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 "constants.h"
  15 #include "files.h"
  16 #include "list.h"
  17 #include "log.h"
  18 #include "maps.h"
  19 #include "params.h"
  20 #include "random.h"
  21 #include "shm.h"
  22 #include "sanitise.h"
  23 #include "uid.h"
  24 #include "utils.h"
  25
  26 static int files_added = 0;
  27 const char **fileindex;
  28 unsigned int files_in_index = 0;
  29
  30 struct namelist {
  31         struct list_head list;
  32         const char *name;
  33 };
  34
  35 static struct namelist *names = NULL;
  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 static void add_to_namelist(const char *name)
 102 {
 103         struct namelist *newnode;
 104         struct list_head *list = (struct list_head *) names;
 105
 106         newnode = zmalloc(sizeof(struct namelist));
 107         newnode->name = strdup(name);
 108         list_add_tail(&newnode->list, list);
 109 }
 110
 111 static int check_stat_file(const struct stat *sb)
 112 {
 113         int openflag;
 114         bool set_read = FALSE;
 115         bool set_write = FALSE;
 116         uid_t target_uid = orig_uid;
 117         gid_t target_gid = orig_gid;
 118
 119         if (dropprivs == TRUE) {
 120                 target_uid = nobody_uid;
 121                 target_gid = nobody_gid;
 122         }
 123
 124         if (S_ISLNK(sb->st_mode))
 125                 return -1;
 126
 127         if (sb->st_uid == target_uid) {
 128                 if (sb->st_mode & S_IRUSR)
 129                         set_read = TRUE;
 130                 if (sb->st_mode & S_IWUSR)
 131                         set_write = TRUE;
 132         }
 133
 134         if (sb->st_gid == target_gid) {
 135                 if (sb->st_mode & S_IRGRP)
 136                         set_read = TRUE;
 137                 if (sb->st_mode & S_IWGRP)
 138                         set_write = TRUE;
 139         }
 140
 141         if (sb->st_mode & S_IROTH)
 142                 set_read = TRUE;
 143         if (sb->st_mode & S_IWOTH)
 144                 set_write = TRUE;
 145
 146
 147         if ((set_read | set_write) == 0)
 148                 return -1;
 149
 150         if (set_read == TRUE)
 151                 openflag = O_RDONLY;
 152         if (set_write == TRUE)
 153                 openflag = O_WRONLY;
 154         if ((set_read == TRUE) && (set_write == TRUE))
 155                 openflag = O_RDWR;
 156
 157         if (S_ISDIR(sb->st_mode))
 158                 openflag = O_RDONLY;
 159
 160         return openflag;
 161 }
 162
 163 static int file_tree_callback(const char *fpath, const struct stat *sb, __unused__ int typeflag, __unused__ struct FTW *ftwbuf)
 164 {
 165
 166         if (ignore_files(fpath)) {
 167                 return FTW_SKIP_SUBTREE;
 168         }
 169
 170         // Check we can read it.
 171         if (check_stat_file(sb) == -1)
 172                 return FTW_CONTINUE;
 173
 174         if (shm->exit_reason != STILL_RUNNING)
 175                 return FTW_STOP;
 176
 177         add_to_namelist(fpath);
 178         files_added++;
 179
 180         return FTW_CONTINUE;
 181 }
 182
 183
 184 static void open_fds(const char *dirpath)
 185 {
 186         int before = files_added;
 187         int flags = FTW_DEPTH | FTW_ACTIONRETVAL | FTW_MOUNT;
 188         int ret;
 189
 190         /* By default, don't follow symlinks so we only get each file once.
 191          * But, if we do something like -V /lib, then follow it
 192          *
 193          * I'm not sure about this, might remove later.
