Re: [PATCH] init/main.c: Initialize early LSMs after arch code

[Guenter Roeck <linux@roeck-us.net>]

On 8/8/24 02:57, KP Singh wrote:
> On Thu, Aug 8, 2024 at 6:07 AM Guenter Roeck <linux@roeck-us.net> wrote:
>>
>> On 8/7/24 19:13, Guenter Roeck wrote:
>> ...
>>>
>>> I'll need to establish a baseline first to determine if the failures
>>> are caused by newly enabled configuration options or by this patch set.
>>> Below are just early test results.
>>>
>>> [ Though if those are all upstream there seems to be be something seriously
>>>     wrong with the lockdown lsm.
>>> ]
>>>
>>
>> Verdict is that all the messages below are from this patch set.
>>
>> On top of the reports below, alpha images fail completely, and the
>> backtraces are seen with several architectures. Please see the
>> "testing" column at https://kerneltests.org/builders for details.
>>
>> The only unrelated problems are the apparmor unit test failures;
>> those apparently fail on all big endian systems.
>>
>> Guenter
>>
>>> Guenter
>>>
>>> ----
>>> arm:
>>>
>>> [    0.000000] ------------[ cut here ]------------
>>> [    0.000000] WARNING: CPU: 0 PID: 0 at kernel/jump_label.c:199 static_key_enable_cpuslocked+0xb0/0xfc
>>> [    0.000000] static_key_enable_cpuslocked(): static key 'security_hook_active_locked_down_0+0x0/0x8' used before call to jump_label_init()
>>> [    0.000000] CPU: 0 UID: 0 PID: 0 Comm: swapper Not tainted 6.11.0-rc2-00134-g679d51771510 #1
>>> [    0.000000] Hardware name: Generic DT based system
>>> [    0.000000] Call trace:
>>> [    0.000000]  unwind_backtrace from show_stack+0x18/0x1c
>>> [    0.000000]  show_stack from dump_stack_lvl+0x48/0x74
>>> [    0.000000]  dump_stack_lvl from __warn+0x7c/0x134
>>> [    0.000000]  __warn from warn_slowpath_fmt+0x9c/0xdc
>>> [    0.000000]  warn_slowpath_fmt from static_key_enable_cpuslocked+0xb0/0xfc
>>> [    0.000000]  static_key_enable_cpuslocked from security_add_hooks+0xa0/0x104
>>> [    0.000000]  security_add_hooks from lockdown_lsm_init+0x1c/0x2c
>>> [    0.000000]  lockdown_lsm_init from initialize_lsm+0x44/0x84
>>> [    0.000000]  initialize_lsm from early_security_init+0x3c/0x58
>>> [    0.000000]  early_security_init from start_kernel+0x78/0x748
>>> [    0.000000]  start_kernel from 0x0
>>> [    0.000000] irq event stamp: 0
>>> [    0.000000] hardirqs last  enabled at (0): [<00000000>] 0x0
>>> [    0.000000] hardirqs last disabled at (0): [<00000000>] 0x0
>>> [    0.000000] softirqs last  enabled at (0): [<00000000>] 0x0
>>> [    0.000000] softirqs last disabled at (0): [<00000000>] 0x0
>>> [    0.000000] ---[ end trace 0000000000000000 ]---
>>>
> 
> This seems very odd for especially ARM as I don't see this error when
> I do it on the next branch. Possibly something in setup_arch is
> initializing jump_tables indirectly between v6.11-rc2 and linux-next
> and/or this is a warning that does not immediately splash up on the
> dmesg.
> 
> Both ARM64 and x86 (the architectures I really have access to)
> initializes jump_tables and x86 is the only architecture that does an
> explicit static_call_init is x86 and it's already in the setup_arch
> code.
> 
> https://elixir.bootlin.com/linux/v6.11-rc2/source/arch/arm64/kernel/setup.c#L295
> https://elixir.bootlin.com/linux/v6.11-rc2/source/arch/x86/kernel/setup.c#L783
> 
> Guenter, I have updated my tree, could you give it another run please?
> 

This version is much better, except for alpha which still crashes hard
with no log output. It bisects to one of your patches (results below).

