Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id A8746C433EF for ; Wed, 8 Dec 2021 04:48:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S244305AbhLHEv6 (ORCPT ); Tue, 7 Dec 2021 23:51:58 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S244293AbhLHEvy (ORCPT ); Tue, 7 Dec 2021 23:51:54 -0500 Received: from mail-yb1-xb4a.google.com (mail-yb1-xb4a.google.com [IPv6:2607:f8b0:4864:20::b4a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A5807C061756 for ; Tue, 7 Dec 2021 20:48:22 -0800 (PST) Received: by mail-yb1-xb4a.google.com with SMTP id y17-20020a2586d1000000b005f6596e8760so2459128ybm.17 for ; Tue, 07 Dec 2021 20:48:22 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=jBlXBnNdAMxSUa7yhIEysIDH76+KtqzmNyIubBtA+w4=; b=SypwgL/uWaUiO5tC4MdvSa7r8QMW3zr/sROnmdA2wikBl9aPLJlgK7YeiJo72Ihjxx te9F/z+Ko3jXg68CNGg9Uzt5zKemJK/1Y2MR0+Cb4IDXvYTWgG7CD/cQH+gOJtw1YB/t vBSUb0rQhA55U+PN4bz5BGA3zgIefxtfuRbeb+ILSk90ovlIvUoKiB1cJlydTSoD60hb cJVUXM2bGNMHTd39Ys6CfTcMKF41gZT41eKYmTwPWQlSXJkwDV9DWj3unRVBH3vt4boE 3PITH31oUGQCQjOK8ITTFXP/WqknPiaAxqpKyUewNFSeaP6BpcJC2BEOQH7A5VLw8wOS 3leQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=jBlXBnNdAMxSUa7yhIEysIDH76+KtqzmNyIubBtA+w4=; b=fmey44/X/64gasCQswyPMvoRktAQ7OstvPz7030K4SCYQopd4ljEQ06hnKGGG4bQQl WLzsaTv3P3T1qUEypzbRQmpzSxYT/QvWYNoUXbq/U/DcnnPwkOQbUaRwUHcZ7+GB4Bin /vabCVHxye0mReT8YrXF5Yt4BIq/f3VyWIE8ZFNVlcPF2Y0UaKmzn99i+uUfIpEhIhKg OTX/l5Pfd6snveM7w+yYV+fw7UnXLPMdTgypbiwooUc3RvYewE5L0epoxHmO/A3nmbkM cq9TBYQ4EEe6z9OPfmfhCcgYmKdNKEe0xBn3LMNjMCZUjOjH09Z/J3W+eIQglMMnprma TAEg== X-Gm-Message-State: AOAM530bAdE5/fu7yIbOzyIrQAdvMXluc2IEZnv1nAd9+cVEqKFJ8trf hrFwtODdAWMrwnT4XU7Tizbhr30= X-Google-Smtp-Source: ABdhPJwQwBHnDVDWeN8wKH2CZAz13EYYVPbKRZ8sxCY+r+igIJYsneorjLfhzDVPwqRgQHujvls1IdQ= X-Received: from pcc-desktop.svl.corp.google.com ([2620:15c:2ce:200:be2d:924d:844b:d2fa]) (user=pcc job=sendgmr) by 2002:a05:6902:102d:: with SMTP id x13mr29987965ybt.114.1638938901833; Tue, 07 Dec 2021 20:48:21 -0800 (PST) Date: Tue, 7 Dec 2021 20:48:04 -0800 In-Reply-To: <20211208044808.872554-1-pcc@google.com> Message-Id: <20211208044808.872554-3-pcc@google.com> Mime-Version: 1.0 References: <20211208044808.872554-1-pcc@google.com> X-Mailer: git-send-email 2.34.1.173.g76aa8bc2d0-goog Subject: [PATCH v3 2/6] uaccess-buffer: add core code From: Peter Collingbourne To: Catalin Marinas , Will Deacon , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Daniel Bristot de Oliveira , Thomas Gleixner , Andy Lutomirski , Kees Cook , Andrew Morton , Masahiro Yamada , Sami Tolvanen , YiFei Zhu , Mark Rutland , Frederic Weisbecker , Viresh Kumar , Andrey Konovalov , Peter Collingbourne , Gabriel Krisman Bertazi , Chris Hyser , Daniel Vetter , Chris Wilson , Arnd Bergmann , Dmitry Vyukov , Christian Brauner , "Eric W. Biederman" , Alexey Gladkov , Ran Xiaokai , David Hildenbrand , Xiaofeng Cao , Cyrill Gorcunov , Thomas Cedeno , Marco Elver , Alexander Potapenko Cc: linux-kernel@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Evgenii Stepanov Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add the core code to support uaccess logging. Subsequent patches will hook this up