From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B4D901170E for ; Mon, 11 Sep 2023 13:53:22 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 36A84C433C8; Mon, 11 Sep 2023 13:53:22 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1694440402; bh=JjCF7Wx0lVt8SeQDM2dFHSKWW7LA9C5vXS8TrSro9wY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=dgApSD54KPFw/fokDBJhgoAmQKUA3aZMDegDwLBMpzLZll0+mIK3cEG+FfpiwDeWN hs3BjwZOZkPLhCi3UYPEcwRyzPh1jBoHsfSUPq/zBGwb6GuzaHdCA1wRDWInbtv7p9 UJeTXcFnxjopgg2jf8uThtc6nd4yBKXnUzZnwlgU= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Russell King , Arnd Bergmann , Lecopzer Chen , Oleg Nesterov , linux-arm-kernel@lists.infradead.org, Arnd Bergmann , Kees Cook , Sasha Levin Subject: [PATCH 6.5 022/739] ARM: ptrace: Restore syscall skipping for tracers Date: Mon, 11 Sep 2023 15:37:01 +0200 Message-ID: <20230911134651.665981774@linuxfoundation.org> X-Mailer: git-send-email 2.42.0 In-Reply-To: <20230911134650.921299741@linuxfoundation.org> References: <20230911134650.921299741@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.5-stable review patch. If anyone has any objections, please let me know. ------------------ From: Kees Cook [ Upstream commit 4697b5848bd933f68ebd04836362c8de0cacaf71 ] Since commit 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall"), the seccomp selftests "syscall_errno" and "syscall_faked" have been broken. Both seccomp and PTRACE depend on using the special value of "-1" for skipping syscalls. This value wasn't working because it was getting masked by __NR_SYSCALL_MASK in both PTRACE_SET_SYSCALL and get_syscall_nr(). Explicitly test for -1 in PTRACE_SET_SYSCALL and get_syscall_nr(), leaving it exposed when present, allowing tracers to skip syscalls again. Cc: Russell King Cc: Arnd Bergmann Cc: Lecopzer Chen Cc: Oleg Nesterov Cc: linux-arm-kernel@lists.infradead.org Fixes: 4e57a4ddf6b0 ("ARM: 9107/1: syscall: always store thread_info->abi_syscall") Reviewed-by: Arnd Bergmann Link: https://lore.kernel.org/r/20230810195422.2304827-2-keescook@chromium.org Signed-off-by: Kees Cook Signed-off-by: Sasha Levin --- arch/arm/include/asm/syscall.h | 3 +++ arch/arm/kernel/ptrace.c | 5 +++-- 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/arch/arm/include/asm/syscall.h b/arch/arm/include/asm/syscall.h index dfeed440254a8..fe4326d938c18 100644 --- a/arch/arm/include/asm/syscall.h +++ b/arch/arm/include/asm/syscall.h @@ -25,6 +25,9 @@ static inline int syscall_get_nr(struct task_struct *task, if (IS_ENABLED(CONFIG_AEABI) && !IS_ENABLED(CONFIG_OABI_COMPAT)) return task_thread_info(task)->abi_syscall; + if (task_thread_info(task)->abi_syscall == -1) + return -1; + return task_thread_info(task)->abi_syscall & __NR_SYSCALL_MASK; } diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c index 2d8e2516906b6..fef32d73f9120 100644 --- a/arch/arm/kernel/ptrace.c +++ b/arch/arm/kernel/ptrace.c @@ -783,8 +783,9 @@ long arch_ptrace(struct task_struct *child, long request, break; case PTRACE_SET_SYSCALL: - task_thread_info(child)->abi_syscall = data & - __NR_SYSCALL_MASK; + if (data != -1) + data &= __NR_SYSCALL_MASK; + task_thread_info(child)->abi_syscall = data; ret = 0; break; -- 2.40.1