 and copy existing data).
 447  */
 448 static int grow_probes(void)
 449 {
 450         int i;
 451         struct kern_modules_param *tmp_probes;
 452
 453         /* Initialize capacity to 1 if 0. */
 454         if (probes_capacity == 0) {
 455                 probes = zmalloc(sizeof(*probes));
 456                 if (!probes) {
 457                         PERROR("malloc probe list");
 458                         return -ENOMEM;
 459                 }
 460
 461                 probes_capacity = 1;
 462                 return 0;
 463         }
 464
 465         /* Double size. */
 466         probes_capacity *= 2;
 467
 468         tmp_probes = zmalloc(sizeof(*tmp_probes) * probes_capacity);
 469         if (!tmp_probes) {
 470                 PERROR("malloc probe list");
 471                 return -ENOMEM;
 472         }
 473
 474         for (i = 0; i < nr_probes; ++i) {
 475                 /* Move name pointer. */
 476                 tmp_probes[i].name = probes[i].name;
 477         }
 478
 479         /* Replace probes with larger copy. */
 480         free(probes);
 481         probes = tmp_probes;
 482
 483         return 0;
 484 }
 485
 486 /*
 487  * Appends a comma-separated list of probes to the global list
 488  * of probes.
 489  */
 490 static int append_list_to_probes(const char *list)
 491 {
 492         char *next;
 493         int ret;
 494         char *tmp_list, *cur_list;
 495
 496         assert(list);
 497
 498         cur_list = tmp_list = strdup(list);
 499         if (!tmp_list) {
 500                 PERROR("strdup temp list");
 501                 return -ENOMEM;
 502         }
 503
 504         for (;;) {
 505                 size_t name_len;
 506                 struct kern_modules_param *cur_mod;
 507
 508                 next = strtok(cur_list, ",");
 509                 if (!next) {
 510                         break;
 511                 }
 512                 cur_list = NULL;
 513
 514                 /* filter leading spaces */
 515                 while (*next == ' ') {
 516                         next++;
 517                 }
 518
 519                 if (probes_capacity <= nr_probes) {
 520                         ret = grow_probes();
 521                         if (ret) {
 522                                 goto error;
 523                         }
 524                 }
 525
 526                 /* Length 13 is "lttng-probe-" + \0 */
 527                 name_len = strlen(next) + 13;
 528
 529                 cur_mod = &probes[nr_probes];
 530                 cur_mod->name = zmalloc(name_len);
 531                 if (!cur_mod->name) {
 532                         PERROR("malloc probe list");
 533                         ret = -ENOMEM;
 534                         goto error;
 535                 }
 536
 537                 ret = snprintf(cur_mod->name, name_len, "lttng-probe-%s", next);
 538                 if (ret < 0) {
 539                         PERROR("snprintf modprobe name");
 540                         ret = -ENOMEM;
 541                         goto error;
 542                 }
 543
 544                 nr_probes++;
 545         }
 546
 547         free(tmp_list);
 548         return 0;
 549
 550 error:
 551         free(tmp_list);
 552         free_probes();
 553         return ret;
 554 }
 555
 556 /*
 557  * Load data kernel module(s).
 558  */
 559 int modprobe_lttng_data(void)
 560 {
 561         int ret, i;
 562         char *list;
 563
 564         /*
 565          * Base probes: either from command line option, environment
 566          * variable or default list.
 567          */
 568         list = config.kmod_probes_list.value;
 569         if (list) {
 570                 /* User-specified probes. */
 571                 ret = append_list_to_probes(list);
 572                 if (ret) {
 573                         return ret;
 574                 }
 575         } else {
 576                 /* Default probes. */
 577                 int def_len = ARRAY_SIZE(kern_modules_probes_default);
 578
 579                 probes = zmalloc(sizeof(*probes) * def_len);
 580                 if (!probes) {
 581                         PERROR("malloc probe list");
 582                         return -ENOMEM;
 583                 }
 584
 585                 nr_probes = probes_capacity = def_len;
 586
 587                 for (i = 0; i < def_len; ++i) {
 588                         char* name = strdup(kern_modules_probes_default[i].name);
 589
 590                         if (!name) {
 591                                 PERROR("strdup probe item");
 592                                 ret = -ENOMEM;
 593                                 goto error;
 594                         }
 595
 596                         probes[i].name = name;
 597                 }
 598         }
 599
 600         /*
 601          * Extra modules? Append them to current probes list.
 602          */
 603         list = config.kmod_extra_probes_list.value;
 604         if (list) {
 605                 ret = append_list_to_probes(list);
 606                 if (ret) {
 607                         goto error;
 608                 }
 609         }
 610
 611         /*
 612          * Load probes modules now.
 613          */
 614         ret = modprobe_lttng(probes, nr_probes, LTTNG_MOD_OPTIONAL);
 615         if (ret) {
 616                 goto error;
 617         }
 618         return ret;
 619
 620 error:
 621         free_probes();
 622         return ret;
 623 }