| Message ID | 20201209194212.5131-4-tusharsu@linux.microsoft.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | IMA: support for measuring kernel integrity critical data | expand |
On 2020-12-09 11:42:07, 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> > --- > Documentation/ABI/testing/ima_policy | 2 +- > include/linux/ima.h | 6 +++++ > security/integrity/ima/ima.h | 1 + > security/integrity/ima/ima_api.c | 2 +- > security/integrity/ima/ima_main.c | 36 ++++++++++++++++++++++++++++ > security/integrity/ima/ima_policy.c | 2 ++ > 6 files changed, 47 insertions(+), 2 deletions(-) > > diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy > index e35263f97fc1..6ec7daa87cba 100644 > --- a/Documentation/ABI/testing/ima_policy > +++ b/Documentation/ABI/testing/ima_policy > @@ -32,7 +32,7 @@ Description: > func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK]MODULE_CHECK] > [FIRMWARE_CHECK] > [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] > - [KEXEC_CMDLINE] [KEY_CHECK] > + [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA] > mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] > [[^]MAY_EXEC] > fsmagic:= hex value > 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 03aad13e9e70..ae59f4a4dd70 100644 > --- a/security/integrity/ima/ima_main.c > +++ b/security/integrity/ima/ima_main.c > @@ -922,6 +922,42 @@ 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 kernel in-memory r/o structures, ^ @buf > + * hash of the memory structures, or data that represents subsystem state > + * change. > + * > + * 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 ^ @measure_buf_hash > + * is too large. > + * > + * The data (buf) can only be measured, not appraised. ^ @buf > + */ > +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) { > + pr_err("Invalid arguments passed to %s().\n", __func__); This is a problem for the developer making use of the ima_measure_critical_data() API and shouldn't be logged, IMO, because a user/admin can do nothing about it. I think the error message should be dropped. > + 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; > diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c > index 25419c7ff50b..2a0c0603626e 100644 > --- a/security/integrity/ima/ima_policy.c > +++ b/security/integrity/ima/ima_policy.c > @@ -1251,6 +1251,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) > else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) && > strcmp(args[0].from, "KEY_CHECK") == 0) > entry->func = KEY_CHECK; > + else if (strcmp(args[0].from, "CRITICAL_DATA") == 0) > + entry->func = CRITICAL_DATA; > else > result = -EINVAL; > if (!result) This hunk and the above change to Documentation/ABI/testing/ima_policy need to be moved to the next patch when you introduce the policy changes. Tyler > -- > 2.17.1 >
On 2020-12-10 3:02 p.m., Tyler Hicks wrote: > On 2020-12-09 11:42:07, 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> >> --- >> Documentation/ABI/testing/ima_policy | 2 +- >> include/linux/ima.h | 6 +++++ >> security/integrity/ima/ima.h | 1 + >> security/integrity/ima/ima_api.c | 2 +- >> security/integrity/ima/ima_main.c | 36 ++++++++++++++++++++++++++++ >> security/integrity/ima/ima_policy.c | 2 ++ >> 6 files changed, 47 insertions(+), 2 deletions(-) >> >> diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy >> index e35263f97fc1..6ec7daa87cba 100644 >> --- a/Documentation/ABI/testing/ima_policy >> +++ b/Documentation/ABI/testing/ima_policy >> @@ -32,7 +32,7 @@ Description: >> func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK]MODULE_CHECK] >> [FIRMWARE_CHECK] >> [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] >> - [KEXEC_CMDLINE] [KEY_CHECK] >> + [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA] >> mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] >> [[^]MAY_EXEC] >> fsmagic:= hex value >> 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 03aad13e9e70..ae59f4a4dd70 100644 >> --- a/security/integrity/ima/ima_main.c >> +++ b/security/integrity/ima/ima_main.c >> @@ -922,6 +922,42 @@ 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 kernel in-memory r/o structures, > ^ > @buf > Will do. >> + * hash of the memory structures, or data that represents subsystem state >> + * change. >> + * >> + * 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 > ^ > @measure_buf_hash > >> + * is too large. >> + * >> + * The data (buf) can only be measured, not appraised. > ^ > @buf > Will do. >> + */ >> +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) { >> + pr_err("Invalid arguments passed to %s().\n", __func__); > > This is a problem for the developer making use of the > ima_measure_critical_data() API and shouldn't be logged, IMO, because a > user/admin can do nothing about it. I think the error message should be > dropped. > >> + 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; >> diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c >> index 25419c7ff50b..2a0c0603626e 100644 >> --- a/security/integrity/ima/ima_policy.c >> +++ b/security/integrity/ima/ima_policy.c >> @@ -1251,6 +1251,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) >> else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) && >> strcmp(args[0].from, "KEY_CHECK") == 0) >> entry->func = KEY_CHECK; >> + else if (strcmp(args[0].from, "CRITICAL_DATA") == 0) >> + entry->func = CRITICAL_DATA; >> else >> result = -EINVAL; >> if (!result) > > This hunk and the above change to Documentation/ABI/testing/ima_policy > need to be moved to the next patch when you introduce the policy > changes. > Will do. ~Tushar > Tyler > >> -- >> 2.17.1 >>
<snip> >> + */ >> +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) { >> + pr_err("Invalid arguments passed to %s().\n", __func__); > > This is a problem for the developer making use of the > ima_measure_critical_data() API and shouldn't be logged, IMO, because a > user/admin can do nothing about it. I think the error message should be > dropped. > Thanks Tyler. Will drop the message.
diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index e35263f97fc1..6ec7daa87cba 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -32,7 +32,7 @@ Description: func:= [BPRM_CHECK][MMAP_CHECK][CREDS_CHECK][FILE_CHECK]MODULE_CHECK] [FIRMWARE_CHECK] [KEXEC_KERNEL_CHECK] [KEXEC_INITRAMFS_CHECK] - [KEXEC_CMDLINE] [KEY_CHECK] + [KEXEC_CMDLINE] [KEY_CHECK] [CRITICAL_DATA] mask:= [[^]MAY_READ] [[^]MAY_WRITE] [[^]MAY_APPEND] [[^]MAY_EXEC] fsmagic:= hex value 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 03aad13e9e70..ae59f4a4dd70 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -922,6 +922,42 @@ 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 kernel in-memory r/o structures, + * hash of the memory structures, or data that represents subsystem state + * change. + * + * 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) { + pr_err("Invalid arguments passed to %s().\n", __func__); + 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; diff --git a/security/integrity/ima/ima_policy.c b/security/integrity/ima/ima_policy.c index 25419c7ff50b..2a0c0603626e 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -1251,6 +1251,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) else if (IS_ENABLED(CONFIG_IMA_MEASURE_ASYMMETRIC_KEYS) && strcmp(args[0].from, "KEY_CHECK") == 0) entry->func = KEY_CHECK; + else if (strcmp(args[0].from, "CRITICAL_DATA") == 0) + entry->func = CRITICAL_DATA; else result = -EINVAL; if (!result)
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> --- Documentation/ABI/testing/ima_policy | 2 +- include/linux/ima.h | 6 +++++ security/integrity/ima/ima.h | 1 + security/integrity/ima/ima_api.c | 2 +- security/integrity/ima/ima_main.c | 36 ++++++++++++++++++++++++++++ security/integrity/ima/ima_policy.c | 2 ++ 6 files changed, 47 insertions(+), 2 deletions(-)