From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: [PATCH 4/5] fs: Call security_ops->inode_killpriv on truncate Date: Thu, 18 Dec 2014 13:49:05 +0100 Message-ID: <1418906946-30695-5-git-send-email-jack@suse.cz> References: <1418906946-30695-1-git-send-email-jack@suse.cz> Cc: linux-fsdevel@vger.kernel.org, xfs@oss.sgi.com, linux-security-module@vger.kernel.org, Jan Kara To: Al Viro Return-path: Received: from cantor2.suse.de ([195.135.220.15]:38263 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752438AbaLRMtV (ORCPT ); Thu, 18 Dec 2014 07:49:21 -0500 In-Reply-To: <1418906946-30695-1-git-send-email-jack@suse.cz> Sender: linux-fsdevel-owner@vger.kernel.org List-ID: Comment in include/linux/security.h says that ->inode_killpriv() should be call when setuid bit is being removed and that similar security labels should be removed at this time as well. However we don't call ->inode_killpriv() when we remove suid bit on truncate. We fix the problem by calling ->inode_need_killpriv() and subsequently ->inode_killpriv() on truncate the same way as we do it on file write. After this patch there's only one user of should_remove_suid() - ocfs2 - and indeed it's buggy because it doesn't clear security attributes on write. However fixing it is difficult because of special locking constraints. Signed-off-by: Jan Kara --- fs/inode.c | 5 ++--- fs/open.c | 6 ++++-- include/linux/fs.h | 6 +++++- 3 files changed, 11 insertions(+), 6 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index 77942fac4121..b5211a541437 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1603,9 +1603,8 @@ EXPORT_SYMBOL(should_remove_suid); * response to write or truncate. Return 0 if nothing has to be changed. * Negative value on error (change should be denied). */ -int file_needs_remove_privs(struct file *file) +int dentry_needs_remove_privs(struct dentry *dentry) { - struct dentry *dentry = file->f_path.dentry; struct inode *inode = dentry->d_inode; int mask = 0; int ret; @@ -1621,7 +1620,7 @@ int file_needs_remove_privs(struct file *file) mask |= ATTR_KILL_PRIV; return mask; } -EXPORT_SYMBOL(file_needs_remove_privs); +EXPORT_SYMBOL(dentry_needs_remove_privs); static int __remove_privs(struct dentry *dentry, int kill) { diff --git a/fs/open.c b/fs/open.c index de92c13b58be..e4e0863855d0 100644 --- a/fs/open.c +++ b/fs/open.c @@ -51,8 +51,10 @@ int do_truncate(struct dentry *dentry, loff_t length, unsigned int time_attrs, newattrs.ia_valid |= ATTR_FILE; } - /* Remove suid/sgid on truncate too */ - ret = should_remove_suid(dentry); + /* Remove suid/sgid and security markings on truncate too */ + ret = dentry_needs_remove_privs(dentry); + if (ret < 0) + return ret; if (ret) newattrs.ia_valid |= ret | ATTR_FORCE; diff --git a/include/linux/fs.h b/include/linux/fs.h index aac707cced66..c5ccc311e8fb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2429,7 +2429,11 @@ extern struct inode *new_inode(struct super_block *sb); extern void free_inode_nonrcu(struct inode *inode); extern int should_remove_suid(struct dentry *); extern int file_remove_privs(struct file *); -extern int file_needs_remove_privs(struct file *file); +extern int dentry_needs_remove_privs(struct dentry *dentry); +static inline int file_needs_remove_privs(struct file *file) +{ + return dentry_needs_remove_privs(file->f_path.dentry); +} extern void __insert_inode_hash(struct inode *, unsigned long hashval); static inline void insert_inode_hash(struct inode *inode) -- 1.8.4.5