Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 487 insertions, 0 deletions

diff --git a/fs/afs/security.c b/fs/afs/security.c
new file mode 100644
index 000000000..7c6a63a30
--- /dev/null
+++ b/fs/afs/security.c
@@ -0,0 +1,487 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/* AFS security handling
+ *
+ * Copyright (C) 2007, 2017 Red Hat, Inc. All Rights Reserved.
+ * Written by David Howells (dhowells@redhat.com)
+ */
+
+#include <linux/init.h>
+#include <linux/slab.h>
+#include <linux/fs.h>
+#include <linux/ctype.h>
+#include <linux/sched.h>
+#include <linux/hashtable.h>
+#include <keys/rxrpc-type.h>
+#include "internal.h"
+
+static DEFINE_HASHTABLE(afs_permits_cache, 10);
+static DEFINE_SPINLOCK(afs_permits_lock);
+
+/*
+ * get a key
+ */
+struct key *afs_request_key(struct afs_cell *cell)
+{
+	struct key *key;
+
+	_enter("{%x}", key_serial(cell->anonymous_key));
+
+	_debug("key %s", cell->anonymous_key->description);
+	key = request_key_net(&key_type_rxrpc, cell->anonymous_key->description,
+			      cell->net->net, NULL);
+	if (IS_ERR(key)) {
+		if (PTR_ERR(key) != -ENOKEY) {
+			_leave(" = %ld", PTR_ERR(key));
+			return key;
+		}
+
+		/* act as anonymous user */
+		_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
+		return key_get(cell->anonymous_key);
+	} else {
+		/* act as authorised user */
+		_leave(" = {%x} [auth]", key_serial(key));
+		return key;
+	}
+}
+
+/*
+ * Get a key when pathwalk is in rcuwalk mode.
+ */
+struct key *afs_request_key_rcu(struct afs_cell *cell)
+{
+	struct key *key;
+
+	_enter("{%x}", key_serial(cell->anonymous_key));
+
+	_debug("key %s", cell->anonymous_key->description);
+	key = request_key_net_rcu(&key_type_rxrpc,
+				  cell->anonymous_key->description,
+				  cell->net->net);
+	if (IS_ERR(key)) {
+		if (PTR_ERR(key) != -ENOKEY) {
+			_leave(" = %ld", PTR_ERR(key));
+			return key;
+		}
+
+		/* act as anonymous user */
+		_leave(" = {%x} [anon]", key_serial(cell->anonymous_key));
+		return key_get(cell->anonymous_key);
+	} else {
+		/* act as authorised user */
+		_leave(" = {%x} [auth]", key_serial(key));
+		return key;
+	}
+}
+
+/*
+ * Dispose of a list of permits.
+ */
+static void afs_permits_rcu(struct rcu_head *rcu)
+{
+	struct afs_permits *permits =
+		container_of(rcu, struct afs_permits, rcu);
+	int i;
+
+	for (i = 0; i < permits->nr_permits; i++)
+		key_put(permits->permits[i].key);
+	kfree(permits);
+}
+
+/*
+ * Discard a permission cache.
+ */
+void afs_put_permits(struct afs_permits *permits)
+{
+	if (permits && refcount_dec_and_test(&permits->usage)) {
+		spin_lock(&afs_permits_lock);
+		hash_del_rcu(&permits->hash_node);
+		spin_unlock(&afs_permits_lock);
+		call_rcu(&permits->rcu, afs_permits_rcu);
+	}
+}
+
+/*
+ * Clear a permit cache on callback break.
+ */
+void afs_clear_permits(struct afs_vnode *vnode)
+{
+	struct afs_permits *permits;
+
+	spin_lock(&vnode->lock);
+	permits = rcu_dereference_protected(vnode->permit_cache,
+					    lockdep_is_held(&vnode->lock));
+	RCU_INIT_POINTER(vnode->permit_cache, NULL);
+	spin_unlock(&vnode->lock);
+
+	afs_put_permits(permits);
+}
+
+/*
+ * Hash a list of permits.  Use simple addition to make it easy to add an extra
+ * one at an as-yet indeterminate position in the list.
