Commit graph

111 commits

Author SHA1 Message Date
Michal Suchanek
358fcf5ddb debugfs: lockdown: Allow reading debugfs files that are not world readable
When the kernel is locked down the kernel allows reading only debugfs
files with mode 444. Mode 400 is also valid but is not allowed.

Make the 444 into a mask.

Fixes: 5496197f9b ("debugfs: Restrict debugfs when the kernel is locked down")
Signed-off-by: Michal Suchanek <msuchanek@suse.de>
Link: https://lore.kernel.org/r/20220104170505.10248-1-msuchanek@suse.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2022-01-06 15:47:41 +01:00
Sven Eckelmann
112cedc8e6 debugfs: Return error during {full/open}_proxy_open() on rmmod
If a kernel module gets unloaded then it printed report about a leak before
commit 275678e7a9 ("debugfs: Check module state before warning in
{full/open}_proxy_open()"). An additional check was added in this commit to
avoid this printing. But it was forgotten that the function must return an
error in this case because it was not actually opened.

As result, the systems started to crash or to hang when a module was
unloaded while something was trying to open a file.

Fixes: 275678e7a9 ("debugfs: Check module state before warning in {full/open}_proxy_open()")
Cc: Taehee Yoo <ap420073@gmail.com>
Reported-by: Mário Lopes <ml@simonwunderlich.de>
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Link: https://lore.kernel.org/r/20210802162444.7848-1-sven@narfation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-08-05 14:42:40 +02:00
Greg Kroah-Hartman
68afbd8459 Linux 5.13-rc6
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Merge tag 'v5.13-rc6' into driver-core-next

We need the driver core fix in here as well.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-14 09:07:45 +02:00
Dietmar Eggemann
f501b6a231 debugfs: Fix debugfs_read_file_str()
Read the entire size of the buffer, including the trailing new line
character.
Discovered while reading the sched domain names of CPU0:

before:

cat /sys/kernel/debug/sched/domains/cpu0/domain*/name
SMTMCDIE

after:

cat /sys/kernel/debug/sched/domains/cpu0/domain*/name
SMT
MC
DIE

Fixes: 9af0440ec8 ("debugfs: Implement debugfs_create_str()")
Reviewed-by: Steven Rostedt (VMware) <rostedt@goodmis.org>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Dietmar Eggemann <dietmar.eggemann@arm.com>
Link: https://lore.kernel.org/r/20210527091105.258457-1-dietmar.eggemann@arm.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-06-04 15:01:08 +02:00
Greg Kroah-Hartman
fb05b14c5b debugfs: remove return value of debugfs_create_ulong()
No one checks the return value of debugfs_create_ulong(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20210521184340.1348539-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-21 20:59:55 +02:00
Greg Kroah-Hartman
393b06383f debugfs: remove return value of debugfs_create_bool()
No one checks the return value of debugfs_create_bool(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20210521184519.1356639-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-21 20:59:03 +02:00
Wolfram Sang
d616f56d34 debugfs: only accept read attributes for blobs
Blobs can only be read. So, keep only 'read' file attributes because the
others will not work and only confuse users.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Link: https://lore.kernel.org/r/20210504131350.46586-1-wsa+renesas@sang-engineering.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-05-14 13:36:18 +02:00
Linus Torvalds
16b3d0cf5b Scheduler updates for this cycle are:
- Clean up SCHED_DEBUG: move the decades old mess of sysctl, procfs and debugfs interfaces
    to a unified debugfs interface.
 
  - Signals: Allow caching one sigqueue object per task, to improve performance & latencies.
 
  - Improve newidle_balance() irq-off latencies on systems with a large number of CPU cgroups.
 
  - Improve energy-aware scheduling
 
  - Improve the PELT metrics for certain workloads
 
  - Reintroduce select_idle_smt() to improve load-balancing locality - but without the previous
    regressions
 
  - Add 'scheduler latency debugging': warn after long periods of pending need_resched. This
    is an opt-in feature that requires the enabling of the LATENCY_WARN scheduler feature,
    or the use of the resched_latency_warn_ms=xx boot parameter.
 
  - CPU hotplug fixes for HP-rollback, and for the 'fail' interface. Fix remaining
    balance_push() vs. hotplug holes/races
 
  - PSI fixes, plus allow /proc/pressure/ files to be written by CAP_SYS_RESOURCE tasks as well
 
  - Fix/improve various load-balancing corner cases vs. capacity margins
 
  - Fix sched topology on systems with NUMA diameter of 3 or above
 
  - Fix PF_KTHREAD vs to_kthread() race
 
  - Minor rseq optimizations
 
  - Misc cleanups, optimizations, fixes and smaller updates
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Clean up SCHED_DEBUG: move the decades old mess of sysctl, procfs and
   debugfs interfaces to a unified debugfs interface.

 - Signals: Allow caching one sigqueue object per task, to improve
   performance & latencies.

 - Improve newidle_balance() irq-off latencies on systems with a large
   number of CPU cgroups.

 - Improve energy-aware scheduling

 - Improve the PELT metrics for certain workloads

 - Reintroduce select_idle_smt() to improve load-balancing locality -
   but without the previous regressions

 - Add 'scheduler latency debugging': warn after long periods of pending
   need_resched. This is an opt-in feature that requires the enabling of
   the LATENCY_WARN scheduler feature, or the use of the
   resched_latency_warn_ms=xx boot parameter.

