From 05895219627c416e3ba78de84b83c6937387786b Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek
Date: Fri, 22 Feb 2019 15:57:12 +0100
Subject: kernfs: clean up struct kernfs_iattrs

Right now, kernfs_iattrs embeds the whole struct iattr, even though it
doesn't really use half of its fields... This both leads to wasting
space and makes the code look awkward. Let's just list the few fields
we need directly in struct kernfs_iattrs.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: merged a number of chunks manually due to fuzz]
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 fs/kernfs/dir.c             | 10 ++++------
 fs/kernfs/inode.c           | 47 +++++++++++++++++++--------------------------
 fs/kernfs/kernfs-internal.h |  6 +++++-
 fs/kernfs/symlink.c         |  4 ++--
 4 files changed, 31 insertions(+), 36 deletions(-)

(limited to 'fs/kernfs')

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index b84d635567d3..1654d9136458 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -795,9 +795,8 @@ int kernfs_add_one(struct kernfs_node *kn)
 	/* Update timestamps on the parent */
 	ps_iattr = parent->iattr;
 	if (ps_iattr) {
-		struct iattr *ps_iattrs = &ps_iattr->ia_iattr;
-		ktime_get_real_ts64(&ps_iattrs->ia_ctime);
-		ps_iattrs->ia_mtime = ps_iattrs->ia_ctime;
+		ktime_get_real_ts64(&ps_iattr->ia_ctime);
+		ps_iattr->ia_mtime = ps_iattr->ia_ctime;
 	}
 
 	mutex_unlock(&kernfs_mutex);
@@ -1329,9 +1328,8 @@ static void __kernfs_remove(struct kernfs_node *kn)
 
 			/* update timestamps on the parent */
 			if (ps_iattr) {
-				ktime_get_real_ts64(&ps_iattr->ia_iattr.ia_ctime);
-				ps_iattr->ia_iattr.ia_mtime =
-					ps_iattr->ia_iattr.ia_ctime;
+				ktime_get_real_ts64(&ps_iattr->ia_ctime);
+				ps_iattr->ia_mtime = ps_iattr->ia_ctime;
 			}
 
 			kernfs_put(pos);
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 0c1fd945ce42..7d30b4949a84 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -35,7 +35,6 @@ static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
 {
 	static DEFINE_MUTEX(iattr_mutex);
 	struct kernfs_iattrs *ret;
-	struct iattr *iattrs;
 
 	mutex_lock(&iattr_mutex);
 
@@ -45,16 +44,14 @@ static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
 	kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
 	if (!kn->iattr)
 		goto out_unlock;
-	iattrs = &kn->iattr->ia_iattr;
 
 	/* assign default attributes */
-	iattrs->ia_mode = kn->mode;
-	iattrs->ia_uid = GLOBAL_ROOT_UID;
-	iattrs->ia_gid = GLOBAL_ROOT_GID;
+	kn->iattr->ia_uid = GLOBAL_ROOT_UID;
+	kn->iattr->ia_gid = GLOBAL_ROOT_GID;
 
-	ktime_get_real_ts64(&iattrs->ia_atime);
-	iattrs->ia_mtime = iattrs->ia_atime;
-	iattrs->ia_ctime = iattrs->ia_atime;
+	ktime_get_real_ts64(&kn->iattr->ia_atime);
+	kn->iattr->ia_mtime = kn->iattr->ia_atime;
+	kn->iattr->ia_ctime = kn->iattr->ia_atime;
 
 	simple_xattrs_init(&kn->iattr->xattrs);
 out_unlock:
@@ -66,29 +63,24 @@ out_unlock:
 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
 {
 	struct kernfs_iattrs *attrs;
-	struct iattr *iattrs;
 	unsigned int ia_valid = iattr->ia_valid;
 
 	attrs = kernfs_iattrs(kn);
 	if (!attrs)
 		return -ENOMEM;
 
-	iattrs = &attrs->ia_iattr;
-
 	if (ia_valid & ATTR_UID)
-		iattrs->ia_uid = iattr->ia_uid;
+		attrs->ia_uid = iattr->ia_uid;
 	if (ia_valid & ATTR_GID)
-		iattrs->ia_gid = iattr->ia_gid;
+		attrs->ia_gid = iattr->ia_gid;
 	if (ia_valid & ATTR_ATIME)
-		iattrs->ia_atime = iattr->ia_atime;
+		attrs->ia_atime = iattr->ia_atime;
 	if (ia_valid & ATTR_MTIME)
-		iattrs->ia_mtime = iattr->ia_mtime;
+		attrs->ia_mtime = iattr->ia_mtime;
 	if (ia_valid & ATTR_CTIME)
-		iattrs->ia_ctime = iattr->ia_ctime;
-	if (ia_valid & ATTR_MODE) {
-		umode_t mode = iattr->ia_mode;
-		iattrs->ia_mode = kn->mode = mode;
-	}
+		attrs->ia_ctime = iattr->ia_ctime;
+	if (ia_valid & ATTR_MODE)
+		kn->mode = iattr->ia_mode;
 	return 0;
 }
 
