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Ilias Apalodimas d4a9aa7db5 efivarfs: force RO when remounting if SetVariable is not supported 
[ Upstream commit 0e8d244416 ]

If SetVariable at runtime is not supported by the firmware we never assign
a callback for that function. At the same time mount the efivarfs as
RO so no one can call that.  However, we never check the permission flags
when someone remounts the filesystem as RW. As a result this leads to a
crash looking like this:

$ mount -o remount,rw /sys/firmware/efi/efivars
$ efi-updatevar -f PK.auth PK

[  303.279166] Unable to handle kernel NULL pointer dereference at virtual address 0000000000000000
[  303.280482] Mem abort info:
[  303.280854]   ESR = 0x0000000086000004
[  303.281338]   EC = 0x21: IABT (current EL), IL = 32 bits
[  303.282016]   SET = 0, FnV = 0
[  303.282414]   EA = 0, S1PTW = 0
[  303.282821]   FSC = 0x04: level 0 translation fault
[  303.283771] user pgtable: 4k pages, 48-bit VAs, pgdp=000000004258c000
[  303.284913] [0000000000000000] pgd=0000000000000000, p4d=0000000000000000
[  303.286076] Internal error: Oops: 0000000086000004 [#1] PREEMPT SMP
[  303.286936] Modules linked in: qrtr tpm_tis tpm_tis_core crct10dif_ce arm_smccc_trng rng_core drm fuse ip_tables x_tables ipv6
[  303.288586] CPU: 1 PID: 755 Comm: efi-updatevar Not tainted 6.3.0-rc1-00108-gc7d0c4695c68 #1
[  303.289748] Hardware name: Unknown Unknown Product/Unknown Product, BIOS 2023.04-00627-g88336918701d 04/01/2023
[  303.291150] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--)
[  303.292123] pc : 0x0
[  303.292443] lr : efivar_set_variable_locked+0x74/0xec
[  303.293156] sp : ffff800008673c10
[  303.293619] x29: ffff800008673c10 x28: ffff0000037e8000 x27: 0000000000000000
[  303.294592] x26: 0000000000000800 x25: ffff000002467400 x24: 0000000000000027
[  303.295572] x23: ffffd49ea9832000 x22: ffff0000020c9800 x21: ffff000002467000
[  303.296566] x20: 0000000000000001 x19: 00000000000007fc x18: 0000000000000000
[  303.297531] x17: 0000000000000000 x16: 0000000000000000 x15: 0000aaaac807ab54
[  303.298495] x14: ed37489f673633c0 x13: 71c45c606de13f80 x12: 47464259e219acf4
[  303.299453] x11: ffff000002af7b01 x10: 0000000000000003 x9 : 0000000000000002
[  303.300431] x8 : 0000000000000010 x7 : ffffd49ea8973230 x6 : 0000000000a85201
[  303.301412] x5 : 0000000000000000 x4 : ffff0000020c9800 x3 : 00000000000007fc
[  303.302370] x2 : 0000000000000027 x1 : ffff000002467400 x0 : ffff000002467000
[  303.303341] Call trace:
[  303.303679]  0x0
[  303.303938]  efivar_entry_set_get_size+0x98/0x16c
[  303.304585]  efivarfs_file_write+0xd0/0x1a4
[  303.305148]  vfs_write+0xc4/0x2e4
[  303.305601]  ksys_write+0x70/0x104
[  303.306073]  __arm64_sys_write+0x1c/0x28
[  303.306622]  invoke_syscall+0x48/0x114
[  303.307156]  el0_svc_common.constprop.0+0x44/0xec
[  303.307803]  do_el0_svc+0x38/0x98
[  303.308268]  el0_svc+0x2c/0x84
[  303.308702]  el0t_64_sync_handler+0xf4/0x120
[  303.309293]  el0t_64_sync+0x190/0x194
[  303.309794] Code: ???????? ???????? ???????? ???????? (????????)
[  303.310612] ---[ end trace 0000000000000000 ]---

Fix this by adding a .reconfigure() function to the fs operations which
we can use to check the requested flags and deny anything that's not RO
if the firmware doesn't implement SetVariable at runtime.

