From b3b4283f7e46f563b438e587a0a567118a45a3fd Mon Sep 17 00:00:00 2001 From: Miklos Szeredi Date: Fri, 16 Sep 2016 12:44:20 +0200 Subject: vfs: move permission checking into notify_change() for utimes(NULL) commit f2b20f6ee842313a0d681dbbf7f87b70291a6a3b upstream. This fixes a bug where the permission was not properly checked in overlayfs. The testcase is ltp/utimensat01. It is also cleaner and safer to do the permission checking in the vfs helper instead of the caller. This patch introduces an additional ia_valid flag ATTR_TOUCH (since touch(1) is the most obvious user of utimes(NULL)) that is passed into notify_change whenever the conditions for this special permission checking mode are met. Reported-by: Aihua Zhang Signed-off-by: Miklos Szeredi Tested-by: Aihua Zhang Signed-off-by: Greg Kroah-Hartman --- fs/attr.c | 15 +++++++++++++++ fs/utimes.c | 16 +--------------- 2 files changed, 16 insertions(+), 15 deletions(-) (limited to 'fs') diff --git a/fs/attr.c b/fs/attr.c index 6530ced19697..d62f674a605f 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -202,6 +202,21 @@ int notify_change(struct dentry * dentry, struct iattr * attr, struct inode **de return -EPERM; } + /* + * If utimes(2) and friends are called with times == NULL (or both + * times are UTIME_NOW), then we need to check for write permission + */ + if (ia_valid & ATTR_TOUCH) { + if (IS_IMMUTABLE(inode)) + return -EPERM; + + if (!inode_owner_or_capable(inode)) { + error = inode_permission(inode, MAY_WRITE); + if (error) + return error; + } + } + if ((ia_valid & ATTR_MODE)) { umode_t amode = attr->ia_mode; /* Flag setting protected by i_mutex */ diff --git a/fs/utimes.c b/fs/utimes.c index aa138d64560a..cb771c30d102 100644 --- a/fs/utimes.c +++ b/fs/utimes.c @@ -87,20 +87,7 @@ static int utimes_common(struct path *path, struct timespec *times) */ newattrs.ia_valid |= ATTR_TIMES_SET; } else { - /* - * If times is NULL (or both times are UTIME_NOW), - * then we need to check permissions, because - * inode_change_ok() won't do it. - */ - error = -EACCES; - if (IS_IMMUTABLE(inode)) - goto mnt_drop_write_and_out; - - if (!inode_owner_or_capable(inode)) { - error = inode_permission(inode, MAY_WRITE); - if (error) - goto mnt_drop_write_and_out; - } + newattrs.ia_valid |= ATTR_TOUCH; } retry_deleg: mutex_lock(&inode->i_mutex); @@ -112,7 +99,6 @@ retry_deleg: goto retry_deleg; } -mnt_drop_write_and_out: mnt_drop_write(path->mnt); out: return error; -- cgit v1.2.3