@@ -171,14 +163,15 @@ static inline void set_default_inode_attr(struct inode *inode, umode_t mode)
 		inode->i_ctime = current_time(inode);
 }
 
-static inline void set_inode_attr(struct inode *inode, struct iattr *iattr)
+static inline void set_inode_attr(struct inode *inode,
+				  struct kernfs_iattrs *attrs)
 {
 	struct super_block *sb = inode->i_sb;
-	inode->i_uid = iattr->ia_uid;
-	inode->i_gid = iattr->ia_gid;
-	inode->i_atime = timespec64_trunc(iattr->ia_atime, sb->s_time_gran);
-	inode->i_mtime = timespec64_trunc(iattr->ia_mtime, sb->s_time_gran);
-	inode->i_ctime = timespec64_trunc(iattr->ia_ctime, sb->s_time_gran);
+	inode->i_uid = attrs->ia_uid;
+	inode->i_gid = attrs->ia_gid;
+	inode->i_atime = timespec64_trunc(attrs->ia_atime, sb->s_time_gran);
+	inode->i_mtime = timespec64_trunc(attrs->ia_mtime, sb->s_time_gran);
+	inode->i_ctime = timespec64_trunc(attrs->ia_ctime, sb->s_time_gran);
 }
 
 static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
@@ -191,7 +184,7 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
 		 * kernfs_node has non-default attributes get them from
 		 * persistent copy in kernfs_node.
 		 */
-		set_inode_attr(inode, &attrs->ia_iattr);
+		set_inode_attr(inode, attrs);
 		security_inode_notifysecctx(inode, attrs->ia_secdata,
 					    attrs->ia_secdata_len);
 	}
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 0b7d197a904c..385a5ca0b2f6 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -20,7 +20,11 @@
 #include <linux/fs_context.h>
 
 struct kernfs_iattrs {
-	struct iattr		ia_iattr;
+	kuid_t			ia_uid;
+	kgid_t			ia_gid;
+	struct timespec64	ia_atime;
+	struct timespec64	ia_mtime;
+	struct timespec64	ia_ctime;
 	void			*ia_secdata;
 	u32			ia_secdata_len;
 
diff --git a/fs/kernfs/symlink.c b/fs/kernfs/symlink.c
index 162f43b80c84..eb46c3a16e2f 100644
--- a/fs/kernfs/symlink.c
+++ b/fs/kernfs/symlink.c
@@ -33,8 +33,8 @@ struct kernfs_node *kernfs_create_link(struct kernfs_node *parent,
 	kgid_t gid = GLOBAL_ROOT_GID;
 
 	if (target->iattr) {
-		uid = target->iattr->ia_iattr.ia_uid;
-		gid = target->iattr->ia_iattr.ia_gid;
+		uid = target->iattr->ia_uid;
+		gid = target->iattr->ia_gid;
 	}
 
 	kn = kernfs_new_node(parent, name, S_IFLNK|S_IRWXUGO, uid, gid,
-- 
cgit v1.2.3-55-g7522


From d0c9c153b4bd6963c8fcccbc0caa12e8fa8d971d Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek
Date: Fri, 22 Feb 2019 15:57:13 +0100
Subject: kernfs: do not alloc iattrs in kernfs_xattr_get

This is a read-only operation, so we can simply return -ENODATA if
kn->iattr is NULL.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: minor merge fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 fs/kernfs/inode.c | 18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

(limited to 'fs/kernfs')

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 7d30b4949a84..5c5569fb2110 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -31,14 +31,14 @@ static const struct inode_operations kernfs_iops = {
 	.listxattr	= kernfs_iop_listxattr,
 };
 
-static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
+static struct kernfs_iattrs *__kernfs_iattrs(struct kernfs_node *kn, int alloc)
 {
 	static DEFINE_MUTEX(iattr_mutex);
 	struct kernfs_iattrs *ret;
 
 	mutex_lock(&iattr_mutex);
 
-	if (kn->iattr)
+	if (kn->iattr || !alloc)
 		goto out_unlock;
 
 	kn->iattr = kmem_cache_zalloc(kernfs_iattrs_cache, GFP_KERNEL);
@@ -60,6 +60,16 @@ out_unlock:
 	return ret;
 }
 
