From 2e72d51b4ac32989496870cd8171b3682fea1839 Mon Sep 17 00:00:00 2001 From: Kees Cook Date: Tue, 16 Oct 2012 07:32:07 +1030 Subject: security: introduce kernel_module_from_file hook Now that kernel module origins can be reasoned about, provide a hook to the LSMs to make policy decisions about the module file. This will let Chrome OS enforce that loadable kernel modules can only come from its read-only hash-verified root filesystem. Other LSMs can, for example, read extended attributes for signatures, etc. Signed-off-by: Kees Cook Acked-by: Serge E. Hallyn Acked-by: Eric Paris Acked-by: Mimi Zohar Acked-by: James Morris Signed-off-by: Rusty Russell --- security/capability.c | 6 ++++++ security/security.c | 5 +++++ 2 files changed, 11 insertions(+) (limited to 'security') diff --git a/security/capability.c b/security/capability.c index b14a30c234b8..0fe5a026aef8 100644 --- a/security/capability.c +++ b/security/capability.c @@ -395,6 +395,11 @@ static int cap_kernel_module_request(char *kmod_name) return 0; } +static int cap_kernel_module_from_file(struct file *file) +{ + return 0; +} + static int cap_task_setpgid(struct task_struct *p, pid_t pgid) { return 0; @@ -967,6 +972,7 @@ void __init security_fixup_ops(struct security_operations *ops) set_to_cap_if_null(ops, kernel_act_as); set_to_cap_if_null(ops, kernel_create_files_as); set_to_cap_if_null(ops, kernel_module_request); + set_to_cap_if_null(ops, kernel_module_from_file); set_to_cap_if_null(ops, task_fix_setuid); set_to_cap_if_null(ops, task_setpgid); set_to_cap_if_null(ops, task_getpgid); diff --git a/security/security.c b/security/security.c index 8dcd4ae10a5f..ce88630de15d 100644 --- a/security/security.c +++ b/security/security.c @@ -820,6 +820,11 @@ int security_kernel_module_request(char *kmod_name) return security_ops->kernel_module_request(kmod_name); } +int security_kernel_module_from_file(struct file *file) +{ + return security_ops->kernel_module_from_file(file); +} + int security_task_fix_setuid(struct cred *new, const struct cred *old, int flags) { -- cgit v1.2.3 From fdf90729e57812cb12d7938e2dee7c71e875fb08 Mon Sep 17 00:00:00 2001 From: Mimi Zohar Date: Tue, 16 Oct 2012 12:40:08 +1030 Subject: ima: support new kernel module syscall With the addition of the new kernel module syscall, which defines two arguments - a file descriptor to the kernel module and a pointer to a NULL terminated string of module arguments - it is now possible to measure and appraise kernel modules like any other file on the file system. This patch adds support to measure and appraise kernel modules in an extensible and consistent manner. To support filesystems without extended attribute support, additional patches could pass the signature as the first parameter. Signed-off-by: Mimi Zohar Signed-off-by: Rusty Russell --- Documentation/ABI/testing/ima_policy | 3 ++- include/linux/ima.h | 6 ++++++ security/integrity/ima/ima.h | 2 +- security/integrity/ima/ima_api.c | 4 ++-- security/integrity/ima/ima_main.c | 21 +++++++++++++++++++++ security/integrity/ima/ima_policy.c | 3 +++ security/security.c | 7 ++++++- 7 files changed, 41 insertions(+), 5 deletions(-) (limited to 'security') diff --git a/Documentation/ABI/testing/ima_policy b/Documentation/ABI/testing/ima_policy index 986946613542..ec0a38ef3145 100644 --- a/Documentation/ABI/testing/ima_policy +++ b/Documentation/ABI/testing/ima_policy @@ -23,7 +23,7 @@ Description: lsm: [[subj_user=] [subj_role=] [subj_type=] [obj_user=] [obj_role=] [obj_type=]] - base: func:= [BPRM_CHECK][FILE_MMAP][FILE_CHECK] + base: func:= [BPRM_CHECK][FILE_MMAP][FILE_CHECK][MODULE_CHECK] mask:= [MAY_READ] [MAY_WRITE] [MAY_APPEND] [MAY_EXEC] fsmagic:= hex value uid:= decimal value @@ -53,6 +53,7 @@ Description: measure func=BPRM_CHECK measure func=FILE_MMAP mask=MAY_EXEC measure func=FILE_CHECK mask=MAY_READ uid=0 + measure func=MODULE_CHECK uid=0 appraise fowner=0 The default policy measures all executables in bprm_check, diff --git a/include/linux/ima.h b/include/linux/ima.h index 2c7223d7e73b..86c361e947b9 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -18,6 +18,7 @@ extern int