Re: [RFC PATCH v2 1/4] security: ima: call ima_init() again at late_initcall_sync for defered TPM

[Mimi Zohar <zohar@linux.ibm.com>]

On Wed, 2026-04-22 at 17:24 +0100, Yeoreum Yun wrote:
> To generate the boot_aggregate log in the IMA subsystem with TPM PCR values,
> the TPM driver must be built as built-in and
> must be probed before the IMA subsystem is initialized.
> 
> However, when the TPM device operates over the FF-A protocol using
> the CRB interface, probing fails and returns -EPROBE_DEFER if
> the tpm_crb_ffa device — an FF-A device that provides the communication
> interface to the tpm_crb driver — has not yet been probed.
> 
> To ensure the TPM device operating over the FF-A protocol with
> the CRB interface is probed before IMA initialization,
> the following conditions must be met:
> 
>    1. The corresponding ffa_device must be registered,
>       which is done via ffa_init().
> 
>    2. The tpm_crb_driver must successfully probe this device via
>       tpm_crb_ffa_init().
> 
>    3. The tpm_crb driver using CRB over FF-A can then
>       be probed successfully. (See crb_acpi_add() and
>       tpm_crb_ffa_init() for reference.)
> 
> Unfortunately, ffa_init(), tpm_crb_ffa_init(), and crb_acpi_driver_init() are
> all registered with device_initcall, which means crb_acpi_driver_init() may
> be invoked before ffa_init() and tpm_crb_ffa_init() are completed.
> 
> When this occurs, probing the TPM device is deferred.
> However, the deferred probe can happen after the IMA subsystem
> has already been initialized, since IMA initialization is performed
> during late_initcall, and deferred_probe_initcall() is performed
> at the same level.
> 
> To resolve this, call ima_init() again at late_inicall_sync level
> so that let IMA not miss TPM PCR value when generating boot_aggregate
> log though TPM device presents in the system.
> 
> Signed-off-by: Yeoreum Yun <yeoreum.yun@arm.com>

A lot of change for just detecting whether ima_init() is being called on
late_initcall or late_initcall_sync(), without any explanation for all the other
changes (e.g. ima_init_core).

Please just limit the change to just calling ima_init() twice.