+static struct kernfs_iattrs *kernfs_iattrs(struct kernfs_node *kn)
+{
+	return __kernfs_iattrs(kn, 1);
+}
+
+static struct kernfs_iattrs *kernfs_iattrs_noalloc(struct kernfs_node *kn)
+{
+	return __kernfs_iattrs(kn, 0);
+}
+
 int __kernfs_setattr(struct kernfs_node *kn, const struct iattr *iattr)
 {
 	struct kernfs_iattrs *attrs;
@@ -306,9 +316,9 @@ static int kernfs_xattr_get(const struct xattr_handler *handler,
 	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
 
-	attrs = kernfs_iattrs(kn);
+	attrs = kernfs_iattrs_noalloc(kn);
 	if (!attrs)
-		return -ENOMEM;
+		return -ENODATA;
 
 	return simple_xattr_get(&attrs->xattrs, name, value, size);
 }
-- 
cgit v1.2.3-55-g7522


From 0ac6075a32fc05bc7fa025965914e8dcd448a668 Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek
Date: Fri, 22 Feb 2019 15:57:15 +0100
Subject: kernfs: use simple_xattrs for security attributes

Replace the special handling of security xattrs with simple_xattrs, as
is already done for the trusted xattrs. This simplifies the code and
allows LSMs to use more than just a single xattr to do their business.

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: manual merge fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 fs/kernfs/dir.c             |  3 ---
 fs/kernfs/inode.c           | 55 ++-------------------------------------------
 fs/kernfs/kernfs-internal.h |  2 --
 3 files changed, 2 insertions(+), 58 deletions(-)

(limited to 'fs/kernfs')

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index 1654d9136458..bd48e315347b 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -532,9 +532,6 @@ void kernfs_put(struct kernfs_node *kn)
 	kfree_const(kn->name);
 
 	if (kn->iattr) {
-		if (kn->iattr->ia_secdata)
-			security_release_secctx(kn->iattr->ia_secdata,
-						kn->iattr->ia_secdata_len);
 		simple_xattrs_free(&kn->iattr->xattrs);
 		kmem_cache_free(kernfs_iattrs_cache, kn->iattr);
 	}
diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 5c5569fb2110..a365088caa3c 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -137,23 +137,6 @@ out:
 	return error;
 }
 
-static int kernfs_node_setsecdata(struct kernfs_iattrs *attrs, void **secdata,
-				  u32 *secdata_len)
-{
-	void *old_secdata;
-	size_t old_secdata_len;
-
-	old_secdata = attrs->ia_secdata;
-	old_secdata_len = attrs->ia_secdata_len;
-
-	attrs->ia_secdata = *secdata;
-	attrs->ia_secdata_len = *secdata_len;
-
-	*secdata = old_secdata;
-	*secdata_len = old_secdata_len;
-	return 0;
-}
-
 ssize_t kernfs_iop_listxattr(struct dentry *dentry, char *buf, size_t size)
 {
 	struct kernfs_node *kn = kernfs_dentry_node(dentry);
@@ -189,15 +172,12 @@ static void kernfs_refresh_inode(struct kernfs_node *kn, struct inode *inode)
 	struct kernfs_iattrs *attrs = kn->iattr;
 
 	inode->i_mode = kn->mode;
-	if (attrs) {
+	if (attrs)
 		/*
 		 * kernfs_node has non-default attributes get them from
 		 * persistent copy in kernfs_node.
 		 */
 		set_inode_attr(inode, attrs);
-		security_inode_notifysecctx(inode, attrs->ia_secdata,
-					    attrs->ia_secdata_len);
-	}
 
 	if (kernfs_type(kn) == KERNFS_DIR)
 		set_nlink(inode, kn->dir.subdirs + 2);
@@ -345,41 +325,10 @@ static const struct xattr_handler kernfs_trusted_xattr_handler = {
 	.set = kernfs_xattr_set,
 };
 
-static int kernfs_security_xattr_set(const struct xattr_handler *handler,
-				     struct dentry *unused, struct inode *inode,
-				     const char *suffix, const void *value,
-				     size_t size, int flags)
-{
-	struct kernfs_node *kn = inode->i_private;
-	struct kernfs_iattrs *attrs;
-	void *secdata;
-	u32 secdata_len = 0;
-	int error;
-
-	attrs = kernfs_iattrs(kn);
-	if (!attrs)
-		return -ENOMEM;
-
-	error = security_inode_setsecurity(inode, suffix, value, size, flags);
-	if (error)
-		return error;
-	error = security_inode_getsecctx(inode, &secdata, &secdata_len);
-	if (error)
-		return error;
-
-	mutex_lock(&kernfs_mutex);
-	error = kernfs_node_setsecdata(attrs, &secdata, &secdata_len);
-	mutex_unlock(&kernfs_mutex);
-
-	if (secdata)
-		security_release_secctx(secdata, secdata_len);
-	return error;
-}
-
 static const struct xattr_handler kernfs_security_xattr_handler = {
 	.prefix = XATTR_SECURITY_PREFIX,
 	.get = kernfs_xattr_get,
-	.set = kernfs_security_xattr_set,
+	.set = kernfs_xattr_set,
 };
 
