[RFC,17/21] Add a general, global device notification watch list

Message ID	157117622273.15019.10638125968293561486.stgit@warthog.procyon.org.uk (mailing list archive)
State	New, archived
Headers	show Return-Path: <SRS0=phTe=YI=vger.kernel.org=linux-usb-owner@kernel.org> Organization: Red Hat UK Ltd. Registered Address: Red Hat UK Ltd, Amberley Place, 107-111 Peascod Street, Windsor, Berkshire, SI4 1TE, United Kingdom. Registered in England and Wales under Company Registration No. 3798903 Subject: [RFC PATCH 17/21] Add a general, global device notification watch list From: David Howells <dhowells@redhat.com> To: torvalds@linux-foundation.org Cc: dhowells@redhat.com, Casey Schaufler <casey@schaufler-ca.com>, Stephen Smalley <sds@tycho.nsa.gov>, Greg Kroah-Hartman <gregkh@linuxfoundation.org>, nicolas.dichtel@6wind.com, raven@themaw.net, Christian Brauner <christian@brauner.io>, dhowells@redhat.com, keyrings@vger.kernel.org, linux-usb@vger.kernel.org, linux-block@vger.kernel.org, linux-security-module@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org Date: Tue, 15 Oct 2019 22:50:22 +0100 Message-ID: <157117622273.15019.10638125968293561486.stgit@warthog.procyon.org.uk> In-Reply-To: <157117606853.15019.15459271147790470307.stgit@warthog.procyon.org.uk> References: <157117606853.15019.15459271147790470307.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 Sender: linux-usb-owner@vger.kernel.org Precedence: bulk
Series	pipe: Keyrings, Block and USB notifications \| expand [RFC,00/21] pipe: Keyrings, Block and USB notifications [RFC,01/21] pipe: Reduce #inclusion of pipe_fs_i.h [RFC,02/21] Add a prelocked wake-up [RFC,03/21] pipe: Use head and tail pointers for the ring, not cursor and length [RFC,04/21] pipe: Advance tail pointer inside of wait spinlock in pipe_read() [RFC,05/21] pipe: Conditionalise wakeup in pipe_read() [RFC,06/21] pipe: Rearrange sequence in pipe_write() to preallocate slot [RFC,07/21] pipe: Remove redundant wakeup from pipe_write() [RFC,08/21] pipe: Check for ring full inside of the spinlock in pipe_write() [RFC,09/21] uapi: General notification queue definitions [RFC,10/21] security: Add hooks to rule on setting a watch [RFC,11/21] security: Add a hook for the point of notification insertion [RFC,12/21] pipe: Add general notification queue support [RFC,13/21] keys: Add a notification facility [RFC,14/21] Add sample notification program [RFC,15/21] pipe: Allow buffers to be marked read-whole-or-error for notifications [RFC,16/21] pipe: Add notification lossage handling [RFC,17/21] Add a general, global device notification watch list [RFC,18/21] block: Add block layer notifications [RFC,19/21] usb: Add USB subsystem notifications [RFC,20/21] selinux: Implement the watch_key security hook [RFC,21/21] smack: Implement the watch_key and post_notification hooks

diff --git a/Documentation/watch_queue.rst b/Documentation/watch_queue.rst index d8f70282d247..ed592700be0e 100644 --- a/Documentation/watch_queue.rst +++ b/Documentation/watch_queue.rst @@ -223,6 +223,25 @@ The ``id`` is the ID of the source object (such as the serial number on a key). Only watches that have the same ID set in them will see this notification. +Global Device Watch List +======================== + +There is a global watch list that hardware generated events, such as device +connection, disconnection, failure and error can be posted upon. It must be +enabled