+ */
+static void afs_hash_permits(struct afs_permits *permits)
+{
+	unsigned long h = permits->nr_permits;
+	int i;
+
+	for (i = 0; i < permits->nr_permits; i++) {
+		h += (unsigned long)permits->permits[i].key / sizeof(void *);
+		h += permits->permits[i].access;
+	}
+
+	permits->h = h;
+}
+
+/*
+ * Cache the CallerAccess result obtained from doing a fileserver operation
+ * that returned a vnode status for a particular key.  If a callback break
+ * occurs whilst the operation was in progress then we have to ditch the cache
+ * as the ACL *may* have changed.
+ */
+void afs_cache_permit(struct afs_vnode *vnode, struct key *key,
+		      unsigned int cb_break, struct afs_status_cb *scb)
+{
+	struct afs_permits *permits, *xpermits, *replacement, *zap, *new = NULL;
+	afs_access_t caller_access = scb->status.caller_access;
+	size_t size = 0;
+	bool changed = false;
+	int i, j;
+
+	_enter("{%llx:%llu},%x,%x",
+	       vnode->fid.vid, vnode->fid.vnode, key_serial(key), caller_access);
+
+	rcu_read_lock();
+
+	/* Check for the common case first: We got back the same access as last
+	 * time we tried and already have it recorded.
+	 */
+	permits = rcu_dereference(vnode->permit_cache);
+	if (permits) {
+		if (!permits->invalidated) {
+			for (i = 0; i < permits->nr_permits; i++) {
+				if (permits->permits[i].key < key)
+					continue;
+				if (permits->permits[i].key > key)
+					break;
+				if (permits->permits[i].access != caller_access) {
+					changed = true;
+					break;
+				}
+
+				if (afs_cb_is_broken(cb_break, vnode)) {
+					changed = true;
+					break;
+				}
+
+				/* The cache is still good. */
+				rcu_read_unlock();
+				return;
+			}
+		}
+
+		changed |= permits->invalidated;
+		size = permits->nr_permits;
+
+		/* If this set of permits is now wrong, clear the permits
+		 * pointer so that no one tries to use the stale information.
+		 */
+		if (changed) {
+			spin_lock(&vnode->lock);
+			if (permits != rcu_access_pointer(vnode->permit_cache))
+				goto someone_else_changed_it_unlock;
+			RCU_INIT_POINTER(vnode->permit_cache, NULL);
+			spin_unlock(&vnode->lock);
+
+			afs_put_permits(permits);
+			permits = NULL;
+			size = 0;
+		}
+	}
+
+	if (afs_cb_is_broken(cb_break, vnode))
+		goto someone_else_changed_it;
+
+	/* We need a ref on any permits list we want to copy as we'll have to
+	 * drop the lock to do memory allocation.
+	 */
+	if (permits && !refcount_inc_not_zero(&permits->usage))
+		goto someone_else_changed_it;
+
+	rcu_read_unlock();
+
+	/* Speculatively create a new list with the revised permission set.  We
+	 * discard this if we find an extant match already in the hash, but
+	 * it's easier to compare with memcmp this way.
+	 *
+	 * We fill in the key pointers at this time, but we don't get the refs
+	 * yet.