Mimi


> ---
>  include/linux/lsm_hooks.h           |  2 +
>  security/integrity/ima/ima.h        |  4 +-
>  security/integrity/ima/ima_init.c   | 10 +++-
>  security/integrity/ima/ima_main.c   | 76 +++++++++++++++++++++++------
>  security/integrity/ima/ima_policy.c |  3 ++
>  security/lsm_init.c                 | 13 ++++-
>  6 files changed, 87 insertions(+), 21 deletions(-)
> 
> diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
> index d48bf0ad26f4..88fe105b7f00 100644
> --- a/include/linux/lsm_hooks.h
> +++ b/include/linux/lsm_hooks.h
> @@ -166,6 +166,7 @@ enum lsm_order {
>   * @initcall_fs: LSM callback for fs_initcall setup, optional
>   * @initcall_device: LSM callback for device_initcall() setup, optional
>   * @initcall_late: LSM callback for late_initcall() setup, optional
> + * @initcall_late_sync: LSM callback for late_initcall_sync() setup, optional
>   */
>  struct lsm_info {
>  	const struct lsm_id *id;
> @@ -181,6 +182,7 @@ struct lsm_info {
>  	int (*initcall_fs)(void);
>  	int (*initcall_device)(void);
>  	int (*initcall_late)(void);
> +	int (*initcall_late_sync)(void);
>  };
> 
>  #define DEFINE_LSM(lsm)							\
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index 89ebe98ffc5e..75ee7ad184d0 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -62,6 +62,8 @@ extern int ima_hash_algo_idx __ro_after_init;
>  extern int ima_extra_slots __ro_after_init;
>  extern struct ima_algo_desc *ima_algo_array __ro_after_init;
> 
> +extern bool ima_initialised __ro_after_init;
> +
>  extern int ima_appraise;
>  extern struct tpm_chip *ima_tpm_chip;
>  extern const char boot_aggregate_name[];
> @@ -257,7 +259,7 @@ static inline void ima_measure_kexec_event(const char *event_name) {}
>  extern bool ima_canonical_fmt;
> 
>  /* Internal IMA function definitions */
> -int ima_init(void);
> +int ima_init(bool late);
>  int ima_fs_init(void);
>  int ima_add_template_entry(struct ima_template_entry *entry, int violation,
>  			   const char *op, struct inode *inode,
> diff --git a/security/integrity/ima/ima_init.c b/security/integrity/ima/ima_init.c
> index a2f34f2d8ad7..c28c71090ad2 100644
> --- a/security/integrity/ima/ima_init.c
> +++ b/security/integrity/ima/ima_init.c
> @@ -115,13 +115,19 @@ void __init ima_load_x509(void)
>  }
>  #endif
> 
> -int __init ima_init(void)
> +int __init ima_init(bool late)
>  {
>  	int rc;
> 
>  	ima_tpm_chip = tpm_default_chip();
> -	if (!ima_tpm_chip)
> +	if (!ima_tpm_chip) {
> +		if (!late) {
> +			pr_info("Defer initialisation to the late_initcall_sync stage.\n");
> +			return -EPROBE_DEFER;
> +		}
> +
>  		pr_info("No TPM chip found, activating TPM-bypass!\n");
> +	}
> 
>  	rc = integrity_init_keyring(INTEGRITY_KEYRING_IMA);
>  	if (rc)
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 1d6229b156fb..ac444ee600e2 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -38,6 +38,7 @@ int ima_appraise;
>  #endif
> 
>  int __ro_after_init ima_hash_algo = HASH_ALGO_SHA1;
> +bool ima_initialised __ro_after_init = false;
>  static int hash_setup_done;
>  static int ima_disabled __ro_after_init;
> 
> @@ -1237,6 +1238,35 @@ static int ima_kernel_module_request(char *kmod_name)
> 
>  #endif /* CONFIG_INTEGRITY_ASYMMETRIC_KEYS */
> 
> +static int __init init_ima_core(bool late)
> +{
> +	int err;
> +
> +	if (ima_initialised)
> +		return 0;
> +
> +	err = ima_init(late);
> +	if (err == -EPROBE_DEFER)
> +		return 0;
> +
> +	if (err && strcmp(hash_algo_name[ima_hash_algo],
> +			  CONFIG_IMA_DEFAULT_HASH) != 0) {
> +		pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
> +			hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
> +		hash_setup_done = 0;
> +		hash_setup(CONFIG_IMA_DEFAULT_HASH);
> +		err = ima_init(late);
> +	}
> +
> +	if (!err) {
> +		ima_update_policy_flags();
> +		ima_initialised = true;
> +	} else
> +		ima_disabled = 1;
> +
> +	return err;
> +}
> +
>  static int __init init_ima(void)
>  {
>  	int error;
> @@ -1250,30 +1280,42 @@ static int __init init_ima(void)
>  	ima_appraise_parse_cmdline();
>  	ima_init_template_list();
>  	hash_setup(CONFIG_IMA_DEFAULT_HASH);
> -	error = ima_init();
> -
> -	if (error && strcmp(hash_algo_name[ima_hash_algo],
> -			    CONFIG_IMA_DEFAULT_HASH) != 0) {
> -		pr_info("Allocating %s failed, going to use default hash algorithm %s\n",
> -			hash_algo_name[ima_hash_algo], CONFIG_IMA_DEFAULT_HASH);
> -		hash_setup_done = 0;
> -		hash_setup(CONFIG_IMA_DEFAULT_HASH);
> -		error = ima_init();
> -	}
> -
> -	if (error)
> -		return error;
> 
>  	error = register_blocking_lsm_notifier(&ima_lsm_policy_notifier);
> -	if (error)
> +	if (error) {
>  		pr_warn("Couldn't register LSM notifier, error %d\n", error);
> +		goto disable_ima;
> +	}
> 
> -	if (!error)
> -		ima_update_policy_flags();
> +	error = init_ima_core(false);
> +	if (error) {
> +		unregister_blocking_lsm_notifier(&ima_lsm_policy_notifier);
> +		goto disable_ima;
> +	}
> +
> +	return 0;
> 
> +disable_ima:
> +	ima_disabled = 1;
>  	return error;
>  }
> 
> +static int __init late_init_ima(void)
> +{
> +	int err;
> +
> +	if (ima_disabled)
> +		return 0;
> +
> +	err = init_ima_core(true);
> +	if (err) {
> +		unregister_blocking_lsm_notifier(&ima_lsm_policy_notifier);
> +		ima_disabled = 1;
> +	}
> +
> +	return err;
> +}
> +
>  static struct security_hook_list ima_hooks[] __ro_after_init = {
>  	LSM_HOOK_INIT(bprm_check_security, ima_bprm_check),
>  	LSM_HOOK_INIT(bprm_creds_for_exec, ima_bprm_creds_for_exec),
> @@ -1321,4 +1363,6 @@ DEFINE_LSM(ima) = {
>  	.blobs = &ima_blob_sizes,
>  	/* Start IMA after the TPM is available */
>  	.initcall_late = init_ima,
> +	/* Start IMA late in case of probing TPM is deferred. */
> +	.initcall_late_sync = late_init_ima,
>  };
> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c
> index bf2d7ba4c14a..c3bcc3521c81 100644
> --- a/security/integrity/ima/ima_policy.c
> +++ b/security/integrity/ima/ima_policy.c
> @@ -501,6 +501,9 @@ static void ima_lsm_update_rules(void)
>  int ima_lsm_policy_change(struct notifier_block *nb, unsigned long event,
>  			  void *lsm_data)
>  {
> +	if (!ima_initialised)
> +		return NOTIFY_DONE;
> +
>  	if (event != LSM_POLICY_CHANGE)
>  		return NOTIFY_DONE;
> 
> diff --git a/security/lsm_init.c b/security/lsm_init.c
> index 573e2a7250c4..4e5c59beb82a 100644
> --- a/security/lsm_init.c
> +++ b/security/lsm_init.c
> @@ -547,13 +547,22 @@ device_initcall(security_initcall_device);
>   * security_initcall_late - Run the LSM late initcalls
>   */
>  static int __init security_initcall_late(void)
> +{
> +	return lsm_initcall(late);
> +}
> +late_initcall(security_initcall_late);
> +
> +/**
> + * security_initcall_late_sync - Run the LSM late initcalls sync
> + */
> +static int __init security_initcall_late_sync(void)
>  {
>  	int rc;
> 
> -	rc = lsm_initcall(late);
> +	rc = lsm_initcall(late_sync);
>  	lsm_pr_dbg("all enabled LSMs fully activated\n");
>  	call_blocking_lsm_notifier(LSM_STARTED_ALL, NULL);
> 
>  	return rc;
>  }
> -late_initcall(security_initcall_late);
> +late_initcall_sync(security_initcall_late_sync);
> --
> LEVI:{C3F47F37-75D8-414A-A8BA-3980EC8A46D7}