Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 8/4/20 8:29 AM, Stephen Smalley wrote: Perhaps vmalloc would be better than using kmalloc? If there are better options for such large buffer allocation, please let me know. kvmalloc() can be used to select whichever one is most appropriate. Other option would be for ima to compute and save the hash(es) of the payload and not the payload itself for later use. I guess you won't know at that point which hash algorithm is desired? I think IMA hash algorithm would be known at that point, but IMA policy is not loaded yet (which is why I need to queue up the buffer and process when policy is loaded). I tried vmalloc and tested it with upto 16MB buffer (just made up a SELinux policy buffer of size 16MB) - that works fine. I will try kvmalloc(). Also, I fixed the issue with LSM data not measured when using the IMA policy you had. Good catch. Will post the updated patches today. thanks, -lakshmi
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 8/4/20 11:20 AM, Stephen Smalley wrote: On 8/3/20 6:08 PM, Lakshmi Ramasubramanian wrote: On 8/3/20 2:07 PM, Stephen Smalley wrote: [ 68.870715] irq event stamp: 23486085 [ 68.870715] hardirqs last enabled at (23486085): [] _raw_spin_unlock_irqrestore+0x46/0x60 [ 68.870715] hardirqs last disabled at (23486084): [] _raw_spin_lock_irqsave+0x23/0x90 [ 68.870715] softirqs last enabled at (23486074): [] __do_softirq+0x4f3/0x662 [ 68.870715] softirqs last disabled at (23486067): [] 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. The warning has to do with the memory allocation order being above the max order supported for kmalloc. I think the problem is that ima_alloc_data_entry() is using kmemdup() to duplicate a payload of arbitrary size. Policies on e.g. Fedora can be quite large, so you can't assume they can be allocated with kmalloc and friends. Thanks for clarifying. Yes ima_alloc_entry() does use kmemdup to save the given buffer (to be measured) until IMA loads custom policy. On my machine the SELinux policy size is about 2MB. Perhaps vmalloc would be better than using kmalloc? If there are better options for such large buffer allocation, please let me know. kvmalloc() can be used to select whichever one is most appropriate. Other option would be for ima to compute and save the hash(es) of the payload and not the payload itself for later use. I guess you won't know at that point which hash algorithm is desired?
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 8/3/20 6:08 PM, Lakshmi Ramasubramanian wrote: On 8/3/20 2:07 PM, Stephen Smalley wrote: [ 68.870715] irq event stamp: 23486085 [ 68.870715] hardirqs last enabled at (23486085): [] _raw_spin_unlock_irqrestore+0x46/0x60 [ 68.870715] hardirqs last disabled at (23486084): [] _raw_spin_lock_irqsave+0x23/0x90 [ 68.870715] softirqs last enabled at (23486074): [] __do_softirq+0x4f3/0x662 [ 68.870715] softirqs last disabled at (23486067): [] 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. The warning has to do with the memory allocation order being above the max order supported for kmalloc. I think the problem is that ima_alloc_data_entry() is using kmemdup() to duplicate a payload of arbitrary size. Policies on e.g. Fedora can be quite large, so you can't assume they can be allocated with kmalloc and friends. Thanks for clarifying. Yes ima_alloc_entry() does use kmemdup to save the given buffer (to be measured) until IMA loads custom policy. On my machine the SELinux policy size is about 2MB. Perhaps vmalloc would be better than using kmalloc? If there are better options for such large buffer allocation, please let me know. kvmalloc() can be used to select whichever one is most appropriate.
