linux/Documentation
Eric Biggers 705ac26aed fscrypt: return -EXDEV for incompatible rename or link into encrypted dir
commit f5e55e777c upstream.

Currently, trying to rename or link a regular file, directory, or
symlink into an encrypted directory fails with EPERM when the source
file is unencrypted or is encrypted with a different encryption policy,
and is on the same mountpoint.  It is correct for the operation to fail,
but the choice of EPERM breaks tools like 'mv' that know to copy rather
than rename if they see EXDEV, but don't know what to do with EPERM.

Our original motivation for EPERM was to encourage users to securely
handle their data.  Encrypting files by "moving" them into an encrypted
directory can be insecure because the unencrypted data may remain in
free space on disk, where it can later be recovered by an attacker.
It's much better to encrypt the data from the start, or at least try to
securely delete the source data e.g. using the 'shred' program.

However, the current behavior hasn't been effective at achieving its
goal because users tend to be confused, hack around it, and complain;
see e.g. https://github.com/google/fscrypt/issues/76.  And in some cases
it's actually inconsistent or unnecessary.  For example, 'mv'-ing files
between differently encrypted directories doesn't work even in cases
where it can be secure, such as when in userspace the same passphrase
protects both directories.  Yet, you *can* already 'mv' unencrypted
files into an encrypted directory if the source files are on a different
mountpoint, even though doing so is often insecure.

There are probably better ways to teach users to securely handle their
files.  For example, the 'fscrypt' userspace tool could provide a
command that migrates unencrypted files into an encrypted directory,
acting like 'shred' on the source files and providing appropriate
warnings depending on the type of the source filesystem and disk.

Receiving errors on unimportant files might also force some users to
disable encryption, thus making the behavior counterproductive.  It's
desirable to make encryption as unobtrusive as possible.

Therefore, change the error code from EPERM to EXDEV so that tools
looking for EXDEV will fall back to a copy.

This, of course, doesn't prevent users from still doing the right things
to securely manage their files.  Note that this also matches the
behavior when a file is renamed between two project quota hierarchies;
so there's precedent for using EXDEV for things other than mountpoints.

xfstests generic/398 will require an update with this change.

[Rewritten from an earlier patch series by Michael Halcrow.]

