[DFSan] New custom wrappers

[martignlo]

Summary

• Added the following custom wrappers:
  • strstr
  • strrchr
  • memchr
  • nanosleep
  • socketpair
• Tweaked a couple of existing wrappers: if a wrapper returns a pointers derived from an input pointer, then return the label of the input pointer
• Sorted tests invocation

[pcc]

lib/dfsan/dfsan_custom.cc

751

Shouldn't this always be strlen(s)+1? The function always needs to inspect each char in the string, right?

[martignlo]

lib/dfsan/dfsan_custom.cc

751

Right! Fixed.

[pcc]

LGTM.

[Eugene.Zelenko]

Committed in rL197601.

lib/dfsan/dfsan_custom.cc

SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strchr(const char *s, int c,
                                                   dfsan_label s_label,
                                                   dfsan_label c_label,
                                                   dfsan_label *ret_label) {
   for (size_t i = 0;; ++i) {
     if (s[i] == c || s[i] == 0) {
       if (flags().strict_data_dependencies) {
         *ret_label = s_label;
       } else {
-        *ret_label = dfsan_union(dfsan_read_label(s, i + 1), c_label);
+        *ret_label = dfsan_union(dfsan_read_label(s, i + 1),
+                                 dfsan_union(s_label, c_label));
       }
       return s[i] == 0 ? 0 : const_cast<char *>(s+i);
     }
   }
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_memcmp(const void *s1, const void *s2,
                                                 size_t n, dfsan_label s1_label,
__dfsw_strncpy(char *s1, const char *s2, size_t n, dfsan_label s1_label,
   size_t len = strlen(s2);
   if (len < n) {
     dfsan_memcpy(s1, s2, len+1);
     dfsan_memset(s1+len+1, 0, 0, n-len-1);
   } else {
     dfsan_memcpy(s1, s2, n);
   }
 
-  *ret_label = 0;
+  *ret_label = s1_label;
   return s1;
 }
 
 SANITIZER_INTERFACE_ATTRIBUTE ssize_t
 __dfsw_pread(int fd, void *buf, size_t count, off_t offset,
              dfsan_label fd_label, dfsan_label buf_label,
              dfsan_label count_label, dfsan_label offset_label,
              dfsan_label *ret_label) {
if (tv) {
     dfsan_set_label(0, tv, sizeof(struct timeval));
   }
   if (tz) {
     dfsan_set_label(0, tz, sizeof(struct timezone));
   }
   *ret_label = 0;
   return ret;
 }
+
+SANITIZER_INTERFACE_ATTRIBUTE void *__dfsw_memchr(void *s, int c, size_t n,
+                                                  dfsan_label s_label,
+                                                  dfsan_label c_label,
+                                                  dfsan_label n_label,
+                                                  dfsan_label *ret_label) {
+  void *ret = memchr(s, c, n);
+  if (flags().strict_data_dependencies) {
+    *ret_label = ret ? s_label : 0;
+  } else {
+    size_t len =
+        ret ? reinterpret_cast<char *>(ret) - reinterpret_cast<char *>(s) + 1
+            : n;
+    *ret_label =
+        dfsan_union(dfsan_read_label(s, len), dfsan_union(s_label, c_label));
+  }
+  return ret;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strrchr(char *s, int c,
+                                                   dfsan_label s_label,
+                                                   dfsan_label c_label,
+                                                   dfsan_label *ret_label) {
+  char *ret = strrchr(s, c);
+  if (flags().strict_data_dependencies) {
+    *ret_label = ret ? s_label : 0;
+  } else {
+    *ret_label =
+        dfsan_union(dfsan_read_label(s, strlen(s) + 1),
+                    dfsan_union(s_label, c_label));
+  }
+
+  return ret;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE char *__dfsw_strstr(char *haystack, char *needle,
+                                                  dfsan_label haystack_label,
+                                                  dfsan_label needle_label,
+                                                  dfsan_label *ret_label) {
+  char *ret = strstr(haystack, needle);
+  if (flags().strict_data_dependencies) {
+    *ret_label = ret ? haystack_label : 0;
+  } else {
+    size_t len = ret ? ret + strlen(needle) - haystack : strlen(haystack) + 1;
+    *ret_label =
+        dfsan_union(dfsan_read_label(haystack, len),
+                    dfsan_union(dfsan_read_label(needle, strlen(needle) + 1),
+                                dfsan_union(haystack_label, needle_label)));
+  }
+
+  return ret;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE int __dfsw_nanosleep(const struct timespec *req,
+                                                   struct timespec *rem,
+                                                   dfsan_label req_label,
+                                                   dfsan_label rem_label,
+                                                   dfsan_label *ret_label) {
+  int ret = nanosleep(req, rem);
+  *ret_label = 0;
+  if (ret == -1) {
+    // Interrupted by a signal, rem is filled with the remaining time.
+    dfsan_set_label(0, rem, sizeof(struct timespec));
+  }
+  return ret;
+}
+
+SANITIZER_INTERFACE_ATTRIBUTE int
+__dfsw_socketpair(int domain, int type, int protocol, int sv[2],
+                  dfsan_label domain_label, dfsan_label type_label,
+                  dfsan_label protocol_label, dfsan_label sv_label,
+                  dfsan_label *ret_label) {
+  int ret = socketpair(domain, type, protocol, sv);
+  *ret_label = 0;
+  if (ret == 0) {
+    dfsan_set_label(0, sv, sizeof(sv));
+  }
+  return ret;
+}
 }

