Merge tag 'selinux-pr-20211101' of git://git.kernel.org/pub/scm/linux…

…/kernel/git/pcmoore/selinux

Pull selinux updates from Paul Moore:

 - Add LSM/SELinux/Smack controls and auditing for io-uring.

   As usual, the individual commit descriptions have more detail, but we
   were basically missing two things which we're adding here:

      + establishment of a proper audit context so that auditing of
        io-uring ops works similarly to how it does for syscalls (with
        some io-uring additions because io-uring ops are *not* syscalls)

      + additional LSM hooks to enable access control points for some of
        the more unusual io-uring features, e.g. credential overrides.

   The additional audit callouts and LSM hooks were done in conjunction
   with the io-uring folks, based on conversations and RFC patches
   earlier in the year.

 - Fixup the binder credential handling so that the proper credentials
   are used in the LSM hooks; the commit description and the code
   comment which is removed in these patches are helpful to understand
   the background and why this is the proper fix.

 - Enable SELinux genfscon policy support for securityfs, allowing
   improved SELinux filesystem labeling for other subsystems which make
   use of securityfs, e.g. IMA.

* tag 'selinux-pr-20211101' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
  security: Return xattr name from security_dentry_init_security()
  selinux: fix a sock regression in selinux_ip_postroute_compat()
  binder: use cred instead of task for getsecid
  binder: use cred instead of task for selinux checks
  binder: use euid from cred instead of using task
  LSM: Avoid warnings about potentially unused hook variables
  selinux: fix all of the W=1 build warnings
  selinux: make better use of the nf_hook_state passed to the NF hooks
  selinux: fix race condition when computing ocontext SIDs
  selinux: remove unneeded ipv6 hook wrappers
  selinux: remove the SELinux lockdown implementation
  selinux: enable genfscon labeling for securityfs
  Smack: Brutalist io_uring support
  selinux: add support for the io_uring access controls
  lsm,io_uring: add LSM hooks to io_uring
  io_uring: convert io_uring to the secure anon inode interface
  fs: add anon_inode_getfile_secure() similar to anon_inode_getfd_secure()
  audit: add filtering for io_uring records
  audit,io_uring,io-wq: add some basic audit support to io_uring
  audit: prepare audit_context for use in calling contexts beyond syscalls

drivers/android/binder.c

@@ -2056,7 +2056,7 @@ static int binder_translate_binder(struct flat_binder_object *fp,
 		ret = -EINVAL;
 		goto done;
 	}
-	if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) {
+	if (security_binder_transfer_binder(proc->cred, target_proc->cred)) {
 		ret = -EPERM;
 		goto done;
 	}
@@ -2102,7 +2102,7 @@ static int binder_translate_handle(struct flat_binder_object *fp,
 				  proc->pid, thread->pid, fp->handle);
 		return -EINVAL;
 	}
-	if (security_binder_transfer_binder(proc->tsk, target_proc->tsk)) {
+	if (security_binder_transfer_binder(proc->cred, target_proc->cred)) {
 		ret = -EPERM;
 		goto done;
 	}
@@ -2190,7 +2190,7 @@ static int binder_translate_fd(u32 fd, binder_size_t fd_offset,
 		ret = -EBADF;
 		goto err_fget;
 	}
-	ret = security_binder_transfer_file(proc->tsk, target_proc->tsk, file);
+	ret = security_binder_transfer_file(proc->cred, target_proc->cred, file);
 	if (ret < 0) {
 		ret = -EPERM;
 		goto err_security;
@@ -2595,8 +2595,8 @@ static void binder_transaction(struct binder_proc *proc,
 			return_error_line = __LINE__;
 			goto err_invalid_target_handle;
 		}
-		if (security_binder_transaction(proc->tsk,
-						target_proc->tsk) < 0) {
+		if (security_binder_transaction(proc->cred,
+						target_proc->cred) < 0) {
 			return_error = BR_FAILED_REPLY;
 			return_error_param = -EPERM;
 			return_error_line = __LINE__;
@@ -2711,7 +2711,7 @@ static void binder_transaction(struct binder_proc *proc,
 		t->from = thread;
 	else
 		t->from = NULL;
-	t->sender_euid = task_euid(proc->tsk);
+	t->sender_euid = proc->cred->euid;
 	t->to_proc = target_proc;
 	t->to_thread = target_thread;
 	t->code = tr->code;
@@ -2722,16 +2722,7 @@ static void binder_transaction(struct binder_proc *proc,
 		u32 secid;
 		size_t added_size;
 