 const struct xattr_handler *kernfs_xattr_handlers[] = {
diff --git a/fs/kernfs/kernfs-internal.h b/fs/kernfs/kernfs-internal.h
index 385a5ca0b2f6..3c437990f39a 100644
--- a/fs/kernfs/kernfs-internal.h
+++ b/fs/kernfs/kernfs-internal.h
@@ -25,8 +25,6 @@ struct kernfs_iattrs {
 	struct timespec64	ia_atime;
 	struct timespec64	ia_mtime;
 	struct timespec64	ia_ctime;
-	void			*ia_secdata;
-	u32			ia_secdata_len;
 
 	struct simple_xattrs	xattrs;
 };
-- 
cgit v1.2.3-55-g7522


From b230d5aba2d1a7b0636408889a75bf9eae6b8bc7 Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek
Date: Fri, 22 Feb 2019 15:57:16 +0100
Subject: LSM: add new hook for kernfs node initialization

This patch introduces a new security hook that is intended for
initializing the security data for newly created kernfs nodes, which
provide a way of storing a non-default security context, but need to
operate independently from mounts (and therefore may not have an
associated inode at the moment of creation).

The main motivation is to allow kernfs nodes to inherit the context of
the parent under SELinux, similar to the behavior of
security_inode_init_security(). Other LSMs may implement their own logic
for handling the creation of new nodes.

This patch also adds helper functions to <linux/kernfs.h> for
getting/setting security xattrs of a kernfs node so that LSMs hooks are
able to do their job. Other important attributes should be accessible
direcly in the kernfs_node fields (in case there is need for more, then
new helpers should be added to kernfs.h along with the patch that needs
them).

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
[PM: more manual merge fixes]
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 fs/kernfs/inode.c         | 48 ++++++++++++++++++++++++++++++++++++++---------
 include/linux/kernfs.h    | 15 +++++++++++++++
 include/linux/lsm_hooks.h | 13 +++++++++++++
 include/linux/security.h  |  9 +++++++++
 security/security.c       |  6 ++++++
 5 files changed, 82 insertions(+), 9 deletions(-)

(limited to 'fs/kernfs')

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index a365088caa3c..673ef598d97d 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -288,12 +288,11 @@ int kernfs_iop_permission(struct inode *inode, int mask)
 	return generic_permission(inode, mask);
 }
 
-static int kernfs_xattr_get(const struct xattr_handler *handler,
-			    struct dentry *unused, struct inode *inode,
-			    const char *suffix, void *value, size_t size)
+static int kernfs_node_xattr_get(const struct xattr_handler *handler,
+				 struct kernfs_node *kn, const char *suffix,
+				 void *value, size_t size)
 {
 	const char *name = xattr_full_name(handler, suffix);
-	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
 
 	attrs = kernfs_iattrs_noalloc(kn);
@@ -303,13 +302,11 @@ static int kernfs_xattr_get(const struct xattr_handler *handler,
 	return simple_xattr_get(&attrs->xattrs, name, value, size);
 }
 
-static int kernfs_xattr_set(const struct xattr_handler *handler,
-			    struct dentry *unused, struct inode *inode,
-			    const char *suffix, const void *value,
-			    size_t size, int flags)
+static int kernfs_node_xattr_set(const struct xattr_handler *handler,
+				 struct kernfs_node *kn, const char *suffix,
+				 const void *value, size_t size, int flags)
 {
 	const char *name = xattr_full_name(handler, suffix);
-	struct kernfs_node *kn = inode->i_private;
 	struct kernfs_iattrs *attrs;
 
 	attrs = kernfs_iattrs(kn);
@@ -319,6 +316,25 @@ static int kernfs_xattr_set(const struct xattr_handler *handler,
 	return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
 }
 
