[PATCH v2 00/63] Introduce strict memcpy() bounds checking

Kees Cook
2021-08-18T06:06:11Z

Hi,

This patch series (based on next-20210816) implements stricter (no struct
member overflows) bounds checking for memcpy(), memmove(), and memset()
under CONFIG_FORTIFY_SOURCE. To quote a later patch in the series:

tl;dr: In order to eliminate a large class of common buffer overflow
flaws that continue to persist in the kernel, have memcpy() (under
CONFIG_FORTIFY_SOURCE) perform bounds checking of the destination struct
member when they have a known size. This would have caught all of the
memcpy()-related buffer write overflow flaws identified in at least the
last three years.

As this series introduces various helpers and performs several phases of
treewide cleanups, I'm expecting to carry this series in my tree, so I'd
love to get some Reviews and Acks. Given the size, I've mostly aimed this
series at various mailing lists, otherwise the CC size got really big. :)

I have separated a few things off of this submission, as things continue
to grow:
- run-time bounds checking (which now has a better solution for unknown
bounds besides "oh well")
- __alloc_size enablement (sent separately[1])
- -Warray-bounds enablement (several cleanups have been sent)

The remaining portions (here) haven't seen as much change, so I think
it's better to get these compile-time portions landed first -- they're
big enough. My intention is to put this in -next soon via my "overflow"
tree, assuming people are happy with it. :)

Another random thing of note, I'm using the "Enhanced-by:" tag to mean
"this was improved by...", inspired by the existing "Fixed-by:" tag (for
"folded fixes"). "Fixed-by:" seemed inaccurate (it wasn't broken; it is
just better now), and "Suggested-by:" seemed too nebulous (what was
suggested?).

Thanks!

-Kees

[1] https://lore.kernel.org/lkml/20210818050841.2226600-1-keescook@chromium.org/

v2:
- fix CC_IS_CLANG typo (nathan)
- bug.h hunk moved later (ndesaulnier)
- various commit log typos (ndesaulnier)
- omap3isp: fix read source (gustavo)
- struct_group can be variadic (rasmus)
- add struct_group_tagged (dan williams)
- move raw __struct_group() to UAPI (gregkh, dan vetter)
- ibmvscsi: add BUILD_BUG_ON() size checks
- net: use memset_after() instead of struct_group() (jakob)
- swap some memset_after() to memset_startat() for readability
- add missing __NO_FORTIFY to arm boot stub (lkp)
- powerpc signal32 struct_group() added (lkp)
- powerpc sata_fsl struct_group() added
- add fortify failure condition arguments to warning funcs to assist debugging
- add ray_cs compile-time fix
- add flexcan compile-time fix
- add af_iucv compile-time fix
- fix dropped strcpy() compile-time write overflow check
- add missing strscpy() compile-time read overflow check
- fix more boot stub build instances where fortification must be disabled
- add reviewed-bys/acks
v1: https://lore.kernel.org/lkml/20210727205855.411487-1-keescook@chromium.org/

Specifically, this series is logically split into several steps:

Clean up remaining simple compile-time memcpy() warnings:
ipw2x00: Avoid field-overflowing memcpy()
net/mlx5e: Avoid field-overflowing memcpy()
rpmsg: glink: Replace strncpy() with strscpy_pad()
pcmcia: ray_cs: Split memcpy() to avoid bounds check warning

Introduce struct_group() and apply it treewide to avoid compile-time
memcpy() warnings:
stddef: Introduce struct_group() helper macro
cxl/core: Replace unions with struct_group()
skbuff: Switch structure bounds to struct_group()
bnxt_en: Use struct_group_attr() for memcpy() region
mwl8k: Use struct_group() for memcpy() region
libertas: Use struct_group() for memcpy() region
libertas_tf: Use struct_group() for memcpy() region
thermal: intel: int340x_thermal: Use struct_group() for memcpy() region
iommu/amd: Use struct_group() for memcpy() region
cxgb3: Use struct_group() for memcpy() region
intersil: Use struct_group() for memcpy() region
cxgb4: Use struct_group() for memcpy() region
bnx2x: Use struct_group() for memcpy() region
drm/amd/pm: Use struct_group() for memcpy() region
staging: wlan-ng: Use struct_group() for memcpy() region
drm/mga/mga_ioc32: Use struct_group() for memcpy() region
net/mlx5e: Use struct_group() for memcpy() region
HID: cp2112: Use struct_group() for memcpy() region
media: omap3isp: Use struct_group() for memcpy() region
sata_fsl: Use struct_group() for memcpy() region

