1 files changed, 105 insertions, 61 deletions

diff --git a/fs/attr.c b/fs/attr.c
index 96d394bdadd..6530ced1969 100644
--- a/fs/attr.c
+++ b/fs/attr.c
@@ -5,60 +5,79 @@
  *  changes by Thomas Schoebel-Theuer
  */
 
-#include <linux/module.h>
+#include <linux/export.h>
 #include <linux/time.h>
 #include <linux/mm.h>
 #include <linux/string.h>
 #include <linux/capability.h>
 #include <linux/fsnotify.h>
 #include <linux/fcntl.h>
-#include <linux/quotaops.h>
 #include <linux/security.h>
+#include <linux/evm.h>
+#include <linux/ima.h>
 
-/* Taken over from the old code... */
-
-/* POSIX UID/GID verification for setting inode attributes. */
+/**
+ * inode_change_ok - check if attribute changes to an inode are allowed
+ * @inode:	inode to check
+ * @attr:	attributes to change
+ *
+ * Check if we are allowed to change the attributes contained in @attr
+ * in the given inode.  This includes the normal unix access permission
+ * checks, as well as checks for rlimits and others.
+ *
+ * Should be called as the first thing in ->setattr implementations,
+ * possibly after taking additional locks.
+ */
 int inode_change_ok(const struct inode *inode, struct iattr *attr)
 {
-	int retval = -EPERM;
 	unsigned int ia_valid = attr->ia_valid;
 
+	/*
+	 * First check size constraints.  These can't be overriden using
+	 * ATTR_FORCE.
+	 */
+	if (ia_valid & ATTR_SIZE) {
+		int error = inode_newsize_ok(inode, attr->ia_size);
+		if (error)
+			return error;
+	}
+
 	/* If force is set do it anyway. */
 	if (ia_valid & ATTR_FORCE)
-		goto fine;
+		return 0;
 
 	/* Make sure a caller can chown. */
 	if ((ia_valid & ATTR_UID) &&
-	    (current_fsuid() != inode->i_uid ||
-	     attr->ia_uid != inode->i_uid) && !capable(CAP_CHOWN))
-		goto error;
+	    (!uid_eq(current_fsuid(), inode->i_uid) ||
+	     !uid_eq(attr->ia_uid, inode->i_uid)) &&
+	    !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
+		return -EPERM;
 
 	/* Make sure caller can chgrp. */
 	if ((ia_valid & ATTR_GID) &&
-	    (current_fsuid() != inode->i_uid ||
-	    (!in_group_p(attr->ia_gid) && attr->ia_gid != inode->i_gid)) &&
-	    !capable(CAP_CHOWN))
-		goto error;
+	    (!uid_eq(current_fsuid(), inode->i_uid) ||
+	    (!in_group_p(attr->ia_gid) && !gid_eq(attr->ia_gid, inode->i_gid))) &&
+	    !capable_wrt_inode_uidgid(inode, CAP_CHOWN))
+		return -EPERM;
 
 	/* Make sure a caller can chmod. */
 	if (ia_valid & ATTR_MODE) {
-		if (!is_owner_or_cap(inode))
-			goto error;
+		if (!inode_owner_or_capable(inode))
+			return -EPERM;
 		/* Also check the setgid bit! */
 		if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid :
-				inode->i_gid) && !capable(CAP_FSETID))
+				inode->i_gid) &&
+		    !capable_wrt_inode_uidgid(inode, CAP_FSETID))
 			attr->ia_mode &= ~S_ISGID;
 	}
 
 	/* Check for setting the inode time. */
 	if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) {
-		if (!is_owner_or_cap(inode))
-			goto error;
+		if (!inode_owner_or_capable(inode))
+			return -EPERM;
 	}
-fine:
-	retval = 0;
-error:
-	return retval;
+
+	return 0;
 }
 EXPORT_SYMBOL(inode_change_ok);
 
@@ -68,21 +87,21 @@ EXPORT_SYMBOL(inode_change_ok);
  * @offset:	the new size to assign to the inode
  * @Returns:	0 on success, -ve errno on failure
  *
+ * inode_newsize_ok must be called with i_mutex held.
+ *
  * 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
  * when necessary. Caller must not proceed with inode size change if failure is
  * returned. @inode must be a file (not directory), with appropriate
  * permissions to allow truncate (inode_newsize_ok does NOT check these
  * conditions).
- *
- * inode_newsize_ok must be called with i_mutex held.
  */
 int inode_newsize_ok(const struct inode *inode, loff_t offset)
 {
 	if (inode->i_size < offset) {
 		unsigned long limit;
 
-		limit = current->signal->rlim[RLIMIT_FSIZE].rlim_cur;
+		limit = rlimit(RLIMIT_FSIZE);
 		if (limit != RLIM_INFINITY && offset > limit)
 			goto out_sig;
 		if (offset > inode->i_sb->s_maxbytes)
@@ -105,17 +124,25 @@ out_big:
 }
 EXPORT_SYMBOL(inode_newsize_ok);
 
