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Registered in England and Wales under Company Registration No. 3798903 Subject: [PATCH 13/13] Add sample notification program [ver #4] From: David Howells To: viro@zeniv.linux.org.uk Cc: dhowells@redhat.com, raven@themaw.net, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-block@vger.kernel.org, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 07 Jun 2019 15:19:22 +0100 Message-ID: <155991716200.15579.16029014441668335389.stgit@warthog.procyon.org.uk> In-Reply-To: <155991702981.15579.6007568669839441045.stgit@warthog.procyon.org.uk> References: <155991702981.15579.6007568669839441045.stgit@warthog.procyon.org.uk> User-Agent: StGit/unknown-version MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Fri, 07 Jun 2019 14:19:32 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This needs to be linked with -lkeyutils. It is run like: ./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 # mount -t tmpfs none /mnt/nfsv3tcp/ # umount /mnt/nfsv3tcp producing: # ./watch_test ptrs h=4 t=2 m=20003 NOTIFY[00000004-00000002] ty=0003 sy=0002 i=01000010 KEY 2ffc2e5d change=2[linked] aux=1035096409 ptrs h=6 t=4 m=20003 NOTIFY[00000006-00000004] ty=0003 sy=0003 i=01000010 KEY 2ffc2e5d change=3[unlinked] aux=1035096409 ptrs h=8 t=6 m=20003 NOTIFY[00000008-00000006] ty=0001 sy=0000 i=02000010 MOUNT 00000013 change=0[new_mount] aux=168 ptrs h=a t=8 m=20003 NOTIFY[0000000a-00000008] ty=0001 sy=0001 i=02000010 MOUNT 00000013 change=1[unmount] aux=168 Other events may be produced, such as with a failing disk: ptrs h=5 t=2 m=6000004 NOTIFY[00000005-00000002] ty=0004 sy=0006 i=04000018 BLOCK 00800050 e=6[critical medium] s=5be8 This corresponds to: print_req_error: critical medium error, dev sdf, sector 23528 flags 0 in dmesg. Signed-off-by: David Howells --- samples/Kconfig | 6 + samples/Makefile | 1 samples/watch_queue/Makefile | 9 + samples/watch_queue/watch_test.c | 308 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 324 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 0561a94f6fdb..a2b7a7babee5 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -160,4 +160,10 @@ config SAMPLE_VFS as mount API and statx(). Note that this is restricted to the x86 arch whilst it accesses system calls that aren't yet in all arches. +config SAMPLE_WATCH_QUEUE + bool "Build example /dev/watch_queue notification consumer" + 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 debf8925f06f..ed3b8bab6e9b 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -20,3 +20,4 @@ obj-$(CONFIG_SAMPLE_TRACE_PRINTK) += trace_printk/ obj-$(CONFIG_VIDEO_PCI_SKELETON) += v4l/ obj-y += vfio-mdev/ subdir-$(CONFIG_SAMPLE_VFS) += vfs +subdir-$(CONFIG_SAMPLE_WATCH_QUEUE) += watch_queue diff --git a/samples/watch_queue/Makefile b/samples/watch_queue/Makefile new file mode 100644 index 000000000000..42b694430d0f --- /dev/null +++ b/samples/watch_queue/Makefile @@ -0,0 +1,9 @@ +# 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 + +HOSTLOADLIBES_watch_test += -lkeyutils diff --git a/samples/watch_queue/watch_test.c b/samples/watch_queue/watch_test.c new file mode 100644 index 000000000000..73e70e7dfc36 --- /dev/null +++ b/samples/watch_queue/watch_test.c @@ -0,0 +1,308 @@ +// SPDX-License-Identifier: GPL-2.0 +/* Use /dev/watch_queue to watch for notifications. + * + * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#ifndef __NR_watch_mount +#define __NR_watch_mount -1 +#endif +#ifndef __NR_watch_sb +#define __NR_watch_sb -1 +#endif +#ifndef __NR_watch_devices +#define __NR_watch_devices -1 +#endif +#ifndef KEYCTL_WATCH_KEY +#define KEYCTL_WATCH_KEY -1 +#endif + +#define BUF_SIZE 4 + +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) +{ + struct key_notification *k = (struct key_notification *)n; + unsigned int len = n->info & WATCH_INFO_LENGTH; + + if (len != sizeof(struct key_notification)) + return; + + printf("KEY %08x change=%u[%s] aux=%u\n", + k->key_id, n->subtype, key_subtypes[n->subtype], k->aux); +} + +static const char *mount_subtypes[256] = { + [NOTIFY_MOUNT_NEW_MOUNT] = "new_mount", + [NOTIFY_MOUNT_UNMOUNT] = "unmount", + [NOTIFY_MOUNT_EXPIRY] = "expiry", + [NOTIFY_MOUNT_READONLY] = "readonly", + [NOTIFY_MOUNT_SETATTR] = "setattr", + [NOTIFY_MOUNT_MOVE_FROM] = "move_from", + [NOTIFY_MOUNT_MOVE_TO] = "move_to", +}; + +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 void saw_mount_change(struct watch_notification *n) +{ + struct mount_notification *m = (struct mount_notification *)n; + unsigned int len = n->info & WATCH_INFO_LENGTH; + + if (len != sizeof(struct mount_notification)) + return; + + printf("MOUNT %08x change=%u[%s] aux=%u\n", + m->triggered_on, n->subtype, mount_subtypes[n->subtype], m->changed_mount); +} + +static const char *super_subtypes[256] = { + [NOTIFY_SUPERBLOCK_READONLY] = "readonly", + [NOTIFY_SUPERBLOCK_ERROR] = "error", + [NOTIFY_SUPERBLOCK_EDQUOT] = "edquot", + [NOTIFY_SUPERBLOCK_NETWORK] = "network", +}; + +static void saw_super_change(struct watch_notification *n) +{ + struct superblock_notification *s = (struct superblock_notification *)n; + unsigned int len = n->info & WATCH_INFO_LENGTH; + + if (len < sizeof(struct superblock_notification)) + return; + + printf("SUPER %08llx change=%u[%s]\n", + s->sb_id, n->subtype, super_subtypes[n->subtype]); +} + +static const char *block_subtypes[256] = { + [NOTIFY_BLOCK_ERROR_TIMEOUT] = "timeout", + [NOTIFY_BLOCK_ERROR_NO_SPACE] = "critical space allocation", + [NOTIFY_BLOCK_ERROR_RECOVERABLE_TRANSPORT] = "recoverable transport", + [NOTIFY_BLOCK_ERROR_CRITICAL_TARGET] = "critical target", + [NOTIFY_BLOCK_ERROR_CRITICAL_NEXUS] = "critical nexus", + [NOTIFY_BLOCK_ERROR_CRITICAL_MEDIUM] = "critical medium", + [NOTIFY_BLOCK_ERROR_PROTECTION] = "protection", + [NOTIFY_BLOCK_ERROR_KERNEL_RESOURCE] = "kernel resource", + [NOTIFY_BLOCK_ERROR_DEVICE_RESOURCE] = "device resource", + [NOTIFY_BLOCK_ERROR_IO] = "I/O", +}; + +static void saw_block_change(struct watch_notification *n) +{ + struct block_notification *b = (struct block_notification *)n; + unsigned int len = n->info & WATCH_INFO_LENGTH; + + if (len < sizeof(struct block_notification)) + return; + + printf("BLOCK %08llx e=%u[%s] s=%llx\n", + (unsigned long long)b->dev, + n->subtype, block_subtypes[n->subtype], + (unsigned long long)b->sector); +} + +static const char *usb_subtypes[256] = { + [NOTIFY_USB_DEVICE_ADD] = "dev-add", + [NOTIFY_USB_DEVICE_REMOVE] = "dev-remove", + [NOTIFY_USB_BUS_ADD] = "bus-add", + [NOTIFY_USB_BUS_REMOVE] = "bus-remove", + [NOTIFY_USB_DEVICE_RESET] = "dev-reset", + [NOTIFY_USB_DEVICE_ERROR] = "dev-error", +}; + +static void saw_usb_event(struct watch_notification *n) +{ + struct usb_notification *u = (struct usb_notification *)n; + unsigned int len = n->info & WATCH_INFO_LENGTH; + + if (len < sizeof(struct usb_notification)) + return; + + printf("USB %*.