From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Howells Date: Wed, 18 Mar 2020 15:04:17 +0000 Subject: [PATCH 07/17] Add sample notification program [ver #5] Message-Id: <158454385716.2863966.7866246304503905992.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit List-Id: References: <158454378820.2863966.10496767254293183123.stgit@warthog.procyon.org.uk> In-Reply-To: <158454378820.2863966.10496767254293183123.stgit@warthog.procyon.org.uk> To: torvalds@linux-foundation.org, viro@zeniv.linux.org.uk Cc: dhowells@redhat.com, casey@schaufler-ca.com, sds@tycho.nsa.gov, nicolas.dichtel@6wind.com, raven@themaw.net, christian@brauner.io, andres@anarazel.de, jlayton@redhat.com, dray@redhat.com, kzak@redhat.com, keyrings@vger.kernel.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org The sample program is run like: ./samples/watch_queue/watch_test and watches "/" for mount changes and the current session keyring for key changes: # keyctl add user a a @s 1035096409 # keyctl unlink 1035096409 @s producing: # ./watch_test read() = 16 NOTIFY[000]: ty0001 sy i000110 KEY 2ffc2e5d change=2[linked] aux35096409 read() = 16 NOTIFY[000]: ty0001 sy i000110 KEY 2ffc2e5d change=3[unlinked] aux35096409 Other events may be produced, such as with a failing disk: read() = 22 NOTIFY[000]: ty0003 sy i000416 USB 3-7.7 dev-reset e=0 r=0 read() = 24 NOTIFY[000]: ty0002 sy i000418 BLOCK 00800050 e=6[critical medium] sd000ef8 This corresponds to: blk_update_request: critical medium error, dev sdf, sector 1677725432 op 0x0:(READ) flags 0x0 phys_seg 1 prio class 0 in dmesg. Signed-off-by: David Howells --- samples/Kconfig | 6 + samples/Makefile | 1 samples/watch_queue/Makefile | 7 + samples/watch_queue/watch_test.c | 183 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 197 insertions(+) create mode 100644 samples/watch_queue/Makefile create mode 100644 samples/watch_queue/watch_test.c diff --git a/samples/Kconfig b/samples/Kconfig index 9d236c346de5..5c31971a5745 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -190,5 +190,11 @@ config SAMPLE_INTEL_MEI help Build a sample program to work with mei device. +config SAMPLE_WATCH_QUEUE + bool "Build example /dev/watch_queue notification consumer" + depends on HEADERS_INSTALL + help + Build example userspace program to use the new mount_notify(), + sb_notify() syscalls and the KEYCTL_WATCH_KEY keyctl() function. endif # SAMPLES diff --git a/samples/Makefile b/samples/Makefile index f8f847b4f61f..8617edf7f19a 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -24,3 +24,4 @@ obj-$(CONFIG_VIDEO_PCI_SKELETON) += v4l/ obj-y += vfio-mdev/ subdir-$(CONFIG_SAMPLE_VFS) += vfs obj-$(CONFIG_SAMPLE_INTEL_MEI) += mei/ +subdir-$(CONFIG_SAMPLE_WATCH_QUEUE) += watch_queue diff --git a/samples/watch_queue/Makefile b/samples/watch_queue/Makefile new file mode 100644 index 000000000000..eec00dd0a8df --- /dev/null +++ b/samples/watch_queue/Makefile @@ -0,0 +1,7 @@ +# List of programs to build +hostprogs-y := watch_test + +# Tell kbuild to always build the programs +always := $(hostprogs-y) + +HOSTCFLAGS_watch_test.o += -I$(objtree)/usr/include diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c new file mode 100644 index 000000000000..4a311790d4ca --- /dev/null +++ b/samples/watch_queue/watch_test.c @@ -0,0 +1,183 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Use /dev/watch_queue to watch for notifications. + * + * Copyright (C) 