-int inode_setattr(struct inode * inode, struct iattr * attr)
+/**
+ * setattr_copy - copy simple metadata updates into the generic inode
+ * @inode:	the inode to be updated
+ * @attr:	the new attributes
+ *
+ * setattr_copy must be called with i_mutex held.
+ *
+ * setattr_copy updates the inode's metadata with that specified
+ * in attr. Noticeably missing is inode size update, which is more complex
+ * as it requires pagecache updates.
+ *
+ * The inode is not marked as dirty after this operation. The rationale is
+ * that for "simple" filesystems, the struct inode is the inode storage.
+ * The caller is free to mark the inode dirty afterwards if needed.
+ */
+void setattr_copy(struct inode *inode, const struct iattr *attr)
 {
 	unsigned int ia_valid = attr->ia_valid;
 
-	if (ia_valid & ATTR_SIZE &&
-	    attr->ia_size != i_size_read(inode)) {
-		int error = vmtruncate(inode, attr->ia_size);
-		if (error)
-			return error;
-	}
-
 	if (ia_valid & ATTR_UID)
 		inode->i_uid = attr->ia_uid;
 	if (ia_valid & ATTR_GID)
@@ -132,29 +159,56 @@ int inode_setattr(struct inode * inode, struct iattr * attr)
 	if (ia_valid & ATTR_MODE) {
 		umode_t mode = attr->ia_mode;
 
-		if (!in_group_p(inode->i_gid) && !capable(CAP_FSETID))
+		if (!in_group_p(inode->i_gid) &&
+		    !capable_wrt_inode_uidgid(inode, CAP_FSETID))
 			mode &= ~S_ISGID;
 		inode->i_mode = mode;
 	}
-	mark_inode_dirty(inode);
-
-	return 0;
 }
-EXPORT_SYMBOL(inode_setattr);
+EXPORT_SYMBOL(setattr_copy);
 
-int notify_change(struct dentry * dentry, struct iattr * attr)
+/**
+ * notify_change - modify attributes of a filesytem object
+ * @dentry:	object affected
+ * @iattr:	new attributes
+ * @delegated_inode: returns inode, if the inode is delegated
+ *
+ * The caller must hold the i_mutex 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.
+ *
+ * Alternatively, a caller may pass NULL for delegated_inode.  This may
+ * be appropriate for callers that expect the underlying filesystem not
+ * to be NFS exported.  Also, passing NULL is fine for callers holding
+ * the file open for write, as there can be no conflicting delegation in
+ * that case.
+ */
+int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **delegated_inode)
 {
 	struct inode *inode = dentry->d_inode;
-	mode_t mode = inode->i_mode;
+	umode_t mode = inode->i_mode;
 	int error;
 	struct timespec now;
 	unsigned int ia_valid = attr->ia_valid;
 
+	WARN_ON_ONCE(!mutex_is_locked(&inode->i_mutex));
+
 	if (ia_valid & (ATTR_MODE | ATTR_UID | ATTR_GID | ATTR_TIMES_SET)) {
 		if (IS_IMMUTABLE(inode) || IS_APPEND(inode))
 			return -EPERM;
 	}
 
+	if ((ia_valid & ATTR_MODE)) {
+		umode_t amode = attr->ia_mode;
+		/* Flag setting protected by i_mutex */
+		if (is_sxid(amode))
+			inode->i_flags &= ~S_NOSEC;
+	}
+
 	now = current_fs_time(inode->i_sb);
 
 	attr->ia_ctime = now;
@@ -204,31 +258,21 @@ int notify_change(struct dentry * dentry, struct iattr * attr)
 	error = security_inode_setattr(dentry, attr);
 	if (error)
 		return error;
+	error = try_break_deleg(inode, delegated_inode);
+	if (error)
+		return error;
 
-	if (ia_valid & ATTR_SIZE)
-		down_write(&dentry->d_inode->i_alloc_sem);
-
-	if (inode->i_op && inode->i_op->setattr) {
+	if (inode->i_op->setattr)
 		error = inode->i_op->setattr(dentry, attr);
-	} else {
-		error = inode_change_ok(inode, attr);
-		if (!error) {
-			if ((ia_valid & ATTR_UID && attr->ia_uid != inode->i_uid) ||
-			    (ia_valid & ATTR_GID && attr->ia_gid != inode->i_gid))
-				error = vfs_dq_transfer(inode, attr) ?
-					-EDQUOT : 0;
-			if (!error)
-				error = inode_setattr(inode, attr);
-		}
-	}
+	else
+		error = simple_setattr(dentry, attr);
 
-	if (ia_valid & ATTR_SIZE)
-		up_write(&dentry->d_inode->i_alloc_sem);
-
-	if (!error)
+	if (!error) {
 		fsnotify_change(dentry, ia_valid);
+		ima_inode_post_setattr(dentry);
+		evm_inode_post_setattr(dentry, ia_valid);
+	}
 
 	return error;
 }
-
 EXPORT_SYMBOL(notify_change);