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ima: update builtin policies

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This patch defines a builtin measurement policy "tcb", similar to the
existing "ima_tcb", but with additional rules to also measure files
based on the effective uid and to measure files opened with the "read"
mode bit set (eg. read, read-write).

Changing the builtin "ima_tcb" policy could potentially break existing
users.  Instead of defining a new separate boot command line option each
time the builtin measurement policy is modified, this patch defines a
single generic boot command line option "ima_policy=" to specify the
builtin policy and deprecates the use of the builtin ima_tcb policy.

[The "ima_policy=" boot command line option is based on Roberto Sassu's
"ima: added new policy type exec" patch.]

Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com>
Signed-off-by: Dr. Greg Wettstein <gw@idfusion.org>
Cc: stable@vger.kernel.org
This commit is contained in:
Mimi Zohar 2015-06-11 20:48:33 -04:00
parent 4351c294b8
commit 24fd03c876
2 changed files with 65 additions and 10 deletions
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10
Documentation/kernel-parameters.txt
View File

@ -1398,7 +1398,15 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
The list of supported hash algorithms is defined
in crypto/hash_info.h.
ima_tcb [IMA]
ima_policy= [IMA]
The builtin measurement policy to load during IMA
setup. Specyfing "tcb" as the value, measures all
programs exec'd, files mmap'd for exec, and all files
opened with the read mode bit set by either the
effective uid (euid=0) or uid=0.
Format: "tcb"
ima_tcb [IMA] Deprecated. Use ima_policy= instead.
Load a policy which meets the needs of the Trusted
Computing Base. This means IMA will measure all
programs exec'd, files mmap'd for exec, and all files

65
security/integrity/ima/ima_policy.c
View File

@ -44,6 +44,8 @@ enum lsm_rule_types { LSM_OBJ_USER, LSM_OBJ_ROLE, LSM_OBJ_TYPE,
LSM_SUBJ_USER, LSM_SUBJ_ROLE, LSM_SUBJ_TYPE
};
enum policy_types { ORIGINAL_TCB = 1, DEFAULT_TCB };
struct ima_rule_entry {
struct list_head list;
int action;
@ -72,7 +74,7 @@ struct ima_rule_entry {
* normal users can easily run the machine out of memory simply building
* and running executables.
*/
static struct ima_rule_entry default_rules[] = {
static struct ima_rule_entry dont_measure_rules[] = {
{.action = DONT_MEASURE, .fsmagic = PROC_SUPER_MAGIC, .flags = IMA_FSMAGIC},
{.action = DONT_MEASURE, .fsmagic = SYSFS_MAGIC, .flags = IMA_FSMAGIC},
{.action = DONT_MEASURE, .fsmagic = DEBUGFS_MAGIC, .flags = IMA_FSMAGIC},
@ -83,13 +85,29 @@ static struct ima_rule_entry default_rules[] = {
{.action = DONT_MEASURE, .fsmagic = SELINUX_MAGIC, .flags = IMA_FSMAGIC},
{.action = DONT_MEASURE, .fsmagic = CGROUP_SUPER_MAGIC,
.flags = IMA_FSMAGIC},
{.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC},
{.action = DONT_MEASURE, .fsmagic = NSFS_MAGIC, .flags = IMA_FSMAGIC}
};
static struct ima_rule_entry original_measurement_rules[] = {
{.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ, .uid = GLOBAL_ROOT_UID,
.flags = IMA_FUNC | IMA_MASK | IMA_UID},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
.uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_MASK | IMA_UID},
{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
{.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
};
static struct ima_rule_entry default_measurement_rules[] = {
{.action = MEASURE, .func = MMAP_CHECK, .mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE, .func = BPRM_CHECK, .mask = MAY_EXEC,
.flags = IMA_FUNC | IMA_MASK},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
.uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_EUID},
{.action = MEASURE, .func = FILE_CHECK, .mask = MAY_READ,
.uid = GLOBAL_ROOT_UID, .flags = IMA_FUNC | IMA_INMASK | IMA_UID},
{.action = MEASURE, .func = MODULE_CHECK, .flags = IMA_FUNC},
{.action = MEASURE, .func = FIRMWARE_CHECK, .flags = IMA_FUNC},
};
@ -121,14 +139,29 @@ static struct list_head *ima_rules;
static DEFINE_MUTEX(ima_rules_mutex);
static bool ima_use_tcb __initdata;
static int ima_policy __initdata;
static int __init default_measure_policy_setup(char *str)
{
ima_use_tcb = 1;
if (ima_policy)
return 1;
ima_policy = ORIGINAL_TCB;
return 1;
}
__setup("ima_tcb", default_measure_policy_setup);
static int __init policy_setup(char *str)
{
if (ima_policy)
return 1;
if (strcmp(str, "tcb") == 0)
ima_policy = DEFAULT_TCB;
return 1;
}
__setup("ima_policy=", policy_setup);
static bool ima_use_appraise_tcb __initdata;
static int __init default_appraise_policy_setup(char *str)
{
@ -352,13 +385,27 @@ void __init ima_init_policy(void)
{
int i, measure_entries, appraise_entries;
/* if !ima_use_tcb set entries = 0 so we load NO default rules */
measure_entries = ima_use_tcb ? ARRAY_SIZE(default_rules) : 0;
/* if !ima_policy set entries = 0 so we load NO default rules */
measure_entries = ima_policy ? ARRAY_SIZE(dont_measure_rules) : 0;
appraise_entries = ima_use_appraise_tcb ?
ARRAY_SIZE(default_appraise_rules) : 0;
for (i = 0; i < measure_entries; i++)
list_add_tail(&default_rules[i].list, &ima_default_rules);
list_add_tail(&dont_measure_rules[i].list, &ima_default_rules);
switch (ima_policy) {
case ORIGINAL_TCB:
for (i = 0; i < ARRAY_SIZE(original_measurement_rules); i++)
list_add_tail(&original_measurement_rules[i].list,
&ima_default_rules);
break;
case DEFAULT_TCB:
for (i = 0; i < ARRAY_SIZE(default_measurement_rules); i++)
list_add_tail(&default_measurement_rules[i].list,
&ima_default_rules);
default:
break;
}
for (i = 0; i < appraise_entries; i++) {
list_add_tail(&default_appraise_rules[i].list,