+static int kernfs_xattr_get(const struct xattr_handler *handler,
+			    struct dentry *unused, struct inode *inode,
+			    const char *suffix, void *value, size_t size)
+{
+	struct kernfs_node *kn = inode->i_private;
+
+	return kernfs_node_xattr_get(handler, kn, suffix, value, size);
+}
+
+static int kernfs_xattr_set(const struct xattr_handler *handler,
+			    struct dentry *unused, struct inode *inode,
+			    const char *suffix, const void *value,
+			    size_t size, int flags)
+{
+	struct kernfs_node *kn = inode->i_private;
+
+	return kernfs_node_xattr_set(handler, kn, suffix, value, size, flags);
+}
+
 static const struct xattr_handler kernfs_trusted_xattr_handler = {
 	.prefix = XATTR_TRUSTED_PREFIX,
 	.get = kernfs_xattr_get,
@@ -336,3 +352,17 @@ const struct xattr_handler *kernfs_xattr_handlers[] = {
 	&kernfs_security_xattr_handler,
 	NULL
 };
+
+int kernfs_security_xattr_get(struct kernfs_node *kn, const char *suffix,
+			      void *value, size_t size)
+{
+	return kernfs_node_xattr_get(&kernfs_security_xattr_handler,
+				     kn, suffix, value, size);
+}
+
+int kernfs_security_xattr_set(struct kernfs_node *kn, const char *suffix,
+			      void *value, size_t size, int flags)
+{
+	return kernfs_node_xattr_set(&kernfs_security_xattr_handler,
+				     kn, suffix, value, size, flags);
+}
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index c8893f663470..39eea07c2900 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -371,6 +371,11 @@ __poll_t kernfs_generic_poll(struct kernfs_open_file *of,
 			     struct poll_table_struct *pt);
 void kernfs_notify(struct kernfs_node *kn);
 
+int kernfs_security_xattr_get(struct kernfs_node *kn, const char *suffix,
+			      void *value, size_t size);
+int kernfs_security_xattr_set(struct kernfs_node *kn, const char *suffix,
+			      void *value, size_t size, int flags);
+
 const void *kernfs_super_ns(struct super_block *sb);
 int kernfs_get_tree(struct fs_context *fc);
 void kernfs_free_fs_context(struct fs_context *fc);
@@ -473,6 +478,16 @@ static inline int kernfs_setattr(struct kernfs_node *kn,
 
 static inline void kernfs_notify(struct kernfs_node *kn) { }
 
+static inline int kernfs_security_xattr_get(struct kernfs_node *kn,
+					    const char *suffix, void *value,
+					    size_t size)
+{ return -ENOSYS; }
+
+static inline int kernfs_security_xattr_set(struct kernfs_node *kn,
+					    const char *suffix, void *value,
+					    size_t size, int flags)
+{ return -ENOSYS; }
+
 static inline const void *kernfs_super_ns(struct super_block *sb)
 { return NULL; }
 
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index a9b8ff578b6b..0dd5bda719e6 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -445,6 +445,15 @@
  *	to abort the copy up. Note that the caller is responsible for reading
  *	and writing the xattrs as this hook is merely a filter.
  *
+ * Security hooks for kernfs node operations
+ *
+ * @kernfs_init_security
+ *	Initialize the security context of a newly created kernfs node based
+ *	on its own and its parent's attributes.
+ *
+ *	@kn_dir the parent kernfs node
+ *	@kn the new child kernfs node
+ *
  * Security hooks for file operations
  *
  * @file_permission:
@@ -1578,6 +1587,9 @@ union security_list_options {
 	int (*inode_copy_up)(struct dentry *src, struct cred **new);
 	int (*inode_copy_up_xattr)(const char *name);
 
+	int (*kernfs_init_security)(struct kernfs_node *kn_dir,
+				    struct kernfs_node *kn);
+
 	int (*file_permission)(struct file *file, int mask);
 	int (*file_alloc_security)(struct file *file);
 	void (*file_free_security)(struct file *file);
@@ -1879,6 +1891,7 @@ struct security_hook_heads {
 	struct hlist_head inode_getsecid;
 	struct hlist_head inode_copy_up;
 	struct hlist_head inode_copy_up_xattr;
+	struct hlist_head kernfs_init_security;
 	struct hlist_head file_permission;
 	struct hlist_head file_alloc_security;
 	struct hlist_head file_free_security;
diff --git a/include/linux/security.h b/include/linux/security.h
index 49f2685324b0..d543293216b9 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -51,6 +51,7 @@ struct fown_struct;
 struct file_operations;
 struct msg_msg;
 struct xattr;
+struct kernfs_node;
 struct xfrm_sec_ctx;
 struct mm_struct;
 struct fs_context;
@@ -299,6 +300,8 @@ int security_inode_listsecurity(struct inode *inode, char *buffer, size_t buffer
 void security_inode_getsecid(struct inode *inode, u32 *secid);
 int security_inode_copy_up(struct dentry *src, struct cred **new);
 int security_inode_copy_up_xattr(const char *name);
+int security_kernfs_init_security(struct kernfs_node *kn_dir,
+				  struct kernfs_node *kn);
 int security_file_permission(struct file *file, int mask);
 int security_file_alloc(struct file *file);
 void security_file_free(struct file *file);
@@ -801,6 +804,12 @@ static inline int security_inode_copy_up(struct dentry *src, struct cred **new)
 	return 0;
 }
 
