samples/watch_queue/watch_test.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /* Use watch_queue API to watch for notifications.
   3  *
   4  * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  */
   7
   8 #define _GNU_SOURCE
   9 #include <stdbool.h>
  10 #include <stdarg.h>
  11 #include <stdio.h>
  12 #include <stdlib.h>
  13 #include <string.h>
  14 #include <signal.h>
  15 #include <unistd.h>
  16 #include <errno.h>
  17 #include <sys/ioctl.h>
  18 #include <limits.h>
  19 #include <linux/watch_queue.h>
  20 #include <linux/unistd.h>
  21 #include <linux/keyctl.h>
  22
  23 #ifndef KEYCTL_WATCH_KEY
  24 #define KEYCTL_WATCH_KEY -1
  25 #endif
  26 #ifndef __NR_keyctl
  27 #define __NR_keyctl -1
  28 #endif
  29
  30 #define BUF_SIZE 256
  31
  32 static long keyctl_watch_key(int key, int watch_fd, int watch_id)
  33 {
  34         return syscall(__NR_keyctl, KEYCTL_WATCH_KEY, key, watch_fd, watch_id);
  35 }
  36
  37 static const char *key_subtypes[256] = {
  38         [NOTIFY_KEY_INSTANTIATED]       = "instantiated",
  39         [NOTIFY_KEY_UPDATED]            = "updated",
  40         [NOTIFY_KEY_LINKED]             = "linked",
  41         [NOTIFY_KEY_UNLINKED]           = "unlinked",
  42         [NOTIFY_KEY_CLEARED]            = "cleared",
  43         [NOTIFY_KEY_REVOKED]            = "revoked",
  44         [NOTIFY_KEY_INVALIDATED]        = "invalidated",
  45         [NOTIFY_KEY_SETATTR]            = "setattr",
  46 };
  47
  48 static void saw_key_change(struct watch_notification *n, size_t len)
  49 {
  50         struct key_notification *k = (struct key_notification *)n;
  51
  52         if (len != sizeof(struct key_notification)) {
  53                 fprintf(stderr, "Incorrect key message length\n");
  54                 return;
  55         }
  56
  57         printf("KEY %08x change=%u[%s] aux=%u\n",
  58                k->key_id, n->subtype, key_subtypes[n->subtype], k->aux);
  59 }
  60
  61 /*
  62  * Consume and display events.
  63  */
  64 static void consumer(int fd)
  65 {
  66         unsigned char buffer[433], *p, *end;
  67         union {
  68                 struct watch_notification n;
  69                 unsigned char buf1[128];
  70         } n;
  71         ssize_t buf_len;
  72
  73         for (;;) {
  74                 buf_len = read(fd, buffer, sizeof(buffer));
  75                 if (buf_len == -1) {
  76                         perror("read");
  77                         exit(1);
  78                 }
  79
  80                 if (buf_len == 0) {
  81                         printf("-- END --\n");
  82                         return;
  83                 }
  84
  85                 if (buf_len > sizeof(buffer)) {
  86                         fprintf(stderr, "Read buffer overrun: %zd\n", buf_len);
  87                         return;
  88                 }
  89
  90                 printf("read() = %zd\n", buf_len);
  91
  92                 p = buffer;
  93                 end = buffer + buf_len;
  94                 while (p < end) {
  95                         size_t largest, len;
  96
  97                         largest = end - p;
  98                         if (largest > 128)
  99                                 largest = 128;
 100                         if (largest < sizeof(struct watch_notification)) {
 101                                 fprintf(stderr, "Short message header: %zu\n", largest);
 102                                 return;
 103                         }
 104                         memcpy(&n, p, largest);
 105
 106                         printf("NOTIFY[%03zx]: ty=%06x sy=%02x i=%08x\n",
 107                                p - buffer, n.n.type, n.n.subtype, n.n.info);
 108
 109                         len = n.n.info & WATCH_INFO_LENGTH;
 110                         if (len < sizeof(n.n) || len > largest) {
 111                                 fprintf(stderr, "Bad message length: %zu/%zu\n", len, largest);
 112                                 exit(1);
 113                         }
 114
 115                         switch (n.n.type) {
 116                         case WATCH_TYPE_META:
 117                                 switch (n.n.subtype) {
 118                                 case WATCH_META_REMOVAL_NOTIFICATION:
 119                                         printf("REMOVAL of watchpoint %08x\n",
 120                                                (n.n.info & WATCH_INFO_ID) >>
 121                                                WATCH_INFO_ID__SHIFT);
 122                                         break;
 123                                 case WATCH_META_LOSS_NOTIFICATION:
 124                                         printf("-- LOSS --\n");
 125                                         break;
 126                                 default:
 127                                         printf("other meta record\n");
 128                                         break;
 129                                 }
 130                                 break;
 131                         case WATCH_TYPE_KEY_NOTIFY:
 132                                 saw_key_change(&n.n, len);
 133                                 break;
 134                         default:
 135                                 printf("other type\n");
 136                                 break;
 137                         }
 138
 139                         p += len;
 140                 }
 141         }
 142 }
 143
 144 static struct watch_notification_filter filter = {
 145         .nr_filters     = 1,
 146         .filters = {
 147                 [0]     = {
 148                         .type                   = WATCH_TYPE_KEY_NOTIFY,
 149                         .subtype_filter[0]      = UINT_MAX,
 150                 },
 151         },
 152 };
 153
 154 int main(int argc, char **argv)
 155 {
 156         int pipefd[2], fd;
 157
 158         if (pipe2(pipefd, O_NOTIFICATION_PIPE) == -1) {
 159                 perror("pipe2");
 160                 exit(1);
 161         }
 162         fd = pipefd[0];
 163
 164         if (ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, BUF_SIZE) == -1) {
 165                 perror("watch_queue(size)");
 166                 exit(1);
 167         }
 168
 169         if (ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter) == -1) {
 170                 perror("watch_queue(filter)");
 171                 exit(1);
 172         }
 173
 174         if (keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fd, 0x01) == -1) {
 175                 perror("keyctl");
 176                 exit(1);
 177         }
 178
 179         if (keyctl_watch_key(KEY_SPEC_USER_KEYRING, fd, 0x02) == -1) {
 180                 perror("keyctl");
 181                 exit(1);
 182         }
 183
 184         consumer(fd);
 185         exit(0);
 186 }