 - CPU hotplug fixes for HP-rollback, and for the 'fail' interface. Fix
   remaining balance_push() vs. hotplug holes/races

 - PSI fixes, plus allow /proc/pressure/ files to be written by
   CAP_SYS_RESOURCE tasks as well

 - Fix/improve various load-balancing corner cases vs. capacity margins

 - Fix sched topology on systems with NUMA diameter of 3 or above

 - Fix PF_KTHREAD vs to_kthread() race

 - Minor rseq optimizations

 - Misc cleanups, optimizations, fixes and smaller updates

* tag 'sched-core-2021-04-28' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (61 commits)
  cpumask/hotplug: Fix cpu_dying() state tracking
  kthread: Fix PF_KTHREAD vs to_kthread() race
  sched/debug: Fix cgroup_path[] serialization
  sched,psi: Handle potential task count underflow bugs more gracefully
  sched: Warn on long periods of pending need_resched
  sched/fair: Move update_nohz_stats() to the CONFIG_NO_HZ_COMMON block to simplify the code & fix an unused function warning
  sched/debug: Rename the sched_debug parameter to sched_verbose
  sched,fair: Alternative sched_slice()
  sched: Move /proc/sched_debug to debugfs
  sched,debug: Convert sysctl sched_domains to debugfs
  debugfs: Implement debugfs_create_str()
  sched,preempt: Move preempt_dynamic to debug.c
  sched: Move SCHED_DEBUG sysctl to debugfs
  sched: Don't make LATENCYTOP select SCHED_DEBUG
  sched: Remove sched_schedstats sysctl out from under SCHED_DEBUG
  sched/numa: Allow runtime enabling/disabling of NUMA balance without SCHED_DEBUG
  sched: Use cpu_dying() to fix balance_push vs hotplug-rollback
  cpumask: Introduce DYING mask
  cpumask: Make cpu_{online,possible,present,active}() inline
  rseq: Optimise rseq_get_rseq_cs() and clear_rseq_cs()
  ...
2021-04-28 13:33:57 -07:00
Peter Zijlstra
9af0440ec8 debugfs: Implement debugfs_create_str()
Implement debugfs_create_str() to easily display names and such in
debugfs.

Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: Valentin Schneider <valentin.schneider@arm.com>
Link: https://lkml.kernel.org/r/20210412102001.415407080@infradead.org
2021-04-16 17:06:34 +02:00
Rasmus Villemoes
c8a9c285f1 debugfs: drop pointless nul-termination in debugfs_read_file_bool()
simple_read_from_buffer() doesn't care about any bytes in the buffer
beyond "available". Making the buffer nul-terminated is therefore
completely pointless.

Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Link: https://lore.kernel.org/r/20210326151411.732220-1-linux@rasmusvillemoes.dk
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2021-04-05 13:17:51 +02:00
Greg Kroah-Hartman
0d519cbf38 debugfs: remove return value of debugfs_create_devm_seqfile()
No one checks the return value of debugfs_create_devm_seqfile(), as it's
not needed, so make the return value void, so that no one tries to do so
in the future.

Link: https://lore.kernel.org/r/20201023131037.2500765-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-10-30 08:37:39 +01:00
Vladis Dronov
e3b9fc7eec debugfs: Fix module state check condition
The '#ifdef MODULE' check in the original commit does not work as intended.
The code under the check is not built at all if CONFIG_DEBUG_FS=y. Fix this
by using a correct check.

Fixes: 275678e7a9 ("debugfs: Check module state before warning in {full/open}_proxy_open()")
Signed-off-by: Vladis Dronov <vdronov@redhat.com>
Cc: stable <stable@vger.kernel.org>
Link: https://lore.kernel.org/r/20200811150129.53343-1-vdronov@redhat.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-09-04 18:12:52 +02:00
Linus Torvalds
47ec5303d7 Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from David Miller:

 1) Support 6Ghz band in ath11k driver, from Rajkumar Manoharan.

 2) Support UDP segmentation in code TSO code, from Eric Dumazet.

 3) Allow flashing different flash images in cxgb4 driver, from Vishal
    Kulkarni.

 4) Add drop frames counter and flow status to tc flower offloading,
    from Po Liu.

 5) Support n-tuple filters in cxgb4, from Vishal Kulkarni.

 6) Various new indirect call avoidance, from Eric Dumazet and Brian
    Vazquez.

 7) Fix BPF verifier failures on 32-bit pointer arithmetic, from
    Yonghong Song.

 8) Support querying and setting hardware address of a port function via
    devlink, use this in mlx5, from Parav Pandit.

 9) Support hw ipsec offload on bonding slaves, from Jarod Wilson.

10) Switch qca8k driver over to phylink, from Jonathan McDowell.

11) In bpftool, show list of processes holding BPF FD references to
    maps, programs, links, and btf objects. From Andrii Nakryiko.

12) Several conversions over to generic power management, from Vaibhav
    Gupta.

13) Add support for SO_KEEPALIVE et al. to bpf_setsockopt(), from Dmitry
    Yakunin.

14) Various https url conversions, from Alexander A. Klimov.

15) Timestamping and PHC support for mscc PHY driver, from Antoine
    Tenart.

16) Support bpf iterating over tcp and udp sockets, from Yonghong Song.

17) Support 5GBASE-T i40e NICs, from Aleksandr Loktionov.

18) Add kTLS RX HW offload support to mlx5e, from Tariq Toukan.

19) Fix the ->ndo_start_xmit() return type to be netdev_tx_t in several
    drivers. From Luc Van Oostenryck.