2020 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef KEYCTL_WATCH_KEY +#define KEYCTL_WATCH_KEY -1 +#endif +#ifndef __NR_keyctl +#define __NR_keyctl -1 +#endif + +#define BUF_SIZE 256 + +static long keyctl_watch_key(int key, int watch_fd, int watch_id) +{ + return syscall(__NR_keyctl, KEYCTL_WATCH_KEY, key, watch_fd, watch_id); +} + +static const char *key_subtypes[256] = { + [NOTIFY_KEY_INSTANTIATED] = "instantiated", + [NOTIFY_KEY_UPDATED] = "updated", + [NOTIFY_KEY_LINKED] = "linked", + [NOTIFY_KEY_UNLINKED] = "unlinked", + [NOTIFY_KEY_CLEARED] = "cleared", + [NOTIFY_KEY_REVOKED] = "revoked", + [NOTIFY_KEY_INVALIDATED] = "invalidated", + [NOTIFY_KEY_SETATTR] = "setattr", +}; + +static void saw_key_change(struct watch_notification *n, size_t len) +{ + struct key_notification *k = (struct key_notification *)n; + + if (len != sizeof(struct key_notification)) { + fprintf(stderr, "Incorrect key message length\n"); + return; + } + + printf("KEY %08x change=%u[%s] aux=%u\n", + k->key_id, n->subtype, key_subtypes[n->subtype], k->aux); +} + +/* + * Consume and display events. + */ +static void consumer(int fd) +{ + unsigned char buffer[4096], *p, *end; + union { + struct watch_notification n; + unsigned char buf1[128]; + } n; + ssize_t buf_len; + + for (;;) { + buf_len = read(fd, buffer, sizeof(buffer)); + if (buf_len = -1) { + perror("read"); + exit(1); + } + + if (buf_len = 0) { + printf("-- END --\n"); + return; + } + + if (buf_len > sizeof(buffer)) { + fprintf(stderr, "Read buffer overrun: %zd\n", buf_len); + return; + } + + printf("read() = %zd\n", buf_len); + + p = buffer; + end = buffer + buf_len; + while (p < end) { + size_t largest, len; + + largest = end - p; + if (largest > 128) + largest = 128; + if (largest < sizeof(struct watch_notification)) { + fprintf(stderr, "Short message header: %zu\n", largest); + return; + } + memcpy(&n, p, largest); + + printf("NOTIFY[%03zx]: ty=%06x sy=%02x i=%08x\n", + p - buffer, n.n.type, n.n.subtype, n.n.info); + + len = n.n.info & WATCH_INFO_LENGTH; + if (len < sizeof(n.n) || len > largest) { + fprintf(stderr, "Bad message length: %zu/%zu\n", len, largest); + exit(1); + } + + switch (n.n.type) { + case WATCH_TYPE_META: + switch (n.n.subtype) { + case WATCH_META_REMOVAL_NOTIFICATION: + printf("REMOVAL of watchpoint %08x\n", + (n.n.info & WATCH_INFO_ID) >> + WATCH_INFO_ID__SHIFT); + break; + default: + printf("other meta record\n"); + break; + } + break; + case WATCH_TYPE_KEY_NOTIFY: + saw_key_change(&n.n, len); + break; + default: + printf("other type\n"); + break; + } + + p += len; + } + } +} + +static struct watch_notification_filter filter = { + .nr_filters = 1, + .filters = { + [0] = { + .type = WATCH_TYPE_KEY_NOTIFY, + .subtype_filter[0] = UINT_MAX, + }, + }, +}; + +int main(int argc, char **argv) +{ + int pipefd[2], fd; + + if (pipe2(pipefd, O_NOTIFICATION_PIPE) = -1) { + perror("pipe2"); + exit(1); + } + fd = pipefd[0]; + + if (ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, BUF_SIZE) = -1) { + perror("watch_queue(size)"); + exit(1); + } + + if (ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter) = -1) { + perror("watch_queue(filter)"); + exit(1); + } + + if (keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fd, 0x01) = -1) { + perror("keyctl"); + exit(1); + } + + if (keyctl_watch_key(KEY_SPEC_USER_KEYRING, fd, 0x02) = -1) { + perror("keyctl"); + exit(1); + } + + consumer(fd); + exit(0); +}