src/fuzz/fuzz-varlink.c

   1 /* SPDX-License-Identifier: LGPL-2.1+ */
   2
   3 #include <unistd.h>
   4
   5 #include "errno-util.h"
   6 #include "fd-util.h"
   7 #include "fuzz.h"
   8 #include "hexdecoct.h"
   9 #include "io-util.h"
  10 #include "varlink.h"
  11 #include "log.h"
  12
  13 static FILE *null = NULL;
  14
  15 static int method_something(Varlink *v, JsonVariant *p, VarlinkMethodFlags flags, void *userdata) {
  16         json_variant_dump(p, JSON_FORMAT_NEWLINE|JSON_FORMAT_PRETTY, null, NULL);
  17         return 0;
  18 }
  19
  20 static int reply_callback(Varlink *v, JsonVariant *p, const char *error_id, VarlinkReplyFlags flags, void *userdata) {
  21         json_variant_dump(p, JSON_FORMAT_NEWLINE|JSON_FORMAT_PRETTY, null, NULL);
  22         return 0;
  23 }
  24
  25 static int io_callback(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
  26         struct iovec *iov = userdata;
  27         bool write_eof = false, read_eof = false;
  28
  29         assert(s);
  30         assert(fd >= 0);
  31         assert(iov);
  32
  33         if ((revents & (EPOLLOUT|EPOLLHUP|EPOLLERR)) && iov->iov_len > 0) {
  34                 ssize_t n;
  35
  36                 /* never write more than 143 bytes a time, to make broken up recv()s on the other side more
  37                  * likely, and thus test some additional code paths. */
  38                 n = send(fd, iov->iov_base, MIN(iov->iov_len, 143U), MSG_NOSIGNAL|MSG_DONTWAIT);
  39                 if (n < 0) {
  40                         if (ERRNO_IS_DISCONNECT(errno))
  41                                 write_eof = true;
  42                         else
  43                                 assert_se(errno == EAGAIN);
  44                 } else
  45                         IOVEC_INCREMENT(iov, 1, n);
  46         }
  47
  48         if (revents & EPOLLIN) {
  49                 char c[137];
  50                 ssize_t n;
  51
  52                 n = recv(fd, c, sizeof(c), MSG_DONTWAIT);
  53                 if (n < 0) {
  54                         if (ERRNO_IS_DISCONNECT(errno))
  55                                 read_eof = true;
  56                         else
  57                                 assert_se(errno == EAGAIN);
  58                 } else if (n == 0)
  59                         read_eof = true;
  60                 else
  61                         hexdump(null, c, (size_t) n);
  62         }
  63
  64         /* After we wrote everything we could turn off EPOLLOUT. And if we reached read EOF too turn off the
  65          * whole thing. */
  66         if (write_eof || iov->iov_len == 0) {
  67
  68                 if (read_eof)
  69                         assert_se(sd_event_source_set_enabled(s, SD_EVENT_OFF) >= 0);
  70                 else
  71                         assert_se(sd_event_source_set_io_events(s, EPOLLIN) >= 0);
  72         }
  73
  74         return 0;
  75 }
  76
  77 static int idle_callback(sd_event_source *s, void *userdata) {
  78         assert(s);
  79
  80         /* Called as idle callback when there's nothing else to do anymore */
  81         sd_event_exit(sd_event_source_get_event(s), 0);
  82         return 0;
  83 }
  84
  85 int LLVMFuzzerTestOneInput(const uint8_t *data, size_t size) {
  86         struct iovec server_iov = IOVEC_MAKE((void*) data, size), client_iov = IOVEC_MAKE((void*) data, size);
  87         /* Important: the declaration order matters here! we want that the fds are closed on return after the
  88          * event sources, hence we declare the fds first, the event sources second */
  89         _cleanup_close_pair_ int server_pair[2] = { -1, -1 }, client_pair[2] = { -1, -1 };
  90         _cleanup_(sd_event_source_unrefp) sd_event_source *idle_event_source = NULL,
  91                 *server_event_source = NULL, *client_event_source = NULL;
  92         _cleanup_(varlink_server_unrefp) VarlinkServer *s = NULL;
  93         _cleanup_(varlink_flush_close_unrefp) Varlink *c = NULL;
  94         _cleanup_(sd_event_unrefp) sd_event *e = NULL;
  95
  96         log_set_max_level(LOG_CRIT);
  97         log_parse_environment();
  98
  99         assert_se(null = fopen("/dev/null", "we"));
 100
 101         assert_se(sd_event_default(&e) >= 0);
 102
 103         /* Test one: write the data as method call to a server */
 104         assert_se(socketpair(AF_UNIX, SOCK_STREAM, 0, server_pair) >= 0);
 105         assert_se(varlink_server_new(&s, 0) >= 0);
 106         assert_se(varlink_server_set_description(s, "myserver") >= 0);
 107         assert_se(varlink_server_attach_event(s, e, 0) >= 0);
 108         assert_se(varlink_server_add_connection(s, server_pair[0], NULL) >= 0);
 109         TAKE_FD(server_pair[0]);
 110         assert_se(varlink_server_bind_method(s, "io.test.DoSomething", method_something) >= 0);
 111         assert_se(sd_event_add_io(e, &server_event_source, server_pair[1], EPOLLIN|EPOLLOUT, io_callback, &server_iov) >= 0);
 112
 113         /* Test two: write the data as method response to a client */
 114         assert_se(socketpair(AF_UNIX, SOCK_STREAM, 0, client_pair) >= 0);
 115         assert_se(varlink_connect_fd(&c, client_pair[0]) >= 0);
 116         TAKE_FD(client_pair[0]);
 117         assert_se(varlink_set_description(c, "myclient") >= 0);
 118         assert_se(varlink_attach_event(c, e, 0) >= 0);
 119         assert_se(varlink_bind_reply(c, reply_callback) >= 0);
 120         assert_se(varlink_invoke(c, "io.test.DoSomething", NULL) >= 0);
 121         assert_se(sd_event_add_io(e, &client_event_source, client_pair[1], EPOLLIN|EPOLLOUT, io_callback, &client_iov) >= 0);
 122
 123         assert_se(sd_event_add_defer(e, &idle_event_source, idle_callback, NULL) >= 0);
 124         assert_se(sd_event_source_set_priority(idle_event_source, SD_EVENT_PRIORITY_IDLE) >= 0);
 125
 126         assert_se(sd_event_loop(e) >= 0);
 127
 128         null = safe_fclose(null);
 129
 130         return 0;
 131 }