src/bin/lttng-sessiond/syscall.c

   1 /*
   2  * Copyright (C) 2014 - David Goulet <dgoulet@efficios.com>
   3  *
   4  * This program is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License, version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
  11  * more details.
  12  *
  13  * You should have received a copy of the GNU General Public License along with
  14  * this program; if not, write to the Free Software Foundation, Inc., 51
  15  * Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
  16  */
  17
  18 #define _GNU_SOURCE
  19 #define _LGPL_SOURCE
  20 #include <common/bitfield.h>
  21 #include <common/common.h>
  22 #include <common/kernel-ctl/kernel-ctl.h>
  23
  24 #include "lttng-sessiond.h"
  25 #include "kernel.h"
  26 #include "syscall.h"
  27 #include "utils.h"
  28
  29 /* Global syscall table. */
  30 struct syscall *syscall_table;
  31
  32 /* Number of entry in the syscall table. */
  33 static size_t syscall_table_nb_entry;
  34
  35 /*
  36  * Populate the system call table using the kernel tracer.
  37  *
  38  * Return 0 on success and the syscall table is allocated. On error, a negative
  39  * value is returned.
  40  */
  41 int syscall_init_table(void)
  42 {
  43         int ret, fd, err;
  44         size_t nbmem;
  45         FILE *fp;
  46         /* Syscall data from the kernel. */
  47         size_t index;
  48         uint32_t bitness;
  49         char name[SYSCALL_NAME_LEN];
  50
  51         DBG3("Syscall init system call table");
  52
  53         fd = kernctl_syscall_list(kernel_tracer_fd);
  54         if (fd < 0) {
  55                 ret = -errno;
  56                 PERROR("kernelctl syscall list");
  57                 goto error_ioctl;
  58         }
  59
  60         fp = fdopen(fd, "r");
  61         if (!fp) {
  62                 ret = -errno;
  63                 PERROR("syscall list fdopen");
  64                 goto error_fp;
  65         }
  66
  67         nbmem = SYSCALL_TABLE_INIT_SIZE;
  68         syscall_table = zmalloc(sizeof(struct syscall) * nbmem);
  69         if (!syscall_table) {
  70                 ret = -errno;
  71                 PERROR("syscall list zmalloc");
  72                 goto error;
  73         }
  74
  75         while (fscanf(fp,
  76                                 "syscall { index = %lu; \
  77                                 name = %" XSTR(SYSCALL_NAME_LEN) "[^;]; \
  78                                 bitness = %u; };\n",
  79                                 &index, name, &bitness) == 3) {
  80                 if (index >= nbmem ) {
  81                         struct syscall *new_list;
  82                         size_t new_nbmem;
  83
  84                         /* Double memory size. */
  85                         new_nbmem = max(index, nbmem << 1);
  86                         if (new_nbmem < nbmem) {
  87                                 /* Overflow, stop everything, something went really wrong. */
  88                                 ERR("Syscall listing memory size overflow. Stopping");
  89                                 free(syscall_table);
  90                                 syscall_table = NULL;
  91                                 ret = -EINVAL;
  92                                 goto error;
  93                         }
  94
  95                         DBG("Reallocating syscall table from %zu to %zu entries", nbmem,
  96                                         new_nbmem);
  97                         new_list = realloc(syscall_table, new_nbmem * sizeof(*new_list));
  98                         if (!new_list) {
  99                                 ret = -errno;
 100                                 PERROR("syscall list realloc");
 101                                 goto error;
 102                         }
 103
 104                         /* Zero out the new memory. */
 105                         memset(new_list + nbmem, 0,
 106                                         (new_nbmem - nbmem) * sizeof(*new_list));
 107                         nbmem = new_nbmem;
 108                         syscall_table = new_list;
 109                 }
 110                 syscall_table[index].index = index;
 111                 syscall_table[index].bitness = bitness;
 112                 strncpy(syscall_table[index].name, name,
 113                                 sizeof(syscall_table[index].name));
 114                 /*
 115                 DBG("Syscall name '%s' at index %" PRIu32 " of bitness %u",
 116                                 syscall_table[index].name,
 117                                 syscall_table[index].index,
 118                                 syscall_table[index].bitness);
 119                 */
 120         }
 121
 122         syscall_table_nb_entry = index;
 123
 124         ret = 0;
 125
 126 error:
 127         err = fclose(fp);
 128         if (err) {
 129                 PERROR("syscall list fclose");
 130         }
 131         return ret;
 132
 133 error_fp:
 134         err = close(fd);
 135         if (err) {
 136                 PERROR("syscall list close");
 137         }
 138
 139 error_ioctl:
 140         return ret;
 141 }
 142
 143 /*
 144  * Helper function for the list syscalls command that empty the temporary
 145  * syscall hashtable used to track duplicate between 32 and 64 bit arch.
