files.c

   1 #include <ftw.h>
   2 #include <stdio.h>
   3 #include <stdlib.h>
   4 #include <string.h>
   5 #include <unistd.h>
   6 #include <fcntl.h>
   7 #include <dirent.h>
   8 #include <errno.h>
   9 #include <sys/types.h>
  10 #include <sys/stat.h>
  11
  12 #include "trinity.h"    // __unused__
  13 #include "arch.h"       // page_size
  14 #include "files.h"
  15 #include "log.h"
  16 #include "maps.h"
  17 #include "shm.h"
  18 #include "sanitise.h"
  19 #include "constants.h"
  20 #include "list.h"
  21 #include "random.h"
  22
  23 static int files_added = 0;
  24 const char **fileindex;
  25 unsigned int files_in_index = 0;
  26
  27 struct namelist {
  28         struct list_head list;
  29         const char *name;
  30 };
  31
  32 static struct namelist *names = NULL;
  33
  34 static uid_t my_uid;
  35 static gid_t my_gid;
  36
  37 static int ignore_files(const char *path)
  38 {
  39         unsigned int i, j;
  40         unsigned int pathlen, offset = 0;
  41
  42         /* These are exact matches. */
  43         const char *ignored_paths[] = {
  44                 ".", "..",
  45
  46                 /* dangerous/noisy/annoying stuff in /proc */
  47                 "/proc/sysrq-trigger", "/proc/kmem", "/proc/kcore",
  48
  49                 /* dangerous/noisy/annoying stuff in /dev */
  50                 "/dev/log", "/dev/mem", "/dev/kmsg",
  51                 NULL
  52         };
  53
  54         /* Partial matches. */  //FIXME: This whole function should just use globs to pattern match.
  55         const char *ignored_patterns[] = {
  56
  57                 /* dangerous/noisy/annoying per-process stuff. */
  58                 "coredump_filter", "make-it-fail", "oom_adj", "oom_score_adj",
  59                 NULL
  60         };
  61
  62         pathlen = strlen(path);
  63
  64         /* First do the exact matches */
  65         for (i = 0; ignored_paths[i]; i++) {
  66                 if (strlen(ignored_paths[i]) != pathlen) {
  67                         continue;
  68                 }
  69
  70                 if (!strcmp(path, ignored_paths[i])) {
  71                         debugf("Skipping %s\n", path);
  72                         return 1;
  73                 }
  74         }
  75
  76         /* Now make sure none of the patterns match the end of the pathname */
  77         for (j = 0; j < pathlen; j++) {
  78                 if (path[j] == '/')
  79                         offset = j;
  80         }
  81         offset++;
  82
  83         if (offset == 1)
  84                 return 0;
  85
  86         for (i = 0; ignored_patterns[i]; i++) {
  87                 if (!strcmp(path + offset, ignored_patterns[i])) {
  88                         debugf("Skipping pattern %s\n", path);
  89                         return 1;
  90                 }
  91         }
  92
  93         /* special case to match tty* until I do globbing */
  94         if (!strncmp(path + offset, "tty", 3)) {
  95                 debugf("Skipping %s\n", path);
  96                 return 1;
  97         }
  98         return 0;
  99 }
 100
 101
 102 static struct namelist * alloc_namenode(void)
 103 {
 104         struct namelist *newnode;
 105
 106         newnode = malloc(sizeof(struct namelist));
 107         if (newnode == NULL)
 108                 exit(EXIT_FAILURE);
 109
 110         memset(newnode, 0, sizeof(struct namelist));
 111         return newnode;
 112 }
 113
 114 static void add_to_namelist(const char *name)
 115 {
 116         struct namelist *newnode;
 117         struct list_head *list = (struct list_head *) names;
 118
 119         newnode = alloc_namenode();
 120         newnode->name = strdup(name);
 121         list_add_tail(&newnode->list, list);
 122 }
 123
 124 static int check_stat_file(const struct stat *sb)
 125 {
 126         int openflag;
 127         bool set_read = FALSE;
 128         bool set_write = FALSE;
 129
 130         if (S_ISLNK(sb->st_mode))
 131                 return -1;
 132
 133         if (sb->st_uid == my_uid) {
 134                 if (sb->st_mode & S_IRUSR)
 135                         set_read = TRUE;
 136                 if (sb->st_mode & S_IWUSR)
 137                         set_write = TRUE;
 138         }
 139
 140         if (sb->st_gid == my_gid) {
 141                 if (sb->st_mode & S_IRGRP)
 142                         set_read = TRUE;
 143                 if (sb->st_mode & S_IWGRP)
 144                         set_write = TRUE;
 145         }
 146
 147         if (sb->st_mode & S_IROTH)
 148                 set_read = TRUE;
 149         if (sb->st_mode & S_IWOTH)
 150                 set_write = TRUE;
 151
 152
 153         if ((set_read | set_write) == 0)
 154                 return -1;
 155
 156         if (set_read == TRUE)
 157                 openflag = O_RDONLY;
 158         if (set_write == TRUE)
 159                 openflag = O_WRONLY;
 160         if ((set_read == TRUE) && (set_write == TRUE))
 161                 openflag = O_RDWR;
 162
 163         if (S_ISDIR(sb->st_mode))
 164                 openflag = O_RDONLY;
 165
 166         return openflag;
 167 }
 168
 169 static int file_tree_callback(const char *fpath, const struct stat *sb, __unused__ int typeflag, __unused__ struct FTW *ftwbuf)
 170 {
 171
 172         if (ignore_files(fpath)) {
 173                 return FTW_SKIP_SUBTREE;
 174         }
 175
 176         // Check we can read it.