Also, there is a backtrace on ppc (also see below), but that is unrelated
to your patches and only seen now because I enabled the security modules
on that architecture. I'll bring that up with ppc maintainers.

Thanks,
Guenter

---
bisect:

# bad: [b92c86ad4f4311706fe436a1545d9a97e6aebcf8] lsm: replace indirect LSM hook calls with static calls
# good: [de9c2c66ad8e787abec7c9d7eff4f8c3cdd28aed] Linux 6.11-rc2
git bisect start 'HEAD' 'v6.11-rc2'
# good: [bd2c890317b2d60b4afd89a374a56a7c9a0275bd] kernel: Add helper macros for loop unrolling
git bisect good bd2c890317b2d60b4afd89a374a56a7c9a0275bd
# good: [6a1e94163fc53a4f1b47a8689f416a1a3d0a154a] lsm: count the LSMs enabled at compile time
git bisect good 6a1e94163fc53a4f1b47a8689f416a1a3d0a154a
# first bad commit: [b92c86ad4f4311706fe436a1545d9a97e6aebcf8] lsm: replace indirect LSM hook calls with static calls

---
ppc backtrace:

LSM: initializing lsm=lockdown,capability,landlock,yama,loadpin,safesetid
------------[ cut here ]------------
WARNING: CPU: 0 PID: 0 at kernel/smp.c:779 smp_call_function_many_cond+0x518/0x9d4
Modules linked in:
CPU: 0 UID: 0 PID: 0 Comm: swapper/0 Not tainted 6.11.0-rc2-00127-g2e3e7093e9c8 #1
Hardware name: MPC8544DS e500v2 0x80210030 MPC8544 DS
NIP:  c0172ca8 LR: c01731b0 CTR: 00000000
REGS: c2669d60 TRAP: 0700   Not tainted  (6.11.0-rc2-00127-g2e3e7093e9c8)
MSR:  00021000 <CE,ME>  CR: 24004288  XER: 20000000
GPR00: c002255c c2669e50 c253b5c0 c267b484 00000000 00000000 00000001 c2680000
GPR08: 00000000 00000003 c2680000 00000000 44004288 020a1e18 00000000 00000000
GPR16: 00000000 00000000 00000001 00000000 c0000000 c01731b0 00000000 c267b484
GPR24: c00224fc c0773760 c0770b50 00000000 00000000 00029000 00000000 00000000
NIP [c0172ca8] smp_call_function_many_cond+0x518/0x9d4
LR [c01731b0] smp_call_function+0x3c/0x58
Call Trace:
[c2669eb0] [84000282] 0x84000282
[c2669ec0] [c002255c] flush_tlb_kernel_range+0x2c/0x50
[c2669ed0] [c0023b8c] patch_instruction+0x108/0x1b0
[c2669ef0] [c00188a4] arch_static_call_transform+0x104/0x148
[c2669f10] [c2033ebc] security_add_hooks+0x138/0x24c
[c2669f40] [c2032e24] capability_init+0x24/0x38
[c2669f50] [c203322c] initialize_lsm+0x48/0x90
[c2669f70] [c2033b68] security_init+0x31c/0x538
[c2669fa0] [c2001154] start_kernel+0x5d4/0x81c
[c2669ff0] [c0000478] set_ivor+0x150/0x18c
Code: 91220000 81620004 3d20c209 3929e478 556b103a 7c84582e 7c89202e 81220000 2c040000 3929ffff 91220000 40a2fbb8 <0fe00000> 4bfffbb0 80e20000 2c070000
irq event stamp: 1204
hardirqs last  enabled at (1203): [<c11d85f8>] _raw_spin_unlock_irqrestore+0x70/0xa8
hardirqs last disabled at (1204): [<c0023bcc>] patch_instruction+0x148/0x1b0
softirqs last  enabled at (50): [<c0064b4c>] handle_softirqs+0x348/0x508
softirqs last disabled at (43): [<c0006fd0>] do_softirq_own_stack+0x34/0x4c
---[ end trace 0000000000000000 ]---
landlock: Up and running.
Yama: becoming mindful.
LoadPin: ready to pin (currently not enforcing)