using:: + + CONFIG_DEVICE_NOTIFICATIONS + +Watchpoints are set in userspace using the device_notify(2) system call. +Within the kernel events are posted upon it using:: + + void post_device_notification(struct watch_notification *n, u64 id); + +where ``n`` is the formatted notification record to post. ``id`` is an +identifier that can be used to direct to specific watches, but it should be 0 +for general use on this queue. + + Watch Sources ============= @@ -238,7 +257,8 @@ Any particular buffer can be fed from multiple sources. Sources include: * WATCH_TYPE_BLOCK_NOTIFY Notifications of this type indicate block layer events, such as I/O errors - or temporary link loss. Watches of this type are set on a global queue. + or temporary link loss. Watches of this type are set on the global device + watch list. Event Filtering diff --git a/arch/alpha/kernel/syscalls/syscall.tbl b/arch/alpha/kernel/syscalls/syscall.tbl index 728fe028c02c..8e841d8e4c22 100644 --- a/arch/alpha/kernel/syscalls/syscall.tbl +++ b/arch/alpha/kernel/syscalls/syscall.tbl @@ -475,3 +475,4 @@ 543 common fspick sys_fspick 544 common pidfd_open sys_pidfd_open # 545 reserved for clone3 +546 common watch_devices sys_watch_devices diff --git a/arch/arm/tools/syscall.tbl b/arch/arm/tools/syscall.tbl index 6da7dc4d79cc..0f080cf44cc9 100644 --- a/arch/arm/tools/syscall.tbl +++ b/arch/arm/tools/syscall.tbl @@ -449,3 +449,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open 435 common clone3 sys_clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/arm64/include/asm/unistd.h b/arch/arm64/include/asm/unistd.h index 2629a68b8724..368761302768 100644 --- a/arch/arm64/include/asm/unistd.h +++ b/arch/arm64/include/asm/unistd.h @@ -38,7 +38,7 @@ #define __ARM_NR_compat_set_tls (__ARM_NR_COMPAT_BASE + 5) #define __ARM_NR_COMPAT_END (__ARM_NR_COMPAT_BASE + 0x800) -#define __NR_compat_syscalls 436 +#define __NR_compat_syscalls 437 #endif #define __ARCH_WANT_SYS_CLONE diff --git a/arch/arm64/include/asm/unistd32.h b/arch/arm64/include/asm/unistd32.h index 94ab29cf4f00..b5310789ce7a 100644 --- a/arch/arm64/include/asm/unistd32.h +++ b/arch/arm64/include/asm/unistd32.h @@ -879,6 +879,8 @@ __SYSCALL(__NR_fspick, sys_fspick) __SYSCALL(__NR_pidfd_open, sys_pidfd_open) #define __NR_clone3 435 __SYSCALL(__NR_clone3, sys_clone3) +#define __NR_watch_devices 436 +__SYSCALL(__NR_watch_devices, sys_watch_devices) /* * Please add new compat syscalls above this comment and update diff --git a/arch/ia64/kernel/syscalls/syscall.tbl b/arch/ia64/kernel/syscalls/syscall.tbl index 36d5faf4c86c..2f33f5db2fed 100644 --- a/arch/ia64/kernel/syscalls/syscall.tbl +++ b/arch/ia64/kernel/syscalls/syscall.tbl @@ -356,3 +356,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open # 435 reserved for clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/m68k/kernel/syscalls/syscall.tbl b/arch/m68k/kernel/syscalls/syscall.tbl index a88a285a0e5f..83e4e8784b88 100644 --- a/arch/m68k/kernel/syscalls/syscall.tbl +++ b/arch/m68k/kernel/syscalls/syscall.tbl @@ -435,3 +435,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open # 435 reserved for clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/microblaze/kernel/syscalls/syscall.tbl b/arch/microblaze/kernel/syscalls/syscall.tbl index 09b0cd7dab0a..9a70a3be3b7b 100644 --- a/arch/microblaze/kernel/syscalls/syscall.tbl +++ b/arch/microblaze/kernel/syscalls/syscall.tbl @@ -441,3 +441,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open 435 common clone3 sys_clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/mips/kernel/syscalls/syscall_n32.tbl b/arch/mips/kernel/syscalls/syscall_n32.tbl index e7c5ab38e403..b39527fc32c9 100644 --- a/arch/mips/kernel/syscalls/syscall_n32.tbl +++ b/arch/mips/kernel/syscalls/syscall_n32.tbl @@ -374,3 +374,4 @@ 433 n32 fspick sys_fspick 434 n32 pidfd_open sys_pidfd_open 435 n32 clone3 __sys_clone3 +436 n32 watch_devices sys_watch_devices diff --git a/arch/mips/kernel/syscalls/syscall_n64.tbl b/arch/mips/kernel/syscalls/syscall_n64.tbl index 13cd66581f3b..a7f0c5e71768 100644 --- a/arch/mips/kernel/syscalls/syscall_n64.tbl +++ b/arch/mips/kernel/syscalls/syscall_n64.tbl @@ -350,3 +350,4 @@ 433 n64 fspick sys_fspick 434 n64 pidfd_open sys_pidfd_open 435 n64 clone3 __sys_clone3 +436 n64 watch_devices sys_watch_devices diff --git a/arch/mips/kernel/syscalls/syscall_o32.tbl b/arch/mips/kernel/syscalls/syscall_o32.tbl index 353539ea4140..6f378288598c 100644 --- a/arch/mips/kernel/syscalls/syscall_o32.tbl +++ b/arch/mips/kernel/syscalls/syscall_o32.tbl @@ -423,3 +423,4 @@ 433 o32 fspick sys_fspick 434 o32 pidfd_open sys_pidfd_open 435 o32 clone3 __sys_clone3 +436 o32 watch_devices sys_watch_devices diff --git a/arch/parisc/kernel/syscalls/syscall.tbl b/arch/parisc/kernel/syscalls/syscall.tbl index 285ff516150c..b64bbafa5919 100644 --- a/arch/parisc/kernel/syscalls/syscall.tbl +++ b/arch/parisc/kernel/syscalls/syscall.tbl @@ -433,3 +433,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open 435 common clone3 sys_clone3_wrapper +436 common watch_devices sys_watch_devices diff --git a/arch/powerpc/kernel/syscalls/syscall.tbl b/arch/powerpc/kernel/syscalls/syscall.tbl index 43f736ed47f2..0a503239ab5c 100644 --- a/arch/powerpc/kernel/syscalls/syscall.tbl +++ b/arch/powerpc/kernel/syscalls/syscall.tbl @@ -517,3 +517,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open 435 nospu clone3 ppc_clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/s390/kernel/syscalls/syscall.tbl b/arch/s390/kernel/syscalls/syscall.tbl index 3054e9c035a3..19b43c0d928a 100644 --- a/arch/s390/kernel/syscalls/syscall.tbl +++ b/arch/s390/kernel/syscalls/syscall.tbl @@ -438,3 +438,4 @@ 433 common fspick sys_fspick sys_fspick 434 common pidfd_open sys_pidfd_open sys_pidfd_open 435 common clone3 sys_clone3 sys_clone3 +436 common watch_devices sys_watch_devices sys_watch_devices diff --git a/arch/sh/kernel/syscalls/syscall.tbl b/arch/sh/kernel/syscalls/syscall.tbl index b5ed26c4c005..b454e07c9372 100644 --- a/arch/sh/kernel/syscalls/syscall.tbl +++ b/arch/sh/kernel/syscalls/syscall.tbl @@ -438,3 +438,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open # 435 reserved for clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/sparc/kernel/syscalls/syscall.tbl b/arch/sparc/kernel/syscalls/syscall.tbl index 8c8cc7537fb2..8ef43c27457e 100644 --- a/arch/sparc/kernel/syscalls/syscall.tbl +++ b/arch/sparc/kernel/syscalls/syscall.tbl @@ -481,3 +481,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open # 435 reserved for clone3 +436 common watch_devices sys_watch_devices diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl index 3fe02546aed3..9b225c0d5240 100644 --- a/arch/x86/entry/syscalls/syscall_32.tbl +++ b/arch/x86/entry/syscalls/syscall_32.tbl @@ -440,3 +440,4 @@ 433 i386 fspick sys_fspick __ia32_sys_fspick 434 i386 pidfd_open sys_pidfd_open __ia32_sys_pidfd_open 435 i386 clone3 sys_clone3 __ia32_sys_clone3 +436 i386 watch_devices sys_watch_devices __ia32_sys_watch_devices diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl index c29976eca4a8..29293d103829 100644 --- a/arch/x86/entry/syscalls/syscall_64.tbl +++ b/arch/x86/entry/syscalls/syscall_64.tbl @@ -357,6 +357,7 @@ 433 common fspick __x64_sys_fspick 434 common pidfd_open __x64_sys_pidfd_open 435 common clone3 __x64_sys_clone3/ptregs +436 common watch_devices __x64_sys_watch_devices # # x32-specific system call numbers start at 512 to avoid cache impact diff --git a/arch/xtensa/kernel/syscalls/syscall.tbl b/arch/xtensa/kernel/syscalls/syscall.tbl index 25f4de729a6d..243fa18b8d1e 100644 --- a/arch/xtensa/kernel/syscalls/syscall.tbl +++ b/arch/xtensa/kernel/syscalls/syscall.tbl @@ -406,3 +406,4 @@ 433 common fspick sys_fspick 434 common pidfd_open sys_pidfd_open 435 common clone3 sys_clone3 +436 common watch_devices sys_watch_devices diff --git a/drivers/base/Kconfig b/drivers/base/Kconfig index 28b92e3cc570..e37d37684132 100644 --- a/drivers/base/Kconfig +++ b/drivers/base/Kconfig @@ -1,6 +1,15 @@ # SPDX-License-Identifier: GPL-2.0 menu "Generic Driver Options" +config DEVICE_NOTIFICATIONS + bool "Provide device event notifications" + depends on WATCH_QUEUE + help + This option provides support for getting hardware event notifications + on devices, buses and interfaces. This makes use of the + /dev/watch_queue misc device to handle the notification buffer. + device_notify(2) is used to set/remove watches. + config UEVENT_HELPER bool "Support for uevent helper" help diff --git a/drivers/base/Makefile b/drivers/base/Makefile index 157452080f3d..4db2e8f1a1f4 100644 --- a/drivers/base/Makefile +++ b/drivers/base/Makefile @@ -7,6 +7,7 @@ obj-y := component.o core.o bus.o dd.o syscore.o \ attribute_container.o transport_class.o \ topology.o container.o property.o cacheinfo.o \ devcon.o swnode.o +obj-$(CONFIG_DEVICE_NOTIFICATIONS) += watch.o obj-$(CONFIG_DEVTMPFS) += devtmpfs.o obj-y += power/ obj-$(CONFIG_ISA_BUS_API) += isa.o diff --git a/drivers/base/watch.c b/drivers/base/watch.c new file mode 100644 index 000000000000..725aaa24275b --- /dev/null +++ b/drivers/base/watch.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Event notifications. + * + * Copyright (C) 2019 Red Hat, Inc. All Rights Reserved. + * Written by David Howells (dhowells@redhat.com) + */ + +#include <linux/device.h> +#include <linux/watch_queue.h> +#include <linux/syscalls.h> +#include <linux/init_task.h> +#include <linux/security.h> + +/* + * Global queue for watching for device layer events. + */ +static struct watch_list device_watchers = { + .watchers = HLIST_HEAD_INIT, + .lock = __SPIN_LOCK_UNLOCKED(&device_watchers.lock), +}; + +static DEFINE_SPINLOCK(device_watchers_lock); + +/** + * post_device_notification - Post notification of a device event + * @n - The notification to post + * @id - The device ID + * + * Note that there's only a global queue to which all events are posted. Might + * want to provide per-dev queues also. + */ +void post_device_notification(struct watch_notification *n, u64 id) +{ + post_watch_notification(&device_watchers, n, &init_cred, id); +} +EXPORT_SYMBOL(post_device_notification); + +/** + * sys_watch_devices - Watch for device events. + * @watch_fd: The watch queue to send notifications