20) XDP support for xen-netfront, from Denis Kirjanov.

21) Support receive buffer autotuning in MPTCP, from Florian Westphal.

22) Support EF100 chip in sfc driver, from Edward Cree.

23) Add XDP support to mvpp2 driver, from Matteo Croce.

24) Support MPTCP in sock_diag, from Paolo Abeni.

25) Commonize UDP tunnel offloading code by creating udp_tunnel_nic
    infrastructure, from Jakub Kicinski.

26) Several pci_ --> dma_ API conversions, from Christophe JAILLET.

27) Add FLOW_ACTION_POLICE support to mlxsw, from Ido Schimmel.

28) Add SK_LOOKUP bpf program type, from Jakub Sitnicki.

29) Refactor a lot of networking socket option handling code in order to
    avoid set_fs() calls, from Christoph Hellwig.

30) Add rfc4884 support to icmp code, from Willem de Bruijn.

31) Support TBF offload in dpaa2-eth driver, from Ioana Ciornei.

32) Support XDP_REDIRECT in qede driver, from Alexander Lobakin.

33) Support PCI relaxed ordering in mlx5 driver, from Aya Levin.

34) Support TCP syncookies in MPTCP, from Flowian Westphal.

35) Fix several tricky cases of PMTU handling wrt. briding, from Stefano
    Brivio.

* git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2056 commits)
  net: thunderx: initialize VF's mailbox mutex before first usage
  usb: hso: remove bogus check for EINPROGRESS
  usb: hso: no complaint about kmalloc failure
  hso: fix bailout in error case of probe
  ip_tunnel_core: Fix build for archs without _HAVE_ARCH_IPV6_CSUM
  selftests/net: relax cpu affinity requirement in msg_zerocopy test
  mptcp: be careful on subflow creation
  selftests: rtnetlink: make kci_test_encap() return sub-test result
  selftests: rtnetlink: correct the final return value for the test
  net: dsa: sja1105: use detected device id instead of DT one on mismatch
  tipc: set ub->ifindex for local ipv6 address
  ipv6: add ipv6_dev_find()
  net: openvswitch: silence suspicious RCU usage warning
  Revert "vxlan: fix tos value before xmit"
  ptp: only allow phase values lower than 1 period
  farsync: switch from 'pci_' to 'dma_' API
  wan: wanxl: switch from 'pci_' to 'dma_' API
  hv_netvsc: do not use VF device if link is down
  dpaa2-eth: Fix passing zero to 'PTR_ERR' warning
  net: macb: Properly handle phylink on at91sam9x
  ...
2020-08-05 20:13:21 -07:00
Jakub Kicinski
a2b992c828 debugfs: make sure we can remove u32_array files cleanly
debugfs_create_u32_array() allocates a small structure to wrap
the data and size information about the array. If users ever
try to remove the file this leads to a leak since nothing ever
frees this wrapper.

That said there are no upstream users of debugfs_create_u32_array()
that'd remove a u32 array file (we only have one u32 array user in
CMA), so there is no real bug here.

Make callers pass a wrapper they allocated. This way the lifetime
management of the wrapper is on the caller, and we can avoid the
potential leak in debugfs.

CC: Chucheng Luo <luochucheng@vivo.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
2020-07-10 13:54:00 -07:00
Xu Wang
c80a67bd5d debugfs: file: Remove unnecessary cast in kfree()
Remove unnecassary casts in the argument to kfree.

Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Link: https://lore.kernel.org/r/20200709054033.30148-1-vulab@iscas.ac.cn
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-07-10 15:07:56 +02:00
Greg Kroah-Hartman
2b07021a94 debugfs: remove return value of debugfs_create_u32()
No one checks the return value of debugfs_create_u32(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20200416145448.GA1380878@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-04-17 17:08:50 +02:00
Linus Torvalds
72f35423e8 Merge branch 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6
Pull crypto updates from Herbert Xu:
 "API:
   - Fix out-of-sync IVs in self-test for IPsec AEAD algorithms

  Algorithms:
   - Use formally verified implementation of x86/curve25519

  Drivers:
   - Enhance hwrng support in caam

   - Use crypto_engine for skcipher/aead/rsa/hash in caam

   - Add Xilinx AES driver

   - Add uacce driver

   - Register zip engine to uacce in hisilicon

   - Add support for OCTEON TX CPT engine in marvell"

* 'linus' of git://git.kernel.org/pub/scm/linux/kernel/git/herbert/crypto-2.6: (162 commits)
  crypto: af_alg - bool type cosmetics
  crypto: arm[64]/poly1305 - add artifact to .gitignore files
  crypto: caam - limit single JD RNG output to maximum of 16 bytes
  crypto: caam - enable prediction resistance in HRWNG
  bus: fsl-mc: add api to retrieve mc version
  crypto: caam - invalidate entropy register during RNG initialization
  crypto: caam - check if RNG job failed
  crypto: caam - simplify RNG implementation
  crypto: caam - drop global context pointer and init_done
  crypto: caam - use struct hwrng's .init for initialization
  crypto: caam - allocate RNG instantiation descriptor with GFP_DMA
  crypto: ccree - remove duplicated include from cc_aead.c
  crypto: chelsio - remove set but not used variable 'adap'
  crypto: marvell - enable OcteonTX cpt options for build
  crypto: marvell - add the Virtual Function driver for CPT
  crypto: marvell - add support for OCTEON TX CPT engine
  crypto: marvell - create common Kconfig and Makefile for Marvell
  crypto: arm/neon - memzero_explicit aes-cbc key
  crypto: bcm - Use scnprintf() for avoiding potential buffer overflow
  crypto: atmel-i2c - Fix wakeup fail
  ...
2020-04-01 14:47:40 -07:00
Taehee Yoo
275678e7a9 debugfs: Check module state before warning in {full/open}_proxy_open()
When the module is being removed, the module state is set to
MODULE_STATE_GOING. At this point, try_module_get() fails.
And when {full/open}_proxy_open() is being called,
it calls try_module_get() to try to hold module reference count.
If it fails, it warns about the possibility of debugfs file leak.