 146  *
 147  * This empty the hash table and destroys it after. After this, the pointer is
 148  * unsuable. RCU read side lock MUST be acquired before calling this.
 149  */
 150 static void destroy_syscall_ht(struct lttng_ht *ht)
 151 {
 152         struct lttng_ht_iter iter;
 153         struct syscall *ksyscall;
 154
 155         DBG3("Destroying syscall hash table.");
 156
 157         if (!ht) {
 158                 return;
 159         }
 160
 161         cds_lfht_for_each_entry(ht->ht, &iter.iter, ksyscall, node.node) {
 162                 int ret;
 163
 164                 ret = lttng_ht_del(ht, &iter);
 165                 assert(!ret);
 166                 free(ksyscall);
 167         }
 168         ht_cleanup_push(ht);
 169 }
 170
 171 /*
 172  * Allocate the given hashtable pointer.
 173  *
 174  * Return 0 on success else a negative LTTNG error value.
 175  */
 176 static int init_syscall_ht(struct lttng_ht **ht)
 177 {
 178         int ret;
 179
 180         *ht = lttng_ht_new(0, LTTNG_HT_TYPE_STRING);
 181         if (!*ht) {
 182                 ret = -LTTNG_ERR_NOMEM;
 183         } else {
 184                 ret = 0;
 185         }
 186
 187         return ret;
 188 }
 189
 190 /*
 191  * Lookup a syscall in the given hash table by name.
 192  *
 193  * Return syscall object if found or else NULL.
 194  */
 195 static struct syscall *lookup_syscall(struct lttng_ht *ht, const char *name)
 196 {
 197         struct lttng_ht_node_str *node;
 198         struct lttng_ht_iter iter;
 199         struct syscall *ksyscall = NULL;
 200
 201         assert(ht);
 202         assert(name);
 203
 204         lttng_ht_lookup(ht, (void *) name, &iter);
 205         node = lttng_ht_iter_get_node_str(&iter);
 206         if (node) {
 207                 ksyscall = caa_container_of(node, struct syscall, node);
 208         }
 209
 210         return ksyscall;
 211 }
 212
 213 /*
 214  * Using the given syscall object in the events array with the bitness of the
 215  * syscall at index in the syscall table.
 216  */
 217 static void update_event_syscall_bitness(struct lttng_event *events,
 218                 unsigned int index, unsigned int syscall_index)
 219 {
 220         assert(events);
 221
 222         if (syscall_table[index].bitness == 32) {
 223                 events[syscall_index].flags |= LTTNG_EVENT_FLAG_SYSCALL_32;
 224         } else {
 225                 events[syscall_index].flags |= LTTNG_EVENT_FLAG_SYSCALL_64;
 226         }
 227 }
 228
 229 /*
 230  * Allocate and initialize syscall object and add it to the given hashtable.
 231  *
 232  * Return 0 on success else -LTTNG_ERR_NOMEM.
 233  */
 234 static int add_syscall_to_ht(struct lttng_ht *ht, unsigned int index,
 235                 unsigned int syscall_index)
 236 {
 237         int ret;
 238         struct syscall *ksyscall;
 239
 240         assert(ht);
 241
 242         ksyscall = zmalloc(sizeof(*ksyscall));
 243         if (!ksyscall) {
 244                 ret = -LTTNG_ERR_NOMEM;
 245                 goto error;
 246         }
 247
 248         strncpy(ksyscall->name, syscall_table[index].name,
 249                         sizeof(ksyscall->name));
 250         ksyscall->bitness = syscall_table[index].bitness;
 251         ksyscall->index = syscall_index;
 252         lttng_ht_node_init_str(&ksyscall->node, ksyscall->name);
 253         lttng_ht_add_unique_str(ht, &ksyscall->node);
 254         ret = 0;
 255
 256 error:
 257         return ret;
 258 }
 259
 260 /*
 261  * List syscalls present in the kernel syscall global array, allocate and
 262  * populate the events structure with them. Skip the empty syscall name.
 263  *
 264  * Return the number of entries in the array else a negative value.
 265  */
 266 ssize_t syscall_table_list(struct lttng_event **_events)
 267 {
 268         int i, index = 0;
 269         ssize_t ret;
 270         struct lttng_event *events;
 271         /* Hash table used to filter duplicate out. */
 272         struct lttng_ht *syscalls_ht = NULL;
 273
 274         assert(_events);
 275
 276         DBG("Syscall table listing.");
 277
 278         rcu_read_lock();
 279
 280         /*
 281          * Allocate at least the number of total syscall we have even if some of
 282          * them might not be valid. The count below will make sure to return the
 283          * right size of the events array.