lib/dfsan/done_abilist.txt

 fun:dlopen=custom
 fun:fgets=custom
 fun:fstat=custom
 fun:getcwd=custom
 fun:get_current_dir_name=custom
 fun:gethostname=custom
 fun:getrlimit=custom
 fun:getrusage=custom
+fun:nanosleep=custom
 fun:pread=custom
 fun:read=custom
+fun:socketpair=custom
 fun:stat=custom
 fun:time=custom
 
 # Functions that produce an output that depend on the input (propagate the
 # shadow manually).
 fun:ctime_r=custom
 fun:inet_pton=custom
 fun:localtime_r=custom
 fun:memcpy=custom
 fun:memset=custom
 fun:strcpy=custom
 fun:strdup=custom
 fun:strncpy=custom
 fun:strtod=custom
 fun:strtol=custom
 fun:strtoll=custom
 fun:strtoul=custom
 fun:strtoull=custom
 
 # Functions that produce an output that is computed from the input, but is not
 # necessarily data dependent.
+fun:memchr=custom
 fun:memcmp=custom
 fun:strcasecmp=custom
 fun:strchr=custom
 fun:strcmp=custom
 fun:strlen=custom
 fun:strncasecmp=custom
 fun:strncmp=custom
+fun:strrchr=custom
+fun:strstr=custom
 
 # Functions that take a callback (wrap the callback manually).
 fun:dl_iterate_phdr=custom
 
 fun:getpwuid_r=custom
 fun:poll=custom
 fun:sched_getaffinity=custom
 fun:select=custom

lib/dfsan/lit_tests/custom.c

int dl_iterate_phdr_test_cb(struct dl_phdr_info *info, size_t size,
   ASSERT_ZERO_LABEL(data);
   return 0;
 }
 
 void test_dl_iterate_phdr() {
   dl_iterate_phdr(dl_iterate_phdr_test_cb, (void *)3);
 }
 
