From: Mimi Zohar Date: Sun, 31 Jan 2016 03:23:26 +0000 (-0500) Subject: security: define kernel_read_file hook X-Git-Url: https://git.stricted.de/?a=commitdiff_plain;h=39eeb4fb97f60dbdfc823c1a673a8844b9226b60;p=GitHub%2Fmoto-9609%2Fandroid_kernel_motorola_exynos9610.git security: define kernel_read_file hook The kernel_read_file security hook is called prior to reading the file into memory. Changelog v4+: - export security_kernel_read_file() Signed-off-by: Mimi Zohar Acked-by: Kees Cook Acked-by: Luis R. Rodriguez Acked-by: Casey Schaufler --- diff --git a/fs/exec.c b/fs/exec.c index 64cb3bc788c1..8aaa38666119 100644 --- a/fs/exec.c +++ b/fs/exec.c @@ -842,6 +842,10 @@ int kernel_read_file(struct file *file, void **buf, loff_t *size, if (!S_ISREG(file_inode(file)->i_mode) || max_size < 0) return -EINVAL; + ret = security_kernel_read_file(file, id); + if (ret) + return ret; + i_size = i_size_read(file_inode(file)); if (max_size > 0 && i_size > max_size) return -EFBIG; diff --git a/include/linux/ima.h b/include/linux/ima.h index 7aea4863c244..6adcaea8101c 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -19,6 +19,7 @@ extern int ima_file_check(struct file *file, int mask, int opened); 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); +extern int ima_read_file(struct file *file, enum kernel_read_file_id id); extern int ima_post_read_file(struct file *file, void *buf, loff_t size, enum kernel_read_file_id id); @@ -48,6 +49,11 @@ static inline int ima_module_check(struct file *file) return 0; } +static inline int ima_read_file(struct file *file, enum kernel_read_file_id id) +{ + return 0; +} + static inline int ima_post_read_file(struct file *file, void *buf, loff_t size, enum kernel_read_file_id id) { diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h index 7d04a1220223..d32b7bd13635 100644 --- a/include/linux/lsm_hooks.h +++ b/include/linux/lsm_hooks.h @@ -552,6 +552,12 @@ * the kernel module to load. If the module is being loaded from a blob, * this argument will be NULL. * Return 0 if permission is granted. + * @kernel_read_file: + * Read a file specified by userspace. + * @file contains the file structure pointing to the file being read + * by the kernel. + * @id kernel read file identifier + * Return 0 if permission is granted. * @kernel_post_read_file: * Read a file specified by userspace. * @file contains the file structure pointing to the file being read @@ -1455,6 +1461,7 @@ union security_list_options { int (*kernel_create_files_as)(struct cred *new, struct inode *inode); int (*kernel_module_request)(char *kmod_name); int (*kernel_module_from_file)(struct file *file); + int (*kernel_read_file)(struct file *file, enum kernel_read_file_id id); int (*kernel_post_read_file)(struct file *file, char *buf, loff_t size, enum kernel_read_file_id id); int (*task_fix_setuid)(struct cred *new, const struct cred *old, @@ -1715,6 +1722,7 @@ struct security_hook_heads { struct list_head cred_transfer; struct list_head kernel_act_as; struct list_head kernel_create_files_as; + struct list_head kernel_read_file; struct list_head kernel_post_read_file; struct list_head kernel_module_request; struct list_head kernel_module_from_file; diff --git a/include/linux/security.h b/include/linux/security.h index cee1349e1155..071fb747fdbb 100644 --- a/include/linux/security.h +++ b/include/linux/security.h @@ -302,6 +302,7 @@ int security_kernel_act_as(struct cred *new, u32 secid); int security_kernel_create_files_as(struct cred *new, struct inode *inode); int security_kernel_module_request(char *kmod_name); int security_kernel_module_from_file(struct file *file); +int security_kernel_read_file(struct file *file, enum kernel_read_file_id id); int security_kernel_post_read_file(struct file *file, char *buf, loff_t size, enum kernel_read_file_id id); int security_task_fix_setuid(struct cred *new, const struct cred *old, @@ -863,6 +864,12 @@ static inline int security_kernel_module_from_file(struct file *file) return 0; } +static inline int security_kernel_read_file(struct file *file, + enum kernel_read_file_id id) +{ + return 0; +} + static inline int security_kernel_post_read_file(struct file *file, char *buf, loff_t size, enum kernel_read_file_id id) diff --git a/security/integrity/ima/ima_main.c b/security/integrity/ima/ima_main.c index e9651be17b72..bbb80df28fb1 100644 --- a/security/integrity/ima/ima_main.c +++ b/security/integrity/ima/ima_main.c @@ -337,6 +337,22 @@ int ima_module_check(struct file *file) return process_measurement(file, NULL, 0, MAY_EXEC, MODULE_CHECK, 0); } +/** + * ima_read_file - pre-measure/appraise hook decision based on policy + * @file: pointer to the file to be measured/appraised/audit + * @read_id: caller identifier + * + * Permit reading a file based on policy. The policy rules are written + * in terms of the policy identifier. Appraising the integrity of + * a file requires a file descriptor. + * + * For permission return 0, otherwise return -EACCES. + */ +int ima_read_file(struct file *file, enum kernel_read_file_id read_id) +{ + return 0; +} + /** * ima_post_read_file - in memory collect/appraise/audit measurement * @file: pointer to the file to be measured/appraised/audit diff --git a/security/security.c b/security/security.c index cd85be61c416..8e699f98a600 100644 --- a/security/security.c +++ b/security/security.c @@ -899,6 +899,17 @@ int security_kernel_module_from_file(struct file *file) return ima_module_check(file); } +int security_kernel_read_file(struct file *file, enum kernel_read_file_id id) +{ + int ret; + + ret = call_int_hook(kernel_read_file, 0, file, id); + if (ret) + return ret; + return ima_read_file(file, id); +} +EXPORT_SYMBOL_GPL(security_kernel_read_file); + int security_kernel_post_read_file(struct file *file, char *buf, loff_t size, enum kernel_read_file_id id) { @@ -1696,6 +1707,8 @@ struct security_hook_heads security_hook_heads = { LIST_HEAD_INIT(security_hook_heads.kernel_module_request), .kernel_module_from_file = LIST_HEAD_INIT(security_hook_heads.kernel_module_from_file), + .kernel_read_file = + LIST_HEAD_INIT(security_hook_heads.kernel_read_file), .kernel_post_read_file = LIST_HEAD_INIT(security_hook_heads.kernel_post_read_file), .task_fix_setuid =