Re: [PATCH] ima: debugging late_initcall_sync measurements

[Yeoreum Yun <yeoreum.yun@arm.com>]

Hi Mimi,

> On Wed, 2026-05-06 at 14:57 +0100, Yeoreum Yun wrote:
> > > > > On both Z and PowerVM, there are ~30 measurements between boot_aggregate and
> > > > > boot_aggregate_late.  For example, on PowerVM:
> > > > > 
> > > > > # grep -n boot_aggregate
> > > > > /sys/kernel/security/integrity/ima/ascii_runtime_measurements
> > > > > 
> > > > > 1:10 f60a05d7354fb34aabc02965216abd3428ea52bb ima-sig
> > > > > sha256:9887dd089ee19a6517bca10580b02c1bb9aa6cd86c157b6ead8a1c0403f348d5
> > > > > boot_aggregate 
> > > > > 31:10 e2592b0d61da6300d3db447b143897a9792231ea ima-sig
> > > > > sha256:9887dd089ee19a6517bca10580b02c1bb9aa6cd86c157b6ead8a1c0403f348d5
> > > > > boot_aggregate_late
> > > > > 
> > > > > It would be interesting to the results from a Raspberry Pi 5 as well,
> > > > > with/without a TPM.
> > > > 
> > > > Honestly, I find this result hard to accept.
> > > > 
> > > > This effectively means that there is code invoking IMA measurement during late_initcall().
> > > > It also implies that if, in the future, a late_initcall is added that performs
> > > > an IMA measurement before IMA initialization has occurred accoding to order by linker,
> > > > that measurement could be missed.
> > > 
> > > Exactly.  The results are simply from booting with the builtin "tcb" and
> > > "critical_data" policies.
> > > 
> > > $ sudo grubby --args="ima_policy=\"tcb|critical_data\"" --update-kernel
> > > /boot/vmlinuz-${SUFFIX}
> > 
> > Thanks. but I still wonder what meaasurements there are between
> > boot_aggregate and boot_aggregate_late.
> > Might be there would be key measurements if it takes more than
> > 5 mins before generating boot_aggregate_late but this seems rare.
> > 
> > If you don't mind, would you share the contents of the log between
> > boot_aggregate and boot_aggregate_late?
> > since I only get a kernel_version in my environment.
> 
>      1	10 f60a05d7354fb34aabc02965216abd3428ea52bb ima-sig
> sha256:9887dd089ee19a6517bca10580b02c1bb9aa6cd86c157b6ead8a1c0403f348d5
> boot_aggregate 
>      2	10 49ab61dd97ea2f759edcb6c6a3387ac67f0aa576 ima-buf
> sha256:0c907aab3261194f16b0c2a422a82f145bc9b9ecb8fdb633fa43e3e5379f0af2
> kernel_version 372e312e302d7263312b
>      3	10 92c40bfd65512d5224cddb9fb64fef0d72e1c182 ima-sig
> sha256:412bae0d0e85a99971d6eda198dd2fed3c2959715e8a17a4caddc7bc605bdeeb
> /usr/bin/kmod 
>      4	10 a18f997e1e82d0ef416f93683966d7dda875d71c ima-sig
> sha256:0050fcc672e03cfdc3a50c771ca9f5219478e5538980a26fd4484620712d8163
> /usr/lib64/ld64.so.2 
>      5	10 88f343618caeeed92ed8281d627f4565b0499d66 ima-sig
> sha256:a0e83c084d8c227f1150a8cd94eece61f62bc1da30f98d1cf57ca7db241a9c45