If {full/open}_proxy_open() is called while the module is being removed,
it fails to hold the module.
So, It warns about debugfs file leak. But it is not the debugfs file
leak case. So, this patch just adds module state checking routine
in the {full/open}_proxy_open().

Test commands:
    #SHELL1
    while :
    do
        modprobe netdevsim
        echo 1 > /sys/bus/netdevsim/new_device
        modprobe -rv netdevsim
    done

    #SHELL2
    while :
    do
        cat /sys/kernel/debug/netdevsim/netdevsim1/ports/0/ipsec
    done

Splat looks like:
[  298.766738][T14664] debugfs file owner did not clean up at exit: ipsec
[  298.766766][T14664] WARNING: CPU: 2 PID: 14664 at fs/debugfs/file.c:312 full_proxy_open+0x10f/0x650
[  298.768595][T14664] Modules linked in: netdevsim(-) openvswitch nsh nf_conncount nf_nat nf_conntrack nf_defrag_ipv6 n][  298.771343][T14664] CPU: 2 PID: 14664 Comm: cat Tainted: G        W         5.5.0+ #1
[  298.772373][T14664] Hardware name: innotek GmbH VirtualBox/VirtualBox, BIOS VirtualBox 12/01/2006
[  298.773545][T14664] RIP: 0010:full_proxy_open+0x10f/0x650
[  298.774247][T14664] Code: 48 c1 ea 03 80 3c 02 00 0f 85 c1 04 00 00 49 8b 3c 24 e8 e4 b5 78 ff 84 c0 75 2d 4c 89 ee 48
[  298.776782][T14664] RSP: 0018:ffff88805b7df9b8 EFLAGS: 00010282[  298.777583][T14664] RAX: dffffc0000000008 RBX: ffff8880511725c0 RCX: 0000000000000000
[  298.778610][T14664] RDX: 0000000000000000 RSI: 0000000000000006 RDI: ffff8880540c5c14
[  298.779637][T14664] RBP: 0000000000000000 R08: fffffbfff15235ad R09: 0000000000000000
[  298.780664][T14664] R10: 0000000000000001 R11: 0000000000000000 R12: ffffffffc06b5000
[  298.781702][T14664] R13: ffff88804c234a88 R14: ffff88804c22dd00 R15: ffffffff8a1b5660
[  298.782722][T14664] FS:  00007fafa13a8540(0000) GS:ffff88806c800000(0000) knlGS:0000000000000000
[  298.783845][T14664] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[  298.784672][T14664] CR2: 00007fafa0e9cd10 CR3: 000000004b286005 CR4: 00000000000606e0
[  298.785739][T14664] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[  298.786769][T14664] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[  298.787785][T14664] Call Trace:
[  298.788237][T14664]  do_dentry_open+0x63c/0xf50
[  298.788872][T14664]  ? open_proxy_open+0x270/0x270
[  298.789524][T14664]  ? __x64_sys_fchdir+0x180/0x180
[  298.790169][T14664]  ? inode_permission+0x65/0x390
[  298.790832][T14664]  path_openat+0xc45/0x2680
[  298.791425][T14664]  ? save_stack+0x69/0x80
[  298.791988][T14664]  ? save_stack+0x19/0x80
[  298.792544][T14664]  ? path_mountpoint+0x2e0/0x2e0
[  298.793233][T14664]  ? check_chain_key+0x236/0x5d0
[  298.793910][T14664]  ? sched_clock_cpu+0x18/0x170
[  298.794527][T14664]  ? find_held_lock+0x39/0x1d0
[  298.795153][T14664]  do_filp_open+0x16a/0x260
[ ... ]

Fixes: 9fd4dcece4 ("debugfs: prevent access to possibly dead file_operations at file open")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Taehee Yoo <ap420073@gmail.com>
Link: https://lore.kernel.org/r/20200218043150.29447-1-ap420073@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-03-18 12:37:49 +01:00
Geert Uytterhoeven
30332eeefe debugfs: regset32: Add Runtime PM support
Hardware registers of devices under control of power management cannot
be accessed at all times.  If such a device is suspended, register
accesses may lead to undefined behavior, like reading bogus values, or
causing exceptions or system lock-ups.

Extend struct debugfs_regset32 with an optional field to let device
drivers specify the device the registers in the set belong to.  This
allows debugfs_show_regset32() to make sure the device is resumed while
its registers are being read.

Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Niklas Söderlund <niklas.soderlund@ragnatech.se>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
2020-02-22 09:25:42 +08:00
Greg Kroah-Hartman
ae91c92565 debugfs: remove return value of debugfs_create_regset32()
No one checks the return value of debugfs_create_regset32(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20191122104453.GA2017837@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-02-10 13:00:06 -08:00
Eric Snowberg
a37f4958f7 debugfs: Return -EPERM when locked down
When lockdown is enabled, debugfs_is_locked_down returns 1. It will then
trigger the following:

WARNING: CPU: 48 PID: 3747
CPU: 48 PID: 3743 Comm: bash Not tainted 5.4.0-1946.x86_64 #1
Hardware name: Oracle Corporation ORACLE SERVER X7-2/ASM, MB, X7-2, BIOS 41060400 05/20/2019
RIP: 0010:do_dentry_open+0x343/0x3a0
Code: 00 40 08 00 45 31 ff 48 c7 43 28 40 5b e7 89 e9 02 ff ff ff 48 8b 53 28 4c 8b 72 70 4d 85 f6 0f 84 10 fe ff ff e9 f5 fd ff ff <0f> 0b 41 bf ea ff ff ff e9 3b ff ff ff 41 bf e6 ff ff ff e9 b4 fe
RSP: 0018:ffffb8740dde7ca0 EFLAGS: 00010202
RAX: ffffffff89e88a40 RBX: ffff928c8e6b6f00 RCX: 0000000000000000
RDX: 0000000000000000 RSI: ffff928dbfd97778 RDI: ffff9285cff685c0
RBP: ffffb8740dde7cc8 R08: 0000000000000821 R09: 0000000000000030
R10: 0000000000000057 R11: ffffb8740dde7a98 R12: ffff926ec781c900
R13: ffff928c8e6b6f10 R14: ffffffff8936e190 R15: 0000000000000001
FS:  00007f45f6777740(0000) GS:ffff928dbfd80000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fff95e0d5d8 CR3: 0000001ece562006 CR4: 00000000007606e0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
PKRU: 55555554
Call Trace:
 vfs_open+0x2d/0x30
 path_openat+0x2d4/0x1680
 ? tty_mode_ioctl+0x298/0x4c0
 do_filp_open+0x93/0x100
 ? strncpy_from_user+0x57/0x1b0
 ? __alloc_fd+0x46/0x150
 do_sys_open+0x182/0x230
 __x64_sys_openat+0x20/0x30
 do_syscall_64+0x60/0x1b0
 entry_SYSCALL_64_after_hwframe+0x170/0x1d5
RIP: 0033:0x7f45f5e5ce02
Code: 25 00 00 41 00 3d 00 00 41 00 74 4c 48 8d 05 25 59 2d 00 8b 00 85 c0 75 6d 89 f2 b8 01 01 00 00 48 89 fe bf 9c ff ff ff 0f 05 <48> 3d 00 f0 ff ff 0f 87 a2 00 00 00 48 8b 4c 24 28 64 48 33 0c 25
RSP: 002b:00007fff95e0d2e0 EFLAGS: 00000246 ORIG_RAX: 0000000000000101
RAX: ffffffffffffffda RBX: 0000561178c069b0 RCX: 00007f45f5e5ce02
RDX: 0000000000000241 RSI: 0000561178c08800 RDI: 00000000ffffff9c
RBP: 00007fff95e0d3e0 R08: 0000000000000020 R09: 0000000000000005
R10: 00000000000001b6 R11: 0000000000000246 R12: 0000000000000000
R13: 0000000000000003 R14: 0000000000000001 R15: 0000561178c08800

Change the return type to int and return -EPERM when lockdown is enabled
to remove the warning above. Also rename debugfs_is_locked_down to
debugfs_locked_down to make it sound less like it returns a boolean.

Fixes: 5496197f9b ("debugfs: Restrict debugfs when the kernel is locked down")
Signed-off-by: Eric Snowberg <eric.snowberg@oracle.com>
Reviewed-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: stable <stable@vger.kernel.org>
Acked-by: James Morris <jamorris@linux.microsoft.com>
Link: https://lore.kernel.org/r/20191207161603.35907-1-eric.snowberg@oracle.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-14 16:14:48 +01:00
Daniel W. S. Almeida
adc92dd455 debugfs: Fix warnings when building documentation
Fix the following warnings:

fs/debugfs/inode.c:423: WARNING: Inline literal start-string without end-string.
fs/debugfs/inode.c:502: WARNING: Inline literal start-string without end-string.
fs/debugfs/inode.c:534: WARNING: Inline literal start-string without end-string.
fs/debugfs/inode.c:627: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:496: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:502: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:581: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:587: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:846: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:852: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:899: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:905: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:1091: WARNING: Inline literal start-string without end-string.
fs/debugfs/file.c:1097: WARNING: Inline literal start-string without end-string

By replacing %ERR_PTR with ERR_PTR.