ima_bprm_check(struct linux_binprm *bprm); extern int ima_file_check(struct file *file, int mask); extern void ima_file_free(struct file *file); extern int ima_file_mmap(struct file *file, unsigned long prot); +extern int ima_module_check(struct file *file); #else static inline int ima_bprm_check(struct linux_binprm *bprm) @@ -40,6 +41,11 @@ static inline int ima_file_mmap(struct file *file, unsigned long prot) return 0; } +static inline int ima_module_check(struct file *file) +{ + return 0; +} + #endif /* CONFIG_IMA_H */ #ifdef CONFIG_IMA_APPRAISE diff --git a/security/integrity/ima/ima.h b/security/integrity/ima/ima.h index 6ee8826662cc..3b2adb794f15 100644 --- a/security/integrity/ima/ima.h +++ b/security/integrity/ima/ima.h @@ -127,7 +127,7 @@ struct integrity_iint_cache *integrity_iint_insert(struct inode *inode); struct integrity_iint_cache *integrity_iint_find(struct inode *inode); /* IMA policy related functions */ -enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK, POST_SETATTR }; +enum ima_hooks { FILE_CHECK = 1, FILE_MMAP, BPRM_CHECK, MODULE_CHECK, POST_SETATTR }; int ima_match_policy(struct inode *inode, enum ima_hooks func, int mask, int flags); diff --git a/security/integrity/ima/ima_api.c b/security/integrity/ima/ima_api.c index b356884fb3ef..0cea3db21657 100644 --- a/security/integrity/ima/ima_api.c +++ b/security/integrity/ima/ima_api.c @@ -100,12 +100,12 @@ err_out: * ima_get_action - appraise & measure decision based on policy. * @inode: pointer to inode to measure * @mask: contains the permission mask (MAY_READ, MAY_WRITE, MAY_EXECUTE) - * @function: calling function (FILE_CHECK, BPRM_CHECK, FILE_MMAP) + * @function: calling function (FILE_CHECK, BPRM_CHECK, FILE_MMAP, MODULE_CHECK) * * The policy is defined in terms of keypairs: * subj=, obj=, type=, func=, mask=, fsmagic= * subj,obj, and type: are LSM specific. - * func: FILE_CHECK | BPRM_CHECK | FILE_MMAP + * func: FILE_CHECK | BPRM_CHECK | FILE_MMAP | MODULE_CHECK * 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 73c9a268253e..45de18e9a6f2 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -280,6 +280,27 @@ int ima_file_check(struct file *file, int mask) } EXPORT_SYMBOL_GPL(ima_file_check); +/** + * ima_module_check - based on policy, collect/store/appraise measurement. + * @file: pointer to the file to be measured/appraised + * + * Measure/appraise kernel modules based on policy. + * + * Always return 0 and audit dentry_open failures. + * Return code is based upon measurement appraisal. + */ +int ima_module_check(struct file *file) +{ + int rc; + + if (!file) + rc = INTEGRITY_UNKNOWN; + else + rc = process_measurement(file, file->f_dentry->d_name.name, + MAY_EXEC, MODULE_CHECK); + return (ima_appraise & IMA_APPRAISE_ENFORCE) ? rc : 0; +} + 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 c7dacd2eab7a..af7d182d5a46 100644 --- a/security/integrity/ima/ima_policy.c +++ b/security/integrity/ima/ima_policy.c @@ -80,6 +80,7 @@ static struct ima_rule_entry default_rules[] = { .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 = MODULE_CHECK, .flags = IMA_FUNC}, }; static struct ima_rule_entry default_appraise_rules[] = { @@ -401,6 +402,8 @@ static int ima_parse_rule(char *rule, struct ima_rule_entry *entry) /* PATH_CHECK is for backwards compat */ else if (strcmp(args[0].from, "PATH_CHECK") == 0) entry->func = FILE_CHECK; + else if (strcmp(args[0].from, "MODULE_CHECK") == 0) + entry->func = MODULE_CHECK; else if (strcmp(args[0].from, "FILE_MMAP") == 0) entry->func = FILE_MMAP; else if (strcmp(args[0].from, "BPRM_CHECK") == 0) diff --git a/security/security.c b/security/security.c index ce88630de15d..daa97f4ac9d1 100644 --- a/security/security.c +++ b/security/security.c @@ -822,7 +822,12 @@ int security_kernel_module_request(char *kmod_name) int security_kernel_module_from_file(struct file *file) { - return security_ops->kernel_module_from_file(file); + int ret; + + ret = security_ops->kernel_module_from_file(file); + if (ret) + return ret; + return ima_module_check(file); } int security_task_fix_setuid(struct cred *new, const struct cred *old, -- cgit v1.2.3