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. 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]> --- Documentation/ABI/testing/ima_policy | 3 +++ security/integrity/ima/ima_policy.c | 7 ++++++- 2 files changed, 9 insertions(+), 1 deletion(-) diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 19258471b7b26b2c42c1ab2d11b4fd630b2e6f81..b8a763e4c9fb1a5ccca97518e80e0452554c9e96 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -108,6 +108,9 @@ Description: # NSFS_MAGIC dont_measure fsmagic=0x6e736673 dont_appraise fsmagic=0x6e736673 + # CONFIGFS_MAGIC + dont_measure fsmagic=0x62656570 + dont_appraise fsmagic=0x62656570 measure func=BPRM_CHECK measure func=FILE_MMAP mask=MAY_EXEC 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}, -- 2.43.0