+static inline int security_kernfs_init_security(struct kernfs_node *kn_dir,
+						struct kernfs_node *kn)
+{
+	return 0;
+}
+
 static inline int security_inode_copy_up_xattr(const char *name)
 {
 	return -EOPNOTSUPP;
diff --git a/security/security.c b/security/security.c
index 23cbb1a295a3..8d6ef9da94eb 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1318,6 +1318,12 @@ int security_inode_copy_up_xattr(const char *name)
 }
 EXPORT_SYMBOL(security_inode_copy_up_xattr);
 
+int security_kernfs_init_security(struct kernfs_node *kn_dir,
+				  struct kernfs_node *kn)
+{
+	return call_int_hook(kernfs_init_security, 0, kn_dir, kn);
+}
+
 int security_file_permission(struct file *file, int mask)
 {
 	int ret;
-- 
cgit v1.2.3-55-g7522


From e19dfdc83b60f196e0653d683499f7bc5548128f Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek
Date: Fri, 22 Feb 2019 15:57:18 +0100
Subject: kernfs: initialize security of newly created nodes

Use the new security_kernfs_init_security() hook to allow LSMs to
possibly assign a non-default security context to a newly created kernfs
node based on the attributes of the new node and also its parent node.

This fixes an issue with cgroupfs under SELinux, where newly created
cgroup subdirectories/files would not inherit its parent's context if
it had been set explicitly to a non-default value (other than the genfs
context specified by the policy). This can be reproduced as follows (on
Fedora/RHEL):

    # mkdir /sys/fs/cgroup/unified/test
    # # Need permissive to change the label under Fedora policy:
    # setenforce 0
    # chcon -t container_file_t /sys/fs/cgroup/unified/test
    # ls -lZ /sys/fs/cgroup/unified
    total 0
    -r--r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.controllers
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.max.depth
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.max.descendants
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.procs
    -r--r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.stat
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.subtree_control
    -rw-r--r--.  1 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 cgroup.threads
    drwxr-xr-x.  2 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 init.scope
    drwxr-xr-x. 26 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:21 system.slice
    drwxr-xr-x.  3 root root system_u:object_r:container_file_t:s0 0 Jan 29 03:15 test
    drwxr-xr-x.  3 root root system_u:object_r:cgroup_t:s0         0 Jan 29 03:06 user.slice
    # mkdir /sys/fs/cgroup/unified/test/subdir

Actual result:

    # ls -ldZ /sys/fs/cgroup/unified/test/subdir
    drwxr-xr-x. 2 root root system_u:object_r:cgroup_t:s0 0 Jan 29 03:15 /sys/fs/cgroup/unified/test/subdir

Expected result:

    # ls -ldZ /sys/fs/cgroup/unified/test/subdir
    drwxr-xr-x. 2 root root unconfined_u:object_r:container_file_t:s0 0 Jan 29 03:15 /sys/fs/cgroup/unified/test/subdir

Link: https://github.com/SELinuxProject/selinux-kernel/issues/39

Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 fs/kernfs/dir.c | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

(limited to 'fs/kernfs')

diff --git a/fs/kernfs/dir.c b/fs/kernfs/dir.c
index bd48e315347b..79be45df6746 100644
--- a/fs/kernfs/dir.c
+++ b/fs/kernfs/dir.c
@@ -615,6 +615,7 @@ struct kernfs_node *kernfs_node_from_dentry(struct dentry *dentry)
 }
 
 static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
+					     struct kernfs_node *parent,
 					     const char *name, umode_t mode,
 					     kuid_t uid, kgid_t gid,
 					     unsigned flags)
@@ -671,6 +672,12 @@ static struct kernfs_node *__kernfs_new_node(struct kernfs_root *root,
 			goto err_out3;
 	}
 
+	if (parent) {
+		ret = security_kernfs_init_security(parent, kn);
+		if (ret)
+			goto err_out3;
+	}
+
 	return kn;
 
  err_out3:
@@ -689,7 +696,7 @@ struct kernfs_node *kernfs_new_node(struct kernfs_node *parent,
 {
 	struct kernfs_node *kn;
 
-	kn = __kernfs_new_node(kernfs_root(parent),
+	kn = __kernfs_new_node(kernfs_root(parent), parent,
 			       name, mode, uid, gid, flags);
 	if (kn) {
 		kernfs_get(parent);
@@ -958,7 +965,7 @@ struct kernfs_root *kernfs_create_root(struct kernfs_syscall_ops *scops,
 	INIT_LIST_HEAD(&root->supers);
 	root->next_generation = 1;
 
-	kn = __kernfs_new_node(root, "", S_IFDIR | S_IRUGO | S_IXUGO,
+	kn = __kernfs_new_node(root, NULL, "", S_IFDIR | S_IRUGO | S_IXUGO,
 			       GLOBAL_ROOT_UID, GLOBAL_ROOT_GID,
 			       KERNFS_DIR);
 	if (!kn) {
-- 
cgit v1.2.3-55-g7522