> /etc/ld.so.cache 
>      6	10 e047868f01908eb95aa180693291decab82bb6be ima-sig
> sha256:42ebf9cc684419de4d8a1d624102716d88fbcf957f47e50a9a08e38b338023ac
> /usr/lib64/libzstd.so.1.5.5 
>      7	10 da069bc6a44d454510a76c69d3a54c3b238ae27e ima-sig
> sha256:9b7c788e75c16c8827062016cf15826e43661c4b5b56813ea07ff2635bea2710
> /usr/lib64/liblzma.so.5.6.2 
>      8	10 7ade414e736e7b449cda5ec5e0277b99548e89c6 ima-sig
> sha256:d899452e8e6369e436ba1a565833d6dcf0d09c35e40ffc0979cf4de2bdb8f421
> /usr/lib64/libz.so.1.3.1.zlib-ng 
>      9	10 9a9da8326f36237a47d6ed21bdffd0e1ff855e2a ima-sig
> sha256:a848f396db7ad135f851b5e9aeb32f4a3ef1439c7913b9b95ab1cda69251f6ad
> /usr/lib64/libcrypto.so.3.5.1 
>     10	10 3201d27cd4028f02fc9088ec33e2d0ceb72d2c5b ima-sig
> sha256:e52dcd1850555c08d60fefe56694c1179b4eaa5796db0907606552ece8e1bab1
> /usr/lib64/libgcc_s-14-20250617.so.1 
>     11	10 3b4c6f13e52ca060b290709f737b1ff66564226f ima-sig
> sha256:f2a900a5b980b289dc028dd3caab16b1b0ad037f2e875546bb3197d23ff241f0
> /usr/lib64/glibc-hwcaps/power10/libc.so.6 
>     12	10 b23b616cbd3c9dc4c5743d121c1c5a702b461a9c ima-sig
> sha256:5a682022beeea9ee7f36a70f0465942bf32e9675d3f45355088e148787e02175
> /usr/lib/modprobe.d/dist-alsa.conf 
>     13	10 aec07fad18697f295d7e06796fc8dfd3b472f9c3 ima-sig
> sha256:067d949bab3bb085d0936031881ff73b2ab39f34b9a90cbd01396d1987ff6658
> /usr/lib/modprobe.d/dist-blacklist.conf 
>     14	10 c402c56b66e65914148efd6e3cf0b1d616daabe6 ima-sig
> sha256:120a02e9b88ba74949224eca7385825e39880f5687f739ade07d94ee22ffe325
> /etc/modprobe.d/firewalld-sysctls.conf 
>     15	10 e358ca12bd58e1ce4845e299e1aea8b81edf86f9 ima-sig
> sha256:fa27abcd357a16ee1254ba38d1225b7f0724036c07ce3d0e83b29eb72d97c419
> /etc/modprobe.d/l2tp_eth-blacklist.conf 
>     16	10 4b036d41435d7df3a72b38880f5fe231904b7b66 ima-sig
> sha256:ecf5f948bfbfb726879a910b3174d139c8af6b1745c88dcc1e4a1cf532c02299
> /etc/modprobe.d/l2tp_ip-blacklist.conf 
>     17	10 9c53a7a48c1b5218417c4f25c4a34c09a9f39830 ima-sig
> sha256:f76c4ac232d5e96c57961a9f10194703b4df6d119530046f0b23eee70bfcb089
> /etc/modprobe.d/l2tp_ip6-blacklist.conf 
>     18	10 6c41d7b7d251c400b7e0ba76f7b386a746e8f4ec ima-sig
> sha256:5cbc958f893a599ef19437014696dd7b112cf9af6a4348830177f8a8f78aa1b3
> /etc/modprobe.d/l2tp_netlink-blacklist.conf 
>     19	10 f37ef48faef5bc51e29d47531726af0bd0654655 ima-sig
> sha256:7a3d63acb49e4a69b482f26624761b5778fbd6b77be8a3f36926b379b5f965ed
> /etc/modprobe.d/l2tp_ppp-blacklist.conf 
>     20	10 82ef59779acdfd6e9b35521bfa09e6ba86fd6174 ima-sig
> sha256:6a8f2009d87deba7a2de46e3d0c46b114fe388d188b00b9a382fc2156aabb676
> /usr/lib/modules/7.1.0-rc1+/modules.softdep 