to the arch-specific kernel entry and exit code for certain architectures. Link: https://linux-review.googlesource.com/id/I6581765646501a5631b281d670903945ebadc57d Signed-off-by: Peter Collingbourne --- v3: - performance optimizations for entry/exit code - don't use kcur == NULL to mean overflow - fix potential double free in clone() - don't allocate a new kernel-side uaccess buffer for each syscall - fix uaccess buffer leak on exit - fix some sparse warnings v2: - New interface that avoids multiple syscalls per real syscall and is arch-generic - Avoid logging uaccesses done by BPF programs - Add documentation - Split up into multiple patches - Various code moves, renames etc as requested by Marco fs/exec.c | 3 + include/linux/instrumented-uaccess.h | 6 +- include/linux/sched.h | 5 ++ include/linux/uaccess-buffer-info.h | 46 ++++++++++ include/linux/uaccess-buffer.h | 112 +++++++++++++++++++++++ include/uapi/linux/prctl.h | 3 + include/uapi/linux/uaccess-buffer.h | 27 ++++++ kernel/Makefile | 1 + kernel/bpf/helpers.c | 7 +- kernel/fork.c | 4 + kernel/signal.c | 4 +- kernel/sys.c | 6 ++ kernel/uaccess-buffer.c | 129 +++++++++++++++++++++++++++ 13 files changed, 350 insertions(+), 3 deletions(-) create mode 100644 include/linux/uaccess-buffer-info.h create mode 100644 include/linux/uaccess-buffer.h create mode 100644 include/uapi/linux/uaccess-buffer.h create mode 100644 kernel/uaccess-buffer.c diff --git a/fs/exec.c b/fs/exec.c index 537d92c41105..c9975e790f30 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -65,6 +65,7 @@ #include #include #include +#include #include #include @@ -1313,6 +1314,8 @@ int begin_new_exec(struct linux_binprm * bprm) me->personality &= ~bprm->per_clear; clear_syscall_work_syscall_user_dispatch(me); + uaccess_buffer_set_descriptor_addr_addr(0); + uaccess_buffer_free(current); /* * We have to apply CLOEXEC before we change whether the process is diff --git a/include/linux/instrumented-uaccess.h b/include/linux/instrumented-uaccess.h index ece549088e50..b967f4436d15 100644 --- a/include/linux/instrumented-uaccess.h +++ b/include/linux/instrumented-uaccess.h @@ -2,7 +2,8 @@ /* * This header provides generic wrappers for memory access instrumentation for - * uaccess routines that the compiler cannot emit for: KASAN, KCSAN. + * uaccess routines that the compiler cannot emit for: KASAN, KCSAN, + * uaccess buffers. */ #ifndef _LINUX_INSTRUMENTED_UACCESS_H #define _LINUX_INSTRUMENTED_UACCESS_H @@ -11,6 +12,7 @@ #include #include #include +#include /** * instrument_copy_to_user - instrument reads of copy_to_user @@ -27,6 +29,7 @@ instrument_copy_to_user(void __user *to, const void *from, unsigned long n) { kasan_check_read(from, n); kcsan_check_read(from, n); + uaccess_buffer_log_write(to, n); } /** @@ -44,6 +47,7 @@ instrument_copy_from_user(const void *to, const void __user *from, unsigned long { kasan_check_write(to, n); kcsan_check_write(to, n); + uaccess_buffer_log_read(from, n); } #endif /* _LINUX_INSTRUMENTED_UACCESS_H */ diff --git a/include/linux/sched.h b/include/linux/sched.h index 78c351e35fec..7c5278d7b57d 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -34,6 +34,7 @@ #include #include #include +#include #include /* task_struct member predeclarations (sorted alphabetically): */ @@ -1484,6 +1485,10 @@ struct task_struct { struct callback_head l1d_flush_kill; #endif +#ifdef CONFIG_HAVE_ARCH_UACCESS_BUFFER + struct uaccess_buffer_info uaccess_buffer; +#endif + /* * New fields for task_struct should be added above here, so that * they are included in the randomized portion of task_struct. diff --git a/include/linux/uaccess-buffer-info.h b/include/linux/uaccess-buffer-info.h new file mode 100644 index 000000000000..15e2d8f7c074 --- /dev/null +++ b/include/linux/uaccess-buffer-info.h @@ -0,0 +1,46 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_UACCESS_BUFFER_INFO_H +#define _LINUX_UACCESS_BUFFER_INFO_H + +#ifdef CONFIG_HAVE_ARCH_UACCESS_BUFFER + +struct uaccess_buffer_info { + /* + * The pointer to pointer to struct uaccess_descriptor. This is the + * value controlled by prctl(PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR). + */ + struct uaccess_descriptor __user *__user *desc_ptr_ptr; + + /* + * The pointer to struct uaccess_descriptor read at syscall entry time. + */ + struct uaccess_descriptor __user *desc_ptr; + + /* + * A pointer to the kernel's temporary copy of the uaccess log for the + * current syscall. We log to a kernel buffer in order to avoid leaking + * timing information to userspace. + */ + struct uaccess_buffer_entry *kbegin; + + /* + * The position of the next uaccess buffer entry for the current + * syscall, or NULL if we are not logging the current syscall. + */ + struct uaccess_buffer_entry *kcur; + + /* + * A pointer to the end of the kernel's uaccess log. + */ + struct uaccess_buffer_entry *kend; + + /* + * The pointer to the userspace uaccess log, as read from the + * struct uaccess_descriptor. + */ + struct uaccess_buffer_entry __user *ubegin; +}; + +#endif + +#endif /* _LINUX_UACCESS_BUFFER_INFO_H */ diff --git a/include/linux/uaccess-buffer.h b/include/linux/uaccess-buffer.h new file mode 100644 index 000000000000..f2f46db274f3 --- /dev/null +++ b/include/linux/uaccess-buffer.h @@ -0,0 +1,112 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _LINUX_UACCESS_BUFFER_H +#define _LINUX_UACCESS_BUFFER_H + +#include +#include + +#include + +#ifdef CONFIG_HAVE_ARCH_UACCESS_BUFFER + +static inline bool uaccess_buffer_maybe_blocked(struct task_struct *tsk) +{ + return test_task_syscall_work(tsk, UACCESS_BUFFER_ENTRY); +} + +void __uaccess_buffer_syscall_entry(void); +static inline void uaccess_buffer_syscall_entry(void) +{ + __uaccess_buffer_syscall_entry(); +} + +void __uaccess_buffer_syscall_exit(void); +static inline void uaccess_buffer_syscall_exit(void) +{ + __uaccess_buffer_syscall_exit(); +} + +bool __uaccess_buffer_pre_exit_loop(void); +static inline bool uaccess_buffer_pre_exit_loop(void) +{ + if (!test_syscall_work(UACCESS_BUFFER_ENTRY)) + return false; + return __uaccess_buffer_pre_exit_loop(); +} + +void __uaccess_buffer_post_exit_loop(void); +static inline void uaccess_buffer_post_exit_loop(bool pending) +{ + if (pending) + __uaccess_buffer_post_exit_loop(); +} + +static inline int