1 files changed, 75 insertions, 29 deletions

diff --git a/fs/attr.c b/fs/attr.c
index a8ae5f6d9b16..b9ec6b47bab2 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -16,10 +16,6 @@
 #include <linux/fcntl.h>
 #include <linux/filelock.h>
 #include <linux/security.h>
-#include <linux/evm.h>
-#include <linux/ima.h>
-
-#include "internal.h"
 
 /**
  * setattr_should_drop_sgid - determine whether the setgid bit needs to be
@@ -157,7 +153,7 @@ static bool chgrp_ok(struct mnt_idmap *idmap,
  * the vfsmount must be passed through @idmap. This function will then
  * take care to map the inode according to @idmap before checking
  * permissions. On non-idmapped mounts or if permission checking is to be
- * performed on the raw inode simply passs @nop_mnt_idmap.
+ * performed on the raw inode simply pass @nop_mnt_idmap.
  *
  * Should be called as the first thing in ->setattr implementations,
  * possibly after taking additional locks.
@@ -234,7 +230,7 @@ EXPORT_SYMBOL(setattr_prepare);
  * @inode:	the inode to be truncated
  * @offset:	the new size to assign to the inode
  *
- * inode_newsize_ok must be called with i_mutex held.
+ * inode_newsize_ok must be called with i_rwsem held exclusively.
  *
  * inode_newsize_ok will check filesystem limits and ulimits to check that the
  * new inode size is within limits. inode_newsize_ok will also send SIGXFSZ
@@ -276,12 +272,45 @@ out_big:
 EXPORT_SYMBOL(inode_newsize_ok);
 
 /**
+ * setattr_copy_mgtime - update timestamps for mgtime inodes
+ * @inode: inode timestamps to be updated
+ * @attr: attrs for the update
+ *
+ * With multigrain timestamps, take more care to prevent races when
+ * updating the ctime. Always update the ctime to the very latest using
+ * the standard mechanism, and use that to populate the atime and mtime
+ * appropriately (unless those are being set to specific values).
+ */
+static void setattr_copy_mgtime(struct inode *inode, const struct iattr *attr)
+{
+	unsigned int ia_valid = attr->ia_valid;
+	struct timespec64 now;
+
+	if (ia_valid & ATTR_CTIME_SET)
+		now = inode_set_ctime_deleg(inode, attr->ia_ctime);
+	else if (ia_valid & ATTR_CTIME)
+		now = inode_set_ctime_current(inode);
+	else
+		now = current_time(inode);
+
+	if (ia_valid & ATTR_ATIME_SET)
+		inode_set_atime_to_ts(inode, attr->ia_atime);
+	else if (ia_valid & ATTR_ATIME)
+		inode_set_atime_to_ts(inode, now);
+
+	if (ia_valid & ATTR_MTIME_SET)
+		inode_set_mtime_to_ts(inode, attr->ia_mtime);
+	else if (ia_valid & ATTR_MTIME)
+		inode_set_mtime_to_ts(inode, now);
+}
+
+/**
  * setattr_copy - copy simple metadata updates into the generic inode
  * @idmap:	idmap of the mount the inode was found from
  * @inode:	the inode to be updated
  * @attr:	the new attributes
  *
- * setattr_copy must be called with i_mutex held.
+ * setattr_copy must be called with i_rwsem held exclusively.
  *
  * setattr_copy updates the inode's metadata with that specified
  * in attr on idmapped mounts. Necessary permission checks to determine
@@ -307,12 +336,6 @@ void setattr_copy(struct mnt_idmap *idmap, struct inode *inode,
 
 	i_uid_update(idmap, attr, inode);
 	i_gid_update(idmap, attr, inode);
-	if (ia_valid & ATTR_ATIME)
-		inode->i_atime = attr->ia_atime;
-	if (ia_valid & ATTR_MTIME)
-		inode->i_mtime = attr->ia_mtime;
-	if (ia_valid & ATTR_CTIME)
-		inode_set_ctime_to_ts(inode, attr->ia_ctime);
 	if (ia_valid & ATTR_MODE) {
 		umode_t mode = attr->ia_mode;
 		if (!in_group_or_capable(idmap, inode,
@@ -320,6 +343,19 @@ void setattr_copy(struct mnt_idmap *idmap, struct inode *inode,
 			mode &= ~S_ISGID;
 		inode->i_mode = mode;
 	}
+
+	if (is_mgtime(inode))
+		return setattr_copy_mgtime(inode, attr);
+
+	if (ia_valid & ATTR_ATIME)
+		inode_set_atime_to_ts(inode, attr->ia_atime);
+	if (ia_valid & ATTR_MTIME)
+		inode_set_mtime_to_ts(inode, attr->ia_mtime);
+
+	if (ia_valid & ATTR_CTIME_SET)
+		inode_set_ctime_deleg(inode, attr->ia_ctime);
+	else if (ia_valid & ATTR_CTIME)
+		inode_set_ctime_to_ts(inode, attr->ia_ctime);
 }
 EXPORT_SYMBOL(setattr_copy);
 