+	 */
+	size++;
+	new = kzalloc(struct_size(new, permits, size), GFP_NOFS);
+	if (!new)
+		goto out_put;
+
+	refcount_set(&new->usage, 1);
+	new->nr_permits = size;
+	i = j = 0;
+	if (permits) {
+		for (i = 0; i < permits->nr_permits; i++) {
+			if (j == i && permits->permits[i].key > key) {
+				new->permits[j].key = key;
+				new->permits[j].access = caller_access;
+				j++;
+			}
+			new->permits[j].key = permits->permits[i].key;
+			new->permits[j].access = permits->permits[i].access;
+			j++;
+		}
+	}
+
+	if (j == i) {
+		new->permits[j].key = key;
+		new->permits[j].access = caller_access;
+	}
+
+	afs_hash_permits(new);
+
+	/* Now see if the permit list we want is actually already available */
+	spin_lock(&afs_permits_lock);
+
+	hash_for_each_possible(afs_permits_cache, xpermits, hash_node, new->h) {
+		if (xpermits->h != new->h ||
+		    xpermits->invalidated ||
+		    xpermits->nr_permits != new->nr_permits ||
+		    memcmp(xpermits->permits, new->permits,
+			   new->nr_permits * sizeof(struct afs_permit)) != 0)
+			continue;
+
+		if (refcount_inc_not_zero(&xpermits->usage)) {
+			replacement = xpermits;
+			goto found;
+		}
+
+		break;
+	}
+
+	for (i = 0; i < new->nr_permits; i++)
+		key_get(new->permits[i].key);
+	hash_add_rcu(afs_permits_cache, &new->hash_node, new->h);
+	replacement = new;
+	new = NULL;
+
+found:
+	spin_unlock(&afs_permits_lock);
+
+	kfree(new);
+
+	rcu_read_lock();
+	spin_lock(&vnode->lock);
+	zap = rcu_access_pointer(vnode->permit_cache);
+	if (!afs_cb_is_broken(cb_break, vnode) && zap == permits)
+		rcu_assign_pointer(vnode->permit_cache, replacement);
+	else
+		zap = replacement;
+	spin_unlock(&vnode->lock);
+	rcu_read_unlock();
+	afs_put_permits(zap);
+out_put:
+	afs_put_permits(permits);
+	return;
+
+someone_else_changed_it_unlock:
+	spin_unlock(&vnode->lock);
+someone_else_changed_it:
+	/* Someone else changed the cache under us - don't recheck at this
+	 * time.
+	 */
+	rcu_read_unlock();
+	return;
+}
+
+static bool afs_check_permit_rcu(struct afs_vnode *vnode, struct key *key,
+				 afs_access_t *_access)
+{
+	const struct afs_permits *permits;
+	int i;
+
+	_enter("{%llx:%llu},%x",
+	       vnode->fid.vid, vnode->fid.vnode, key_serial(key));
+
+	/* check the permits to see if we've got one yet */
+	if (key == vnode->volume->cell->anonymous_key) {
+		*_access = vnode->status.anon_access;
+		_leave(" = t [anon %x]", *_access);
+		return true;
+	}
+
+	permits = rcu_dereference(vnode->permit_cache);
+	if (permits) {
+		for (i = 0; i < permits->nr_permits; i++) {
+			if (permits->permits[i].key < key)
+				continue;
+			if (permits->permits[i].key > key)
+				break;
+
+			*_access = permits->permits[i].access;
+			_leave(" = %u [perm %x]", !permits->invalidated, *_access);
+			return !permits->invalidated;
+		}
+	}
+
+	_leave(" = f");
+	return false;
+}
+
+/*
+ * check with the fileserver to see if the directory or parent directory is
+ * permitted to be accessed with this authorisation, and if so, what access it
+ * is granted
+ */
+int afs_check_permit(struct afs_vnode *vnode, struct key *key,
+		     afs_access_t *_access)
+{
+	struct afs_permits *permits;
+	bool valid = false;
+	int i, ret;
+
+	_enter("{%llx:%llu},%x",
+	       vnode->fid.vid, vnode->fid.vnode, key_serial(key));
+
+	/* check the permits to see if we've got one yet */
+	if (key == vnode->volume->cell->anonymous_key) {
+		_debug("anon");
+		*_access = vnode->status.anon_access;
+		valid = true;
+	} else {
+		rcu_read_lock();
+		permits = rcu_dereference(vnode->permit_cache);
+		if (permits) {
+			for (i = 0; i < permits->nr_permits; i++) {
+				if (permits->permits[i].key < key)
+					continue;
+				if (permits->permits[i].key > key)
+					break;
+
+				*_access = permits->permits[i].access;
+				valid = !permits->invalidated;
+				break;
+			}
+		}
+		rcu_read_unlock();
+	}
+
+	if (!valid) {
+		/* Check the status on the file we're actually interested in
+		 * (the post-processing will cache the result).
