On 8/3/20 1:29 PM, Stephen Smalley wrote:
On 8/3/20 4:00 PM, Stephen Smalley wrote:
On Mon, Aug 3, 2020 at 12:14 PM Lakshmi Ramasubramanian
<nramas@xxxxxxxxxxxxxxxxxxx> wrote:
On 8/3/20 8:11 AM, Stephen Smalley wrote:
Possibly I'm missing something but with these patches applied on top of
next-integrity, and the following lines added to /etc/ima/ima-policy:
measure func=LSM_STATE template=ima-buf
measure func=LSM_POLICY
I still don't get the selinux-state or selinux-policy-hash entries in
the ascii_runtime_measurements file. No errors during loading of the
ima policy as far as I can see.
Could you please check if the following config is set?
CONFIG_IMA_QUEUE_EARLY_BOOT_DATA=y
Yes, I have that set.
Try changing /sys/fs/selinux/checkreqprot and check
ascii_runtime_measurements file again?
No change. Likewise for changing enforce or running load_policy again.
Also, could you please check if
/sys/kernel/security/integrity/ima/policy contains LSM_STATE and
LSM_POLICY entries?
Yes, it does. However, I noticed that if I reduce the policy to only
contain those entries and no others and reboot, then I get
measurements. Whereas if I append them to an existing policy like the
one below, they seem to be ignored:
dont_measure fsmagic=0x9fa0
dont_measure fsmagic=0x62656572
dont_measure fsmagic=0x64626720
dont_measure fsmagic=0x1021994
dont_measure fsmagic=0x858458f6
dont_measure fsmagic=0x73636673
measure func=BPRM_CHECK
measure func=MMAP_CHECK mask=MAY_EXEC
measure func=MODULE_CHECK uid=0
measure func=LSM_STATE template=ima-buf
measure func=LSM_POLICY
Also, I noticed the following in my dmesg output:
[ 68.870715] ------------[ cut here ]------------
[ 68.870715] WARNING: CPU: 2 PID: 1 at mm/page_alloc.c:4826
__alloc_pages_nodemask+0x627/0x700
[ 68.870715] Modules linked in: 8139too crct10dif_pclmul
crc32_pclmul crc32c_intel ghash_clmulni_intel qxl serio_raw
drm_ttm_helper ttm drm_kms_helper virtio_console cec drm 8139cp
ata_generic mii pata_acpi floppy qemu_fw_cfg fuse
[ 68.870715] CPU: 2 PID: 1 Comm: systemd Not tainted 5.8.0-rc2+ #44
[ 68.870715] RIP: 0010:__alloc_pages_nodemask+0x627/0x700
[ 68.870715] Code: ff ff 75 6c 48 8b 85 48 ff ff ff 4c 89 c2 44 89
e6 44 89 ff 41 c6 45 d0 00 49 89 45 b8 e8 41 e2 ff ff 49 89 c6 e9 9d
fc ff ff <0f> 0b e9 d4 fd ff ff 0f 0b e9 bc fc ff ff 0f 0b e9 f9 fd ff
ff e8
[ 68.870715] RSP: 0000:ffff8881e82a7a18 EFLAGS: 00010246
[ 68.870715] RAX: ffffed103d054f48 RBX: 1ffff1103d054f48 RCX:
0000000000000000
[ 68.870715] RDX: 0000000000000000 RSI: 000000000000000b RDI:
0000000000000000
[ 68.870715] RBP: ffff8881e82a7ae8 R08: ffffffffaa3fe2d5 R09:
0000000000000001
[ 68.870715] R10: fffffbfff5a88f0f R11: 0000000000000001 R12:
00000000007eef6a
[ 68.870715] R13: 0000000000040cc0 R14: 000000000000000b R15:
ffffffffadde766b
[ 68.870715] FS: 00007fdeb168c600(0000) GS:ffff8881e9800000(0000)
knlGS:0000000000000000
[ 68.870715] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[ 68.870715] CR2: 00007fdeb17dd1d6 CR3: 00000001cc2d2002 CR4:
00000000003606e0
[ 68.870715] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
0000000000000000
[ 68.870715] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
0000000000000400
[ 68.870715] Call Trace:
[ 68.870715] ? sched_clock_cpu+0xf5/0x110
[ 68.870715] ? __alloc_pages_slowpath.constprop.0+0x17a0/0x17a0
[ 68.870715] ? match_held_lock+0x2e/0x240
