Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1626205
| From | Greg Kroah-Hartman <gregkh@linuxfoundation.org> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | [PATCH 4.10 67/69] mm: Tighten x86 /dev/mem with zeroing reads |
| Date | 2017-04-19 16:50 +0200 |
| Message-ID | <txZ5F-4CC-37@gated-at.bofh.it> (permalink) |
| References | <txYVX-4yJ-3@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
4.10-stable review patch. If anyone has any objections, please let me know.
------------------
From: Kees Cook <keescook@chromium.org>
commit a4866aa812518ed1a37d8ea0c881dc946409de94 upstream.
Under CONFIG_STRICT_DEVMEM, reading System RAM through /dev/mem is
disallowed. However, on x86, the first 1MB was always allowed for BIOS
and similar things, regardless of it actually being System RAM. It was
possible for heap to end up getting allocated in low 1MB RAM, and then
read by things like x86info or dd, which would trip hardened usercopy:
usercopy: kernel memory exposure attempt detected from ffff880000090000 (dma-kmalloc-256) (4096 bytes)
This changes the x86 exception for the low 1MB by reading back zeros for
System RAM areas instead of blindly allowing them. More work is needed to
extend this to mmap, but currently mmap doesn't go through usercopy, so
hardened usercopy won't Oops the kernel.
Reported-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Tested-by: Tommi Rantala <tommi.t.rantala@nokia.com>
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Brad Spengler <spender@grsecurity.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/x86/mm/init.c | 41 +++++++++++++++++++-------
drivers/char/mem.c | 82 +++++++++++++++++++++++++++++++++--------------------
2 files changed, 82 insertions(+), 41 deletions(-)
--- a/arch/x86/mm/init.c
+++ b/arch/x86/mm/init.c
@@ -643,21 +643,40 @@ void __init init_mem_mapping(void)
* devmem_is_allowed() checks to see if /dev/mem access to a certain address
* is valid. The argument is a physical page number.
*
- *
- * On x86, access has to be given to the first megabyte of ram because that area
- * contains BIOS code and data regions used by X and dosemu and similar apps.
- * Access has to be given to non-kernel-ram areas as well, these contain the PCI
- * mmio resources as well as potential bios/acpi data regions.
+ * On x86, access has to be given to the first megabyte of RAM because that
+ * area traditionally contains BIOS code and data regions used by X, dosemu,
+ * and similar apps. Since they map the entire memory range, the whole range
+ * must be allowed (for mapping), but any areas that would otherwise be
+ * disallowed are flagged as being "zero filled" instead of rejected.
+ * Access has to be given to non-kernel-ram areas as well, these contain the
+ * PCI mmio resources as well as potential bios/acpi data regions.
*/
int devmem_is_allowed(unsigned long pagenr)
{
- if (pagenr < 256)
- return 1;
- if (iomem_is_exclusive(pagenr << PAGE_SHIFT))
+ if (page_is_ram(pagenr)) {
+ /*
+ * For disallowed memory regions in the low 1MB range,
+ * request that the page be shown as all zeros.
+ */
+ if (pagenr < 256)
+ return 2;
+
+ return 0;
+ }
+
+ /*
+ * This must follow RAM test, since System RAM is considered a
+ * restricted resource under CONFIG_STRICT_IOMEM.
+ */
+ if (iomem_is_exclusive(pagenr << PAGE_SHIFT)) {
+ /* Low 1MB bypasses iomem restrictions. */
+ if (pagenr < 256)
+ return 1;
+
return 0;
- if (!page_is_ram(pagenr))
- return 1;
- return 0;
+ }
+
+ return 1;
}
void free_init_pages(char *what, unsigned long begin, unsigned long end)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -60,6 +60,10 @@ static inline int valid_mmap_phys_addr_r
#endif
#ifdef CONFIG_STRICT_DEVMEM
+static inline int page_is_allowed(unsigned long pfn)
+{
+ return devmem_is_allowed(pfn);
+}
static inline int range_is_allowed(unsigned long pfn, unsigned long size)
{
u64 from = ((u64)pfn) << PAGE_SHIFT;
@@ -75,6 +79,10 @@ static inline int range_is_allowed(unsig
return 1;
}
#else
+static inline int page_is_allowed(unsigned long pfn)
+{
+ return 1;
+}
static inline int range_is_allowed(unsigned long pfn, unsigned long size)
{
return 1;
@@ -122,23 +130,31 @@ static ssize_t read_mem(struct file *fil
while (count > 0) {
unsigned long remaining;
+ int allowed;
sz = size_inside_page(p, count);
- if (!range_is_allowed(p >> PAGE_SHIFT, count))
+ allowed = page_is_allowed(p >> PAGE_SHIFT);
+ if (!allowed)
return -EPERM;
+ if (allowed == 2) {
+ /* Show zeros for restricted memory. */
+ remaining = clear_user(buf, sz);
+ } else {
+ /*
+ * On ia64 if a page has been mapped somewhere as
+ * uncached, then it must also be accessed uncached
+ * by the kernel or data corruption may occur.
