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From: Sasha Levin <sashal@kernel.org>
To: linux-kernel@vger.kernel.org, stable@vger.kernel.org
Cc: Nadav Amit <namit@vmware.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Andy Lutomirski <luto@amacapital.net>,
	Rick Edgecombe <rick.p.edgecombe@intel.com>,
	Peter Zijlstra <peterz@infradead.org>,
	akpm@linux-foundation.org, ard.biesheuvel@linaro.org,
	deneen.t.dock@intel.com, kernel-hardening@lists.openwall.com,
	kristen@linux.intel.com, linux_dti@icloud.com,
	will.deacon@arm.com, Andy Lutomirski <luto@kernel.org>,
	Borislav Petkov <bp@alien8.de>,
	Dave Hansen <dave.hansen@intel.com>,
	"H . Peter Anvin" <hpa@zytor.com>, Jessica Yu <jeyu@kernel.org>,
	Kees Cook <keescook@chromium.org>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	Masami Hiramatsu <mhiramat@kernel.org>,
	Rik van Riel <riel@surriel.com>, Ingo Molnar <mingo@kernel.org>,
	Sasha Levin <sashal@kernel.org>,
	netdev@vger.kernel.org, bpf@vger.kernel.org
Subject: [PATCH AUTOSEL 4.19 039/244] x86/modules: Avoid breaking W^X while loading modules
Date: Wed, 22 May 2019 15:23:05 -0400	[thread overview]
Message-ID: <20190522192630.24917-39-sashal@kernel.org> (raw)
In-Reply-To: <20190522192630.24917-1-sashal@kernel.org>

From: Nadav Amit <namit@vmware.com>

[ Upstream commit f2c65fb3221adc6b73b0549fc7ba892022db9797 ]

When modules and BPF filters are loaded, there is a time window in
which some memory is both writable and executable. An attacker that has
already found another vulnerability (e.g., a dangling pointer) might be
able to exploit this behavior to overwrite kernel code. Prevent having
writable executable PTEs in this stage.

In addition, avoiding having W+X mappings can also slightly simplify the
patching of modules code on initialization (e.g., by alternatives and
static-key), as would be done in the next patch. This was actually the
main motivation for this patch.

To avoid having W+X mappings, set them initially as RW (NX) and after
they are set as RO set them as X as well. Setting them as executable is
done as a separate step to avoid one core in which the old PTE is cached
(hence writable), and another which sees the updated PTE (executable),
which would break the W^X protection.

Suggested-by: Thomas Gleixner <tglx@linutronix.de>
Suggested-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Nadav Amit <namit@vmware.com>
Signed-off-by: Rick Edgecombe <rick.p.edgecombe@intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: <akpm@linux-foundation.org>
Cc: <ard.biesheuvel@linaro.org>
Cc: <deneen.t.dock@intel.com>
Cc: <kernel-hardening@lists.openwall.com>
Cc: <kristen@linux.intel.com>
Cc: <linux_dti@icloud.com>
Cc: <will.deacon@arm.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Jessica Yu <jeyu@kernel.org>
Cc: Kees Cook <keescook@chromium.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Masami Hiramatsu <mhiramat@kernel.org>
Cc: Rik van Riel <riel@surriel.com>
Link: https://lkml.kernel.org/r/20190426001143.4983-12-namit@vmware.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
 arch/x86/kernel/alternative.c | 28 +++++++++++++++++++++-------
 arch/x86/kernel/module.c      |  2 +-
 include/linux/filter.h        |  1 +
 kernel/module.c               |  5 +++++
 4 files changed, 28 insertions(+), 8 deletions(-)

diff --git a/arch/x86/kernel/alternative.c b/arch/x86/kernel/alternative.c
index b9d5e7c9ef43e..918a23704c0c5 100644
--- a/arch/x86/kernel/alternative.c
+++ b/arch/x86/kernel/alternative.c
@@ -662,15 +662,29 @@ void __init alternative_instructions(void)
  * handlers seeing an inconsistent instruction while you patch.
  */
 void *__init_or_module text_poke_early(void *addr, const void *opcode,
-					      size_t len)
+				       size_t len)
 {
 	unsigned long flags;
-	local_irq_save(flags);
-	memcpy(addr, opcode, len);
-	local_irq_restore(flags);
-	sync_core();
-	/* Could also do a CLFLUSH here to speed up CPU recovery; but
-	   that causes hangs on some VIA CPUs. */
+
+	if (boot_cpu_has(X86_FEATURE_NX) &&
+	    is_module_text_address((unsigned long)addr)) {
+		/*
+		 * Modules text is marked initially as non-executable, so the
+		 * code cannot be running and speculative code-fetches are
+		 * prevented. Just change the code.
+		 */
+		memcpy(addr, opcode, len);
+	} else {
+		local_irq_save(flags);
+		memcpy(addr, opcode, len);
+		local_irq_restore(flags);
+		sync_core();
+
+		/*
+		 * Could also do a CLFLUSH here to speed up CPU recovery; but
+		 * that causes hangs on some VIA CPUs.
+		 */
+	}
 	return addr;
 }
 
diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
index f58336af095c9..6645f123419c6 100644
--- a/arch/x86/kernel/module.c
+++ b/arch/x86/kernel/module.c
@@ -87,7 +87,7 @@ void *module_alloc(unsigned long size)
 	p = __vmalloc_node_range(size, MODULE_ALIGN,
 				    MODULES_VADDR + get_module_load_offset(),
 				    MODULES_END, GFP_KERNEL,
-				    PAGE_KERNEL_EXEC, 0, NUMA_NO_NODE,
+				    PAGE_KERNEL, 0, NUMA_NO_NODE,
 				    __builtin_return_address(0));
 	if (p && (kasan_module_alloc(p, size) < 0)) {
 		vfree(p);
diff --git a/include/linux/filter.h b/include/linux/filter.h
index 037610845892b..6afc2e2d5aeda 100644
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -684,6 +684,7 @@ static inline void bpf_prog_unlock_ro(struct bpf_prog *fp)
 static inline void bpf_jit_binary_lock_ro(struct bpf_binary_header *hdr)
 {
 	set_memory_ro((unsigned long)hdr, hdr->pages);
+	set_memory_x((unsigned long)hdr, hdr->pages);
 }
 
 static inline void bpf_jit_binary_unlock_ro(struct bpf_binary_header *hdr)
diff --git a/kernel/module.c b/kernel/module.c
index 38bf28b5cc202..f797c6ace7121 100644
--- a/kernel/module.c
+++ b/kernel/module.c
@@ -1949,8 +1949,13 @@ void module_enable_ro(const struct module *mod, bool after_init)
 		return;
 
 	frob_text(&mod->core_layout, set_memory_ro);
+	frob_text(&mod->core_layout, set_memory_x);
+
 	frob_rodata(&mod->core_layout, set_memory_ro);
+
 	frob_text(&mod->init_layout, set_memory_ro);
+	frob_text(&mod->init_layout, set_memory_x);
+
 	frob_rodata(&mod->init_layout, set_memory_ro);
 