Prepare fortify for additional hardening:
compiler_types.h: Remove __compiletime_object_size()
lib/string: Move helper functions out of string.c
fortify: Move remaining fortify helpers into fortify-string.h
fortify: Explicitly disable Clang support
fortify: Fix dropped strcpy() compile-time write overflow check
fortify: Prepare to improve strnlen() and strlen() warnings
fortify: Allow strlen() and strnlen() to pass compile-time known lengths

Add compile-time and run-time tests:
fortify: Add compile-time FORTIFY_SOURCE tests
lib: Introduce CONFIG_TEST_MEMCPY

Enable new compile-time memcpy() and memmove() bounds checking:
fortify: Detect struct member overflows in memcpy() at compile-time
fortify: Detect struct member overflows in memmove() at compile-time

Clean up remaining simple compile-time memset() warnings:
scsi: ibmvscsi: Avoid multi-field memset() overflow by aiming at srp

Introduce memset_after() and memset_startat() helpers and apply them
(and struct_group()):
string.h: Introduce memset_after() for wiping trailing members/padding
xfrm: Use memset_after() to clear padding
ipv6: Use memset_after() to zero rt6_info
netfilter: conntrack: Use memset_startat() to zero struct nf_conn
net: 802: Use memset_startat() to clear struct fields
net: dccp: Use memset_startat() for TP zeroing
net: qede: Use memset_startat() for counters
mac80211: Use memset_after() to clear tx status
ath11k: Use memset_startat() for clearing queue descriptors
iw_cxgb4: Use memset_startat() for cpl_t5_pass_accept_rpl
intel_th: msu: Use memset_startat() for clearing hw header
IB/mthca: Use memset_startat() for clearing mpt_entry
btrfs: Use memset_startat() to clear end of struct
tracing: Use memset_startat() to zero struct trace_iterator
drbd: Use struct_group() to zero algs
cm4000_cs: Use struct_group() to zero struct cm4000_dev region
KVM: x86: Use struct_group() to zero decode cache
dm integrity: Use struct_group() to zero struct journal_sector
HID: roccat: Use struct_group() to zero kone_mouse_event
RDMA/mlx5: Use struct_group() to zero struct mlx5_ib_mr
powerpc/signal32: Use struct_group() to zero spe regs
ethtool: stats: Use struct_group() to clear all stats at once
can: flexcan: Use struct_group() to zero struct flexcan_regs regions
net/af_iucv: Use struct_group() to zero struct iucv_sock region
powerpc: Split memset() to avoid multi-field overflow

Enable new compile-time memset() bounds checking:
fortify: Detect struct member overflows in memset() at compile-time