to. + * @watch_id: The watch ID to be placed in the notification (-1 to remove watch) + * @flags: Flags (reserved for future) + */ +SYSCALL_DEFINE3(watch_devices, int, watch_fd, int, watch_id, unsigned int, flags) +{ + struct watch_queue *wqueue; + struct watch *watch = NULL; + long ret = -ENOMEM; + + if (watch_id < -1 || watch_id > 0xff || flags) + return -EINVAL; + + wqueue = get_watch_queue(watch_fd); + if (IS_ERR(wqueue)) { + ret = PTR_ERR(wqueue); + goto err; + } + + if (watch_id >= 0) { + watch = kzalloc(sizeof(*watch), GFP_KERNEL); + if (!watch) + goto err_wqueue; + + init_watch(watch, wqueue); + watch->info_id = (u32)watch_id << WATCH_INFO_ID__SHIFT; + + ret = security_watch_devices(); + if (ret < 0) + goto err_watch; + + spin_lock(&device_watchers_lock); + ret = add_watch_to_object(watch, &device_watchers); + spin_unlock(&device_watchers_lock); + if (ret == 0) + watch = NULL; + } else { + spin_lock(&device_watchers_lock); + ret = remove_watch_from_object(&device_watchers, wqueue, 0, + false); + spin_unlock(&device_watchers_lock); + } + +err_watch: + kfree(watch); +err_wqueue: + put_watch_queue(wqueue); +err: + return ret; +} diff --git a/include/linux/device.h b/include/linux/device.h index 297239a08bb7..f30e80185825 100644 --- a/include/linux/device.h +++ b/include/linux/device.h @@ -43,6 +43,7 @@ struct iommu_group; struct iommu_fwspec; struct dev_pin_info; struct iommu_param; +struct watch_notification; struct bus_attribute { struct attribute attr; @@ -1654,6 +1655,12 @@ struct device_link *device_link_add(struct device *consumer, void device_link_del(struct device_link *link); void device_link_remove(void *consumer, struct device *supplier); +#ifdef CONFIG_DEVICE_NOTIFICATIONS +extern void post_device_notification(struct watch_notification *n, u64 id); +#else +static inline void post_device_notification(struct watch_notification *n, u64 id) {} +#endif + #ifndef dev_fmt #define dev_fmt(fmt) fmt #endif diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h index f7c561c4dcdd..565f033a61bc 100644 --- a/include/linux/syscalls.h +++ b/include/linux/syscalls.h @@ -1000,6 +1000,7 @@ asmlinkage long sys_fspick(int dfd, const char __user *path, unsigned int flags) asmlinkage long sys_pidfd_send_signal(int pidfd, int sig, siginfo_t __user *info, unsigned int flags); +asmlinkage long sys_watch_devices(int watch_fd, int watch_id, unsigned int flags); /* * Architecture-specific system calls diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h index 1fc8faa6e973..4794d3c2afd7 100644 --- a/include/uapi/asm-generic/unistd.h +++ b/include/uapi/asm-generic/unistd.h @@ -850,9 +850,11 @@ __SYSCALL(__NR_pidfd_open, sys_pidfd_open) #define __NR_clone3 435 __SYSCALL(__NR_clone3, sys_clone3) #endif +#define __NR_watch_devices 436 +__SYSCALL(__NR_watch_devices, sys_watch_devices) #undef __NR_syscalls -#define __NR_syscalls 436 +#define __NR_syscalls 437 /* * 32 bit systems traditionally used different diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c index 34b76895b81e..184ad68c087f 100644 --- a/kernel/sys_ni.c +++ b/kernel/sys_ni.c @@ -51,6 +51,7 @@ COND_SYSCALL_COMPAT(io_pgetevents); COND_SYSCALL(io_uring_setup); COND_SYSCALL(io_uring_enter); COND_SYSCALL(io_uring_register); +COND_SYSCALL(watch_devices); /* fs/xattr.c */

[RFC,17/21] Add a general, global device notification watch list

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