+		 */
+		_debug("no valid permit");
+
+		ret = afs_fetch_status(vnode, key, false, _access);
+		if (ret < 0) {
+			*_access = 0;
+			_leave(" = %d", ret);
+			return ret;
+		}
+	}
+
+	_leave(" = 0 [access %x]", *_access);
+	return 0;
+}
+
+/*
+ * check the permissions on an AFS file
+ * - AFS ACLs are attached to directories only, and a file is controlled by its
+ *   parent directory's ACL
+ */
+int afs_permission(struct user_namespace *mnt_userns, struct inode *inode,
+		   int mask)
+{
+	struct afs_vnode *vnode = AFS_FS_I(inode);
+	afs_access_t access;
+	struct key *key;
+	int ret = 0;
+
+	_enter("{{%llx:%llu},%lx},%x,",
+	       vnode->fid.vid, vnode->fid.vnode, vnode->flags, mask);
+
+	if (mask & MAY_NOT_BLOCK) {
+		key = afs_request_key_rcu(vnode->volume->cell);
+		if (IS_ERR(key))
+			return -ECHILD;
+
+		ret = -ECHILD;
+		if (!afs_check_validity(vnode) ||
+		    !afs_check_permit_rcu(vnode, key, &access))
+			goto error;
+	} else {
+		key = afs_request_key(vnode->volume->cell);
+		if (IS_ERR(key)) {
+			_leave(" = %ld [key]", PTR_ERR(key));
+			return PTR_ERR(key);
+		}
+
+		ret = afs_validate(vnode, key);
+		if (ret < 0)
+			goto error;
+
+		/* check the permits to see if we've got one yet */
+		ret = afs_check_permit(vnode, key, &access);
+		if (ret < 0)
+			goto error;
+	}
+
+	/* interpret the access mask */
+	_debug("REQ %x ACC %x on %s",
+	       mask, access, S_ISDIR(inode->i_mode) ? "dir" : "file");
+
+	ret = 0;
+	if (S_ISDIR(inode->i_mode)) {
+		if (mask & (MAY_EXEC | MAY_READ | MAY_CHDIR)) {
+			if (!(access & AFS_ACE_LOOKUP))
+				goto permission_denied;
+		}
+		if (mask & MAY_WRITE) {
+			if (!(access & (AFS_ACE_DELETE | /* rmdir, unlink, rename from */
+					AFS_ACE_INSERT))) /* create, mkdir, symlink, rename to */
+				goto permission_denied;
+		}
+	} else {
+		if (!(access & AFS_ACE_LOOKUP))
+			goto permission_denied;
+		if ((mask & MAY_EXEC) && !(inode->i_mode & S_IXUSR))
+			goto permission_denied;
+		if (mask & (MAY_EXEC | MAY_READ)) {
+			if (!(access & AFS_ACE_READ))
+				goto permission_denied;
+			if (!(inode->i_mode & S_IRUSR))
+				goto permission_denied;
+		} else if (mask & MAY_WRITE) {
+			if (!(access & AFS_ACE_WRITE))
+				goto permission_denied;
+			if (!(inode->i_mode & S_IWUSR))
+				goto permission_denied;
+		}
+	}
+
+	key_put(key);
+	_leave(" = %d", ret);
+	return ret;
+
+permission_denied:
+	ret = -EACCES;
+error:
+	key_put(key);
+	_leave(" = %d", ret);
+	return ret;
+}
+
+void __exit afs_clean_up_permit_cache(void)
+{
+	int i;
+
+	for (i = 0; i < HASH_SIZE(afs_permits_cache); i++)
+		WARN_ON_ONCE(!hlist_empty(&afs_permits_cache[i]));
+
+}