From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Google-Smtp-Source: AB8JxZpQFijGfuIC5WKn5d4NpqJRga817L/9b2xuDsSjMcCYI3dqVpiQDWqzv+JKzn0mDJi3etNA ARC-Seal: i=1; a=rsa-sha256; t=1526937439; cv=none; d=google.com; s=arc-20160816; b=At92/ND/5u5XJyBBa+Ebb4WI1z1uAt+V3OdxtFtWLDfeo85wvT6PePu6I2u+7Bym9Q t7MZ5O+fG6V1BL1L5krlkikldN8YkKQfpHfgDlz6O8f6D1ddZn1sn1NUm6DOIeDb40cO Xewwut+pMFe47JEqYBdBGwHojJUiupI48P6PPJw5suGOZ+8j+JNX70pq2Ji2yHxsLV/p C3FnAIB3Z0RJrY/MYBoP2RKz9Cs6Pcfo2W7w4sYQ74U+3oh9kxAv5arIrPwnMIppC4A/ tqXCRPf/A2IEKLk9Bl4mITUsvPXFL+yOs++5LAsX2cBXw4+WYT6nTPi48nUFs5HTrRVi ajYA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=mime-version:user-agent:references:in-reply-to:message-id:date :subject:cc:to:from:dkim-signature:arc-authentication-results; bh=LVQi3RRZspJIXOrGmwkWqyPpH2vNZnlPitghK5hHp8Y=; b=Bpb4qwwkAPD9dLjMDzs6doppPGchYvfcibE8S3tTIReDWEG+SPgrM0mxB9RSLO3Iep dCXPxz9g0RcJR07Vpm3vbycPUhhuOvy58lkYRvHvgKw4L3JboXdi56hxvFimRlOoDVZ8 TRTYfn1rnkxhSBo7A7qaAsHIBPoSVCwtLmrvRdwo1QEnoJEyLYVTYq1ZVktepAX8BvJd 14PV6d9SCFRHcFsyokH39ynWoNuuctCx7kPlzkRjruH2uz3xHQvqnvtK1JVRxHROPCHM EgTquLEJFAmmqnNh3Y7X8/cFwuNzTvzqxJWNQmh1772QcT0xgR9JuPfYj0GTcFOgsc4c C34Q== ARC-Authentication-Results: i=1; mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=BAuNH46P; spf=pass (google.com: domain of srs0=nia/=ii=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=nia/=II=linuxfoundation.org=gregkh@kernel.org Authentication-Results: mx.google.com; dkim=pass header.i=@kernel.org header.s=default header.b=BAuNH46P; spf=pass (google.com: domain of srs0=nia/=ii=linuxfoundation.org=gregkh@kernel.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=SRS0=nia/=II=linuxfoundation.org=gregkh@kernel.org From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Kees Cook , Thomas Gleixner , David Woodhouse Subject: [PATCH 4.9 55/87] nospec: Allow getting/setting on non-current task Date: Mon, 21 May 2018 23:11:31 +0200 Message-Id: <20180521210425.207854939@linuxfoundation.org> X-Mailer: git-send-email 2.17.0 In-Reply-To: <20180521210420.222671977@linuxfoundation.org> References: <20180521210420.222671977@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-LABELS: =?utf-8?b?IlxcU2VudCI=?= X-GMAIL-THRID: =?utf-8?q?1601109953344318245?= X-GMAIL-MSGID: =?utf-8?q?1601109953344318245?= X-Mailing-List: linux-kernel@vger.kernel.org List-ID: 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook commit 7bbf1373e228840bb0295a2ca26d548ef37f448e upstream Adjust arch_prctl_get/set_spec_ctrl() to operate on tasks other than current. This is needed both for /proc/$pid/status queries and for seccomp (since thread-syncing can trigger seccomp in non-current threads). Signed-off-by: Kees Cook Signed-off-by: Thomas Gleixner Signed-off-by: David Woodhouse Signed-off-by: Greg Kroah-Hartman --- arch/x86/kernel/cpu/bugs.c | 27 ++++++++++++++++----------- include/linux/nospec.h | 7 +++++-- kernel/sys.c | 9 +++++---- 3 files changed, 26 insertions(+), 17 deletions(-) --- a/arch/x86/kernel/cpu/bugs.c +++ b/arch/x86/kernel/cpu/bugs.c @@ -529,31 +529,35 @@ static void ssb_select_mitigation() #undef pr_fmt -static int ssb_prctl_set(unsigned long ctrl) +static int ssb_prctl_set(struct task_struct *task, unsigned long ctrl) { - bool