Cc: Michael Halcrow <mhalcrow@google.com>
Cc: Joe Richey <joerichey@google.com>
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-11-05 11:08:35 +01:00
..
ABI iio: improve IIO_CONCENTRATION channel type description 2020-08-19 08:14:54 +02:00
accelerators ocxl: Document new OCXL IOCTLs 2018-06-03 20:40:33 +10:00
accounting
acpi ACPI: property: graph: Update graph documentation to use generic references 2018-07-23 12:44:52 +02:00
admin-guide x86/fpu: Allow multiple bits in clearcpuid= parameter 2020-10-29 09:55:00 +01:00
aoe
arm ARM: 8833/1: Ensure that NEON code always compiles with Clang 2019-04-05 22:33:08 +02:00
arm64 arm64: errata: Hide CTR_EL0.DIC on systems affected by Neoverse-N1 #1542419 2020-04-29 16:31:08 +02:00
auxdisplay Doc: misc-devices: move lcd-panel-cgram.txt to auxdisplay/ 2018-04-12 16:08:02 +02:00
backlight
block block: Track DISCARD statistics and output them in stat and diskstat 2018-07-18 08:44:22 -06:00
blockdev zram: introduce zram memory tracking 2018-06-07 17:34:34 -07:00
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next 2018-08-07 11:02:05 -07:00
bus-devices
cdrom Documentation/cdrom: fix German sharp s in LaTex 2018-03-08 19:35:29 -07:00
cgroup-v1 page cache: use xa_lock 2018-04-11 10:28:39 -07:00
cma
connector
console Documentation: corrections to console/console.txt 2018-08-10 16:09:40 -06:00
core-api idr: Change documentation license 2018-10-15 16:31:29 -04:00
cpu-freq cpufreq: Drop cpufreq_table_validate_and_show() 2018-04-10 08:40:45 +02:00
cpuidle cpuidle: Add definition of residency to sysfs documentation 2018-04-09 13:44:37 +02:00
crypto crypto: remove redundant type flags from tfm allocation 2018-07-09 00:30:29 +08:00
dev-tools doc: dev-tools: kselftest.rst: update contributing new tests 2018-06-29 09:01:50 -06:00
device-mapper dm raid: bump target version, update comments and documentation 2018-09-06 17:07:58 -04:00
devicetree dt-bindings: sound: wm8994: Correct required supplies based on actual implementaion 2020-10-01 13:14:43 +02:00
doc-guide Documentation/sphinx: allow "functions" with no parameters 2018-06-30 07:52:42 -06:00
driver-api ata: make qc_prep return ata_completion_errors 2020-10-01 13:14:54 +02:00
driver-model dmaengine: add a new helper dmaenginem_async_device_register 2018-07-30 10:50:22 +05:30
early-userspace initramfs: move gen_initramfs_list.sh from scripts/ to usr/ 2018-08-22 23:21:44 +09:00
EDID
extcon
fault-injection Documentation: nvme: Documentation for nvme fault injection 2018-03-26 08:53:43 -06:00
fb uvesafb: Fix URLs in the documentation 2018-09-26 18:11:23 +02:00
features ARM: 8777/1: Hook up SYNC_CORE functionality for sys_membarrier() 2018-07-11 11:02:08 +01:00
filesystems fscrypt: return -EXDEV for incompatible rename or link into encrypted dir 2020-11-05 11:08:35 +01:00
firmware_class
fmc
fpga docs: fpga: add a document for FPGA Device Feature List (DFL) Framework Overview 2018-07-15 13:55:44 +02:00
gpio Documentation: gpio: Move drivers-on-gpio.txt to driver-api 2018-03-23 04:22:29 +01:00
gpu drm/msm/gpu: Add the buffer objects from the submit to the crash dump 2018-07-30 08:50:10 -04:00
hid HID: doc: fix wrong data structure reference for UHID_OUTPUT 2019-12-05 09:20:36 +01:00
hwmon hwmon: (ina2xx) fix sysfs shunt resistor read access 2018-08-26 17:45:25 -07:00
i2c i2c: i801: Add support for Intel Comet Lake 2019-05-04 09:20:15 +02:00
ia64 ia64: doc: tweak whitespace for 'console=' parameter 2018-03-05 14:41:38 -08:00
ide
iio iio: adc: New driver for Cirrus Logic EP93xx ADC 2017-07-25 19:56:23 +01:00
infiniband Documentation/ABI: update infiniband sysfs interfaces 2018-02-23 08:18:33 -07:00
input input: add MT_TOOL_DIAL 2018-07-17 15:33:47 +02:00
ioctl Char/Misc driver patches for 4.19-rc1 2018-08-18 11:04:51 -07:00
isdn Documentation/isdn: check and fix dead links ... 2018-03-26 12:31:13 -04:00
