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Commit 61d612ea authored by Jeff Vander Stoep's avatar Jeff Vander Stoep Committed by Paul Moore
Browse files

selinux: restrict kernel module loading 



Utilize existing kernel_read_file hook on kernel module load.
Add module_load permission to the system class.

Enforces restrictions on kernel module origin when calling the
finit_module syscall. The hook checks that source type has
permission module_load for the target type.
Example for finit_module:

allow foo bar_file:system module_load;

Similarly restrictions are enforced on kernel module loading when
calling the init_module syscall. The hook checks that source
type has permission module_load with itself as the target object
because the kernel module is sourced from the calling process.
Example for init_module:

allow foo foo:system module_load;

Signed-off-by: default avatarJeff Vander Stoep <jeffv@google.com>
[PM: fixed return value of selinux_kernel_read_file()]
Signed-off-by: default avatarPaul Moore <paul@paul-moore.com>
parent 0c6181cb

security/selinux/hooks.c

+47 −0
Original line number Diff line number Diff line
@@ -3722,6 +3722,52 @@ static int selinux_kernel_module_request(char *kmod_name) 
			    SYSTEM__MODULE_REQUEST, &ad);

}



static int selinux_kernel_module_from_file(struct file *file)

{

	struct common_audit_data ad;

	struct inode_security_struct *isec;

	struct file_security_struct *fsec;

	u32 sid = current_sid();

	int rc;



	/* init_module */

	if (file == NULL)

		return avc_has_perm(sid, sid, SECCLASS_SYSTEM,

					SYSTEM__MODULE_LOAD, NULL);



	/* finit_module */

	ad.type = LSM_AUDIT_DATA_PATH;

	ad.u.path = file->f_path;



	isec = inode_security(file_inode(file));

	fsec = file->f_security;



	if (sid != fsec->sid) {

		rc = avc_has_perm(sid, fsec->sid, SECCLASS_FD, FD__USE, &ad);

		if (rc)

			return rc;

	}



	return avc_has_perm(sid, isec->sid, SECCLASS_SYSTEM,

				SYSTEM__MODULE_LOAD, &ad);

}



static int selinux_kernel_read_file(struct file *file,

				    enum kernel_read_file_id id)

{

	int rc = 0;



	switch (id) {

	case READING_MODULE:

		rc = selinux_kernel_module_from_file(file);

		break;

	default:

		break;

	}



	return rc;

}



static int selinux_task_setpgid(struct task_struct *p, pid_t pgid)

{

	return current_has_perm(p, PROCESS__SETPGID);
@@ -6018,6 +6064,7 @@ static struct security_hook_list selinux_hooks[] = { 
	LSM_HOOK_INIT(kernel_act_as, selinux_kernel_act_as),

	LSM_HOOK_INIT(kernel_create_files_as, selinux_kernel_create_files_as),

	LSM_HOOK_INIT(kernel_module_request, selinux_kernel_module_request),

	LSM_HOOK_INIT(kernel_read_file, selinux_kernel_read_file),

	LSM_HOOK_INIT(task_setpgid, selinux_task_setpgid),

	LSM_HOOK_INIT(task_getpgid, selinux_task_getpgid),

	LSM_HOOK_INIT(task_getsid, selinux_task_getsid),

security/selinux/include/classmap.h

+1 −1
Original line number Diff line number Diff line
@@ -32,7 +32,7 @@ struct security_class_mapping secclass_map[] = { 
	    "setsockcreate", NULL } },

	{ "system",

	  { "ipc_info", "syslog_read", "syslog_mod",

	    "syslog_console", "module_request", NULL } },

	    "syslog_console", "module_request", "module_load", NULL } },

	{ "capability",

	  { "chown", "dac_override", "dac_read_search",

	    "fowner", "fsetid", "kill", "setgid", "setuid", "setpcap",