rds = !!test_tsk_thread_flag(current, TIF_RDS); + bool rds = !!test_tsk_thread_flag(task, TIF_RDS); if (ssb_mode != SPEC_STORE_BYPASS_PRCTL) return -ENXIO; if (ctrl == PR_SPEC_ENABLE) - clear_tsk_thread_flag(current, TIF_RDS); + clear_tsk_thread_flag(task, TIF_RDS); else - set_tsk_thread_flag(current, TIF_RDS); + set_tsk_thread_flag(task, TIF_RDS); - if (rds != !!test_tsk_thread_flag(current, TIF_RDS)) + /* + * If being set on non-current task, delay setting the CPU + * mitigation until it is next scheduled. + */ + if (task == current && rds != !!test_tsk_thread_flag(task, TIF_RDS)) speculative_store_bypass_update(); return 0; } -static int ssb_prctl_get(void) +static int ssb_prctl_get(struct task_struct *task) { switch (ssb_mode) { case SPEC_STORE_BYPASS_DISABLE: return PR_SPEC_DISABLE; case SPEC_STORE_BYPASS_PRCTL: - if (test_tsk_thread_flag(current, TIF_RDS)) + if (test_tsk_thread_flag(task, TIF_RDS)) return PR_SPEC_PRCTL | PR_SPEC_DISABLE; return PR_SPEC_PRCTL | PR_SPEC_ENABLE; default: @@ -563,24 +567,25 @@ static int ssb_prctl_get(void) } } -int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl) +int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which, + unsigned long ctrl) { if (ctrl != PR_SPEC_ENABLE && ctrl != PR_SPEC_DISABLE) return -ERANGE; switch (which) { case PR_SPEC_STORE_BYPASS: - return ssb_prctl_set(ctrl); + return ssb_prctl_set(task, ctrl); default: return -ENODEV; } } -int arch_prctl_spec_ctrl_get(unsigned long which) +int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which) { switch (which) { case PR_SPEC_STORE_BYPASS: - return ssb_prctl_get(); + return ssb_prctl_get(task); default: return -ENODEV; } --- a/include/linux/nospec.h +++ b/include/linux/nospec.h @@ -7,6 +7,8 @@ #define _LINUX_NOSPEC_H #include +struct task_struct; + /** * array_index_mask_nospec() - generate a ~0 mask when index < size, 0 otherwise * @index: array element index @@ -57,7 +59,8 @@ static inline unsigned long array_index_ }) /* Speculation control prctl */ -int arch_prctl_spec_ctrl_get(unsigned long which); -int arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl); +int arch_prctl_spec_ctrl_get(struct task_struct *task, unsigned long which); +int arch_prctl_spec_ctrl_set(struct task_struct *task, unsigned long which, + unsigned long ctrl); #endif /* _LINUX_NOSPEC_H */ --- a/kernel/sys.c +++ b/kernel/sys.c @@ -2074,12 +2074,13 @@ static int prctl_get_tid_address(struct } #endif -int __weak arch_prctl_spec_ctrl_get(unsigned long which) +int __weak arch_prctl_spec_ctrl_get(struct task_struct *t, unsigned long which) { return -EINVAL; } -int __weak arch_prctl_spec_ctrl_set(unsigned long which, unsigned long ctrl) +int __weak arch_prctl_spec_ctrl_set(struct task_struct *t, unsigned long which, + unsigned long ctrl) { return -EINVAL; } @@ -2285,12 +2286,12 @@ SYSCALL_DEFINE5(prctl, int, option, unsi case PR_GET_SPECULATION_CTRL: if (arg3 || arg4 || arg5) return -EINVAL; - error = arch_prctl_spec_ctrl_get(arg2); + error = arch_prctl_spec_ctrl_get(me, arg2); break; case PR_SET_SPECULATION_CTRL: if (arg4 || arg5) return -EINVAL; - error = arch_prctl_spec_ctrl_set(arg2, arg3); + error = arch_prctl_spec_ctrl_set(me, arg2, arg3); break; default: error = -EINVAL;