Differentiate between the kernel reading a file specified by userspace
from the kernel loading a buffer containing data provided by userspace.
This patch defines a new LSM hook named security_kernel_load_data().
Signed-off-by: Mimi Zohar <zohar@xxxxxxxxxxxxxxxxxx>
Cc: Eric Biederman <ebiederm@xxxxxxxxxxxx>
Cc: Luis R. Rodriguez <mcgrof@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Acked-by: Serge Hallyn <serge@xxxxxxxxxx>
---
Changelog v6:
- Updated patch description
Changelog v5:
- Share the kernel_load_data_id and kernel_read_file_id values,
simplifying Loadpin's and other LSMs calling one LSM hook from the
other.
Changelog v4:
- Define new LSM hook named security_kernel_load_data.
Changelog v3:
- Rename security_kernel_read_file to security_kernel_read_data().
Changelog v2:
- Define a generic wrapper named security_kernel_read_blob() for
security_kernel_read_file().
Changelog v1:
- Define and call security_kexec_load(), a wrapper for
security_kernel_read_file().
include/linux/lsm_hooks.h | 6 ++++++
include/linux/security.h | 27 +++++++++++++++++++++++++++
security/security.c | 5 +++++
3 files changed, 38 insertions(+)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index 8f1131c8dd54..a08bc2587b96 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -576,6 +576,10 @@
* userspace to load a kernel module with the given name.
* @kmod_name name of the module requested by the kernel
* Return 0 if successful.
+ * @kernel_load_data:
+ * Load data provided by userspace.
+ * @id kernel load data identifier
+ * 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
@@ -1582,6 +1586,7 @@ union security_list_options {
int (*kernel_act_as)(struct cred *new, u32 secid);
int (*kernel_create_files_as)(struct cred *new, struct inode *inode);
int (*kernel_module_request)(char *kmod_name);
+ int (*kernel_load_data)(enum kernel_load_data_id id);
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);
@@ -1872,6 +1877,7 @@ struct security_hook_heads {
struct hlist_head cred_getsecid;
struct hlist_head kernel_act_as;
struct hlist_head kernel_create_files_as;
+ struct hlist_head kernel_load_data;
struct hlist_head kernel_read_file;
struct hlist_head kernel_post_read_file;
struct hlist_head kernel_module_request;
diff --git a/include/linux/security.h b/include/linux/security.h
index 63030c85ee19..3410acfe139c 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -159,6 +159,27 @@ extern int mmap_min_addr_handler(struct ctl_table *table, int write,
typedef int (*initxattrs) (struct inode *inode,
const struct xattr *xattr_array, void *fs_data);
+
+/* Keep the kernel_load_data_id enum in sync with kernel_read_file_id */
+#define __data_id_enumify(ENUM, dummy) LOADING_ ## ENUM,
+#define __data_id_stringify(dummy, str) #str,
+
+enum kernel_load_data_id {
+ __kernel_read_file_id(__data_id_enumify)
+};
+
+static const char * const kernel_load_data_str[] = {
+ __kernel_read_file_id(__data_id_stringify)
+};
+
+static inline const char *kernel_load_data_id_str(enum kernel_load_data_id id)
+{
+ if ((unsigned)id >= LOADING_MAX_ID)
+ return kernel_load_data_str[LOADING_UNKNOWN];
+
+ return kernel_load_data_str[id];
+}
+
#ifdef CONFIG_SECURITY
struct security_mnt_opts {
@@ -320,6 +341,7 @@ void security_cred_getsecid(const struct cred *c, u32 *secid);
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_load_data(enum kernel_load_data_id id);
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);
@@ -909,6 +931,11 @@ static inline int security_kernel_module_request(char *kmod_name)
return 0;
}
+static inline int security_kernel_load_data(enum kernel_load_data_id id)
+{
+ return 0;
+}
+
static inline int security_kernel_read_file(struct file *file,
enum kernel_read_file_id id)
{
diff --git a/security/security.c b/security/security.c
index e7d76a8000a5..05fe5b1932d7 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1061,6 +1061,11 @@ int security_kernel_post_read_file(struct file *file, char *buf, loff_t size,
}
EXPORT_SYMBOL_GPL(security_kernel_post_read_file);
+int security_kernel_load_data(enum kernel_load_data_id id)
+{
+ return call_int_hook(kernel_load_data, 0, id);
+}
+
int security_task_fix_setuid(struct cred *new, const struct cred *old,
int flags)
{
--
2.7.5