uaccess_buffer_set_descriptor_addr_addr(unsigned long addr) +{ + current->uaccess_buffer.desc_ptr_ptr = + (struct uaccess_descriptor __user * __user *)addr; + if (addr) + set_syscall_work(UACCESS_BUFFER_ENTRY); + else + clear_syscall_work(UACCESS_BUFFER_ENTRY); + return 0; +} + +size_t copy_from_user_nolog(void *to, const void __user *from, size_t len); + +void uaccess_buffer_free(struct task_struct *tsk); + +void __uaccess_buffer_log_read(const void __user *from, unsigned long n); +static inline void uaccess_buffer_log_read(const void __user *from, unsigned long n) +{ + if (unlikely(test_syscall_work(UACCESS_BUFFER_EXIT))) + __uaccess_buffer_log_read(from, n); +} + +void __uaccess_buffer_log_write(void __user *to, unsigned long n); +static inline void uaccess_buffer_log_write(void __user *to, unsigned long n) +{ + if (unlikely(test_syscall_work(UACCESS_BUFFER_EXIT))) + __uaccess_buffer_log_write(to, n); +} + +#else + +static inline bool uaccess_buffer_maybe_blocked(struct task_struct *tsk) +{ + return false; +} +static inline void uaccess_buffer_syscall_entry(void) +{ +} +static inline void uaccess_buffer_syscall_exit(void) +{ +} +static inline bool uaccess_buffer_pre_exit_loop(void) +{ + return false; +} +static inline void uaccess_buffer_post_exit_loop(bool pending) +{ +} +static inline int uaccess_buffer_set_descriptor_addr_addr(unsigned long addr) +{ + return -EINVAL; +} +static inline void uaccess_buffer_free(struct task_struct *tsk) +{ +} + +#define copy_from_user_nolog(to, from, len) copy_from_user(to, from, len) + +static inline void uaccess_buffer_log_read(const void __user *from, + unsigned long n) +{ +} +static inline void uaccess_buffer_log_write(void __user *to, unsigned long n) +{ +} + +#endif + +#endif /* _LINUX_UACCESS_BUFFER_H */ diff --git a/include/uapi/linux/prctl.h b/include/uapi/linux/prctl.h index bb73e9a0b24f..74b37469c7b3 100644 --- a/include/uapi/linux/prctl.h +++ b/include/uapi/linux/prctl.h @@ -272,4 +272,7 @@ struct prctl_mm_map { # define PR_SCHED_CORE_SCOPE_THREAD_GROUP 1 # define PR_SCHED_CORE_SCOPE_PROCESS_GROUP 2 +/* Configure uaccess logging feature */ +#define PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR 63 + #endif /* _LINUX_PRCTL_H */ diff --git a/include/uapi/linux/uaccess-buffer.h b/include/uapi/linux/uaccess-buffer.h new file mode 100644 index 000000000000..bf10f7c78857 --- /dev/null +++ b/include/uapi/linux/uaccess-buffer.h @@ -0,0 +1,27 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +#ifndef _UAPI_LINUX_UACCESS_BUFFER_H +#define _UAPI_LINUX_UACCESS_BUFFER_H + +#include + +/* Location of the uaccess log. */ +struct uaccess_descriptor { + /* Address of the uaccess_buffer_entry array. */ + __u64 addr; + /* Size of the uaccess_buffer_entry array in number of elements. */ + __u64 size; +}; + +/* Format of the entries in the uaccess log. */ +struct uaccess_buffer_entry { + /* Address being accessed. */ + __u64 addr; + /* Number of bytes that were accessed. */ + __u64 size; + /* UACCESS_BUFFER_* flags. */ + __u64 flags; +}; + +#define UACCESS_BUFFER_FLAG_WRITE 1 /* access was a write */ + +#endif /* _UAPI_LINUX_UACCESS_BUFFER_H */ diff --git a/kernel/Makefile