Signed-off-by: Daniel W. S. Almeida <dwlsalmeida@gmail.com>
Link: https://lore.kernel.org/r/20191227010035.854913-1-dwlsalmeida@gmail.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2020-01-06 20:35:37 +01:00
Greg Kroah-Hartman
9927c6fa3e debugfs: remove return value of debugfs_create_atomic_t()
No one checks the return value of debugfs_create_atomic_t(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20191016130332.GA28240@kroah.com
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-03 14:03:01 +01:00
Greg Kroah-Hartman
c7c1168909 debugfs: remove return value of debugfs_create_x8()
No one checks the return value of debugfs_create_x8(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20191011132931.1186197-5-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-11-02 18:09:12 +01:00
Greg Kroah-Hartman
0864c408fb debugfs: remove return value of debugfs_create_x64()
No one checks the return value of debugfs_create_x64(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20191011132931.1186197-8-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-16 06:07:56 -07:00
Greg Kroah-Hartman
f5cb0a7e64 debugfs: remove return value of debugfs_create_x32()
No one checks the return value of debugfs_create_x32(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20191011132931.1186197-7-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-16 06:07:55 -07:00
Greg Kroah-Hartman
e40d38f28c debugfs: remove return value of debugfs_create_x16()
No one checks the return value of debugfs_create_x16(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Link: https://lore.kernel.org/r/20191011132931.1186197-6-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-16 06:07:55 -07:00
Greg Kroah-Hartman
8e5802635f debugfs: remove return value of debugfs_create_size_t()
No one checks the return value of debugfs_create_size_t(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20191011132931.1186197-4-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-14 12:18:07 +02:00
Greg Kroah-Hartman
ad26221fb9 debugfs: remove return value of debugfs_create_u64()
No one checks the return value of debugfs_create_u64(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20191011132931.1186197-3-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-14 12:18:07 +02:00
Greg Kroah-Hartman
313f5dbba4 debugfs: remove return value of debugfs_create_u16()
No one checks the return value of debugfs_create_u16(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20191011132931.1186197-2-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-14 12:18:06 +02:00
Greg Kroah-Hartman
9655ac4aca debugfs: remove return value of debugfs_create_u8()
No one checks the return value of debugfs_create_u8(), as it's not
needed, so make the return value void, so that no one tries to do so in
the future.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Link: https://lore.kernel.org/r/20191011132931.1186197-1-gregkh@linuxfoundation.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-10-14 12:18:06 +02:00
Linus Torvalds
aefcf2f4b5 Merge branch 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
Pull kernel lockdown mode from James Morris:
 "This is the latest iteration of the kernel lockdown patchset, from
  Matthew Garrett, David Howells and others.

  From the original description:

    This patchset introduces an optional kernel lockdown feature,
    intended to strengthen the boundary between UID 0 and the kernel.
    When enabled, various pieces of kernel functionality are restricted.
    Applications that rely on low-level access to either hardware or the
    kernel may cease working as a result - therefore this should not be
    enabled without appropriate evaluation beforehand.

    The majority of mainstream distributions have been carrying variants
    of this patchset for many years now, so there's value in providing a
    doesn't meet every distribution requirement, but gets us much closer
    to not requiring external patches.

  There are two major changes since this was last proposed for mainline:

   - Separating lockdown from EFI secure boot. Background discussion is
     covered here: https://lwn.net/Articles/751061/

   -  Implementation as an LSM, with a default stackable lockdown LSM
      module. This allows the lockdown feature to be policy-driven,
      rather than encoding an implicit policy within the mechanism.

  The new locked_down LSM hook is provided to allow LSMs to make a
  policy decision around whether kernel functionality that would allow
  tampering with or examining the runtime state of the kernel should be
  permitted.

  The included lockdown LSM provides an implementation with a simple
  policy intended for general purpose use. This policy provides a coarse
  level of granularity, controllable via the kernel command line:

    lockdown={integrity|confidentiality}

  Enable the kernel lockdown feature. If set to integrity, kernel features
  that allow userland to modify the running kernel are disabled. If set to
  confidentiality, kernel features that allow userland to extract
  confidential information from the kernel are also disabled.

  This may also be controlled via /sys/kernel/security/lockdown and
  overriden by kernel configuration.

  New or existing LSMs may implement finer-grained controls of the
  lockdown features. Refer to the lockdown_reason documentation in
  include/linux/security.h for details.

  The lockdown feature has had signficant design feedback and review
  across many subsystems. This code has been in linux-next for some
  weeks, with a few fixes applied along the way.

  Stephen Rothwell noted that commit 9d1f8be5cf ("bpf: Restrict bpf
  when kernel lockdown is in confidentiality mode") is missing a
  Signed-off-by from its author. Matthew responded that he is providing
  this under category (c) of the DCO"

* 'next-lockdown' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (31 commits)
  kexec: Fix file verification on S390
  security: constify some arrays in lockdown LSM
  lockdown: Print current->comm in restriction messages
  efi: Restrict efivar_ssdt_load when the kernel is locked down
  tracefs: Restrict tracefs when the kernel is locked down
  debugfs: Restrict debugfs when the kernel is locked down
  kexec: Allow kexec_file() with appropriate IMA policy when locked down
  lockdown: Lock down perf when in confidentiality mode
  bpf: Restrict bpf when kernel lockdown is in confidentiality mode
  lockdown: Lock down tracing and perf kprobes when in confidentiality mode
  lockdown: Lock down /proc/kcore
  x86/mmiotrace: Lock down the testmmiotrace module
  lockdown: Lock down module params that specify hardware parameters (eg. ioport)
  lockdown: Lock down TIOCSSERIAL
  lockdown: Prohibit PCMCIA CIS storage when the kernel is locked down
  acpi: Disable ACPI table override if the kernel is locked down
  acpi: Ignore acpi_rsdp kernel param when the kernel has been locked down
  ACPI: Limit access to custom_method when the kernel is locked down
  x86/msr: Restrict MSR access when the kernel is locked down
  x86: Lock down IO port access when the kernel is locked down
  ...
2019-09-28 08:14:15 -07:00
David Howells
5496197f9b debugfs: Restrict debugfs when the kernel is locked down
Disallow opening of debugfs files that might be used to muck around when
the kernel is locked down as various drivers give raw access to hardware
through debugfs.  Given the effort of auditing all 2000 or so files and
manually fixing each one as necessary, I've chosen to apply a heuristic
instead.  The following changes are made:

 (1) chmod and chown are disallowed on debugfs objects (though the root dir
     can be modified by mount and remount, but I'm not worried about that).

