On Wed, 2021-04-14 at 22:32 +0200, Christian Brauner wrote:
On Wed, Apr 14, 2021, 22:21 Mimi Zohar [off-list ref] wrote:
quoted
On Wed, 2021-04-14 at 20:19 +0200, Christian Brauner wrote:
quoted
On Wed, Apr 14, 2021 at 01:46:46PM -0400, Mimi Zohar wrote:
quoted
Hi Christian,
On Wed, 2021-04-14 at 13:50 +0200, Christian Brauner wrote:
quoted
Hey,
[Resending since the previous mail somehow hasn't made it onto the list.]
While working on a patch to port ecryptfs to use clone_private_mount() I
hit the splat in [1] with v5.12-rc6 (Without any of my changes.). To
reproduce this you can use the config in [5]. Then run the scripts [2]
and [3] in two terminals. The kernel command line was [4]:
while true; do ./test.sh; done
while true; do ./test2.sh; done
and wait for [1] to appear.
The two test scripts aren't specifically designed to trigger this issue.
They were stress tests for my ecryptfs clone_private_mount() port. They
just allow to trigger this issue.
From a very uninformed position it seemed that:
void integrity_inode_free(struct inode *inode)
{
struct integrity_iint_cache *iint;
if (!IS_IMA(inode))
return;
Thank you for all the details.
A builtin IMA policy wasn't specified on the boot command line. Unless
a custom IMA policy is loaded, it shouldn't get beyond this
point. Before looking any farther, I would appreciate your confirming
that you've loaded a custom IMA policy. To see if a policy has been
loaded, cat /sys/kernel/security/ima/policy.
Ah, interesting thank you. Here's the output:
sudo cat /sys/kernel/security/ima/policy
dont_measure fsmagic=0x9fa0
dont_measure fsmagic=0x62656572
dont_measure fsmagic=0x64626720
dont_measure fsmagic=0x1021994
dont_measure fsmagic=0x1cd1
dont_measure fsmagic=0x42494e4d
dont_measure fsmagic=0x73636673
dont_measure fsmagic=0xf97cff8c
dont_measure fsmagic=0x43415d53
dont_measure fsmagic=0x27e0eb
dont_measure fsmagic=0x63677270
dont_measure fsmagic=0x6e736673
dont_measure fsmagic=0xde5e81e4
measure func=MMAP_CHECK mask=MAY_EXEC
measure func=BPRM_CHECK mask=MAY_EXEC
measure func=FILE_CHECK mask=^MAY_READ euid=0
measure func=FILE_CHECK mask=^MAY_READ uid=0
measure func=MODULE_CHECK
measure func=FIRMWARE_CHECK
measure func=POLICY_CHECK
Hm, note that ecryptfs is not in this list so I guess ecryptfs would be
measured?
That's the "tcb" policy, which can be specified as "policy=tcb" on the
boot command line. The builtin policy rules are generic and would
normally be replaced with more specific policy rules based on LSM
labels.
Ah, thank you.
quoted
Right, ecryptfs files are being measured.
There's somehow a race freeing the inode. The fix is straight forward.
Did you want to fix it or should I?
Please do fix it. I've reach eod over here. :)
You're simply going to handle the NULL case when freeing the iint?
Yes, but it would be nice to understand the race and whether this is
something or has been there from the beginning.
Mimi