+ */
+ ptr = xlate_dev_mem_ptr(p);
+ if (!ptr)
+ return -EFAULT;
- /*
- * On ia64 if a page has been mapped somewhere as uncached, then
- * it must also be accessed uncached by the kernel or data
- * corruption may occur.
- */
- ptr = xlate_dev_mem_ptr(p);
- if (!ptr)
- return -EFAULT;
+ remaining = copy_to_user(buf, ptr, sz);
+
+ unxlate_dev_mem_ptr(p, ptr);
+ }
- remaining = copy_to_user(buf, ptr, sz);
- unxlate_dev_mem_ptr(p, ptr);
if (remaining)
return -EFAULT;
@@ -181,30 +197,36 @@ static ssize_t write_mem(struct file *fi
#endif
while (count > 0) {
+ int allowed;
+
sz = size_inside_page(p, count);
- if (!range_is_allowed(p >> PAGE_SHIFT, sz))
+ allowed = page_is_allowed(p >> PAGE_SHIFT);
+ if (!allowed)
return -EPERM;
- /*
- * On ia64 if a page has been mapped somewhere as uncached, then
- * it must also be accessed uncached by the kernel or data
- * corruption may occur.
- */
- ptr = xlate_dev_mem_ptr(p);
- if (!ptr) {
- if (written)
- break;
- return -EFAULT;
- }
+ /* Skip actual writing when a page is marked as restricted. */
+ if (allowed == 1) {
+ /*
+ * On ia64 if a page has been mapped somewhere as
+ * uncached, then it must also be accessed uncached
+ * by the kernel or data corruption may occur.
+ */
+ ptr = xlate_dev_mem_ptr(p);
+ if (!ptr) {
+ if (written)
+ break;
+ return -EFAULT;
+ }
- copied = copy_from_user(ptr, buf, sz);
- unxlate_dev_mem_ptr(p, ptr);
- if (copied) {
- written += sz - copied;
- if (written)
- break;
- return -EFAULT;
+ copied = copy_from_user(ptr, buf, sz);
+ unxlate_dev_mem_ptr(p, ptr);
+ if (copied) {
+ written += sz - copied;
+ if (written)
+ break;
+ return -EFAULT;
+ }
}
buf += sz;
Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread
[PATCH 4.10 00/69] 4.10.12-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 18/69] CIFS: store results of cifs_reopen_file to avoid infinite wait Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 20/69] perf annotate s390: Fix perf annotate error -95 (4.10 regression) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 48/69] cpufreq: Bring CPUs up even if cpufreq_online() failed Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 35/69] scsi: sr: Sanity check returned mode data Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 15/69] drm/etnaviv: fix missing unlock on error in etnaviv_gpu_submit() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 08/69] zsmalloc: expand class bit Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 11/69] drm/nouveau/mmu/nv4a: use nv04 mmu rather than the nv44 one Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 26/69] x86/vdso: Ensure vdso32_enabled gets set to valid values only Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:40 +0200
[PATCH 4.10 42/69] make skb_copy_datagram_msg() et.al. preserve ->msg_iter on error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 67/69] mm: Tighten x86 /dev/mem with zeroing reads Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 39/69] target: Avoid mappedlun symlink creation during lun shutdown Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 52/69] char: lack of bool string made CONFIG_DEVPORT always on Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 34/69] iscsi-target: Drop work-around for legacy GlobalSAN initiator Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 43/69] libnvdimm: fix blk free space accounting Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 40/69] xen, fbfront: fix connecting to backend Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 69/69] virtio-console: avoid DMA from stack Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 65/69] ACPI / EC: Use busy polling mode when GPE is not enabled Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 66/69] rtc: tegra: Implement clock handling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 41/69] [iov_iter] new privimitive: iov_iter_revert() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 37/69] scsi: qla2xxx: Add fix to read correct register value for ISP82xx. Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 16:50 +0200
[PATCH 4.10 56/69] crypto: algif_aead - Fix bogus request dereference in completion function Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 54/69] zram: do not use copy_page with non-page aligned address Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 58/69] crypto: ahash - Fix EINPROGRESS notification callback Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 61/69] [media] dvb-usb-v2: avoid use-after-free Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 36/69] scsi: sd: Consider max_xfer_blocks if opt_xfer_blocks is unusable Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 59/69] crypto: lrw - Fix use-after-free on EINPROGRESS Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 38/69] scsi: sd: Fix capacity calculation with 32-bit sector_t Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 57/69] crypto: xts - Fix use-after-free on EINPROGRESS Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 64/69] x86/xen: Fix APIC id mismatch warning on Intel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 62/69] ASoC: Intel: select DW_DMAC_CORE since its mandatory Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:20 +0200