Enable Clang support:
fortify: Work around Clang inlining bugs

arch/arm/boot/compressed/string.c | 1 +
arch/powerpc/include/asm/processor.h | 6 +-
arch/powerpc/kernel/signal_32.c | 6 +-
arch/s390/lib/string.c | 3 +
arch/x86/boot/compressed/misc.c | 3 +-
arch/x86/boot/compressed/misc.h | 2 +
arch/x86/boot/compressed/pgtable_64.c | 2 +
arch/x86/kvm/emulate.c | 3 +-
arch/x86/kvm/kvm_emulate.h | 19 +-
arch/x86/lib/memcpy_32.c | 1 +
arch/x86/lib/string_32.c | 1 +
drivers/ata/sata_fsl.c | 10 +-
drivers/block/drbd/drbd_main.c | 3 +-
drivers/block/drbd/drbd_protocol.h | 6 +-
drivers/block/drbd/drbd_receiver.c | 3 +-
drivers/char/pcmcia/cm4000_cs.c | 9 +-
drivers/cxl/cxl.h | 61 +---
drivers/gpu/drm/amd/include/atomfirmware.h | 9 +-
.../drm/amd/pm/inc/smu11_driver_if_arcturus.h | 3 +-
.../drm/amd/pm/inc/smu11_driver_if_navi10.h | 3 +-
.../amd/pm/inc/smu13_driver_if_aldebaran.h | 3 +-
.../gpu/drm/amd/pm/swsmu/smu11/arcturus_ppt.c | 6 +-
.../gpu/drm/amd/pm/swsmu/smu11/navi10_ppt.c | 12 +-
.../drm/amd/pm/swsmu/smu13/aldebaran_ppt.c | 6 +-
drivers/gpu/drm/mga/mga_ioc32.c | 27 +-
drivers/hid/hid-cp2112.c | 14 +-
drivers/hid/hid-roccat-kone.c | 2 +-
drivers/hid/hid-roccat-kone.h | 12 +-
drivers/hwtracing/intel_th/msu.c | 4 +-
drivers/infiniband/hw/cxgb4/cm.c | 5 +-
drivers/infiniband/hw/mlx5/mlx5_ib.h | 4 +-
drivers/infiniband/hw/mthca/mthca_mr.c | 3 +-
drivers/iommu/amd/init.c | 9 +-
drivers/macintosh/smu.c | 3 +-
drivers/md/dm-integrity.c | 9 +-
drivers/media/platform/omap3isp/ispstat.c | 5 +-
drivers/net/can/flexcan.c | 68 ++--
.../net/ethernet/broadcom/bnx2x/bnx2x_stats.c | 7 +-
.../net/ethernet/broadcom/bnx2x/bnx2x_stats.h | 14 +-
drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.c | 4 +-
drivers/net/ethernet/broadcom/bnxt/bnxt_dcb.h | 14 +-
drivers/net/ethernet/chelsio/cxgb3/sge.c | 9 +-
drivers/net/ethernet/chelsio/cxgb4/sge.c | 8 +-
drivers/net/ethernet/chelsio/cxgb4/t4_msg.h | 2 +-
drivers/net/ethernet/chelsio/cxgb4/t4fw_api.h | 10 +-
drivers/net/ethernet/chelsio/cxgb4vf/sge.c | 7 +-
drivers/net/ethernet/mellanox/mlx5/core/en.h | 4 +-
.../net/ethernet/mellanox/mlx5/core/en/xdp.c | 4 +-
.../net/ethernet/mellanox/mlx5/core/en_tx.c | 2 +-
drivers/net/ethernet/qlogic/qede/qede_main.c | 2 +-
drivers/net/wireguard/queueing.h | 4 +-
drivers/net/wireless/ath/ath11k/hal_rx.c | 13 +-
drivers/net/wireless/ath/carl9170/tx.c | 11 +-
.../net/wireless/intel/ipw2x00/libipw_rx.c | 56 +---
.../net/wireless/intersil/hostap/hostap_hw.c | 5 +-
.../wireless/intersil/hostap/hostap_wlan.h | 14 +-
drivers/net/wireless/intersil/p54/txrx.c | 6 +-
drivers/net/wireless/marvell/libertas/host.h | 10 +-
drivers/net/wireless/marvell/libertas/tx.c | 5 +-
.../marvell/libertas_tf/libertas_tf.h | 10 +-
.../net/wireless/marvell/libertas_tf/main.c | 3 +-
drivers/net/wireless/marvell/mwl8k.c | 10 +-
drivers/net/wireless/ray_cs.c | 4 +-
drivers/rpmsg/qcom_glink_native.c | 2 +-
drivers/scsi/ibmvscsi/ibmvscsi.c | 3 +-
drivers/staging/wlan-ng/hfa384x.h | 16 +-
drivers/staging/wlan-ng/hfa384x_usb.c | 4 +-
.../intel/int340x_thermal/acpi_thermal_rel.c | 5 +-
.../intel/int340x_thermal/acpi_thermal_rel.h | 48 +--
fs/btrfs/root-tree.c | 6 +-
include/linux/compiler-gcc.h | 2 -
include/linux/compiler_types.h | 4 -
include/linux/fortify-string.h | 308 +++++++++++++-----
include/linux/if_vlan.h | 6 +-
include/linux/skbuff.h | 9 +-
include/linux/stddef.h | 47 +++
