From: Tyler Hicks <tyhicks@linux.microsoft.com>
To: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Cc: zohar@linux.ibm.com, stephen.smalley.work@gmail.com,
casey@schaufler-ca.com, agk@redhat.com, snitzer@redhat.com,
gmazyland@gmail.com, paul@paul-moore.com, sashal@kernel.org,
jmorris@namei.org, nramas@linux.microsoft.com,
linux-integrity@vger.kernel.org, selinux@vger.kernel.org,
linux-security-module@vger.kernel.org,
linux-kernel@vger.kernel.org, dm-devel@redhat.com
Subject: Re: [PATCH v8 3/8] IMA: define a hook to measure kernel integrity critical data
Date: Fri, 11 Dec 2020 18:13:43 -0600 [thread overview]
Message-ID: <20201212001343.GE4951@sequoia> (raw)
In-Reply-To: <20201211235807.30815-4-tusharsu@linux.microsoft.com>
On 2020-12-11 15:58:02, Tushar Sugandhi wrote:
> IMA provides capabilities to measure file data, and in-memory buffer
> data. However, various data structures, policies, and states
> stored in kernel memory also impact the integrity of the system.
> Several kernel subsystems contain such integrity critical data. These
> kernel subsystems help protect the integrity of a device. Currently,
> IMA does not provide a generic function for kernel subsystems to measure
> their integrity critical data.
>
> Define a new IMA hook - ima_measure_critical_data to measure kernel
> integrity critical data.
>
> Signed-off-by: Tushar Sugandhi <tusharsu@linux.microsoft.com>
Reviewed-by: Tyler Hicks <tyhicks@linux.microsoft.com>
Tyler
> ---
> include/linux/ima.h | 6 ++++++
> security/integrity/ima/ima.h | 1 +
> security/integrity/ima/ima_api.c | 2 +-
> security/integrity/ima/ima_main.c | 34 +++++++++++++++++++++++++++++++
> 4 files changed, 42 insertions(+), 1 deletion(-)
>
> diff --git a/include/linux/ima.h b/include/linux/ima.h
> index ac3d82f962f2..675f54db6264 100644
> --- a/include/linux/ima.h
> +++ b/include/linux/ima.h
> @@ -30,6 +30,9 @@ 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 void ima_measure_critical_data(const char *event_name,
> + const void *buf, int buf_len,
> + bool measure_buf_hash);
>
> #ifdef CONFIG_IMA_APPRAISE_BOOTPARAM
> extern void ima_appraise_parse_cmdline(void);
> @@ -122,6 +125,9 @@ 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 void ima_measure_critical_data(const char *event_name,
> + const void *buf, int buf_len,
> + bool measure_buf_hash) {}
> #endif /* CONFIG_IMA */
>
> #ifndef CONFIG_IMA_KEXEC
> diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h
> index fa3044a7539f..7d9deda6a8b3 100644
> --- a/security/integrity/ima/ima.h
> +++ b/security/integrity/ima/ima.h
> @@ -201,6 +201,7 @@ static inline unsigned int ima_hash_key(u8 *digest)
> hook(POLICY_CHECK, policy) \
> hook(KEXEC_CMDLINE, kexec_cmdline) \
> hook(KEY_CHECK, key) \
> + hook(CRITICAL_DATA, critical_data) \
> hook(MAX_CHECK, none)
>
> #define __ima_hook_enumify(ENUM, str) ENUM,
> diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c
> index af218babd198..9917e1730cb6 100644
> --- a/security/integrity/ima/ima_api.c
> +++ b/security/integrity/ima/ima_api.c
> @@ -176,7 +176,7 @@ void ima_add_violation(struct file *file, const unsigned char *filename,
> * subj=, obj=, type=, func=, mask=, fsmagic=
> * subj,obj, and type: are LSM specific.
> * func: FILE_CHECK | BPRM_CHECK | CREDS_CHECK | MMAP_CHECK | MODULE_CHECK
> - * | KEXEC_CMDLINE | KEY_CHECK
> + * | KEXEC_CMDLINE | KEY_CHECK | CRITICAL_DATA
> * mask: contains the permission mask
> * fsmagic: hex value
> *
> diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c
> index 0f8409d77602..dff4bce4fb09 100644
> --- a/security/integrity/ima/ima_main.c
> +++ b/security/integrity/ima/ima_main.c
> @@ -922,6 +922,40 @@ void ima_kexec_cmdline(int kernel_fd, const void *buf, int size)
> fdput(f);
> }
>
> +/**
> + * ima_measure_critical_data - measure kernel integrity critical data
> + * @event_name: event name to be used for the buffer entry
> + * @buf: pointer to buffer containing data to measure
> + * @buf_len: length of buffer(in bytes)
> + * @measure_buf_hash: measure buffer hash
> + *
> + * Measure the kernel subsystem data, critical to the integrity of the kernel,
> + * into the IMA log and extend the @pcr.
> + *
> + * Use @event_name to describe the state/buffer data change.
> + * Examples of critical data (@buf) could be various data structures,
> + * policies, and states stored in kernel memory that can impact the integrity
> + * of the system.
> + *
> + * If @measure_buf_hash is set to true - measure hash of the buffer data,
> + * else measure the buffer data itself.
> + * @measure_buf_hash can be used to save space, if the data being measured
> + * is too large.
> + *
> + * The data (@buf) can only be measured, not appraised.
> + */
> +void ima_measure_critical_data(const char *event_name,
> + const void *buf, int buf_len,
> + bool measure_buf_hash)
> +{
> + if (!event_name || !buf || !buf_len)
> + return;
> +
> + process_buffer_measurement(NULL, buf, buf_len, event_name,
> + CRITICAL_DATA, 0, NULL,
> + measure_buf_hash);
> +}
> +
> static int __init init_ima(void)
> {
> int error;
> --
> 2.17.1
>
next prev parent reply other threads:[~2020-12-12 0:44 UTC|newest]
Thread overview: 18+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-11 23:57 [PATCH v8 0/8] IMA: support for measuring kernel integrity critical data Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 1/8] IMA: generalize keyring specific measurement constructs Tushar Sugandhi
2020-12-12 0:08 ` Tyler Hicks
2020-12-11 23:58 ` [PATCH v8 2/8] IMA: add support to measure buffer data hash Tushar Sugandhi
2020-12-12 0:09 ` Tyler Hicks
2020-12-11 23:58 ` [PATCH v8 3/8] IMA: define a hook to measure kernel integrity critical data Tushar Sugandhi
2020-12-12 0:13 ` Tyler Hicks [this message]
2020-12-11 23:58 ` [PATCH v8 4/8] IMA: add policy rule to measure " Tushar Sugandhi
2020-12-12 0:25 ` Tyler Hicks
2020-12-12 1:17 ` Tushar Sugandhi
2020-12-12 14:47 ` Tyler Hicks
2020-12-12 17:34 ` Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 5/8] IMA: limit critical data measurement based on a label Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 6/8] IMA: extend critical data hook to limit the " Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 7/8] IMA: define a builtin critical data measurement policy Tushar Sugandhi
2020-12-11 23:58 ` [PATCH v8 8/8] selinux: include a consumer of the new IMA critical data hook Tushar Sugandhi
2020-12-12 0:32 ` Tyler Hicks
2020-12-12 0:33 ` Lakshmi Ramasubramanian
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