From patchwork Tue Mar 31 04:48:20 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Russell Currey X-Patchwork-Id: 11466713 Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 1B7B8912 for ; Tue, 31 Mar 2020 04:49:17 +0000 (UTC) Received: from mother.openwall.net (mother.openwall.net [195.42.179.200]) by mail.kernel.org (Postfix) with SMTP id 720C1206DB for ; Tue, 31 Mar 2020 04:49:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=russell.cc header.i=@russell.cc header.b="aa7Y09bC"; dkim=pass (2048-bit key) header.d=messagingengine.com header.i=@messagingengine.com header.b="pJiRJMWO" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 720C1206DB Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=russell.cc Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kernel-hardening-return-18316-patchwork-kernel-hardening=patchwork.kernel.org@lists.openwall.com Received: (qmail 17772 invoked by uid 550); 31 Mar 2020 04:49:01 -0000 Mailing-List: contact kernel-hardening-help@lists.openwall.com; run by ezmlm Precedence: bulk List-Post: List-Help: List-Unsubscribe: List-Subscribe: List-ID: Delivered-To: mailing list kernel-hardening@lists.openwall.com Received: (qmail 17599 invoked from network); 31 Mar 2020 04:49:00 -0000 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=russell.cc; h= from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; s=fm1; bh=j31fQE86XUAg1 3xgkmTRfBdrUL53tEWPF3K3/cROCJY=; b=aa7Y09bC6z7iniz0c7hM8dl8Lm+ZJ U7X0FwcIHe6BCfTuCbZUxmeSLqI9R/Oib4nlnnZJJ2P/4Rk0IpF+peaTlH2r9Cxi WbSt6Tf6bRo2qUYjWS5WToE3JJOvM0tzMb1ZDaNHAeueiPNyqQXdcssot99jjcPx xH9a6W/xzElveLSjy4bkDX31jsqdX2p9djbd+93sSnb4eAYSa4+5qXmOkzl1Knfk O1FRR83M1ayCmUdEyb3zsph41xRp8ydHWW69qTHg7hp25vgDz9Ii7jNrhplTbbY5 HNoqTGBfuMmSGc21yBg7ATM5e9yA8VFZJpElyB/c5DgMDFGE4NjntLacA== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:date:from :in-reply-to:message-id:mime-version:references:subject:to :x-me-proxy:x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s= fm2; bh=j31fQE86XUAg13xgkmTRfBdrUL53tEWPF3K3/cROCJY=; b=pJiRJMWO qvZolekZGS4avsQ6fP9dvS4SXVwn0OOTg+1mY9bKUgW9W4JdxfnPhyInf5P9IG4a l3AcQcDcyUd0FpQnpWWkFZOOyhPJebVrxEqQw6Cy33h0jNDMoLh0cS0lxCQ50JMS +5Yk6ezkAq+MnLJZqxWq1Z9TLHqPJOJ2jLmdD+Fjstu3oZUKlmB5+d//dhaWVSjh lFh8d+EPHdI5y4+tlHw76kIJCX0iWCJqyTc1INvXn92j8wlQ5sorNy3jm/j/Q4te OHT3Bs5IzJuvNTNgiEbT6TsN42bRL9V3duk7xQHzNIkgLMHBRkwXxgCmQ/QhFCvj 5Qx+9d0m4qe4sg== X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrudeiiedgkeeiucetufdoteggodetrfdotf fvucfrrhhofhhilhgvmecuhfgrshhtofgrihhlpdfqfgfvpdfurfetoffkrfgpnffqhgen uceurghilhhouhhtmecufedttdenucgfrhhlucfvnfffucdluddtmdenucfjughrpefhvf fufffkofgjfhgggfestdekredtredttdenucfhrhhomheptfhushhsvghllhcuvehurhhr vgihuceorhhushgtuhhrsehruhhsshgvlhhlrdgttgeqnecukfhppeduvddurdeghedrvd duvddrvdefleenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhr ohhmpehruhhstghurhesrhhushhsvghllhdrtggt X-ME-Proxy: From: Russell Currey To: linuxppc-dev@lists.ozlabs.org Cc: Russell Currey , christophe.leroy@c-s.fr, mpe@ellerman.id.au, ajd@linux.ibm.com, dja@axtens.net, npiggin@gmail.com, kernel-hardening@lists.openwall.com Subject: [PATCH v7 2/7] powerpc/kprobes: Mark newly allocated probes as RO Date: Tue, 31 Mar 2020 15:48:20 +1100 Message-Id: <20200331044825.591653-3-ruscur@russell.cc> X-Mailer: git-send-email 2.26.0 In-Reply-To: <20200331044825.591653-1-ruscur@russell.cc> References: <20200331044825.591653-1-ruscur@russell.cc> MIME-Version: 1.0 With CONFIG_STRICT_KERNEL_RWX=y and CONFIG_KPROBES=y, there will be one W+X page at boot by default. This can be tested with CONFIG_PPC_PTDUMP=y and CONFIG_PPC_DEBUG_WX=y set, and checking the kernel log during boot. powerpc doesn't implement its own alloc() for kprobes like other architectures do, but we couldn't immediately mark RO anyway since we do a memcpy to the page we allocate later. After that, nothing should be allowed to modify the page, and write permissions are removed well before the kprobe is armed. The memcpy() would fail if >1 probes were allocated, so use patch_instruction() instead which is safe for RO. Reviewed-by: Daniel Axtens Signed-off-by: Russell Currey Signed-off-by: Christophe Leroy --- arch/powerpc/kernel/kprobes.c | 17 +++++++++++++---- 1 file changed, 13 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kernel/kprobes.c b/arch/powerpc/kernel/kprobes.c index 2d27ec4feee4..bfab91ded234 100644 --- a/arch/powerpc/kernel/kprobes.c +++ b/arch/powerpc/kernel/kprobes.c @@ -24,6 +24,8 @@ #include #include #include +#include +#include DEFINE_PER_CPU(struct kprobe *, current_kprobe) = NULL; DEFINE_PER_CPU(struct kprobe_ctlblk, kprobe_ctlblk); @@ -102,6 +104,16 @@ kprobe_opcode_t *kprobe_lookup_name(const char *name, unsigned int offset) return addr; } +void *alloc_insn_page(void) +{ + void *page = vmalloc_exec(PAGE_SIZE); + + if (page) + set_memory_ro((unsigned long)page, 1); + + return page; +} + int arch_prepare_kprobe(struct kprobe *p) { int ret = 0; @@ -124,11 +136,8 @@ int arch_prepare_kprobe(struct kprobe *p) } if (!ret) { - memcpy(p->ainsn.insn, p->addr, - MAX_INSN_SIZE * sizeof(kprobe_opcode_t)); + patch_instruction(p->ainsn.insn, *p->addr); p->opcode = *p->addr; - flush_icache_range((unsigned long)p->ainsn.insn, - (unsigned long)p->ainsn.insn + sizeof(kprobe_opcode_t)); } p->ainsn.boostable = 0;