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 8/3/20 2:07 PM, Stephen Smalley wrote: [ 68.870715] irq event stamp: 23486085 [ 68.870715] hardirqs last enabled at (23486085): [] _raw_spin_unlock_irqrestore+0x46/0x60 [ 68.870715] hardirqs last disabled at (23486084): [] _raw_spin_lock_irqsave+0x23/0x90 [ 68.870715] softirqs last enabled at (23486074): [] __do_softirq+0x4f3/0x662 [ 68.870715] softirqs last disabled at (23486067): [] 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. The warning has to do with the memory allocation order being above the max order supported for kmalloc. I think the problem is that ima_alloc_data_entry() is using kmemdup() to duplicate a payload of arbitrary size. Policies on e.g. Fedora can be quite large, so you can't assume they can be allocated with kmalloc and friends. Thanks for clarifying. Yes ima_alloc_entry() does use kmemdup to save the given buffer (to be measured) until IMA loads custom policy. On my machine the SELinux policy size is about 2MB. Perhaps vmalloc would be better than using kmalloc? If there are better options for such large buffer allocation, please let me know. -lakshmi
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 8/3/20 4:37 PM, Lakshmi Ramasubramanian wrote: 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 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: :8881e82a7a18 EFLAGS: 00010246 [ 68.870715] RAX: ed103d054f48 RBX: 11103d054f48 RCX: [ 68.870715] RDX: RSI: 000b RDI: [ 68.870715] RBP: 8881e82a7ae8 R08: aa3fe2d5 R09: 0001 [ 68.870715] R10: fbfff5a88f0f R11: 0001 R12: 007eef6a [ 68.870715] R13: 00040cc0 R14: 000b R15: adde766b [ 68.870715] FS: 7fdeb168c600() GS:8881e980() knlGS: [ 68.870715] CS: 0010 DS: ES: CR0: 80050033 [ 68.870715] CR2: 7fdeb17dd1d6 CR3: 0001cc2d2002 CR4: 003606e0 [ 68.870715] DR0: DR1: DR2: [ 68.870715] DR3: DR6: fffe0ff0 DR7: 0400 [ 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:7fff6352b308 EFLAGS: 0246 ORIG_RAX: 0001 [ 68.870715] RAX: ffda RBX: 0020 RCX: 7fdeb2539497 [ 68.870715] RDX: 007eef6a RSI: 7fdeb0de1000 RDI: 0
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
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 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: :8881e82a7a18 EFLAGS: 00010246 [ 68.870715] RAX: ed103d054f48 RBX: 11103d054f48 RCX: [ 68.870715] RDX: RSI: 000b RDI: [ 68.870715] RBP: 8881e82a7ae8 R08: aa3fe2d5 R09: 0001 [ 68.870715] R10: fbfff5a88f0f R11: 0001 R12: 007eef6a [ 68.870715] R13: 00040cc0 R14: 000b R15: adde766b [ 68.870715] FS: 7fdeb168c600() GS:8881e980() knlGS: [ 68.870715] CS: 0010 DS: ES: CR0: 80050033 [ 68.870715] CR2: 7fdeb17dd1d6 CR3: 0001cc2d2002 CR4: 003606e0 [ 68.870715] DR0: DR1: DR2: [ 68.870715] DR3: DR6: fffe0ff0 DR7: 0400 [ 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:7fff6352b308 EFLAGS: 0246 ORIG_RAX: 0001 [ 68.870715] RAX: ffda RBX: 0020 RCX: 7fdeb2539497 [ 68.870715] RDX: 007eef6a RSI: 7fdeb0de1000 RDI: 0004 [ 68.870715] RBP: 0004 R08: 000
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 8/3/20 4:00 PM, Stephen Smalley wrote: On Mon, Aug 3, 2020 at 12:14 PM Lakshmi Ramasubramanian 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: :8881e82a7a18 EFLAGS: 00010246 [ 68.870715] RAX: ed103d054f48 RBX: 11103d054f48 RCX: [ 68.870715] RDX: RSI: 000b RDI: [ 68.870715] RBP: 8881e82a7ae8 R08: aa3fe2d5 R09: 0001 [ 68.870715] R10: fbfff5a88f0f R11: 0001 R12: 007eef6a [ 68.870715] R13: 00040cc0 R14: 000b R15: adde766b [ 68.870715] FS: 7fdeb168c600() GS:8881e980() knlGS: [ 68.870715] CS: 0010 DS: ES: CR0: 80050033 [ 68.870715] CR2: 7fdeb17dd1d6 CR3: 0001cc2d2002 CR4: 003606e0 [ 68.870715] DR0: DR1: DR2: [ 68.870715] DR3: DR6: fffe0ff0 DR7: 0400 [ 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:7fff6352b308 EFLAGS: 0246 ORIG_RAX: 0001 [ 68.870715] RAX: ffda RBX: 0020 RCX: 7fdeb2539497 [ 68.870715] RDX: 007eef6a RSI: 7fdeb0de1000 RDI: 0004 [ 68.870715] RBP: 0004 R08: 7fdeb25d0040 R09: 7fff6352b1a0 [ 68.870715] R10:
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On Mon, Aug 3, 2020 at 12:14 PM Lakshmi Ramasubramanian 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: :8881e82a7a18 EFLAGS: 00010246 [ 68.870715] RAX: ed103d054f48 RBX: 11103d054f48 RCX: [ 68.870715] RDX: RSI: 000b RDI: [ 68.870715] RBP: 8881e82a7ae8 R08: aa3fe2d5 R09: 0001 [ 68.870715] R10: fbfff5a88f0f R11: 0001 R12: 007eef6a [ 68.870715] R13: 00040cc0 R14: 000b R15: adde766b [ 68.870715] FS: 7fdeb168c600() GS:8881e980() knlGS: [ 68.870715] CS: 0010 DS: ES: CR0: 80050033 [ 68.870715] CR2: 7fdeb17dd1d6 CR3: 0001cc2d2002 CR4: 003606e0 [ 68.870715] DR0: DR1: DR2: [ 68.870715] DR3: DR6: fffe0ff0 DR7: 0400 [ 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:7fff6352b308 EFLAGS: 0246 ORIG_RAX: 0001 [ 68.870715] RAX: ffda RBX: 0020 RCX: 7fdeb2539497 [ 68.870715] RDX: 007eef6a RSI: 7fdeb0de1000 RDI: 0004 [ 68.870715] RBP: 0004 R08: 7fdeb25d0040 R09: 7fff6352b1a0 [ 68.8
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
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 Try changing /sys/fs/selinux/checkreqprot and check ascii_runtime_measurements file again? Also, could you please check if /sys/kernel/security/integrity/ima/policy contains LSM_STATE and LSM_POLICY entries? -lakshmi
Re: [PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
On 7/29/20 11:47 PM, Lakshmi Ramasubramanian wrote: SELinux configuration and policy are some of the critical data for this security module that needs to be measured. This measurement can be used by an attestation service, for instance, to verify if the configuration and policies have been setup correctly and that they haven't been tampered with at runtime. Measure SELinux configuration, policy capabilities settings, and the loaded policy by calling the IMA hooks ima_measure_lsm_state() and ima_measure_lsm_policy() respectively. Sample measurement of SELinux state and hash of the policy: 10 e32e...5ac3 ima-buf sha256:86e8...4594 selinux-state-1595389364:287899386 696e697469616c697a65643d313b656e61626c65643d313b656e666f7263696e673d303b636865636b72657170726f743d313b6e6574776f726b5f706565725f636f6e74726f6c733d313b6f70656e5f7065726d733d313b657874656e6465645f736f636b65745f636c6173733d313b616c776179735f636865636b5f6e6574776f726b3d303b6367726f75705f7365636c6162656c3d313b6e6e705f6e6f737569645f7472616e736974696f6e3d313b67656e66735f7365636c6162656c5f73796d6c696e6b733d303 10 f4a7...9408 ima-ng sha256:8d1d...1834 selinux-policy-hash-1595389353:863934271 To verify the measurement check the following: Execute the following command to extract the measured data from the IMA log for SELinux configuration (selinux-state). grep -m 1 "selinux-state" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | cut -d' ' -f 6 | xxd -r -p The output should be the list of key-value pairs. For example, initialized=1;enabled=1;enforcing=0;checkreqprot=1;network_peer_controls=1;open_perms=1;extended_socket_class=1;always_check_network=0;cgroup_seclabel=1;nnp_nosuid_transition=1;genfs_seclabel_symlinks=0; To verify the measured data with the current SELinux state: => enabled should be set to 1 if /sys/fs/selinux folder exists, 0 otherwise For other entries, compare the integer value in the files => /sys/fs/selinux/enforce => /sys/fs/selinux/checkreqprot And, each of the policy capabilities files under => /sys/fs/selinux/policy_capabilities For selinux-policy-hash, the hash of SELinux policy is included in the IMA log entry. To verify the measured data with the current SELinux policy run the following commands and verify the output hash values match. sha256sum /sys/fs/selinux/policy | cut -d' ' -f 1 grep -m 1 "selinux-policy-hash" /sys/kernel/security/integrity/ima/ascii_runtime_measurements | cut -d' ' -f 4 Signed-off-by: Lakshmi Ramasubramanian Suggested-by: Stephen Smalley Reported-by: kernel test robot # error: implicit declaration of function 'vfree' Reported-by: kernel test robot # error: implicit declaration of function 'crypto_alloc_shash' Reported-by: kernel test robot # sparse: symbol 'security_read_selinux_policy' was not declared. Should it be static? 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.
[PATCH v5 3/4] LSM: Define SELinux function to measure state and policy
SELinux configuration and policy are some of the critical data for this
security module that needs to be measured. This measurement can be used
by an attestation service, for instance, to verify if the configuration
and policies have been setup correctly and that they haven't been tampered
with at runtime.
Measure SELinux configuration, policy capabilities settings, and the
loaded policy by calling the IMA hooks ima_measure_lsm_state() and
ima_measure_lsm_policy() respectively.