[ 68.870715] ? policy_nodemask+0x1a/0xa0
[ 68.870715] ? policy_node+0x56/0x60
[ 68.870715] kmalloc_order+0x25/0xc0
[ 68.870715] kmalloc_order_trace+0x1d/0x140
[ 68.870715] kmemdup+0x1a/0x40
[ 68.870715] ima_queue_data+0x61/0x370
[ 68.870715] ima_measure_lsm_data+0x32/0x60
[ 68.870715] selinux_measure_state+0x2b8/0x2bd
[ 68.870715] ? selinux_event_name+0xe0/0xe0
[ 68.870715] ? rcu_is_watching+0x39/0x50
[ 68.870715] security_load_policy+0x44c/0x8e0
[ 68.870715] ? mark_lock+0xa6/0xbd0
[ 68.870715] ? security_change_sid+0x90/0x90
[ 68.870715] ? mark_held_locks+0x3e/0xa0
[ 68.870715] ? lockdep_hardirqs_on_prepare+0x100/0x260
[ 68.870715] ? asm_exc_page_fault+0x1e/0x30
[ 68.870715] ? lockdep_hardirqs_on+0xc5/0x1b0
[ 68.870715] ? asm_exc_page_fault+0x1e/0x30
[ 68.870715] ? copy_user_enhanced_fast_string+0xe/0x30
[ 68.870715] sel_write_load+0x157/0x260
[ 68.870715] vfs_write+0x135/0x290
[ 68.870715] ksys_write+0xb1/0x140
[ 68.870715] ? __ia32_sys_read+0x50/0x50
[ 68.870715] ? lockdep_hardirqs_on_prepare+0x100/0x260
[ 68.870715] ? do_syscall_64+0x12/0xb0
[ 68.870715] do_syscall_64+0x52/0xb0
[ 68.870715] entry_SYSCALL_64_after_hwframe+0x44/0xa9
[ 68.870715] RIP: 0033:0x7fdeb2539497
[ 68.870715] Code: Bad RIP value.
[ 68.870715] RSP: 002b:00007fff6352b308 EFLAGS: 00000246 ORIG_RAX:
0000000000000001
[ 68.870715] RAX: ffffffffffffffda RBX: 0000000000000020 RCX:
00007fdeb2539497
[ 68.870715] RDX: 00000000007eef6a RSI: 00007fdeb0de1000 RDI:
0000000000000004
[ 68.870715] RBP: 0000000000000004 R08: 00007fdeb25d0040 R09:
00007fff6352b1a0
[ 68.870715] R10: 0000000000000000 R11: 0000000000000246 R12:
00007fdeb0de1000
[ 68.870715] R13: 00000000007eef6a R14: 000000000000000f R15:
0000000000000003
[ 68.870715] irq event stamp: 23486085
[ 68.870715] hardirqs last enabled at (23486085):
[<ffffffffaa419406>] _raw_spin_unlock_irqrestore+0x46/0x60
[ 68.870715] hardirqs last disabled at (23486084):
[<ffffffffaa419443>] _raw_spin_lock_irqsave+0x23/0x90
[ 68.870715] softirqs last enabled at (23486074):
[<ffffffffaa8004f3>] __do_softirq+0x4f3/0x662
[ 68.870715] softirqs last disabled at (23486067):
[<ffffffffaa601072>] asm_call_on_stack+0x12/0x20
[ 68.870715] ---[ end trace fb02740ff6f4d0cd ]---
I think one issue here is that systemd loads SELinux policy first, then
IMA policy, so it doesn't know whether it needs to measure SELinux
policy on first policy load, and another issue is that the policy is too
large to just queue the policy data itself this way (or you need to use
an allocator that can handle larger sizes).
The problem seems to be that a lock is held when the IMA hook to measure
the LSM state is called. So memory allocation is not allowed, but the
hook is doing an allocation. I'll address this - thanks for catching it.
I have the following CONFIGs enabled, but I still don't see the above
issue on my machine.
Could you please let me know what CONFIG(s) to enable?
#
# Lock Debugging (spinlocks, mutexes, etc...)
#
CONFIG_LOCK_DEBUGGING_SUPPORT=y
CONFIG_PROVE_LOCKING=y
CONFIG_DEBUG_RT_MUTEXES=y
CONFIG_DEBUG_SPINLOCK=y
CONFIG_DEBUG_MUTEXES=y
CONFIG_DEBUG_WW_MUTEX_SLOWPATH=y
CONFIG_DEBUG_RWSEMS=y
CONFIG_DEBUG_LOCK_ALLOC=y
CONFIG_LOCKDEP=y
CONFIG_DEBUG_ATOMIC_SLEEP=y
I'll also try with the policy you have, check why the LSM policy is
ignored when there are other policy entries.
thanks,
-lakshmi