>     21	10 6ae994e33a6313ab4535da90f5cb6c3beaec7b86 ima-sig
> sha256:268695dbf23bd0170ec9a95b10e8d596205fd7436617d10101907171bf004b7c
> /etc/modprobe.d/sctp-blacklist.conf 
>     22	10 b2c238ae66b03f56191d9955a5ad0f3110bb7e2b ima-sig
> sha256:64a8ebb0a1fd712a9aeb7aa0f0ad0b72d3277034c8bfa3b66ab063e201d6527e
> /etc/modprobe.d/sctp_diag-blacklist.conf 
>     23	10 c0443f2d3c078959ae86276df23abe172234a55d ima-sig
> sha256:e5a3958cbd3684b63f3cada6604469cc56f727b106d5524daf5aefa6935a48ce
> /usr/lib/modprobe.d/systemd.conf 
>     24	10 5c46e012bc7fffc3256b166282a7eaa4bea5fa33 ima-sig
> sha256:6560abcdd2cdb41e1d0fe73052298d612920d5bccb4a3a7c82bc73895128e760
> /etc/modprobe.d/tipc_diag-blacklist.conf 
>     25	10 d5fb1836364732fbc4f87aa7d2c984cf30bdbfd3 ima-sig
> sha256:358703c09ac2d2c653e11bbc7c65d378c8496e87ca47307f86c36b0b29640598
> /etc/modprobe.d/tuned.conf 
>     26	10 a85107163729f696f316d46c0bf3f65f713ba972 ima-sig
> sha256:7410bb4cec56892e8b0010c5c8b72be532784ccf0240aa0677c5be085a530f65
> /usr/lib/modules/7.1.0-rc1+/modules.dep.bin 
>     27	10 80eb261ffb2cc3528d90c33b1c624f657a045867 ima-sig
> sha256:856e0f083226f8b4fb7d1d71447fb841dae18ea9a50ea6d8505a206167288e1d
> /usr/lib/modules/7.1.0-rc1+/modules.alias.bin 
>     28	10 6af2d661da470d7a1c9909ddbc074d3d265eb1d7 ima-sig
> sha256:4853ca200598c52970c380fda99484068e7db4961a4f94faac6abcfbbd52d150
> /usr/lib/modules/7.1.0-rc1+/modules.symbols.bin 
>     29	10 6f9cd405bd57d925baae6ae66c273c61c90b3bc8 ima-sig
> sha256:193d1e1004848f7d391877507b69a7953e1f94ddbe70eb0e2cf6dc45fce7cd6a
> /usr/lib/modules/7.1.0-rc1+/modules.builtin.alias.bin 
>     30	10 4e20b980bf3a825a866be0c46033ed654df4aeba ima-sig
> sha256:3a0e3c56d51ba98258ff13f93f82c837de22f4b707d24678f82893babf4d77ea
> /usr/lib/modules/7.1.0-rc1+/modules.builtin.bin 
>     31	10 e2592b0d61da6300d3db447b143897a9792231ea ima-sig
> sha256:9887dd089ee19a6517bca10580b02c1bb9aa6cd86c157b6ead8a1c0403f348d5
> boot_aggregate_late 
>     32	10 81830cd3d799e006698258dc1b11fe29a56eeef5 ima-sig
> sha256:d1651dc50bb5b92c1badcab9aa4dbbca40cb704cdc707d1c536b41d7b1aa465e
> /usr/lib/systemd/systemd 

Hmm... Theses measurements seems to happen while populating
initramfs which triggers file_post_open as async
(and I see the RAMFS seems not part of DONT_MEASURE in IMA).

If you don't mind, Could you check whether this measurements still
happen with initramfs_async=0?

If this measurements aren't generated with above option,
there is a question whether let IMA measure initramfs which can be
measured or not depending on boot option or timing (some file measurements
could be lost all when do_populate_rootfs() executes concurrently while
running late_initcall).


[...]

-- 
Sincerely,
Yeoreum Yun