kbuild kbuild: support LLVM=1 to switch the default tools to Clang/LLVM 2020-09-26 18:01:32 +02:00
kdump
kernel-hacking doc:it_IT: translation for kernel-hacking 2018-07-26 16:21:09 -06:00
laptops platform/x86: thinkpad_acpi: silence HKEY 0x6032, 0x60f0, 0x6030 2018-05-07 15:10:31 +03:00
leds Documentation: leds: Update 00-INDEX file 2017-10-23 20:17:03 +02:00
lightnvm
livepatch livepatch: Remove not longer valid limitations from the documentation 2018-05-24 15:37:57 +02:00
locking locking: Implement an algorithm choice for Wound-Wait mutexes 2018-07-03 09:44:36 +02:00
m68k
maintainer docs: Fix more broken references 2018-06-15 18:11:26 -03:00
md raid5-ppl: PPL support for disks with write-back cache enabled 2018-01-15 14:29:42 -08:00
media media: replace ADOBERGB by OPRGB 2018-11-13 11:08:54 -08:00
memory-devices
mic
mips Documentation: mips: Update AU1xxx_IDE Kconfig dependencies 2018-02-01 12:45:35 -07:00
misc-devices pci_endpoint_test: Add 2 ioctl commands 2018-07-19 11:46:57 +01:00
mmc
mtd mtd: spi-nor: add an API to restore the status of SPI flash chip 2017-12-13 00:36:00 +01:00
namespaces
netlabel
networking icmp: randomize the global rate limiter 2020-10-29 09:54:58 +01:00
nfc
nios2
nvdimm
nvmem NVMEM documentation fix: A minor typo 2017-08-24 13:31:58 -06:00
openrisc Documentation: openrisc: Updates to README 2017-10-30 21:37:53 +09:00
parisc
PCI Merge branch 'remotes/lorenzo/pci/dwc' 2018-08-15 14:59:11 -05:00
pcmcia pcmcia: remove long deprecated pcmcia_request_exclusive_irq() function 2018-08-18 12:30:42 -07:00
perf drivers/bus: Move Arm CCN PMU driver 2018-03-06 17:26:15 +01:00
phy
platform
power PM / reboot: Eliminate race between reboot and suspend 2018-08-06 12:35:20 +02:00
powerpc powerpc: Document issues with TM on POWER9 2018-07-02 23:54:29 +10:00
pps drivers/pps: aesthetic tweaks to PPS-related content 2017-09-08 18:26:51 -07:00
process stable-kernel-rules.rst: add link to networking patch queue 2019-03-23 20:10:10 +01:00
pti
ptp ptp: Fix documentation to match code. 2018-03-26 12:13:21 -04:00
rapidio Documentation: rapidio: move sysfs interface to ABI 2018-02-23 08:25:45 -07:00
RCU rculist: Improve documentation for list_for_each_entry_from_rcu() 2018-07-12 15:39:25 -07:00
riscv perf: riscv: Add Document for Future Porting Guide 2018-06-04 14:02:11 -07:00
s390 vfio-ccw: update documentation 2018-03-01 17:32:14 +01:00
scheduler sched/fair: Fix low cpu usage with high throttling by removing expiration of cpu-local slices 2019-11-12 19:20:50 +01:00
scsi scsi: documentation: add scsi_mod.use_blk_mq to scsi-parameters 2018-08-27 12:26:10 -04:00
security Kbuild: rename CC_STACKPROTECTOR[_STRONG] config variables 2018-06-14 12:21:18 +09:00
serial
sh
sound ALSA: hda/realtek - Remove now-unnecessary XPS 13 headphone noise fixups 2020-04-17 10:48:45 +02:00
sparc sparc64: Add support for ADI (Application Data Integrity) 2018-03-18 07:38:48 -07:00
sphinx doc: Cope with Sphinx logging deprecations 2019-06-09 09:17:21 +02:00
sphinx-static
spi
sysctl bpf: add bpf_jit_limit knob to restrict unpriv allocations 2019-05-31 06:46:03 -07:00
target
thermal thermal: Add cooling device's statistics in sysfs 2018-04-02 21:49:01 +08:00
timers timekeeping.txt: Correct maxCount of n-bit binary counter 2018-07-23 09:33:06 -06:00
trace This was a moderately busy cycle for docs, with the usual collection of 2018-08-14 14:29:31 -07:00
translations This was a moderately busy cycle for docs, with the usual collection of 2018-08-14 14:29:31 -07:00
usb USB: rio500: Remove Rio 500 kernel driver 2019-10-17 13:44:47 -07:00
userspace-api Documentation: Add section about CPU vulnerabilities for Spectre 2019-07-14 08:11:17 +02:00
virtual x86/kvm/hyper-v: Explicitly align hcall param for kvm_hyperv_exit 2020-06-22 09:05:12 +02:00
vm docs/vm: move ksm and transhuge from "user" to "internals" section. 2018-05-29 06:45:55 -06:00