[PATCH 4.10 55/69] ftrace: Fix function pid filter on instances Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 06/69] thp: fix MADV_DONTNEED vs. MADV_FREE race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 23/69] x86/signals: Fix lower/upper bound reporting in compat siginfo Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 45/69] libnvdimm: band aid btt vs clear poison locking Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 07/69] thp: fix MADV_DONTNEED vs clear soft dirty race Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 50/69] ftrace: Fix removing of second function probe Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 49/69] irqchip/irq-imx-gpcv2: Fix spinlock initialization Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 51/69] drm/i915/gvt: set the correct default value of CTX STATUS PTR Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 46/69] can: ifi: use correct register to read rx status Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 31/69] efi/libstub: Skip GOP with PIXEL_BLT_ONLY format Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 22/69] x86/efi: Dont try to reserve runtime regions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 25/69] x86, pmem: fix broken __copy_user_nocache cache-bypass assumptions Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 28/69] acpi, nfit, libnvdimm: fix interleave set cookie calculation (64-bit comparison) Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 27/69] x86/vdso: Plug race between mapping and ELF header setup Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 53/69] Revert "MIPS: Lantiq: Fix cascaded IRQ setup" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 32/69] efi/fb: Avoid reconfiguration of BAR that covers the framebuffer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 09/69] orangefs: free superblock when mount fails Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 03/69] tcmu: Fix possible overwrite of t_data_sgs last iov[] Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 04/69] tcmu: Fix wrongly calculating of the base_command_size Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 29/69] ACPI / scan: Set the visited flag for all enumerated devices Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 47/69] pwm: rockchip: State of PWM clock should synchronize with PWM enabled state Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 05/69] tcmu: Skip Data-Out blocks before gathering Data-In buffer for BIDI case Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 60/69] parisc: Fix get_user() for 64-bit value on 32-bit kernel Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 44/69] libnvdimm: fix reconfig_mutex, mmap_sem, and jbd2_handle lockdep splat Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:30 +0200
[PATCH 4.10 19/69] Input: xpad - add support for Razer Wildcat gamepad Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
[PATCH 4.10 17/69] CIFS: reconnect thread reschedule itself Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
[PATCH 4.10 13/69] drm/nouveau/kms/nv50: fix double dma_fence_put() when destroying plane state Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
[PATCH 4.10 02/69] audit: make sure we dont let the retry queue grow without bounds Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
[PATCH 4.10 01/69] cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
[PATCH 4.10 10/69] drm/nouveau/mpeg: mthd returns true on success now Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
[PATCH 4.10 12/69] drm/nouveau/kms/nv50: fix setting of HeadSetRasterVertBlankDmi method Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-19 17:40 +0200
Re: [PATCH 4.10 00/69] 4.10.12-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-04-19 22:40 +0200
Re: [PATCH 4.10 00/69] 4.10.12-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-20 08:40 +0200
Re: [PATCH 4.10 00/69] 4.10.12-stable review Guenter Roeck <linux@roeck-us.net> - 2017-04-20 01:30 +0200
Re: [PATCH 4.10 00/69] 4.10.12-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-04-20 08:40 +0200
csiph-web