From 1537ad15c9c59ce852748578eb5633139053e86b Mon Sep 17 00:00:00 2001
From: Ondrej Mosnacek
Date: Wed, 3 Apr 2019 09:29:41 +0200
Subject: kernfs: fix xattr name handling in LSM helpers

The implementation of kernfs_security_xattr_*() helpers reuses the
kernfs_node_xattr_*() functions, which take the suffix of the xattr name
and extract full xattr name from it using xattr_full_name(). However,
this function relies on the fact that the suffix passed to xattr
handlers from VFS is always constructed from the full name by just
incerementing the pointer. This doesn't necessarily hold for the callers
of kernfs_security_xattr_*(), so their usage will easily lead to
out-of-bounds access.

Fix this by moving the xattr name reconstruction to the VFS xattr
handlers and replacing the kernfs_security_xattr_*() helpers with more
general kernfs_xattr_*() helpers that take full xattr name and allow
accessing all kernfs node's xattrs.

Reported-by: kernel test robot <rong.a.chen@intel.com>
Fixes: b230d5aba2d1 ("LSM: add new hook for kernfs node initialization")
Fixes: ec882da5cda9 ("selinux: implement the kernfs_init_security hook")
Signed-off-by: Ondrej Mosnacek <omosnace@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
---
 fs/kernfs/inode.c        | 62 ++++++++++++++++--------------------------------
 include/linux/kernfs.h   | 18 +++++++-------
 security/selinux/hooks.c |  9 ++++---
 3 files changed, 33 insertions(+), 56 deletions(-)

(limited to 'fs/kernfs')

diff --git a/fs/kernfs/inode.c b/fs/kernfs/inode.c
index 673ef598d97d..f89a0f13840e 100644
--- a/fs/kernfs/inode.c
+++ b/fs/kernfs/inode.c
@@ -288,63 +288,57 @@ int kernfs_iop_permission(struct inode *inode, int mask)
 	return generic_permission(inode, mask);
 }
 
-static int kernfs_node_xattr_get(const struct xattr_handler *handler,
-				 struct kernfs_node *kn, const char *suffix,
-				 void *value, size_t size)
+int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
+		     void *value, size_t size)
 {
-	const char *name = xattr_full_name(handler, suffix);
-	struct kernfs_iattrs *attrs;
-
-	attrs = kernfs_iattrs_noalloc(kn);
+	struct kernfs_iattrs *attrs = kernfs_iattrs_noalloc(kn);
 	if (!attrs)
 		return -ENODATA;
 
 	return simple_xattr_get(&attrs->xattrs, name, value, size);
 }
 
-static int kernfs_node_xattr_set(const struct xattr_handler *handler,
-				 struct kernfs_node *kn, const char *suffix,
-				 const void *value, size_t size, int flags)
+int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
+		     const void *value, size_t size, int flags)
 {
-	const char *name = xattr_full_name(handler, suffix);
-	struct kernfs_iattrs *attrs;
-
-	attrs = kernfs_iattrs(kn);
+	struct kernfs_iattrs *attrs = kernfs_iattrs(kn);
 	if (!attrs)
 		return -ENOMEM;
 
 	return simple_xattr_set(&attrs->xattrs, name, value, size, flags);
 }
 
-static int kernfs_xattr_get(const struct xattr_handler *handler,
-			    struct dentry *unused, struct inode *inode,
-			    const char *suffix, void *value, size_t size)
+static int kernfs_vfs_xattr_get(const struct xattr_handler *handler,
+				struct dentry *unused, struct inode *inode,
+				const char *suffix, void *value, size_t size)
 {
+	const char *name = xattr_full_name(handler, suffix);
 	struct kernfs_node *kn = inode->i_private;
 
-	return kernfs_node_xattr_get(handler, kn, suffix, value, size);
+	return kernfs_xattr_get(kn, name, value, size);
 }
 
-static int kernfs_xattr_set(const struct xattr_handler *handler,
-			    struct dentry *unused, struct inode *inode,
-			    const char *suffix, const void *value,
-			    size_t size, int flags)
+static int kernfs_vfs_xattr_set(const struct xattr_handler *handler,
+				struct dentry *unused, struct inode *inode,
+				const char *suffix, const void *value,
+				size_t size, int flags)
 {
+	const char *name = xattr_full_name(handler, suffix);
 	struct kernfs_node *kn = inode->i_private;
 
