From patchwork Tue Apr 11 21:17:09 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Beau Belgrave X-Patchwork-Id: 13208267 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 EA50DC77B6F for ; Tue, 11 Apr 2023 21:17:18 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229779AbjDKVRS (ORCPT ); Tue, 11 Apr 2023 17:17:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:38740 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229752AbjDKVRR (ORCPT ); Tue, 11 Apr 2023 17:17:17 -0400 Received: from linux.microsoft.com (linux.microsoft.com [13.77.154.182]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 3C7CF449A; Tue, 11 Apr 2023 14:17:16 -0700 (PDT) Received: from W11-BEAU-MD.localdomain (unknown [76.135.27.212]) by linux.microsoft.com (Postfix) with ESMTPSA id 9C6E521779A8; Tue, 11 Apr 2023 14:17:15 -0700 (PDT) DKIM-Filter: OpenDKIM Filter v2.11.0 linux.microsoft.com 9C6E521779A8 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.microsoft.com; s=default; t=1681247835; bh=5c4d3BEotzSKMJMtgcr0S62whYX8qPpisF7gsoBkDkw=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=WkUcKuIBuTCbVj31WezZoCtuMd/DBX5L//tgE+SDhh9YZhmSUfXIp6LevIyc30PV1 T0DSgumpETd3O1BwU6FNAFnmC3gZnZ7xWCEUdhzF6bs9XsxfGnhCmz7+kTq0aXtn84 B+7D/Q5CLdiHg+Q9QKQ1Emd7lEfInE8R81jTrVjc= From: Beau Belgrave To: rostedt@goodmis.org, mhiramat@kernel.org, mathieu.desnoyers@efficios.com, dcook@linux.microsoft.com, alanau@linux.microsoft.com Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org Subject: [PATCH 3/3] tracing/user_events: Prevent same address and bit per process Date: Tue, 11 Apr 2023 14:17:09 -0700 Message-Id: <20230411211709.15018-4-beaub@linux.microsoft.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20230411211709.15018-1-beaub@linux.microsoft.com> References: <20230411211709.15018-1-beaub@linux.microsoft.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-trace-kernel@vger.kernel.org User processes register an address and bit pair for events. If the same address and bit pair are registered multiple times in the same process, it can cause undefined behavior when events are enabled/disabled. When more than one are used, the bit could be turned off by another event being disabled, while the original event is still enabled. Prevent undefined behavior by checking the current mm to see if any event has already been registered for the address and bit pair. Return EADDRINUSE back to the user process if it's already being used. Update ftrace self-test to ensure this occurs properly. Suggested-by: Doug Cook Signed-off-by: Beau Belgrave --- kernel/trace/trace_events_user.c | 40 +++++++++++++++++++ .../selftests/user_events/ftrace_test.c | 9 ++++- 2 files changed, 48 insertions(+), 1 deletion(-) diff --git a/kernel/trace/trace_events_user.c b/kernel/trace/trace_events_user.c index eb195d697177..ce5357019113 100644 --- a/kernel/trace/trace_events_user.c +++ b/kernel/trace/trace_events_user.c @@ -419,6 +419,20 @@ static int user_event_enabler_write(struct user_event_mm *mm, return 0; } +static bool user_event_enabler_exists(struct user_event_mm *mm, + unsigned long uaddr, unsigned char bit) +{ + struct user_event_enabler *enabler; + struct user_event_enabler *next; + + list_for_each_entry_safe(enabler, next, &mm->enablers, link) + if (enabler->addr == uaddr && + (enabler->values & ENABLE_VAL_BIT_MASK) == bit) + return true; + + return false; +} + static void user_event_enabler_update(struct user_event *user) { struct user_event_enabler *enabler; @@ -657,6 +671,22 @@ void user_event_mm_dup(struct task_struct *t, struct user_event_mm *old_mm) user_event_mm_remove(t); } +static bool current_user_event_enabler_exists(unsigned long uaddr, + unsigned char bit) +{ + struct user_event_mm *user_mm = current_user_event_mm(); + bool exists; + + if (!user_mm) + return false; + + exists = user_event_enabler_exists(user_mm, uaddr, bit); + + user_event_mm_put(user_mm); + + return exists; +} + static struct user_event_enabler *user_event_enabler_create(struct user_reg *reg, struct user_event *user, int *write_result) @@ -2045,6 +2075,16 @@ static long user_events_ioctl_reg(struct user_event_file_info *info, if (ret) return ret; + /* + * Prevent users from using the same address and bit multiple times + * within the same mm address space. This can cause unexpected behavior + * for user processes that is far easier to debug if this is explictly + * an error upon registering. + */ + if (current_user_event_enabler_exists((unsigned long)reg.enable_addr, + reg.enable_bit)) + return -EADDRINUSE; + name = strndup_user((const char __user *)(uintptr_t)reg.name_args, MAX_EVENT_DESC); diff --git a/tools/testing/selftests/user_events/ftrace_test.c b/tools/testing/selftests/user_events/ftrace_test.c index 91272f9d6fce..7c99cef94a65 100644 --- a/tools/testing/selftests/user_events/ftrace_test.c +++ b/tools/testing/selftests/user_events/ftrace_test.c @@ -219,7 +219,12 @@ TEST_F(user, register_events) { ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, ®)); ASSERT_EQ(0, reg.write_index); - /* Multiple registers should result in same index */ + /* Multiple registers to the same addr + bit should fail */ + ASSERT_EQ(-1, ioctl(self->data_fd, DIAG_IOCSREG, ®)); + ASSERT_EQ(EADDRINUSE, errno); + + /* Multiple registers to same name should result in same index */ + reg.enable_bit = 30; ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSREG, ®)); ASSERT_EQ(0, reg.write_index); @@ -242,6 +247,8 @@ TEST_F(user, register_events) { /* Unregister */ ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSUNREG, &unreg)); + unreg.disable_bit = 30; + ASSERT_EQ(0, ioctl(self->data_fd, DIAG_IOCSUNREG, &unreg)); /* Delete should work only after close and unregister */ close(self->data_fd);