 177         if (check_stat_file(sb) == -1)
 178                 return FTW_CONTINUE;
 179
 180         if (shm->exit_reason != STILL_RUNNING)
 181                 return FTW_STOP;
 182
 183         add_to_namelist(fpath);
 184         files_added++;
 185
 186         return FTW_CONTINUE;
 187 }
 188
 189
 190 static void open_fds(const char *dirpath)
 191 {
 192         int before = files_added;
 193         int flags = FTW_DEPTH | FTW_ACTIONRETVAL | FTW_MOUNT;
 194         int ret;
 195
 196         /* By default, don't follow symlinks so we only get each file once.
 197          * But, if we do something like -V /lib, then follow it
 198          *
 199          * I'm not sure about this, might remove later.
 200          */
 201         if (victim_path == NULL)
 202                 flags |= FTW_PHYS;
 203
 204         ret = nftw(dirpath, file_tree_callback, 32, flags);
 205         if (ret != 0) {
 206                 if (shm->exit_reason != EXIT_SIGINT)
 207                         output(0, "Something went wrong during nftw(%s). (%d:%s)\n",
 208                                 dirpath, ret, strerror(errno));
 209                 return;
 210         }
 211
 212         output(0, "Added %d filenames from %s\n", files_added - before, dirpath);
 213 }
 214
 215 void generate_filelist(void)
 216 {
 217         unsigned int i = 0;
 218         struct list_head *node;
 219         struct namelist *nl;
 220
 221         my_uid = getuid();
 222         my_gid = getgid();
 223
 224         names = alloc_namenode();
 225         INIT_LIST_HEAD(&names->list);
 226
 227         output(1, "Generating file descriptors\n");
 228
 229         if (victim_path != NULL) {
 230                 open_fds(victim_path);
 231         } else {
 232                 open_fds("/dev");
 233                 open_fds("/proc");
 234                 open_fds("/sys");
 235         }
 236
 237         if (shm->exit_reason != STILL_RUNNING)
 238                 return;
 239
 240         if (files_added == 0) {
 241                 output(1, "Didn't add any files!!\n");
 242                 return;
 243         }
 244
 245         /* Generate an index of pointers to the filenames */
 246
 247         fileindex = malloc(sizeof(char *) * files_added);
 248
 249         list_for_each(node, &names->list) {
 250                 nl = (struct namelist *) node;
 251                 fileindex[i++] = nl->name;
 252         }
 253         files_in_index = i;
 254 }
 255
 256 static int open_file(void)
 257 {
 258         int fd;
 259         int ret;
 260         const char *filename;
 261         int flags;
 262         const char *modestr;
 263         struct stat sb;
 264
 265 retry:
 266         filename = get_filename();
 267         ret = lstat(filename, &sb);
 268         if (ret == -1)
 269                 goto retry;
 270
 271         flags = check_stat_file(&sb);
 272         if (flags == -1)
 273                 goto retry;
 274
 275         fd = open(filename, flags | O_NONBLOCK);
 276         if (fd < 0) {
 277                 output(2, "Couldn't open %s : %s\n", filename, strerror(errno));
 278                 return fd;
 279         }
 280
 281         switch (flags) {
 282         case O_RDONLY:  modestr = "read-only";  break;
 283         case O_WRONLY:  modestr = "write-only"; break;
 284         case O_RDWR:    modestr = "read-write"; break;
 285         default: modestr = "unknown"; break;
 286         }
 287         output(2, "fd[%i] = %s (%s)\n", fd, filename, modestr);
 288         return fd;
 289 }
 290
 291 void open_files(void)
 292 {
 293         unsigned int i, nr_to_open;
 294         int fd;
 295
 296         if (files_in_index < NR_FILE_FDS)
 297                 nr_to_open = files_in_index;
 298         else
 299                 nr_to_open = NR_FILE_FDS;
 300
 301         if (fileindex == NULL)  /* this can happen if we ctrl-c'd */
 302                 return;
 303
 304         for (i = 0; i < nr_to_open; i++) {
 305                 fd = open_file();
 306
 307                 shm->file_fds[i] = fd;
 308                 nr_file_fds++;
 309         }
 310 }
 311
 312 void close_files(void)
 313 {
 314         unsigned int i;
 315         int fd;
 316
 317         shm->current_fd = 0;
 318         shm->fd_lifetime = 0;
 319
 320         // FIXME: Does this need locking? At the least, check for NULL fd's
 321         for (i = 0; i < nr_file_fds; i++) {
 322                 fd = shm->file_fds[i];
 323                 shm->file_fds[i] = 0;
 324                 if (fd != 0)
 325                         close(fd);
 326         }
 327
 328         nr_file_fds = 0;
 329 }
 330
 331 const char * get_filename(void)
 332 {
 333         if (files_in_index == 0)        /* This can happen if we run with -n. Should we do something else ? */
 334                 return NULL;
 335
 336         return fileindex[rand() % files_in_index];
 337 }