 	if (after_init)
-- 
2.20.1


  parent reply	other threads:[~2019-05-22 19:27 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-05-22 19:22 [PATCH AUTOSEL 4.19 001/244] gfs2: Fix lru_count going negative Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 002/244] cxgb4: Fix error path in cxgb4_init_module Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 003/244] NFS: make nfs_match_client killable Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 004/244] IB/hfi1: Fix WQ_MEM_RECLAIM warning Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 005/244] gfs2: Fix occasional glock use-after-free Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 006/244] mmc: core: Verify SD bus width Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 007/244] batman-adv: mcast: fix multicast tt/tvlv worker locking Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 008/244] tools/bpf: fix perf build error with uClibc (seen on ARC) Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 009/244] selftests/bpf: set RLIMIT_MEMLOCK properly for test_libbpf_open.c Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 010/244] bpftool: exclude bash-completion/bpftool from .gitignore pattern Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 011/244] dmaengine: tegra210-dma: free dma controller in remove() Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 012/244] net: ena: gcc 8: fix compilation warning Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 013/244] hv_netvsc: fix race that may miss tx queue wakeup Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 014/244] orangefs: truncate before updating size Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 015/244] Bluetooth: Ignore CC events not matching the last HCI command Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 016/244] pinctrl: zte: fix leaked of_node references Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 017/244] ASoC: Intel: kbl_da7219_max98357a: Map BTN_0 to KEY_PLAYPAUSE Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 018/244] usb: dwc2: gadget: Increase descriptors count for ISOC's Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 019/244] usb: dwc3: move synchronize_irq() out of the spinlock protected block Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 020/244] ASoC: hdmi-codec: unlock the device on startup errors Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 021/244] leds: avoid races with workqueue Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 022/244] powerpc/perf: Return accordingly on invalid chip-id in Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 023/244] powerpc/boot: Fix missing check of lseek() return value Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 024/244] powerpc/perf: Fix loop exit condition in nest_imc_event_init Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 025/244] ASoC: imx: fix fiq dependencies Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 026/244] spi: pxa2xx: fix SCR (divisor) calculation Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 027/244] brcm80211: potential NULL dereference in brcmf_cfg80211_vndr_cmds_dcmd_handler() Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 028/244] ACPI / property: fix handling of data_nodes in acpi_get_next_subnode() Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 029/244] drm/nouveau/bar/nv50: ensure BAR is mapped Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 030/244] media: stm32-dcmi: return appropriate error codes during probe Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 031/244] ARM: vdso: Remove dependency with the arch_timer driver internals Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 032/244] arm64: Fix compiler warning from pte_unmap() with -Wunused-but-set-variable Sasha Levin
2019-05-22 19:22 ` [PATCH AUTOSEL 4.19 033/244] powerpc/watchdog: Use hrtimers for per-CPU heartbeat Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 034/244] sched/cpufreq: Fix kobject memleak Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 035/244] scsi: qla2xxx: Fix a qla24xx_enable_msix() error path Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 036/244] scsi: qla2xxx: Fix abort handling in tcm_qla2xxx_write_pending() Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 037/244] scsi: qla2xxx: Avoid that lockdep complains about unsafe locking in tcm_qla2xxx_close_session() Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 038/244] scsi: qla2xxx: Fix hardirq-unsafe locking Sasha Levin
2019-05-22 19:23 ` Sasha Levin [this message]
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 040/244] Btrfs: fix data bytes_may_use underflow with fallocate due to failed quota reserve Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 041/244] btrfs: fix panic during relocation after ENOSPC before writeback happens Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 042/244] btrfs: Don't panic when we can't find a root key Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 043/244] iwlwifi: pcie: don't crash on invalid RX interrupt Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 044/244] rtc: 88pm860x: prevent use-after-free on device remove Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 045/244] rtc: stm32: manage the get_irq probe defer case Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 046/244] scsi: qedi: Abort ep termination if offload not scheduled Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 047/244] s390/kexec_file: Fix detection of text segment in ELF loader Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 048/244] sched/nohz: Run NOHZ idle load balancer on HK_FLAG_MISC CPUs Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 049/244] w1: fix the resume command API Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 050/244] s390: qeth: address type mismatch warning Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 051/244] dmaengine: pl330: _stop: clear interrupt status Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 052/244] mac80211/cfg80211: update bss channel on channel switch Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 053/244] USB: serial: fix initial-termios handling Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 054/244] libbpf: fix samples/bpf build failure due to undefined UINT32_MAX Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 055/244] slimbus: fix a potential NULL pointer dereference in of_qcom_slim_ngd_register Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 056/244] driver core: platform: Fix the usage of platform device name(pdev->name) Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 057/244] ASoC: fsl_sai: Update is_slave_mode with correct value Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 058/244] mwifiex: prevent an array overflow Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 059/244] rsi: Fix NULL pointer dereference in kmalloc Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 060/244] net: cw1200: fix a NULL pointer dereference Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 061/244] at76c50x-usb: Don't register led_trigger if usb_register_driver failed Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 062/244] nvme: set 0 capacity if namespace block size exceeds PAGE_SIZE Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 063/244] nvme-rdma: fix a NULL deref when an admin connect times out Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 064/244] ssb: Fix possible NULL pointer dereference in ssb_host_pcmcia_exit Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 065/244] crypto: sun4i-ss - Fix invalid calculation of hash end Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 066/244] bcache: avoid potential memleak of list of journal_replay(s) in the CACHE_SYNC branch of run_cache_set Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 067/244] bcache: return error immediately in bch_journal_replay() Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 068/244] bcache: fix failure in journal relplay Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 069/244] bcache: add failure check to run_cache_set() for journal replay Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 070/244] bcache: avoid clang -Wunintialized warning Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 071/244] RDMA/cma: Consider scope_id while binding to ipv6 ll address Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 072/244] vfio-ccw: Do not call flush_workqueue while holding the spinlock Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 073/244] vfio-ccw: Release any channel program when releasing/removing vfio-ccw mdev Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 074/244] x86/build: Move _etext to actual end of .text Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 075/244] smpboot: Place the __percpu annotation correctly Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 076/244] x86/mm: Remove in_nmi() warning from 64-bit implementation of vmalloc_fault() Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 077/244] mlxsw: spectrum_router: Prevent ipv6 gateway with v4 route via replace and append Sasha Levin
2019-05-22 19:29   ` David Ahern
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 078/244] mm/uaccess: Use 'unsigned long' to placate UBSAN warnings on older GCC versions Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 079/244] Bluetooth: hci_qca: Give enough time to ROME controller to bootup Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 080/244] HID: logitech-hidpp: use RAP instead of FAP to get the protocol version Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 081/244] pinctrl: pistachio: fix leaked of_node references Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 082/244] pinctrl: samsung: " Sasha Levin
2019-05-22 19:23 ` [PATCH AUTOSEL 4.19 083/244] clk: rockchip: undo several noc and special clocks as critical on rk3288 Sasha Levin

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