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SubjectRe: [PATCH v5 2/4] IMA: Define IMA hooks to measure LSM state and policy
On 2020-07-29 20:47:22, Lakshmi Ramasubramanian wrote:
> IMA subsystem needs to define IMA hooks that the security modules can
> call to measure state and policy data.
>
> Define two new IMA hooks, namely ima_lsm_state() and ima_lsm_policy(),
> that the security modules can call to measure LSM state and LSM policy
> respectively. Return the status of the measurement operation from these
> two IMA hooks.
>
> Signed-off-by: Lakshmi Ramasubramanian <nramas@linux.microsoft.com>

Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>

Tyler

> ---
> include/linux/ima.h | 14 +++++++++
> security/integrity/ima/ima.h | 6 ++--
> security/integrity/ima/ima_main.c | 50 ++++++++++++++++++++++++++-----
> 3 files changed, 60 insertions(+), 10 deletions(-)
>
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index d15100de6cdd..442ca0dce3c8 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -26,6 +26,10 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size,
> extern void ima_post_path_mknod(struct dentry *dentry);
> extern int ima_file_hash(struct file *file, char *buf, size_t buf_size);
> extern void ima_kexec_cmdline(int kernel_fd, const void *buf, int size);
> +extern int ima_measure_lsm_state(const char *lsm_event_name, const void *buf,
> + int size);
> +extern int ima_measure_lsm_policy(const char *lsm_event_name, const void *buf,
> + int size);
>
> #ifdef CONFIG_IMA_KEXEC
> extern void ima_add_kexec_buffer(struct kimage *image);
> @@ -104,6 +108,16 @@ static inline int ima_file_hash(struct file *file, char *buf, size_t buf_size)
> }
>
> static inline void ima_kexec_cmdline(int kernel_fd, const void *buf, int size) {}
> +static inline int ima_measure_lsm_state(const char *lsm_event_name,
> + const void *buf, int size)
> +{
> + return -EOPNOTSUPP;
> +}
> +static inline int ima_measure_lsm_policy(const char *lsm_event_name,
> + const void *buf, int size)
> +{
> + return -EOPNOTSUPP;
> +}
> #endif /* CONFIG_IMA */
>
> #ifndef CONFIG_IMA_KEXEC
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index 1b5f4b2f17d0..8ed9f5e1dd40 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -267,9 +267,9 @@ void ima_store_measurement(struct integrity_iint_cache *iint, struct file *file,
> struct evm_ima_xattr_data *xattr_value,
> int xattr_len, const struct modsig *modsig, int pcr,
> struct ima_template_desc *template_desc);
> -void process_buffer_measurement(struct inode *inode, const void *buf, int size,
> - const char *eventname, enum ima_hooks func,
> - int pcr, const char *keyring);
> +int process_buffer_measurement(struct inode *inode, const void *buf, int size,
> + const char *eventname, enum ima_hooks func,
> + int pcr, const char *keyring);
> void ima_audit_measurement(struct integrity_iint_cache *iint,
> const unsigned char *filename);
> int ima_alloc_init_template(struct ima_event_data *event_data,
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 8a91711ca79b..74d421e40c8f 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -736,9 +736,9 @@ int ima_load_data(enum kernel_load_data_id id)
> *
> * Based on policy, the buffer is measured into the ima log.
> */
> -void process_buffer_measurement(struct inode *inode, const void *buf, int size,
> - const char *eventname, enum ima_hooks func,
> - int pcr, const char *keyring)
> +int process_buffer_measurement(struct inode *inode, const void *buf, int size,
> + const char *eventname, enum ima_hooks func,
> + int pcr, const char *keyring)
> {
> int ret = 0;
> const char *audit_cause = "ENOMEM";
> @@ -758,7 +758,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
> u32 secid;
>
> if (!ima_policy_flag)
> - return;
> + return 0;
>
> /*
> * Both LSM hooks and auxilary based buffer measurements are
> @@ -772,7 +772,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
> action = ima_get_action(inode, current_cred(), secid, 0, func,
> &pcr, &template, keyring);
> if (!(action & IMA_MEASURE))
> - return;
> + return 0;
> }
>
> if (!pcr)
> @@ -787,7 +787,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
> pr_err("template %s init failed, result: %d\n",
> (strlen(template->name) ?
> template->name : template->fmt), ret);
> - return;
> + return ret;
> }
> }
>
> @@ -819,7 +819,7 @@ void process_buffer_measurement(struct inode *inode, const void *buf, int size,
> func_measure_str(func),
> audit_cause, ret, 0, ret);
>
> - return;
> + return ret;
> }
>
> /**
> @@ -846,6 +846,42 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
> fdput(f);
> }
>
> +/**
> + * ima_measure_lsm_state - measure LSM specific state
> + * @lsm_event_name: LSM event
> + * @buf: pointer to buffer containing LSM specific state
> + * @size: Number of bytes in buf
> + *
> + * Buffers can only be measured, not appraised.
> + */
> +int ima_measure_lsm_state(const char *lsm_event_name, const void *buf,
> + int size)
> +{
> + if (!lsm_event_name || !buf || !size)
> + return -EINVAL;
> +
> + return process_buffer_measurement(NULL, buf, size, lsm_event_name,
> + LSM_STATE, 0, NULL);
> +}
> +
> +/**
> + * ima_measure_lsm_policy - measure LSM specific policy
> + * @lsm_event_name: LSM event
> + * @buf: pointer to buffer containing LSM specific policy
> + * @size: Number of bytes in buf
> + *
> + * Buffers can only be measured, not appraised.
> + */
> +int ima_measure_lsm_policy(const char *lsm_event_name, const void *buf,
> + int size)
> +{
> + if (!lsm_event_name || !buf || !size)
> + return -EINVAL;
> +
> + return process_buffer_measurement(NULL, buf, size, lsm_event_name,
> + LSM_POLICY, 0, NULL);
> +}
> +
> static int __init init_ima(void)
> {
> int error;
> --
> 2.27.0

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