From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jan Kara Subject: [PATCH 3/5] fs: Provide function telling whether file_remove_privs() will do anything Date: Tue, 19 May 2015 11:46:41 +0200 Message-ID: <1432028803-32296-4-git-send-email-jack@suse.cz> References: <1432028803-32296-1-git-send-email-jack@suse.cz> Cc: Linus Torvalds , linux-fsdevel@vger.kernel.org, dchinner@redhat.com, Serge Hallyn , linux-security-module@vger.kernel.org, Jan Kara To: Al Viro Return-path: In-Reply-To: <1432028803-32296-1-git-send-email-jack@suse.cz> Sender: linux-security-module-owner@vger.kernel.org List-Id: linux-fsdevel.vger.kernel.org Provide function telling whether file_remove_privs() will do anything. Currently we only have should_remove_suid() and that does something slightly different. Signed-off-by: Jan Kara --- fs/inode.c | 44 ++++++++++++++++++++++++++++++++------------ include/linux/fs.h | 1 + 2 files changed, 33 insertions(+), 12 deletions(-) diff --git a/fs/inode.c b/fs/inode.c index aa140f7bf336..547bcd7033c5 100644 --- a/fs/inode.c +++ b/fs/inode.c @@ -1660,7 +1660,32 @@ int should_remove_suid(struct dentry *dentry) } EXPORT_SYMBOL(should_remove_suid); -static int __remove_suid(struct dentry *dentry, int kill) +/* + * Return mask of changes for notify_change() that need to be done as a + * 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) +{ + struct dentry *dentry = file->f_path.dentry; + struct inode *inode = d_inode(dentry); + int mask = 0; + int ret; + + if (IS_NOSEC(inode)) + return 0; + + mask = should_remove_suid(dentry); + ret = security_inode_need_killpriv(dentry); + if (ret < 0) + return ret; + if (ret) + mask |= ATTR_KILL_PRIV; + return mask; +} +EXPORT_SYMBOL(file_needs_remove_privs); + +static int __remove_privs(struct dentry *dentry, int kill) { struct iattr newattrs; @@ -1680,23 +1705,18 @@ int file_remove_privs(struct file *file) { struct dentry *dentry = file->f_path.dentry; struct inode *inode = d_inode(dentry); - int killsuid; - int killpriv; + int kill; int error = 0; /* Fast path for nothing security related */ if (IS_NOSEC(inode)) return 0; - killsuid = should_remove_suid(dentry); - killpriv = security_inode_need_killpriv(dentry); - - if (killpriv < 0) - return killpriv; - if (killpriv) - error = security_inode_killpriv(dentry); - if (!error && killsuid) - error = __remove_suid(dentry, killsuid); + kill = file_needs_remove_privs(file); + if (kill < 0) + return kill; + if (kill) + error = __remove_privs(dentry, kill); if (!error) inode_has_no_xattr(inode); diff --git a/include/linux/fs.h b/include/linux/fs.h index 082f66274e63..a0b21f1ae7cb 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -2553,6 +2553,7 @@ 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 void __insert_inode_hash(struct inode *, unsigned long hashval); static inline void insert_inode_hash(struct inode *inode) -- 2.1.4