-	return kernfs_node_xattr_set(handler, kn, suffix, value, size, flags);
+	return kernfs_xattr_set(kn, name, value, size, flags);
 }
 
 static const struct xattr_handler kernfs_trusted_xattr_handler = {
 	.prefix = XATTR_TRUSTED_PREFIX,
-	.get = kernfs_xattr_get,
-	.set = kernfs_xattr_set,
+	.get = kernfs_vfs_xattr_get,
+	.set = kernfs_vfs_xattr_set,
 };
 
 static const struct xattr_handler kernfs_security_xattr_handler = {
 	.prefix = XATTR_SECURITY_PREFIX,
-	.get = kernfs_xattr_get,
-	.set = kernfs_xattr_set,
+	.get = kernfs_vfs_xattr_get,
+	.set = kernfs_vfs_xattr_set,
 };
 
 const struct xattr_handler *kernfs_xattr_handlers[] = {
@@ -352,17 +346,3 @@ const struct xattr_handler *kernfs_xattr_handlers[] = {
 	&kernfs_security_xattr_handler,
 	NULL
 };
-
-int kernfs_security_xattr_get(struct kernfs_node *kn, const char *suffix,
-			      void *value, size_t size)
-{
-	return kernfs_node_xattr_get(&kernfs_security_xattr_handler,
-				     kn, suffix, value, size);
-}
-
-int kernfs_security_xattr_set(struct kernfs_node *kn, const char *suffix,
-			      void *value, size_t size, int flags)
-{
-	return kernfs_node_xattr_set(&kernfs_security_xattr_handler,
-				     kn, suffix, value, size, flags);
-}
diff --git a/include/linux/kernfs.h b/include/linux/kernfs.h
index 39eea07c2900..7987e0f89b69 100644
--- a/include/linux/kernfs.h
+++ b/include/linux/kernfs.h
@@ -371,10 +371,10 @@ __poll_t kernfs_generic_poll(struct kernfs_open_file *of,
 			     struct poll_table_struct *pt);
 void kernfs_notify(struct kernfs_node *kn);
 
-int kernfs_security_xattr_get(struct kernfs_node *kn, const char *suffix,
-			      void *value, size_t size);
-int kernfs_security_xattr_set(struct kernfs_node *kn, const char *suffix,
-			      void *value, size_t size, int flags);
+int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
+		     void *value, size_t size);
+int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
+		     const void *value, size_t size, int flags);
 
 const void *kernfs_super_ns(struct super_block *sb);
 int kernfs_get_tree(struct fs_context *fc);
@@ -478,14 +478,12 @@ static inline int kernfs_setattr(struct kernfs_node *kn,
 
 static inline void kernfs_notify(struct kernfs_node *kn) { }
 
-static inline int kernfs_security_xattr_get(struct kernfs_node *kn,
-					    const char *suffix, void *value,
-					    size_t size)
+static inline int kernfs_xattr_get(struct kernfs_node *kn, const char *name,
+				   void *value, size_t size)
 { return -ENOSYS; }
 
-static inline int kernfs_security_xattr_set(struct kernfs_node *kn,
-					    const char *suffix, void *value,
-					    size_t size, int flags)
+static inline int kernfs_xattr_set(struct kernfs_node *kn, const char *name,
+				   const void *value, size_t size, int flags)
 { return -ENOSYS; }
 
 static inline const void *kernfs_super_ns(struct super_block *sb)
diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index b6e61524d68d..d5fdcb0d26fe 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3394,7 +3394,7 @@ static int selinux_kernfs_init_security(struct kernfs_node *kn_dir,
 	int rc;
 	char *context;
 
-	rc = kernfs_security_xattr_get(kn_dir, XATTR_SELINUX_SUFFIX, NULL, 0);
+	rc = kernfs_xattr_get(kn_dir, XATTR_NAME_SELINUX, NULL, 0);
 	if (rc == -ENODATA)
 		return 0;
 	else if (rc < 0)
@@ -3405,8 +3405,7 @@ static int selinux_kernfs_init_security(struct kernfs_node *kn_dir,
 	if (!context)
 		return -ENOMEM;
 
-	rc = kernfs_security_xattr_get(kn_dir, XATTR_SELINUX_SUFFIX, context,
-				       clen);
+	rc = kernfs_xattr_get(kn_dir, XATTR_NAME_SELINUX, context, clen);
 	if (rc < 0) {
 		kfree(context);
 		return rc;
@@ -3439,8 +3438,8 @@ static int selinux_kernfs_init_security(struct kernfs_node *kn_dir,
 	if (rc)
 		return rc;
 
-	rc = kernfs_security_xattr_set(kn, XATTR_SELINUX_SUFFIX, context, clen,
-				       XATTR_CREATE);
+	rc = kernfs_xattr_set(kn, XATTR_NAME_SELINUX, context, clen,
+			      XATTR_CREATE);
 	kfree(context);
 	return rc;
 }
-- 
cgit v1.2.3-55-g7522