*s %s e=%x r=%x\n", + u->name_len, u->name_len, u->name, + usb_subtypes[n->subtype], + u->error, u->reserved); +} + +/* + * Consume and display events. + */ +static int consumer(int fd, struct watch_queue_buffer *buf) +{ + struct watch_notification *n; + struct pollfd p[1]; + unsigned int head, tail, mask = buf->meta.mask; + + for (;;) { + p[0].fd = fd; + p[0].events = POLLIN | POLLERR; + p[0].revents = 0; + + if (poll(p, 1, -1) == -1) { + perror("poll"); + break; + } + + printf("ptrs h=%x t=%x m=%x\n", + buf->meta.head, buf->meta.tail, buf->meta.mask); + + while (head = __atomic_load_n(&buf->meta.head, __ATOMIC_ACQUIRE), + tail = buf->meta.tail, + tail != head + ) { + n = &buf->slots[tail & mask]; + printf("NOTIFY[%08x-%08x] ty=%04x sy=%04x i=%08x\n", + head, tail, n->type, n->subtype, n->info); + if ((n->info & WATCH_INFO_LENGTH) == 0) + goto out; + + switch (n->type) { + case WATCH_TYPE_META: + if (n->subtype == WATCH_META_REMOVAL_NOTIFICATION) + printf("REMOVAL of watchpoint %08x\n", + n->info & WATCH_INFO_ID); + break; + case WATCH_TYPE_MOUNT_NOTIFY: + saw_mount_change(n); + break; + case WATCH_TYPE_SB_NOTIFY: + saw_super_change(n); + break; + case WATCH_TYPE_KEY_NOTIFY: + saw_key_change(n); + break; + case WATCH_TYPE_BLOCK_NOTIFY: + saw_block_change(n); + break; + case WATCH_TYPE_USB_NOTIFY: + saw_usb_event(n); + break; + } + + tail += (n->info & WATCH_INFO_LENGTH) >> WATCH_LENGTH_SHIFT; + __atomic_store_n(&buf->meta.tail, tail, __ATOMIC_RELEASE); + } + } + +out: + return 0; +} + +static struct watch_notification_filter filter = { + .nr_filters = 5, + .__reserved = 0, + .filters = { + [0] = { + .type = WATCH_TYPE_MOUNT_NOTIFY, + // Reject move-from notifications + .subtype_filter[0] = UINT_MAX & ~(1 << NOTIFY_MOUNT_MOVE_FROM), + }, + [1] = { + .type = WATCH_TYPE_SB_NOTIFY, + // Only accept notification of changes to R/O state + .subtype_filter[0] = (1 << NOTIFY_SUPERBLOCK_READONLY), + // Only accept notifications of change-to-R/O + .info_mask = WATCH_INFO_FLAG_0, + .info_filter = WATCH_INFO_FLAG_0, + }, + [2] = { + .type = WATCH_TYPE_KEY_NOTIFY, + .subtype_filter[0] = UINT_MAX, + }, + [3] = { + .type = WATCH_TYPE_BLOCK_NOTIFY, + .subtype_filter[0] = UINT_MAX, + }, + [4] = { + .type = WATCH_TYPE_USB_NOTIFY, + .subtype_filter[0] = UINT_MAX, + }, + }, +}; + +int main(int argc, char **argv) +{ + struct watch_queue_buffer *buf; + size_t page_size; + int fd; + + fd = open("/dev/watch_queue", O_RDWR); + if (fd == -1) { + perror("/dev/watch_queue"); + exit(1); + } + + if (ioctl(fd, IOC_WATCH_QUEUE_SET_SIZE, BUF_SIZE) == -1) { + perror("/dev/watch_queue(size)"); + exit(1); + } + + if (ioctl(fd, IOC_WATCH_QUEUE_SET_FILTER, &filter) == -1) { + perror("/dev/watch_queue(filter)"); + exit(1); + } + + page_size = sysconf(_SC_PAGESIZE); + buf = mmap(NULL, BUF_SIZE * page_size, PROT_READ | PROT_WRITE, + MAP_SHARED, fd, 0); + if (buf == MAP_FAILED) { + perror("mmap"); + exit(1); + } + + if (keyctl_watch_key(KEY_SPEC_SESSION_KEYRING, fd, 0x01) == -1) { + perror("keyctl"); + exit(1); + } + + if (syscall(__NR_watch_mount, AT_FDCWD, "/", 0, fd, 0x02) == -1) { + perror("watch_mount"); + exit(1); + } + + if (syscall(__NR_watch_sb, AT_FDCWD, "/mnt", 0, fd, 0x03) == -1) { + perror("watch_sb"); + exit(1); + } + + if (syscall(__NR_watch_devices, fd, 0x04) == -1) { + perror("watch_devices"); + exit(1); + } + + return consumer(fd, buf); +}