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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 ([email protected])
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
20// Work around glibc header silliness
21#undef AT_RENAME_NOREPLACE
22#undef AT_RENAME_EXCHANGE
23#undef AT_RENAME_WHITEOUT
24
25#include <linux/watch_queue.h>
26#include <linux/unistd.h>
27#include <linux/keyctl.h>
28
29#ifndef KEYCTL_WATCH_KEY
30#define KEYCTL_WATCH_KEY -1
31#endif
32#ifndef __NR_keyctl
33#define __NR_keyctl -1
34#endif
35
36#define BUF_SIZE 256
37
38static long keyctl_watch_key(int key, int watch_fd, int watch_id)
39{
40 return syscall(__NR_keyctl, KEYCTL_WATCH_KEY, key, watch_fd, watch_id);
41}
42
43static const char *key_subtypes[256] = {
44 [NOTIFY_KEY_INSTANTIATED] = "instantiated",
45 [NOTIFY_KEY_UPDATED] = "updated",
46 [NOTIFY_KEY_LINKED] = "linked",
47 [NOTIFY_KEY_UNLINKED] = "unlinked",
48 [NOTIFY_KEY_CLEARED] = "cleared",
49 [NOTIFY_KEY_REVOKED] = "revoked",
50 [NOTIFY_KEY_INVALIDATED] = "invalidated",
51 [NOTIFY_KEY_SETATTR] = "setattr",
52};
53
54static void saw_key_change(struct watch_notification *n, size_t len)
55{
56 struct key_notification *k = (struct key_notification *)n;
57
58 if (len != sizeof(struct key_notification)) {
59 fprintf(stderr, "Incorrect key message length\n");
60 return;
61 }
62
63 printf("KEY %08x change=%u[%s] aux=%u\n",
64 k->key_id, n->subtype, key_subtypes[n->subtype], k->aux);
65}
66
67/*
68 * Consume and display events.
69 */
70static void consumer(int fd)
71{
72 unsigned char buffer[433], *p, *end;
73 union {
74 struct watch_notification n;
75 unsigned char buf1[128];
76 } n;
77 ssize_t buf_len;
78
79 for (;;) {
80 buf_len = read(fd, buffer, sizeof(buffer));
81 if (buf_len == -1) {
82 perror("read");
83 exit(1);
84 }
85
86 if (buf_len == 0) {
87 printf("-- END --\n");
88 return;
89 }
90
91 if (buf_len > sizeof(buffer)) {
92 fprintf(stderr, "Read buffer overrun: %zd\n", buf_len);
93 return;
94 }
95
96 printf("read() = %zd\n", buf_len);
97
98 p = buffer;
99 end = buffer + buf_len;
100 while (p < end) {
101 size_t largest, len;
102
103 largest = end - p;
104 if (largest > 128)
105 largest = 128;
106 if (largest < sizeof(struct watch_notification)) {
107 fprintf(stderr, "Short message header: %zu\n", largest);
108 return;
109 }
110 memcpy(&n, p, largest);
111
112 printf("NOTIFY[%03zx]: ty=%06x sy=%02x i=%08x\n",
113 p - buffer, n.n.type, n.n.subtype, n.n.info);
114
115 len = n.n.info & WATCH_INFO_LENGTH;
116 if (len < sizeof(n.n) || len > largest) {
117 fprintf(stderr, "Bad message length: %zu/%zu\n", len, largest);
118 exit(1);
119 }
120
121 switch (n.n.type) {
122 case WATCH_TYPE_META:
123 switch (n.n.subtype) {
124 case WATCH_META_REMOVAL_NOTIFICATION:
125 printf("REMOVAL of watchpoint %08x\n",
126 (n.n.info & WATCH_INFO_ID) >>
127 WATCH_INFO_ID__SHIFT);
128 break;
129 case WATCH_META_LOSS_NOTIFICATION:
130 printf("-- LOSS --\n");
131 break;
132 default:
133 printf("other meta record\n");
134 break;
135 }
136 break;
137 case WATCH_TYPE_KEY_NOTIFY:
138 saw_key_change(&n.n, len);
139 break;
140 default:
141 printf("other type\n");
142 break;
143 }
144
145 p += len;
146 }
147 }
148}
149
150static struct watch_notification_filter filter = {
151 .nr_filters = 1,
152 .filters = {
153 [0] = {
154 .type = WATCH_TYPE_KEY_NOTIFY,
155 .subtype_filter[0] = UINT_MAX,
156 },
157 },
158};
159
160int main(int argc, char **argv)
161{
162 int pipefd[2], fd;
163
164 if (pipe2(pipefd, O_NOTIFICATION_PIPE) == -1) {
165 perror("pipe2");
166 exit(1);
167 }
168 fd = pipefd[0];
169
170 if (ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, BUF_SIZE) == -1) {
171 perror("watch_queue(size)");
172 exit(1);
173 }
174
175 if (ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter) == -1) {
176 perror("watch_queue(filter)");
177 exit(1);
178 }
179
180 if (keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fd, 0x01) == -1) {
181 perror("keyctl");
182 exit(1);
183 }
184
185 if (keyctl_watch_key(KEY_SPEC_USER_KEYRING, fd, 0x02) == -1) {
186 perror("keyctl");
187 exit(1);
188 }
189
190 consumer(fd);
191 exit(0);
192}