Stephen Smalley avatar Stephen Smalley committed 0d4cf48

Add permission checking for binder IPC.

Comments (0)

Files changed (6)

drivers/staging/android/binder.c

 #include <linux/slab.h>
 #include <linux/uaccess.h>
 #include <linux/vmalloc.h>
+#include <linux/security.h>
 
 #include "binder.h"
 
 			return_error = BR_DEAD_REPLY;
 			goto err_dead_binder;
 		}
+		if (security_binder_transaction(proc->tsk, target_proc->tsk) < 0) {
+			return_error = BR_FAILED_REPLY;
+			goto err_invalid_target_handle;
+		}
 		if (!(tr->flags & TF_ONE_WAY) && thread->transaction_stack) {
 			struct binder_transaction *tmp;
 			tmp = thread->transaction_stack;
 					fp->cookie, node->cookie);
 				goto err_binder_get_ref_for_node_failed;
 			}
+			if (security_binder_transfer_binder(proc->tsk, target_proc->tsk, node->proc->tsk)) {
+				return_error = BR_FAILED_REPLY;
+				goto err_binder_get_ref_for_node_failed;
+			}
 			ref = binder_get_ref_for_node(target_proc, node);
 			if (ref == NULL) {
 				return_error = BR_FAILED_REPLY;
 				return_error = BR_FAILED_REPLY;
 				goto err_binder_get_ref_failed;
 			}
+			if (security_binder_transfer_binder(proc->tsk, target_proc->tsk, ref->node->proc->tsk)) {
+				return_error = BR_FAILED_REPLY;
+				goto err_binder_get_ref_failed;
+			}
 			if (ref->node->proc == target_proc) {
 				if (fp->type == BINDER_TYPE_HANDLE)
 					fp->type = BINDER_TYPE_BINDER;
 				return_error = BR_FAILED_REPLY;
 				goto err_fget_failed;
 			}
+			if (security_binder_transfer_file(proc->tsk, target_proc->tsk, file) < 0) {
+				fput(file);
+				return_error = BR_FAILED_REPLY;
+				goto err_get_unused_fd_failed;
+			}
 			target_fd = task_get_unused_fd_flags(target_proc, O_CLOEXEC);
 			if (target_fd < 0) {
 				fput(file);
 			ret = -EBUSY;
 			goto err;
 		}
+		ret = security_binder_set_context_mgr(proc->tsk);
+		if (ret < 0)
+			goto err;
 		if (binder_context_mgr_uid != -1) {
 			if (binder_context_mgr_uid != current->cred->euid) {
 				printk(KERN_ERR "binder: BINDER_SET_"

include/linux/security.h

 struct security_operations {
 	char name[SECURITY_NAME_MAX + 1];
 
+	int (*binder_set_context_mgr) (struct task_struct *mgr);
+	int (*binder_transaction) (struct task_struct *from, struct task_struct *to);
+	int (*binder_transfer_binder) (struct task_struct *from, struct task_struct *to, struct task_struct *owner);
+	int (*binder_transfer_file) (struct task_struct *from, struct task_struct *to, struct file *file);
+
 	int (*ptrace_access_check) (struct task_struct *child, unsigned int mode);
 	int (*ptrace_traceme) (struct task_struct *parent);
 	int (*capget) (struct task_struct *target,
 extern int register_security(struct security_operations *ops);
 
 /* Security operations */
+int security_binder_set_context_mgr(struct task_struct *mgr);
+int security_binder_transaction(struct task_struct *from, struct task_struct *to);
+int security_binder_transfer_binder(struct task_struct *from, struct task_struct *to, struct task_struct *owner);
+int security_binder_transfer_file(struct task_struct *from, struct task_struct *to, struct file *file);
 int security_ptrace_access_check(struct task_struct *child, unsigned int mode);
 int security_ptrace_traceme(struct task_struct *parent);
 int security_capget(struct task_struct *target,
 	return 0;
 }
 
+static inline int security_binder_set_context_mgr(struct task_struct *mgr)
+{
+	return 0;
+}
+
+static inline int security_binder_transaction(struct task_struct *from, struct task_struct *to)
+{
+	return 0;
+}
+
+static inline int security_binder_transfer_binder(struct task_struct *from, struct task_struct *to, struct task_struct *owner)
+{
+	return 0;
+}
+
+static inline int security_binder_transfer_file(struct task_struct *from, struct task_struct *to, struct file *file)
+{
+	return 0;
+}
+
 static inline int security_ptrace_access_check(struct task_struct *child,
 					     unsigned int mode)
 {