@@ -352,19 +388,19 @@ int may_setattr(struct mnt_idmap *idmap, struct inode *inode,
 EXPORT_SYMBOL(may_setattr);
 
 /**
- * notify_change - modify attributes of a filesytem object
+ * notify_change - modify attributes of a filesystem object
  * @idmap:	idmap of the mount the inode was found from
  * @dentry:	object affected
  * @attr:	new attributes
  * @delegated_inode: returns inode, if the inode is delegated
  *
- * The caller must hold the i_mutex on the affected object.
+ * The caller must hold the i_rwsem exclusively on the affected object.
  *
  * If notify_change discovers a delegation in need of breaking,
  * it will return -EWOULDBLOCK and return a reference to the inode in
  * delegated_inode.  The caller should then break the delegation and
  * retry.  Because breaking a delegation may take a long time, the
- * caller should drop the i_mutex before doing so.
+ * caller should drop the i_rwsem before doing so.
  *
  * Alternatively, a caller may pass NULL for delegated_inode.  This may
  * be appropriate for callers that expect the underlying filesystem not
@@ -379,7 +415,7 @@ EXPORT_SYMBOL(may_setattr);
  * performed on the raw inode simply pass @nop_mnt_idmap.
  */
 int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
-		  struct iattr *attr, struct inode **delegated_inode)
+		  struct iattr *attr, struct delegated_inode *delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
 	umode_t mode = inode->i_mode;
@@ -411,22 +447,25 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 		if (S_ISLNK(inode->i_mode))
 			return -EOPNOTSUPP;
 
-		/* Flag setting protected by i_mutex */
+		/* Flag setting protected by i_rwsem */
 		if (is_sxid(attr->ia_mode))
 			inode->i_flags &= ~S_NOSEC;
 	}
 
 	now = current_time(inode);
 
-	attr->ia_ctime = now;
-	if (!(ia_valid & ATTR_ATIME_SET))
-		attr->ia_atime = now;
-	else
+	if (ia_valid & ATTR_ATIME_SET)
 		attr->ia_atime = timestamp_truncate(attr->ia_atime, inode);
-	if (!(ia_valid & ATTR_MTIME_SET))
-		attr->ia_mtime = now;
 	else
+		attr->ia_atime = now;
+	if (ia_valid & ATTR_CTIME_SET)
+		attr->ia_ctime = timestamp_truncate(attr->ia_ctime, inode);
+	else
+		attr->ia_ctime = now;
+	if (ia_valid & ATTR_MTIME_SET)
 		attr->ia_mtime = timestamp_truncate(attr->ia_mtime, inode);
+	else
+		attr->ia_mtime = now;
 
 	if (ia_valid & ATTR_KILL_PRIV) {
 		error = security_inode_need_killpriv(dentry);
@@ -491,9 +530,17 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 	error = security_inode_setattr(idmap, dentry, attr);
 	if (error)
 		return error;
-	error = try_break_deleg(inode, delegated_inode);
-	if (error)
-		return error;
+
+	/*
+	 * If ATTR_DELEG is set, then these attributes are being set on
+	 * behalf of the holder of a write delegation. We want to avoid
+	 * breaking the delegation in this case.
+	 */
+	if (!(ia_valid & ATTR_DELEG)) {
+		error = try_break_deleg(inode, delegated_inode);
+		if (error)
+			return error;
+	}
 
 	if (inode->i_op->setattr)
 		error = inode->i_op->setattr(idmap, dentry, attr);
@@ -502,8 +549,7 @@ int notify_change(struct mnt_idmap *idmap, struct dentry *dentry,
 
 	if (!error) {
 		fsnotify_change(dentry, ia_valid);
-		ima_inode_post_setattr(idmap, dentry);
-		evm_inode_post_setattr(dentry, ia_valid);
+		security_inode_post_setattr(idmap, dentry, ia_valid);
 	}
 
 	return error;