-		/*
-		 * Arguably this should be the task's subjective LSM secid but
-		 * we can't reliably access the subjective creds of a task
-		 * other than our own so we must use the objective creds, which
-		 * are safe to access.  The downside is that if a task is
-		 * temporarily overriding it's creds it will not be reflected
-		 * here; however, it isn't clear that binder would handle that
-		 * case well anyway.
-		 */
-		security_task_getsecid_obj(proc->tsk, &secid);
+		security_cred_getsecid(proc->cred, &secid);
 		ret = security_secid_to_secctx(secid, &secctx, &secctx_sz);
 		if (ret) {
 			return_error = BR_FAILED_REPLY;
@@ -4353,6 +4344,7 @@ static void binder_free_proc(struct binder_proc *proc)
 	}
 	binder_alloc_deferred_release(&proc->alloc);
 	put_task_struct(proc->tsk);
+	put_cred(proc->cred);
 	binder_stats_deleted(BINDER_STAT_PROC);
 	kfree(proc);
 }
@@ -4564,7 +4556,7 @@ static int binder_ioctl_set_ctx_mgr(struct file *filp,
 		ret = -EBUSY;
 		goto out;
 	}
-	ret = security_binder_set_context_mgr(proc->tsk);
+	ret = security_binder_set_context_mgr(proc->cred);
 	if (ret < 0)
 		goto out;
 	if (uid_valid(context->binder_context_mgr_uid)) {
@@ -5055,6 +5047,7 @@ static int binder_open(struct inode *nodp, struct file *filp)
 	spin_lock_init(&proc->outer_lock);
 	get_task_struct(current->group_leader);
 	proc->tsk = current->group_leader;
+	proc->cred = get_cred(filp->f_cred);
 	INIT_LIST_HEAD(&proc->todo);
 	init_waitqueue_head(&proc->freeze_wait);
 	proc->default_priority = task_nice(current);

drivers/android/binder_internal.h

@@ -364,6 +364,9 @@ struct binder_ref {
  *                        (invariant after initialized)
  * @tsk                   task_struct for group_leader of process
  *                        (invariant after initialized)
+ * @cred                  struct cred associated with the `struct file`
+ *                        in binder_open()
+ *                        (invariant after initialized)
  * @deferred_work_node:   element for binder_deferred_list
  *                        (protected by binder_deferred_lock)
  * @deferred_work:        bitmap of deferred work to perform
@@ -426,6 +429,7 @@ struct binder_proc {
 	struct list_head waiting_threads;
 	int pid;
 	struct task_struct *tsk;
+	const struct cred *cred;
 	struct hlist_node deferred_work_node;
 	int deferred_work;
 	int outstanding_txns;

fs/anon_inodes.c

@@ -148,6 +148,35 @@ struct file *anon_inode_getfile(const char *name,
 }
 EXPORT_SYMBOL_GPL(anon_inode_getfile);
 
+/**
+ * anon_inode_getfile_secure - Like anon_inode_getfile(), but creates a new
+ *                             !S_PRIVATE anon inode rather than reuse the
+ *                             singleton anon inode and calls the
+ *                             inode_init_security_anon() LSM hook.  This
+ *                             allows for both the inode to have its own
+ *                             security context and for the LSM to enforce
+ *                             policy on the inode's creation.
+ *
+ * @name:    [in]    name of the "class" of the new file
+ * @fops:    [in]    file operations for the new file
+ * @priv:    [in]    private data for the new file (will be file's private_data)
+ * @flags:   [in]    flags
+ * @context_inode:
+ *           [in]    the logical relationship with the new inode (optional)
+ *
+ * The LSM may use @context_inode in inode_init_security_anon(), but a
+ * reference to it is not held.  Returns the newly created file* or an error
+ * pointer.  See the anon_inode_getfile() documentation for more information.
+ */
+struct file *anon_inode_getfile_secure(const char *name,
+				       const struct file_operations *fops,
+				       void *priv, int flags,
+				       const struct inode *context_inode)
+{
+	return __anon_inode_getfile(name, fops, priv, flags,
+				    context_inode, true);
+}
+
 static int __anon_inode_getfd(const char *name,
 			      const struct file_operations *fops,
 			      void *priv, int flags,

fs/ceph/xattr.c

@@ -1311,7 +1311,7 @@ int ceph_security_init_secctx(struct dentry *dentry, umode_t mode,
 	int err;
 
 	err = security_dentry_init_security(dentry, mode, &dentry->d_name,
-					    &as_ctx->sec_ctx,
+					    &name, &as_ctx->sec_ctx,
 					    &as_ctx->sec_ctxlen);
 	if (err < 0) {
 		WARN_ON_ONCE(err != -EOPNOTSUPP);
@@ -1335,7 +1335,6 @@ int ceph_security_init_secctx(struct dentry *dentry, umode_t mode,
 	 * It only supports single security module and only selinux has
 	 * dentry_init_security hook.
 	 */
-	name = XATTR_NAME_SELINUX;
 	name_len = strlen(name);
 	err = ceph_pagelist_reserve(pagelist,
 				    4 * 2 + name_len + as_ctx->sec_ctxlen);

fs/io-wq.c

@@ -14,6 +14,7 @@
 #include <linux/rculist_nulls.h>
 #include <linux/cpu.h>
 #include <linux/tracehook.h>
+#include <linux/audit.h>
 #include <uapi/linux/io_uring.h>
 
 #include "io-wq.h"
@@ -593,6 +594,8 @@ static int io_wqe_worker(void *data)
 	snprintf(buf, sizeof(buf), "iou-wrk-%d", wq->task->pid);
 	set_task_comm(current, buf);
 
+	audit_alloc_kernel(current);
+
 	while (!test_bit(IO_WQ_BIT_EXIT, &wq->state)) {
 		long ret;
 
@@ -631,6 +634,7 @@ static int io_wqe_worker(void *data)
 		io_worker_handle_work(worker);
 	}
 
+	audit_free(current);
 	io_worker_exit(worker);
 	return 0;
 }