 (2) When the kernel is locked down, only files with the following criteria
     are permitted to be opened:

	- The file must have mode 00444
	- The file must not have ioctl methods
	- The file must not have mmap

 (3) When the kernel is locked down, files may only be opened for reading.

Normal device interaction should be done through configfs, sysfs or a
miscdev, not debugfs.

Note that this makes it unnecessary to specifically lock down show_dsts(),
show_devs() and show_call() in the asus-wmi driver.

I would actually prefer to lock down all files by default and have the
the files unlocked by the creator.  This is tricky to manage correctly,
though, as there are 19 creation functions and ~1600 call sites (some of
them in loops scanning tables).

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Andy Shevchenko <andy.shevchenko@gmail.com>
cc: acpi4asus-user@lists.sourceforge.net
cc: platform-driver-x86@vger.kernel.org
cc: Matthew Garrett <mjg59@srcf.ucam.org>
cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Greg KH <greg@kroah.com>
Cc: Rafael J. Wysocki <rafael@kernel.org>
Signed-off-by: Matthew Garrett <matthewgarrett@google.com>
Signed-off-by: James Morris <jmorris@namei.org>
2019-08-19 21:54:17 -07:00
Greg Kroah-Hartman
c9c2c27d7c debugfs: make debugfs_create_u32_array() return void
The single user of debugfs_create_u32_array() does not care about the
return value of it, so make it return void as there is no need to do
anything with the return value.

Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-06-03 16:34:27 +02:00
Ronald Tschalär
9abb24990a debugfs: update documented return values of debugfs helpers
Since commit ff9fb72bc0 ("debugfs: return error values, not NULL")
these helper functions do not return NULL anymore (with the exception
of debugfs_create_u32_array()).

Fixes: ff9fb72bc0 ("debugfs: return error values, not NULL")
Signed-off-by: Ronald Tschalär <ronald@innovation.ch>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2019-04-25 11:56:50 +02:00
Andy Shevchenko
964f8363a1 debugfs: Re-use kstrtobool_from_user()
Re-use kstrtobool_from_user() instead of open coded variant.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2018-05-14 16:48:18 +02:00
Linus Torvalds
a9a08845e9 vfs: do bulk POLL* -> EPOLL* replacement
This is the mindless scripted replacement of kernel use of POLL*
variables as described by Al, done by this script:

    for V in IN OUT PRI ERR RDNORM RDBAND WRNORM WRBAND HUP RDHUP NVAL MSG; do
        L=`git grep -l -w POLL$V | grep -v '^t' | grep -v /um/ | grep -v '^sa' | grep -v '/poll.h$'|grep -v '^D'`
        for f in $L; do sed -i "-es/^\([^\"]*\)\(\<POLL$V\>\)/\\1E\\2/" $f; done
    done

with de-mangling cleanups yet to come.

NOTE! On almost all architectures, the EPOLL* constants have the same
values as the POLL* constants do.  But they keyword here is "almost".
For various bad reasons they aren't the same, and epoll() doesn't
actually work quite correctly in some cases due to this on Sparc et al.

The next patch from Al will sort out the final differences, and we
should be all done.

Scripted-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2018-02-11 14:34:03 -08:00
Al Viro
cfe39442ab use linux/poll.h instead of asm/poll.h
The only place that has any business including asm/poll.h
is linux/poll.h.  Fortunately, asm/poll.h had only been
included in 3 places beyond that one, and all of them
are trivial to switch to using linux/poll.h.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2018-02-01 16:23:11 -05:00
Al Viro
076ccb76e1 fs: annotate ->poll() instances
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-11-27 16:20:05 -05:00
Al Viro
e6c8adca20 anntotate the places where ->poll() return values go
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
2017-11-27 16:19:53 -05:00
Greg Kroah-Hartman
2b2d8788dd debugfs: Remove redundant license text
Now that the SPDX tag is in all debugfs files, that identifies the
license in a specific and legally-defined manner.  So the extra GPL text
wording can be removed as it is no longer needed at all.

This is done on a quest to remove the 700+ different ways that files in
the kernel describe the GPL license text.  And there's unneeded stuff
like the address (sometimes incorrect) for the FSF which is never
needed.

No copyright headers or other non-license-description text was removed.

Cc: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:03 +01:00
Greg Kroah-Hartman
3bce94fd5f debugfs: add SPDX identifiers to all debugfs files
It's good to have SPDX identifiers in all files to make it easier to
audit the kernel tree for correct licenses.

Update the debugfs files files with the correct SPDX license identifier
based on the license text in the file itself.  The SPDX identifier is a
legally binding shorthand, which can be used instead of the full boiler
plate text.

This work is based on a script and data from Thomas Gleixner, Philippe
Ombredanne, and Kate Stewart.

Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Kate Stewart <kstewart@linuxfoundation.org>
Cc: Philippe Ombredanne <pombredanne@nexb.com>
Cc: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:03 +01:00
Nicolai Stange
7d39bc50c4 debugfs: defer debugfs_fsdata allocation to first usage
Currently, __debugfs_create_file allocates one struct debugfs_fsdata
instance for every file created. However, there are potentially many
debugfs file around, most of which are never touched by userspace.