w1 w1: fix w1_ds2438 documentation 2018-07-07 17:27:13 +02:00
watchdog watchdog: remove bfin_wdt driver 2018-03-26 15:57:04 +02:00
wimax
x86 x86/speculation/taa: Add documentation for TSX Async Abort 2019-11-12 19:21:34 +01:00
xtensa xtensa: add support for KASAN 2017-12-16 22:37:12 -08:00
.gitignore
00-INDEX docs: admin-guide: add cgroup-v2 documentation 2018-05-10 15:42:41 -06:00
atomic_bitops.txt locking/atomic/bitops: Document and clarify ordering semantics for failed test_and_{}_bit() 2018-02-13 14:55:53 +01:00
atomic_t.txt x86/atomic: Fix smp_mb__{before,after}_atomic() 2019-07-26 09:14:08 +02:00
bt8xxgpio.txt
btmrvl.txt
bus-virt-phys-mapping.txt
Changes
clearing-warn-once.txt kernel debug: support resetting WARN*_ONCE 2017-11-17 16:10:00 -08:00
CodingStyle
conf.py docs: Fix conf.py for Sphinx 2.0 2019-06-09 09:17:20 +02:00
cpu-load.txt
cputopology.txt
crc32.txt
dcdbas.txt
debugging-modules.txt
debugging-via-ohci1394.txt
dell_rbu.txt Documentation: remove stale firmware API reference 2018-05-14 16:44:41 +02:00
digsig.txt
DMA-API-HOWTO.txt
DMA-API.txt dma-coherent: remove the DMA_MEMORY_MAP and DMA_MEMORY_IO flags 2017-09-01 11:59:17 +02:00
DMA-attributes.txt
DMA-ISA-LPC.txt
docutils.conf
dontdiff Remove gperf usage from toolchain 2017-08-19 11:02:53 -07:00
efi-stub.txt
eisa.txt
flexible-arrays.txt
futex-requeue-pi.txt
gcc-plugins.txt
highuid.txt
hw_random.txt
hwspinlock.txt
index.rst x86/speculation/mds: Add mds_clear_cpu_buffers() 2019-05-14 19:17:54 +02:00
intel_txt.txt
Intel-IOMMU.txt
io_ordering.txt
io-mapping.txt
iostats.txt block: Track DISCARD statistics and output them in stat and diskstat 2018-07-18 08:44:22 -06:00
IPMI.txt ipmi: Make IPMI panic strings always available 2017-09-27 16:03:45 -05:00
IRQ-affinity.txt
IRQ-domain.txt irqdomain: Kill CONFIG_IRQ_DOMAIN_DEBUG 2018-01-24 12:32:58 +01:00
IRQ.txt
irqflags-tracing.txt
isa.txt
isapnp.txt
kernel-per-CPU-kthreads.txt
kobject.txt
kprobes.txt kprobes/Documentation: Fix various typos 2018-06-22 11:10:55 +02:00
kref.txt
ldm.txt
lockup-watchdogs.txt
logo.gif
logo.txt
lsm.txt
lzo.txt
mailbox.txt
Makefile Documentation: add script and build target to check for broken file references 2017-10-12 11:07:42 -06:00
memory-barriers.txt sched/Documentation: Update wake_up() & co. memory-barrier guarantees 2018-07-17 09:30:34 +02:00
memory-hotplug.txt
men-chameleon-bus.txt
nommu-mmap.txt Documentation: nommu-map: Fix duplicate word typo 2018-06-26 09:01:27 -06:00
ntb.txt
numastat.txt
padata.txt
parport-lowlevel.txt
percpu-rw-semaphore.txt
phy.txt
pi-futex.txt Documentation: fix locking rt-mutex doc refs 2017-10-19 12:56:44 -06:00
pnp.txt
preempt-locking.txt
pwm.txt
rbtree.txt rbtree: cache leftmost node internally 2017-09-08 18:26:48 -07:00
remoteproc.txt
rfkill.txt rfkill: Fix several typos in documentation 2018-06-15 13:36:08 +02:00
robust-futex-ABI.txt
robust-futexes.txt futex: Update comments and docs about return values of arch futex code 2019-07-03 13:14:49 +02:00
rpmsg.txt
rtc.txt Documentation: rtc: move iotcl interface documentation to ABI 2018-01-12 00:20:41 +01:00
SAK.txt
sgi-ioc4.txt
siphash.txt
SM501.txt
smsc_ece1099.txt
speculation.txt Documentation: Document array_index_nospec 2018-01-30 21:54:28 +01:00
static-keys.txt jump_label: Provide hotplug context variants 2017-08-10 12:28:59 +02:00
SubmittingPatches
svga.txt documentation/svga.txt: update outdated file 2017-11-20 10:45:50 -07:00
switchtec.txt NTB: switchtec_ntb: Update switchtec documentation with notes for NTB 2017-11-18 20:37:13 -05:00
sync_file.txt
tee.txt
this_cpu_ops.txt
unaligned-memory-access.txt
vfio-mediated-device.txt vfio/mdev: Check globally for duplicate devices 2018-06-08 10:24:27 -06:00
vfio.txt vfio: fix documentation 2018-05-08 09:16:41 -06:00
video-output.txt
xillybus.txt
xz.txt
zorro.txt