security/capability.c

 
 #include <linux/security.h>
 
+static int cap_binder_set_context_mgr(struct task_struct *mgr)
+{
+	return 0;
+}
+
+static int cap_binder_transaction(struct task_struct *from, struct task_struct *to)
+{
+	return 0;
+}
+
+static int cap_binder_transfer_binder(struct task_struct *from, struct task_struct *to, struct task_struct *owner)
+{
+	return 0;
+}
+
+static int cap_binder_transfer_file(struct task_struct *from, struct task_struct *to, struct file *file)
+{
+	return 0;
+}
+
 static int cap_syslog(int type)
 {
 	return 0;
 
 void __init security_fixup_ops(struct security_operations *ops)
 {
+	set_to_cap_if_null(ops, binder_set_context_mgr);
+	set_to_cap_if_null(ops, binder_transaction);
+	set_to_cap_if_null(ops, binder_transfer_binder);
+	set_to_cap_if_null(ops, binder_transfer_file);
 	set_to_cap_if_null(ops, ptrace_access_check);
 	set_to_cap_if_null(ops, ptrace_traceme);
 	set_to_cap_if_null(ops, capget);

security/security.c

 
 /* Security operations */
 
+int security_binder_set_context_mgr(struct task_struct *mgr)
+{
+	return security_ops->binder_set_context_mgr(mgr);
+}
+
+int security_binder_transaction(struct task_struct *from, struct task_struct *to)
+{
+	return security_ops->binder_transaction(from, to);
+}
+
+int security_binder_transfer_binder(struct task_struct *from, struct task_struct *to, struct task_struct *owner)
+{
+	return security_ops->binder_transfer_binder(from, to, owner);
+}
+
+int security_binder_transfer_file(struct task_struct *from, struct task_struct *to, struct file *file)
+{
+	return security_ops->binder_transfer_file(from, to, file);
+}
+
 int security_ptrace_access_check(struct task_struct *child, unsigned int mode)
 {
 	return security_ops->ptrace_access_check(child, mode);

security/selinux/hooks.c

 
 /* Hook functions begin here. */
 
+static int selinux_binder_set_context_mgr(struct task_struct *mgr)
+{
+	u32 mysid = current_sid();
+	u32 mgrsid = task_sid(mgr);
+
+	return avc_has_perm(mysid, mgrsid, SECCLASS_BINDER, BINDER__SET_CONTEXT_MGR, NULL);
+}
+
+static int selinux_binder_transaction(struct task_struct *from, struct task_struct *to)
+{
+	u32 mysid = current_sid();
+	u32 fromsid = task_sid(from);
+	u32 tosid = task_sid(to);
+	int rc;
+
+	if (mysid != fromsid) {
+		rc = avc_has_perm(mysid, fromsid, SECCLASS_BINDER, BINDER__IMPERSONATE, NULL);
+		if (rc)
+			return rc;
+	}
+
+	return avc_has_perm(fromsid, tosid, SECCLASS_BINDER, BINDER__CALL, NULL);
+}
+
+static int selinux_binder_transfer_binder(struct task_struct *from, struct task_struct *to, struct task_struct *owner)
+{
+	u32 fromsid = task_sid(from);
+	u32 tosid = task_sid(to);
+	u32 ownersid = task_sid(owner);
+	int rc;
+
+	rc = avc_has_perm(fromsid, ownersid, SECCLASS_BINDER, BINDER__TRANSFER, NULL);
+	if (rc)
+		return rc;
+
+	return avc_has_perm(tosid, ownersid, SECCLASS_BINDER, BINDER__RECEIVE, NULL);
+}
+
+static int selinux_binder_transfer_file(struct task_struct *from, struct task_struct *to, struct file *file)
+{
+	u32 sid = task_sid(to);
+	struct file_security_struct *fsec = file->f_security;
+	struct inode *inode = file->f_path.dentry->d_inode;
+	struct inode_security_struct *isec = inode->i_security;
+	struct common_audit_data ad;
+	int rc;
+
+	COMMON_AUDIT_DATA_INIT(&ad, PATH);
+	ad.u.path = file->f_path;
+
+	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, isec->sclass, file_to_av(file),
+			    &ad);
+}
+
 static int selinux_ptrace_access_check(struct task_struct *child,
 				     unsigned int mode)
 {
 static struct security_operations selinux_ops = {
 	.name =				"selinux",
 
+	.binder_set_context_mgr =	selinux_binder_set_context_mgr,
+	.binder_transaction =		selinux_binder_transaction,
+	.binder_transfer_binder =	selinux_binder_transfer_binder,
+	.binder_transfer_file =		selinux_binder_transfer_file,
+
 	.ptrace_access_check =		selinux_ptrace_access_check,
 	.ptrace_traceme =		selinux_ptrace_traceme,
 	.capget =			selinux_capget,

security/selinux/include/classmap.h

 	{ "kernel_service", { "use_as_override", "create_files_as", NULL } },
 	{ "tun_socket",
 	  { COMMON_SOCK_PERMS, NULL } },
+	{ "binder", { "impersonate", "call", "set_context_mgr", "transfer", "receive", NULL } },
 	{ NULL }
   };
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