Sample measurement of SELinux state and hash of the policy:
10 e32e...5ac3 ima-buf sha256:86e8...4594 selinux-state-1595389364:287899386
696e697469616c697a65643d313b656e61626c65643d313b656e666f7263696e673d303b636865636b72657170726f743d313b6e6574776f726b5f706565725f636f6e74726f6c733d313b6f70656e5f7065726d733d313b657874656e6465645f736f636b65745f636c6173733d313b616c776179735f636865636b5f6e6574776f726b3d303b6367726f75705f7365636c6162656c3d313b6e6e705f6e6f737569645f7472616e736974696f6e3d313b67656e66735f7365636c6162656c5f73796d6c696e6b733d303
10 f4a7...9408 ima-ng sha256:8d1d...1834
selinux-policy-hash-1595389353:863934271
To verify the measurement check the following:
Execute the following command to extract the measured data
from the IMA log for SELinux configuration (selinux-state).
grep -m 1 "selinux-state"
/sys/kernel/security/integrity/ima/ascii_runtime_measurements | cut -d' ' -f 6
| xxd -r -p
The output should be the list of key-value pairs. For example,
initialized=1;enabled=1;enforcing=0;checkreqprot=1;network_peer_controls=1;open_perms=1;extended_socket_class=1;always_check_network=0;cgroup_seclabel=1;nnp_nosuid_transition=1;genfs_seclabel_symlinks=0;
To verify the measured data with the current SELinux state:
=> enabled should be set to 1 if /sys/fs/selinux folder exists,
0 otherwise
For other entries, compare the integer value in the files
=> /sys/fs/selinux/enforce
=> /sys/fs/selinux/checkreqprot
And, each of the policy capabilities files under
=> /sys/fs/selinux/policy_capabilities
For selinux-policy-hash, the hash of SELinux policy is included
in the IMA log entry.
To verify the measured data with the current SELinux policy run
the following commands and verify the output hash values match.
sha256sum /sys/fs/selinux/policy | cut -d' ' -f 1
grep -m 1 "selinux-policy-hash"
/sys/kernel/security/integrity/ima/ascii_runtime_measurements | cut -d' ' -f 4
Signed-off-by: Lakshmi Ramasubramanian
Suggested-by: Stephen Smalley
Reported-by: kernel test robot # error: implicit declaration
of function 'vfree'
Reported-by: kernel test robot # error: implicit declaration
of function 'crypto_alloc_shash'
Reported-by: kernel test robot # sparse: symbol
'security_read_selinux_policy' was not declared. Should it be static?
---
security/selinux/Makefile | 2 +
security/selinux/hooks.c| 1 +
security/selinux/include/security.h | 15 +++
security/selinux/measure.c | 150
security/selinux/selinuxfs.c| 3 +
security/selinux/ss/services.c | 71 +++--
6 files changed, 233 insertions(+), 9 deletions(-)
create mode 100644 security/selinux/measure.c
diff --git a/security/selinux/Makefile b/security/selinux/Makefile
index 4d8e0e8adf0b..83d512116341 100644
--- a/security/selinux/Makefile
+++ b/security/selinux/Makefile
@@ -16,6 +16,8 @@ selinux-$(CONFIG_NETLABEL) += netlabel.o
selinux-$(CONFIG_SECURITY_INFINIBAND) += ibpkey.o
+selinux-$(CONFIG_IMA) += measure.o
+
ccflags-y := -I$(srctree)/security/selinux
-I$(srctree)/security/selinux/include
$(addprefix $(obj)/,$(selinux-y)): $(obj)/flask.h
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index efa6108b1ce9..5521dfc1900b 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -7394,6 +7394,7 @@ int selinux_disable(struct selinux_state *state)
}
selinux_mark_disabled(state);
+ selinux_measure_state(state);
pr_info("SELinux: Disabled at runtime.\n");
diff --git a/security/selinux/include/security.h
b/security/selinux/include/security.h
index b0e02cfe3ce1..77f42d9b544b 100644
--- a/security/selinux/include/security.h
+++ b/security/selinux/include/security.h
@@ -222,16 +222,31 @@ static inline bool
selinux_policycap_genfs_seclabel_symlinks(void)
return state->policycap[POLICYDB_CAPABILITY_GENFS_SECLABEL_SYMLINKS];
}
+static inline bool selinux_checkreqprot(const struct selinux_state *state)
+{
+ return READ_ONCE(state->checkreqprot);
+}
+
int security_mls_enabled(struct selinux_state *state);
int security_load_policy(struct selinux_state *state,
void *data, size_t len);
int security_read_policy(struct selinux_state *state,
void **data, size_t *len);
+int security_read_policy_kernel(struct selinux_state *state,
+ void **data, size_t *len);
size_t security_policydb_len(struct selinux_state *state