+void test_strrchr() {
+  char str1[] = "str1str1";
+  dfsan_set_label(i_label, &str1[7], 1);
+
+  char *rv = strrchr(str1, 'r');
+  assert(rv == &str1[6]);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_ZERO_LABEL(rv);
+#else
+  ASSERT_LABEL(rv, i_label);
+#endif
+}
+
+void test_strstr() {
+  char str1[] = "str1str1";
+  dfsan_set_label(i_label, &str1[3], 1);
+  dfsan_set_label(j_label, &str1[5], 1);
+
+  char *rv = strstr(str1, "1s");
+  assert(rv == &str1[3]);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_ZERO_LABEL(rv);
+#else
+  ASSERT_LABEL(rv, i_label);
+#endif
+
+  rv = strstr(str1, "2s");
+  assert(rv == NULL);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_ZERO_LABEL(rv);
+#else
+  ASSERT_LABEL(rv, i_j_label);
+#endif
+}
+
+void test_memchr() {
+  char str1[] = "str1";
+  dfsan_set_label(i_label, &str1[3], 1);
+  dfsan_set_label(j_label, &str1[4], 1);
+
+  char *crv = memchr(str1, 'r', sizeof(str1));
+  assert(crv == &str1[2]);
+  ASSERT_ZERO_LABEL(crv);
+
+  crv = memchr(str1, '1', sizeof(str1));
+  assert(crv == &str1[3]);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_ZERO_LABEL(crv);
+#else
+  ASSERT_LABEL(crv, i_label);
+#endif
+
+  crv = memchr(str1, 'x', sizeof(str1));
+  assert(!crv);
+#ifdef STRICT_DATA_DEPENDENCIES
+  ASSERT_ZERO_LABEL(crv);
+#else
+  ASSERT_LABEL(crv, i_j_label);
+#endif
+}
+
+void alarm_handler(int unused) {
+  ;
+}
+
+void test_nanosleep() {
+  struct timespec req, rem;
+  req.tv_sec = 1;
+  req.tv_nsec = 0;
+  dfsan_set_label(i_label, &rem, sizeof(rem));
+
+  // non interrupted
+  int rv = nanosleep(&req, &rem);
+  assert(rv == 0);
+  ASSERT_ZERO_LABEL(rv);
+  ASSERT_READ_LABEL(&rem, 1, i_label);
+
+  // interrupted by an alarm
+  signal(SIGALRM, alarm_handler);
+  req.tv_sec = 3;
+  alarm(1);
+  rv = nanosleep(&req, &rem);
+  assert(rv == -1);
+  ASSERT_ZERO_LABEL(rv);
+  ASSERT_READ_ZERO_LABEL(&rem, sizeof(rem));
+}
+
+void test_socketpair() {
+  int fd[2];
+
+  dfsan_set_label(i_label, fd, sizeof(fd));
+  int rv = socketpair(PF_LOCAL, SOCK_STREAM, 0, fd);
+  assert(rv == 0);
+  ASSERT_ZERO_LABEL(rv);
+  ASSERT_READ_ZERO_LABEL(fd, sizeof(fd));
+}
+
 int main(void) {
   i_label = dfsan_create_label("i", 0);
   j_label = dfsan_create_label("j", 0);
   i_j_label = dfsan_union(i_label, j_label);
 
   test_calloc();
   test_clock_gettime();
+  test_ctime_r();
+  test_dl_iterate_phdr();
   test_dlopen();
+  test_fgets();
   test_fstat();
+  test_get_current_dir_name();
+  test_getcwd();
+  test_gethostname();
+  test_getpwuid_r();
+  test_getrlimit();
+  test_getrusage();
+  test_gettimeofday();
+  test_inet_pton();
+  test_localtime_r();
+  test_memchr();
   test_memcmp();
   test_memcpy();
   test_memset();
+  test_nanosleep();
+  test_poll();
   test_pread();
+  test_pthread_create();
   test_read();
+  test_sched_getaffinity();
+  test_select();
+  test_sigaction();
+  test_sigemptyset();
+  test_socketpair();
   test_stat();
   test_strcasecmp();
   test_strchr();
   test_strcmp();
+  test_strcpy();
   test_strdup();
   test_strlen();
   test_strncasecmp();
   test_strncmp();
   test_strncpy();
-
-  test_ctime_r();
-  test_fgets();
-  test_getcwd();
-  test_get_current_dir_name();
-  test_gethostname();
-  test_getrlimit();
-  test_getrusage();
-  test_strcpy();
+  test_strrchr();
+  test_strstr();
+  test_strtod();
   test_strtol();
   test_strtoll();
-  test_strtod();
   test_strtoul();
   test_strtoull();
   test_time();
-  test_inet_pton();
-  test_localtime_r();
-  test_getpwuid_r();
-  test_poll();
-  test_select();
-  test_sched_getaffinity();
-  test_sigemptyset();
-  test_sigaction();
-  test_gettimeofday();
-
-  test_pthread_create();
-  test_dl_iterate_phdr();
 }