Fixes: f88814cc25 ("efi/efivars: Expose RT service availability via efivars abstraction")
Signed-off-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Signed-off-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
History 2024-01-25 15:27:20 -08:00
arch powerpc/imc-pmu: Add a null pointer check in update_events_in_group() 2024-01-25 15:27:19 -08:00
block blk-mq: don't count completed flush data request as inflight in case of quiesce 2024-01-20 11:50:04 +01:00
certs certs: Fix build error when PKCS#11 URI contains semicolon 2023-02-09 11:28:11 +01:00
crypto crypto: pcrypt - Fix hungtask for PADATA_RESET 2023-11-28 17:06:58 +00:00
Documentation dt-bindings: nvmem: mxs-ocotp: Document fsl,ocotp 2024-01-01 12:39:04 +00:00
drivers cpufreq: scmi: process the result of devm_of_clk_add_hw_provider() 2024-01-25 15:27:20 -08:00
fs efivarfs: force RO when remounting if SetVariable is not supported 2024-01-25 15:27:20 -08:00
include of: Add of_property_present() helper 2024-01-25 15:27:20 -08:00
init btf, scripts: Exclude Rust CUs with pahole 2024-01-20 11:50:10 +01:00
io_uring net: Declare MSG_SPLICE_PAGES internal sendmsg() flag 2024-01-10 17:10:27 +01:00
ipc ipc: fix memory leak in init_mqueue_fs() 2022-12-31 13:32:01 +01:00
kernel ring-buffer: Do not record in NMI if the arch does not support cmpxchg in NMI 2024-01-20 11:50:07 +01:00
lib btf, scripts: Exclude Rust CUs with pahole 2024-01-20 11:50:10 +01:00
LICENSES LICENSES/LGPL-2.1: Add LGPL-2.1-or-later as valid identifiers 2021-12-16 14:33:10 +01:00
mm mm: fix unmap_mapping_range high bits shift bug 2024-01-10 17:10:35 +01:00
net calipso: fix memory leak in netlbl_calipso_add_pass() 2024-01-25 15:27:20 -08:00
rust rust: allocator: Prevent mis-aligned allocation 2023-08-11 12:08:18 +02:00
samples fprobe: Pass entry_data to handlers 2023-10-25 12:03:12 +02:00
scripts powerpc: remove checks for binutils older than 2.25 2024-01-25 15:27:18 -08:00
security KEYS: encrypted: Add check for strsep 2024-01-25 15:27:19 -08:00
sound ASoC: SOF: Intel: hda-codec: Delay the codec device registration 2024-01-20 11:50:10 +01:00
tools selftests/powerpc: Fix error handling in FPU/VMX preemption tests 2024-01-25 15:27:19 -08:00
usr usr/gen_init_cpio.c: remove unnecessary -1 values from int file 2022-10-03 14:21:44 -07:00
virt kvm/vfio: ensure kvg instance stays around in kvm_vfio_group_add() 2023-09-13 09:42:46 +02:00
.clang-format inet: ping: use hlist_nulls rcu iterator during lookup 2022-12-01 12:42:46 +01:00
.cocciconfig scripts: add Linux .cocciconfig for coccinelle 2016-07-22 12:13:39 +02:00
.get_maintainer.ignore get_maintainer: add Alan to .get_maintainer.ignore 2022-08-20 15:17:44 -07:00
.gitattributes .gitattributes: use 'dts' diff driver for dts files 2019-12-04 19:44:11 -08:00
.gitignore Kbuild: add Rust support 2022-09-28 09:02:20 +02:00
.mailmap 9 hotfixes. 6 for MM, 3 for other areas. Four of these patches address 2022-12-10 17:10:52 -08:00
.rustfmt.toml rust: add .rustfmt.toml 2022-09-28 09:02:20 +02:00
COPYING COPYING: state that all contributions really are covered by this file 2020-02-10 13:32:20 -08:00
CREDITS MAINTAINERS: Remove Michal Marek from Kbuild maintainers 2022-11-16 14:53:00 +09:00
Kbuild Kbuild updates for v6.1 2022-10-10 12:00:45 -07:00
Kconfig kbuild: ensure full rebuild when the compiler is updated 2020-05-12 13:28:33 +09:00
MAINTAINERS genirq/affinity: Move group_cpus_evenly() into lib/ 2024-01-10 17:10:33 +01:00
Makefile Linux 6.1.74 2024-01-20 11:50:11 +01:00
README Drop all 00-INDEX files from Documentation/ 2018-09-09 15:08:58 -06:00

README 

Linux kernel
============

There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.

In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``.  The formatted documentation can also be read online at:

    https://www.kernel.org/doc/html/latest/

There are various text files in the Documentation/ subdirectory,
several of them using the Restructured Text markup notation.

Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.