On Tue, 2026-08-18 at 14:35 -0500, Frederick Lawler wrote: > When IMA appraises/measures a file configfs, it has an opportunity to > hold onto the ima_iint_mutex while another file from a different file > system is attempting to appraise/measure. This may cause a cyclical > lock dependency.
The locking description is off a bit. Suggested patch desciption from AI: IMA measurement of a configfs file causes process_measurement() to hold iint- >mutex while performing a kernel_read() to hash it, which re-enters configfs's own file locking (buffer->mutex, frag_sem). Separately, opening any file with O_TRUNC now causes ima_file_truncate() to take iint->mutex to reset the cached action flags, while sb_writers is already held for that mount. When a configfs-backed nvmet namespace is involved, these two independent lock chains combine into a cycle: iint->mutex -> configfs locks -> subsys->lock -> sb_writers -> iint->mutex Add configfs to the builtin don't measure/appraise rules, similarly to other pseudo file systems, so IMA never takes iint->mutex for configfs file in the first place. > > Add configfs to the default don't measure/appraise lists, similarly to > other pseudo file systems. > > Reported-by: [email protected] > Link: https://lore.kernel.org/all/[email protected]/ > Suggested-by: Mimi Zohar <[email protected]> > Signed-off-by: Frederick Lawler <[email protected]> Sashiko is now enabled for the linux-integrity mailing list - https://sashiko.dev/#/?list=org.kernel.vger.linux-integrity. Please address Sashiko's 2/2 review. thanks, Mimi > --- > security/integrity/ima/ima_policy.c | 7 ++++++- > 1 file changed, 6 insertions(+), 1 deletion(-) > > diff --git a/security/integrity/ima/ima_policy.c > b/security/integrity/ima/ima_policy.c > index > f79d07bb63c6fc4ba6fe594140de8d59f57e4f0b..68d9a5e6c232ea0678e9f51f105cebecccccb43e > 100644 > --- a/security/integrity/ima/ima_policy.c > +++ b/security/integrity/ima/ima_policy.c > @@ -165,7 +165,10 @@ static struct ima_rule_entry dont_measure_rules[] > __ro_after_init = { > {.action = DONT_MEASURE, .fsmagic = CGROUP2_SUPER_MAGIC, > .flags = IMA_FSMAGIC}, > {.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}, > - {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, .flags = > IMA_FSMAGIC} > + {.action = DONT_MEASURE, .fsmagic = EFIVARFS_MAGIC, > + .flags = IMA_FSMAGIC}, > + {.action = DONT_MEASURE, .fsmagic = CONFIGFS_MAGIC, > + .flags = IMA_FSMAGIC} > }; > > static struct ima_rule_entry original_measurement_rules[] __ro_after_init = { > @@ -211,6 +214,8 @@ static struct ima_rule_entry default_appraise_rules[] > __ro_after_init = { > {.action = DONT_APPRAISE, .fsmagic = EFIVARFS_MAGIC, .flags = > IMA_FSMAGIC}, > {.action = DONT_APPRAISE, .fsmagic = CGROUP_SUPER_MAGIC, .flags = > IMA_FSMAGIC}, > {.action = DONT_APPRAISE, .fsmagic = CGROUP2_SUPER_MAGIC, .flags = > IMA_FSMAGIC}, > + {.action = DONT_APPRAISE, .fsmagic = CONFIGFS_MAGIC, > + .flags = IMA_FSMAGIC}, > #ifdef CONFIG_IMA_WRITE_POLICY > {.action = APPRAISE, .func = POLICY_CHECK, > .flags = IMA_FUNC | IMA_DIGSIG_REQUIRED},
