From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mx3-rdu2.redhat.com ([66.187.233.73]:49140 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S2387831AbeGWQ2F (ORCPT ); Mon, 23 Jul 2018 12:28:05 -0400 Subject: [PATCH 5/5] Add sample notification program From: David Howells To: viro@zeniv.linux.org.uk Cc: linux-fsdevel@vger.kernel.org, dhowells@redhat.com, linux-kernel@vger.kernel.org, raven@themaw.net, keyrings@vger.kernel.org, linux-security-module@vger.kernel.org Date: Mon, 23 Jul 2018 16:26:18 +0100 Message-ID: <153235957887.32640.8025222191782276269.stgit@warthog.procyon.org.uk> In-Reply-To: <153235954191.32640.5792167066538704794.stgit@warthog.procyon.org.uk> References: <153235954191.32640.5792167066538704794.stgit@warthog.procyon.org.uk> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org List-ID: 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 --- samples/Kconfig | 6 + samples/Makefile | 2 samples/watch_queue/Makefile | 9 + samples/watch_queue/watch_test.c | 232 ++++++++++++++++++++++++++++++++++++++ 4 files changed, 248 insertions(+), 1 deletion(-) 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 1c5658bc6224..dac30cefe895 100644 --- a/samples/Kconfig +++ b/samples/Kconfig @@ -156,4 +156,10 @@ config SAMPLE_MOUNT_API help Build example userspace program(s) that use the new mount API. +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 31d08cc71a5c..ed545cbf65c8 100644 --- a/samples/Makefile +++ b/samples/Makefile @@ -3,4 +3,4 @@ obj-$(CONFIG_SAMPLES) += kobject/ kprobes/ trace_events/ livepatch/ \ hw_breakpoint/ kfifo/ kdb/ hidraw/ rpmsg/ seccomp/ \ configfs/ connector/ v4l/ trace_printk/ \ - vfio-mdev/ statx/ qmi/ mount_api/ + vfio-mdev/ statx/ qmi/ mount_api/ watch_queue/ diff --git a/samples/watch_queue/Makefile b/samples/watch_queue/Makefile new file mode 100644 index 000000000000..1f20ee2b0add --- /dev/null +++ b/samples/watch_queue/Makefile @@ -0,0 +1,9 @@ +# List of programs to build +hostprogs-$(CONFIG_SAMPLE_WATCH_QUEUE) := 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..cdbaaf5a1163 --- /dev/null +++ b/samples/watch_queue/watch_test.c @@ -0,0 +1,232 @@ +/* Use /dev/watch_queue to watch for keyring and mount topology changes. + * + * Copyright (C) 2018 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public Licence + * as published by the Free Software Foundation; either version + * 2 of the Licence, or (at your option) any later version. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define BUF_SIZE 4 + +static const char *key_subtypes[] = { + [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[] = { + [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[] = { + [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]); +} + +/* + * 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 = buf->meta.head, + tail = buf->meta.tail, + tail != head + ) { + asm ("lfence" : : : "memory" ); + 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; + } + + tail += (n->info & WATCH_INFO_LENGTH) >> WATCH_LENGTH_SHIFT; + asm("mfence" ::: "memory"); + buf->meta.tail = tail; + } + } + +out: + return 0; +} + +static struct watch_notification_filter filter = { + .nr_filters = 3, + .__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, + }, + }, +}; + +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_mount_notify, AT_FDCWD, "/", 0, fd, 0x02) == -1) { + perror("mount_notify"); + exit(1); + } + + if (syscall(__NR_sb_notify, AT_FDCWD, "/mnt", 0, fd, 0x03) == -1) { + perror("sb_notify"); + exit(1); + } + + return consumer(fd, buf); +}