b/kernel/Makefile index 186c49582f45..d4d9be5146c3 100644 --- a/kernel/Makefile +++ b/kernel/Makefile @@ -114,6 +114,7 @@ obj-$(CONFIG_KCSAN) += kcsan/ obj-$(CONFIG_SHADOW_CALL_STACK) += scs.o obj-$(CONFIG_HAVE_STATIC_CALL_INLINE) += static_call.o obj-$(CONFIG_CFI_CLANG) += cfi.o +obj-$(CONFIG_HAVE_ARCH_UACCESS_BUFFER) += uaccess-buffer.o obj-$(CONFIG_PERF_EVENTS) += events/ diff --git a/kernel/bpf/helpers.c b/kernel/bpf/helpers.c index 649f07623df6..ab6520a633ef 100644 --- a/kernel/bpf/helpers.c +++ b/kernel/bpf/helpers.c @@ -15,6 +15,7 @@ #include #include #include +#include #include "../../lib/kstrtox.h" @@ -637,7 +638,11 @@ const struct bpf_func_proto bpf_event_output_data_proto = { BPF_CALL_3(bpf_copy_from_user, void *, dst, u32, size, const void __user *, user_ptr) { - int ret = copy_from_user(dst, user_ptr, size); + /* + * Avoid logging uaccesses here as the BPF program may not be following + * the uaccess log rules. + */ + int ret = copy_from_user_nolog(dst, user_ptr, size); if (unlikely(ret)) { memset(dst, 0, size); diff --git a/kernel/fork.c b/kernel/fork.c index 3244cc56b697..8be2ca528a65 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -96,6 +96,7 @@ #include #include #include +#include #include #include @@ -754,6 +755,7 @@ void __put_task_struct(struct task_struct *tsk) delayacct_tsk_free(tsk); put_signal_struct(tsk->signal); sched_core_free(tsk); + uaccess_buffer_free(tsk); if (!profile_handoff_task(tsk)) free_task(tsk); @@ -890,6 +892,8 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node) if (memcg_charge_kernel_stack(tsk)) goto free_stack; + uaccess_buffer_free(orig); + stack_vm_area = task_stack_vm_area(tsk); err = arch_dup_task_struct(tsk, orig); diff --git a/kernel/signal.c b/kernel/signal.c index a629b11bf3e0..69bf21518bd0 100644 --- a/kernel/signal.c +++ b/kernel/signal.c @@ -45,6 +45,7 @@ #include #include #include +#include #define CREATE_TRACE_POINTS #include @@ -1031,7 +1032,8 @@ static void complete_signal(int sig, struct task_struct *p, enum pid_type type) if (sig_fatal(p, sig) && !(signal->flags & SIGNAL_GROUP_EXIT) && !sigismember(&t->real_blocked, sig) && - (sig == SIGKILL || !p->ptrace)) { + (sig == SIGKILL || + !(p->ptrace || uaccess_buffer_maybe_blocked(p)))) { /* * This signal will be fatal to the whole group. */ diff --git a/kernel/sys.c b/kernel/sys.c index 8fdac0d90504..c71a9a9c0f68 100644 --- a/kernel/sys.c +++ b/kernel/sys.c @@ -42,6 +42,7 @@ #include #include #include +#include #include #include @@ -2530,6 +2531,11 @@ SYSCALL_DEFINE5(prctl, int, option, unsigned long, arg2, unsigned long, arg3, error = sched_core_share_pid(arg2, arg3, arg4, arg5); break; #endif + case PR_SET_UACCESS_DESCRIPTOR_ADDR_ADDR: + if (arg3 || arg4 || arg5) + return -EINVAL; + error = uaccess_buffer_set_descriptor_addr_addr(arg2); + break; default: error = -EINVAL; break; diff --git a/kernel/uaccess-buffer.c b/kernel/uaccess-buffer.c new file mode 100644 index 000000000000..088e43f7611c --- /dev/null +++ b/kernel/uaccess-buffer.c @@ -0,0 +1,129 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Support for uaccess logging via uaccess buffers. + * + * Copyright (C) 