 194          */
 195         if (victim_path == NULL)
 196                 flags |= FTW_PHYS;
 197
 198         ret = nftw(dirpath, file_tree_callback, 32, flags);
 199         if (ret != 0) {
 200                 if (shm->exit_reason != EXIT_SIGINT)
 201                         output(0, "Something went wrong during nftw(%s). (%d:%s)\n",
 202                                 dirpath, ret, strerror(errno));
 203                 return;
 204         }
 205
 206         output(0, "Added %d filenames from %s\n", files_added - before, dirpath);
 207 }
 208
 209 void generate_filelist(void)
 210 {
 211         unsigned int i = 0;
 212         struct list_head *node;
 213         struct namelist *nl;
 214
 215         names = zmalloc(sizeof(struct namelist));
 216         INIT_LIST_HEAD(&names->list);
 217
 218         output(1, "Generating file descriptors\n");
 219
 220         if (victim_path != NULL) {
 221                 open_fds(victim_path);
 222         } else {
 223                 open_fds("/dev");
 224                 open_fds("/proc");
 225                 open_fds("/sys");
 226         }
 227
 228         if (shm->exit_reason != STILL_RUNNING)
 229                 return;
 230
 231         if (files_added == 0) {
 232                 output(1, "Didn't add any files!!\n");
 233                 return;
 234         }
 235
 236         /* Generate an index of pointers to the filenames */
 237
 238         fileindex = malloc(sizeof(char *) * files_added);
 239
 240         list_for_each(node, &names->list) {
 241                 nl = (struct namelist *) node;
 242                 fileindex[i++] = nl->name;
 243         }
 244         files_in_index = i;
 245 }
 246
 247 static int open_file(void)
 248 {
 249         int fd;
 250         int ret;
 251         const char *filename;
 252         int flags;
 253         const char *modestr;
 254         struct stat sb;
 255
 256 retry:
 257         filename = get_filename();
 258         ret = lstat(filename, &sb);
 259         if (ret == -1)
 260                 goto retry;
 261
 262         flags = check_stat_file(&sb);
 263         if (flags == -1)
 264                 goto retry;
 265
 266         fd = open(filename, flags | O_NONBLOCK);
 267         if (fd < 0) {
 268                 output(2, "Couldn't open %s : %s\n", filename, strerror(errno));
 269                 return fd;
 270         }
 271
 272         switch (flags) {
 273         case O_RDONLY:  modestr = "read-only";  break;
 274         case O_WRONLY:  modestr = "write-only"; break;
 275         case O_RDWR:    modestr = "read-write"; break;
 276         default: modestr = "unknown"; break;
 277         }
 278         output(2, "fd[%i] = %s (%s)\n", fd, filename, modestr);
 279         return fd;
 280 }
 281
 282 void open_files(void)
 283 {
 284         unsigned int i, nr_to_open;
 285
 286         if (files_in_index < NR_FILE_FDS)
 287                 nr_to_open = files_in_index;
 288         else
 289                 nr_to_open = NR_FILE_FDS;
 290
 291         if (fileindex == NULL)  /* this can happen if we ctrl-c'd */
 292                 return;
 293
 294         for (i = 0; i < nr_to_open; i++) {
 295                 int fd;
 296
 297                 fd = open_file();
 298
 299                 shm->file_fds[i] = fd;
 300                 nr_file_fds++;
 301         }
 302 }
 303
 304 void close_files(void)
 305 {
 306         unsigned int i;
 307
 308         shm->current_fd = 0;
 309         shm->fd_lifetime = 0;
 310
 311         // FIXME: Does this need locking? At the least, check for NULL fd's
 312         for (i = 0; i < nr_file_fds; i++) {
 313                 int fd;
 314
 315                 fd = shm->file_fds[i];
 316                 shm->file_fds[i] = 0;
 317                 if (fd != 0)
 318                         close(fd);
 319         }
 320
 321         nr_file_fds = 0;
 322 }
 323
 324 const char * get_filename(void)
 325 {
 326         if (files_in_index == 0)        /* This can happen if we run with -n. Should we do something else ? */
 327                 return NULL;
 328
 329         return fileindex[rand() % files_in_index];
 330 }