include/linux/string.h | 43 ++-
include/linux/thread_info.h | 2 +-
include/net/iucv/af_iucv.h | 10 +-
include/net/mac80211.h | 7 +-
include/uapi/drm/mga_drm.h | 22 +-
include/uapi/linux/omap3isp.h | 21 +-
include/uapi/linux/stddef.h | 21 ++
kernel/trace/trace.c | 4 +-
lib/.gitignore | 2 +
lib/Kconfig.debug | 7 +
lib/Makefile | 35 ++
lib/string.c | 210 +-----------
lib/string_helpers.c | 201 ++++++++++++
lib/test_fortify/read_overflow-memchr.c | 5 +
lib/test_fortify/read_overflow-memchr_inv.c | 5 +
lib/test_fortify/read_overflow-memcmp.c | 5 +
lib/test_fortify/read_overflow-memscan.c | 5 +
lib/test_fortify/read_overflow2-memcmp.c | 5 +
lib/test_fortify/read_overflow2-memcpy.c | 5 +
lib/test_fortify/read_overflow2-memmove.c | 5 +
.../read_overflow2_field-memcpy.c | 5 +
.../read_overflow2_field-memmove.c | 5 +
lib/test_fortify/test_fortify.h | 35 ++
lib/test_fortify/write_overflow-memcpy.c | 5 +
lib/test_fortify/write_overflow-memmove.c | 5 +
lib/test_fortify/write_overflow-memset.c | 5 +
lib/test_fortify/write_overflow-strcpy-lit.c | 5 +
lib/test_fortify/write_overflow-strcpy.c | 5 +
lib/test_fortify/write_overflow-strlcpy-src.c | 5 +
lib/test_fortify/write_overflow-strlcpy.c | 5 +
lib/test_fortify/write_overflow-strncpy-src.c | 5 +
lib/test_fortify/write_overflow-strncpy.c | 5 +
lib/test_fortify/write_overflow-strscpy.c | 5 +
.../write_overflow_field-memcpy.c | 5 +
.../write_overflow_field-memmove.c | 5 +
.../write_overflow_field-memset.c | 5 +
lib/test_memcpy.c | 288 ++++++++++++++++
net/802/hippi.c | 2 +-
net/core/skbuff.c | 14 +-
net/dccp/trace.h | 4 +-
net/ethtool/stats.c | 15 +-
net/ipv6/route.c | 4 +-
net/iucv/af_iucv.c | 2 +-
net/netfilter/nf_conntrack_core.c | 4 +-
net/xfrm/xfrm_policy.c | 4 +-
net/xfrm/xfrm_user.c | 2 +-
scripts/test_fortify.sh | 59 ++++
security/Kconfig | 3 +
124 files changed, 1489 insertions(+), 686 deletions(-)
create mode 100644 lib/test_fortify/read_overflow-memchr.c
create mode 100644 lib/test_fortify/read_overflow-memchr_inv.c
create mode 100644 lib/test_fortify/read_overflow-memcmp.c
create mode 100644 lib/test_fortify/read_overflow-memscan.c
create mode 100644 lib/test_fortify/read_overflow2-memcmp.c
create mode 100644 lib/test_fortify/read_overflow2-memcpy.c
create mode 100644 lib/test_fortify/read_overflow2-memmove.c
create mode 100644 lib/test_fortify/read_overflow2_field-memcpy.c
create mode 100644 lib/test_fortify/read_overflow2_field-memmove.c
create mode 100644 lib/test_fortify/test_fortify.h
create mode 100644 lib/test_fortify/write_overflow-memcpy.c
create mode 100644 lib/test_fortify/write_overflow-memmove.c
create mode 100644 lib/test_fortify/write_overflow-memset.c
create mode 100644 lib/test_fortify/write_overflow-strcpy-lit.c
create mode 100644 lib/test_fortify/write_overflow-strcpy.c
create mode 100644 lib/test_fortify/write_overflow-strlcpy-src.c
create mode 100644 lib/test_fortify/write_overflow-strlcpy.c
create mode 100644 lib/test_fortify/write_overflow-strncpy-src.c
create mode 100644 lib/test_fortify/write_overflow-strncpy.c
create mode 100644 lib/test_fortify/write_overflow-strscpy.c
create mode 100644 lib/test_fortify/write_overflow_field-memcpy.c
create mode 100644 lib/test_fortify/write_overflow_field-memmove.c
create mode 100644 lib/test_fortify/write_overflow_field-memset.c
create mode 100644 lib/test_memcpy.c
create mode 100644 scripts/test_fortify.sh

--
2.30.2