Thus, defer the allocations to the first usage, i.e. to the first
debugfs_file_get().

A dentry's ->d_fsdata starts out to point to the "real", user provided
fops. After a debugfs_fsdata instance has been allocated (and the real
fops pointer has been moved over into its ->real_fops member),
->d_fsdata is changed to point to it from then on. The two cases are
distinguished by setting BIT(0) for the real fops case.

struct debugfs_fsdata's foremost purpose is to track active users and to
make debugfs_remove() block until they are done. Since no debugfs_fsdata
instance means no active users, make debugfs_remove() return immediately
in this case.

Take care of possible races between debugfs_file_get() and
debugfs_remove(): either debugfs_remove() must see a debugfs_fsdata
instance and thus wait for possible active users or debugfs_file_get() must
see a dead dentry and return immediately.

Make a dentry's ->d_release(), i.e. debugfs_release_dentry(), check whether
->d_fsdata is actually a debugfs_fsdata instance before kfree()ing it.

Similarly, make debugfs_real_fops() check whether ->d_fsdata is actually
a debugfs_fsdata instance before returning it, otherwise emit a warning.

The set of possible error codes returned from debugfs_file_get() has grown
from -EIO to -EIO and -ENOMEM. Make open_proxy_open() and full_proxy_open()
pass the -ENOMEM onwards to their callers.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:03 +01:00
Nicolai Stange
154b9d7512 debugfs: call debugfs_real_fops() only after debugfs_file_get()
The current implementation of debugfs_real_fops() relies on a
debugfs_fsdata instance to be installed at ->d_fsdata.

With future patches introducing lazy allocation of these, this requirement
will be guaranteed to be fullfilled only inbetween a
debugfs_file_get()/debugfs_file_put() pair.

The full proxies' fops implemented by debugfs happen to be the only
offenders. Fix them up by moving their debugfs_real_fops() calls past those
to debugfs_file_get().

full_proxy_release() is special as it doesn't invoke debugfs_file_get() at
all. Leave it alone for now.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:03 +01:00
Nicolai Stange
c9afbec270 debugfs: purge obsolete SRCU based removal protection
Purge the SRCU based file removal race protection in favour of the new,
refcount based debugfs_file_get()/debugfs_file_put() API.

Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:02 +01:00
Nicolai Stange
69d29f9e6a debugfs: convert to debugfs_file_get() and -put()
Convert all calls to the now obsolete debugfs_use_file_start() and
debugfs_use_file_finish() from the debugfs core itself to the new
debugfs_file_get() and debugfs_file_put() API.

Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:02 +01:00
Nicolai Stange
055ab8e3e3 debugfs: debugfs_real_fops(): drop __must_hold sparse annotation
Currently, debugfs_real_fops() is annotated with a
__must_hold(&debugfs_srcu) sparse annotation.

With the conversion of the SRCU based protection of users against
concurrent file removals to a per-file refcount based scheme, this becomes
wrong.

Drop this annotation.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:02 +01:00
Nicolai Stange
e9117a5a4b debugfs: implement per-file removal protection
Since commit 49d200deaa ("debugfs: prevent access to removed files'
private data"), accesses to a file's private data are protected from
concurrent removal by covering all file_operations with a SRCU read section
and sychronizing with those before returning from debugfs_remove() by means
of synchronize_srcu().

As pointed out by Johannes Berg, there are debugfs files with forever
blocking file_operations. Their corresponding SRCU read side sections would
block any debugfs_remove() forever as well, even unrelated ones. This
results in a livelock. Because a remover can't cancel any indefinite
blocking within foreign files, this is a problem.

Resolve this by introducing support for more granular protection on a
per-file basis.

This is implemented by introducing an  'active_users' refcount_t to the
per-file struct debugfs_fsdata state. At file creation time, it is set to
one and a debugfs_remove() will drop that initial reference. The new
debugfs_file_get() and debugfs_file_put(), intended to be used in place of
former debugfs_use_file_start() and debugfs_use_file_finish(), increment
and decrement it respectively. Once the count drops to zero,
debugfs_file_put() will signal a completion which is possibly being waited
for from debugfs_remove().
Thus, as long as there is a debugfs_file_get() not yet matched by a
corresponding debugfs_file_put() around, debugfs_remove() will block.

Actual users of debugfs_use_file_start() and -finish() will get converted
to the new debugfs_file_get() and debugfs_file_put() by followup patches.

Fixes: 49d200deaa ("debugfs: prevent access to removed files' private data")
Reported-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:02 +01:00
Nicolai Stange
7c8d469877 debugfs: add support for more elaborate ->d_fsdata
Currently, the user provided fops, "real_fops", are stored directly into
->d_fsdata.

In order to be able to store more per-file state and thus prepare for more
granular file removal protection, wrap the real_fops into a dynamically
allocated container struct, debugfs_fsdata.

A struct debugfs_fsdata gets allocated at file creation and freed from the
newly intoduced ->d_release().

Finally, move the implementation of debugfs_real_fops() out of the public
debugfs header such that struct debugfs_fsdata's declaration can be kept
private.

Signed-off-by: Nicolai Stange <nicstange@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2017-11-07 20:25:02 +01:00
Mauro Carvalho Chehab
e1b4fc7add fs: update location of filesystems documentation
The filesystem documentation was moved from DocBook to
Documentation/filesystems/. Update it at the sources.

Signed-off-by: Mauro Carvalho Chehab <mchehab@s-opensource.com>
2017-05-16 08:44:22 -03:00