2021, Google LLC. + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +static void uaccess_buffer_log(unsigned long addr, unsigned long size, + unsigned long flags) +{ + struct uaccess_buffer_info *buf = ¤t->uaccess_buffer; + struct uaccess_buffer_entry *entry = buf->kcur; + + if (entry == buf->kend || unlikely(uaccess_kernel())) + return; + entry->addr = addr; + entry->size = size; + entry->flags = flags; + + ++buf->kcur; +} + +void __uaccess_buffer_log_read(const void __user *from, unsigned long n) +{ + uaccess_buffer_log((unsigned long)from, n, 0); +} +EXPORT_SYMBOL(__uaccess_buffer_log_read); + +void __uaccess_buffer_log_write(void __user *to, unsigned long n) +{ + uaccess_buffer_log((unsigned long)to, n, UACCESS_BUFFER_FLAG_WRITE); +} +EXPORT_SYMBOL(__uaccess_buffer_log_write); + +bool __uaccess_buffer_pre_exit_loop(void) +{ + struct uaccess_buffer_info *buf = ¤t->uaccess_buffer; + struct uaccess_descriptor __user *desc_ptr; + sigset_t tmp_mask; + + if (get_user(desc_ptr, buf->desc_ptr_ptr) || !desc_ptr) + return false; + + current->real_blocked = current->blocked; + sigfillset(&tmp_mask); + set_current_blocked(&tmp_mask); + return true; +} + +void __uaccess_buffer_post_exit_loop(void) +{ + spin_lock_irq(¤t->sighand->siglock); + current->blocked = current->real_blocked; + recalc_sigpending(); + spin_unlock_irq(¤t->sighand->siglock); +} + +void uaccess_buffer_free(struct task_struct *tsk) +{ + struct uaccess_buffer_info *buf = &tsk->uaccess_buffer; + + kfree(buf->kbegin); + clear_syscall_work(UACCESS_BUFFER_EXIT); + buf->kbegin = buf->kcur = buf->kend = NULL; +} + +void __uaccess_buffer_syscall_entry(void) +{ + struct uaccess_buffer_info *buf = ¤t->uaccess_buffer; + struct uaccess_descriptor desc; + + if (get_user(buf->desc_ptr, buf->desc_ptr_ptr) || !buf->desc_ptr || + put_user(0, buf->desc_ptr_ptr) || + copy_from_user(&desc, buf->desc_ptr, sizeof(desc))) + return; + + if (desc.size > 1024) + desc.size = 1024; + + if (buf->kend - buf->kbegin != desc.size) + buf->kbegin = + krealloc_array(buf->kbegin, desc.size, + sizeof(struct uaccess_buffer_entry), + GFP_KERNEL); + if (!buf->kbegin) + return; + + set_syscall_work(UACCESS_BUFFER_EXIT); + buf->kcur = buf->kbegin; + buf->kend = buf->kbegin + desc.size; + buf->ubegin = + (struct uaccess_buffer_entry __user *)(unsigned long)desc.addr; +} + +void __uaccess_buffer_syscall_exit(void) +{ + struct uaccess_buffer_info *buf = ¤t->uaccess_buffer; + u64 num_entries = buf->kcur - buf->kbegin; + struct uaccess_descriptor desc; + + clear_syscall_work(UACCESS_BUFFER_EXIT); + desc.addr = (u64)(unsigned long)(buf->ubegin + num_entries); + desc.size = buf->kend - buf->kcur; + buf->kcur = NULL; + if (copy_to_user(buf->ubegin, buf->kbegin, + num_entries * sizeof(struct uaccess_buffer_entry)) == 0) + (void)copy_to_user(buf->desc_ptr, &desc, sizeof(desc)); +} + +size_t copy_from_user_nolog(void *to, const void __user *from, size_t len) +{ + size_t retval; + + clear_syscall_work(UACCESS_BUFFER_EXIT); + retval = copy_from_user(to, from, len); + if (current->uaccess_buffer.kcur) + set_syscall_work(UACCESS_BUFFER_EXIT); + return retval; +} -- 2.34.1.173.g76aa8bc2d0-goog