 284          */
 285         events = zmalloc(syscall_table_nb_entry * sizeof(*events));
 286         if (!events) {
 287                 PERROR("syscall table list zmalloc");
 288                 ret = -LTTNG_ERR_NOMEM;
 289                 goto error;
 290         }
 291
 292         ret = init_syscall_ht(&syscalls_ht);
 293         if (ret < 0) {
 294                 goto error;
 295         }
 296
 297         for (i = 0; i < syscall_table_nb_entry; i++) {
 298                 struct syscall *ksyscall;
 299
 300                 /* Skip empty syscalls. */
 301                 if (*syscall_table[i].name == '\0') {
 302                         continue;
 303                 }
 304
 305                 ksyscall = lookup_syscall(syscalls_ht, syscall_table[i].name);
 306                 if (ksyscall) {
 307                         update_event_syscall_bitness(events, i, ksyscall->index);
 308                         continue;
 309                 }
 310
 311                 ret = add_syscall_to_ht(syscalls_ht, i, index);
 312                 if (ret < 0) {
 313                         goto error;
 314                 }
 315
 316                 /* Copy the event information in the event's array. */
 317                 strncpy(events[index].name, syscall_table[i].name,
 318                                 sizeof(events[index].name));
 319                 update_event_syscall_bitness(events, i, index);
 320                 events[index].type = LTTNG_EVENT_SYSCALL;
 321                 /* This makes the command line not print the enabled/disabled field. */
 322                 events[index].enabled = -1;
 323                 index++;
 324         }
 325
 326         destroy_syscall_ht(syscalls_ht);
 327         *_events = events;
 328         rcu_read_unlock();
 329         return index;
 330
 331 error:
 332         destroy_syscall_ht(syscalls_ht);
 333         free(events);
 334         rcu_read_unlock();
 335         return ret;
 336 }
 337
 338 /*
 339  * Add enabled syscall to the events list using the given kernel channel.
 340  *
 341  * Return the number of entry of the events array that is different from size
 342  * if the array grows. On error, return negative value and events is untouched.
 343  */
 344 ssize_t syscall_list_channel(struct ltt_kernel_channel *kchan,
 345                 struct lttng_event **_events, size_t size)
 346 {
 347         int err, i;
 348         size_t new_size;
 349         ssize_t ret, count;
 350         char *mask = NULL;
 351         uint32_t len;
 352         struct lttng_event *events = NULL;
 353         /* Hash table used to filter duplicate out. */
 354         struct lttng_ht *syscalls_ht = NULL;
 355
 356         assert(kchan);
 357
 358         /* Get syscall mask from the kernel tracer. */
 359         err = kernel_syscall_mask(kchan->fd, &mask, &len);
 360         if (err < 0) {
 361                 ret = err;
 362                 goto error;
 363         }
 364
 365         ret = init_syscall_ht(&syscalls_ht);
 366         if (ret < 0) {
 367                 goto error;
 368         }
 369
 370         count = new_size = size;
 371         events = *_events;
 372
 373         for (i = 0; i < len; i++) {
 374                 unsigned char val;
 375                 struct syscall *ksyscall;
 376
 377                 bitfield_read_be(mask, unsigned char, i, 1, &val);
 378                 if (!val) {
 379                         /* Syscall is disabled, continue the loop. */
 380                         continue;
 381                 }
 382
 383                 /* Skip empty syscall. */
 384                 if (*syscall_table[i].name == '\0') {
 385                         continue;
 386                 }
 387
 388                 /* Syscall is enabled thus add it to the events list. */
 389
 390                 if (count >= new_size) {
 391                         struct lttng_event *new_events;
 392
 393                         /* Get the maximum here since count can be 0. */
 394                         new_size = max(count << 1, 1);
 395                         DBG3("Listing syscall realloc events array from %zu to %zu", count,
 396                                         new_size);
 397                         new_events = realloc(events, new_size * sizeof(*new_events));
 398                         if (!new_events) {
 399                                 PERROR("realloc kernel events list");
 400                                 ret = -ENOMEM;
 401                                 goto error;
 402                         }
 403                         memset(new_events + count, 0,
 404                                         (new_size - count) * sizeof(*new_events));
 405                         events = new_events;
 406                 }
 407
 408                 ksyscall = lookup_syscall(syscalls_ht, syscall_table[i].name);
 409                 if (ksyscall) {
 410                         update_event_syscall_bitness(events, i, ksyscall->index);
 411                         continue;
 412                 }
 413
 414                 ret = add_syscall_to_ht(syscalls_ht, i, count);
 415                 if (ret < 0) {
 416                         goto error;
 417                 }
 418
 419                 update_event_syscall_bitness(events, i, count);
 420                 strncpy(events[count].name, syscall_table[i].name,
 421                                 sizeof(events[count].name));
 422                 events[count].enabled = 1;
 423                 events[count].type = LTTNG_KERNEL_SYSCALL;
 424                 count++;
 425         }
 426
 427         *_events = events;
 428
 429         return count;
 430
 431 error:
 432         destroy_syscall_ht(syscalls_ht);
 433         free(events);
 434         return ret;
 435 }