From: "Aneesh Kumar K.V" Subject: [PATCH -V4 11/11] vfs: Add permission flags for setting file attributes Date: Fri, 24 Sep 2010 18:18:14 +0530 Message-ID: <1285332494-12756-12-git-send-email-aneesh.kumar@linux.vnet.ibm.com> References: <1285332494-12756-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Cc: aneesh.kumar@linux.vnet.ibm.com, linux-fsdevel@vger.kernel.org, nfsv4@linux-nfs.org, linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org To: sfrench@us.ibm.com, ffilz@us.ibm.com, agruen@suse.de, adilger@sun.com, sandeen@redhat.com, tytso@mit.edu, bfields@citi.umich.edu, jlayton@redhat.com Return-path: Received: from e28smtp06.in.ibm.com ([122.248.162.6]:42585 "EHLO e28smtp06.in.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932170Ab0IXMtK (ORCPT ); Fri, 24 Sep 2010 08:49:10 -0400 In-Reply-To: <1285332494-12756-1-git-send-email-aneesh.kumar@linux.vnet.ibm.com> Sender: linux-ext4-owner@vger.kernel.org List-ID: From: Andreas Gruenbacher Some permission models can allow processes to take ownership of a file, change the file permissions, and set the file timestamps. Introduce new permission mask flags and check for those permissions in inode_change_ok(). Signed-off-by: Andreas Gruenbacher Signed-off-by: Aneesh Kumar K.V --- fs/attr.c | 49 ++++++++++++++++++++++++++++++++++++++----------- include/linux/fs.h | 3 +++ 2 files changed, 41 insertions(+), 11 deletions(-) diff --git a/fs/attr.c b/fs/attr.c index f081b5a..00f971a 100644 --- a/fs/attr.c +++ b/fs/attr.c @@ -13,6 +13,20 @@ #include #include #include +#include + +static int richacl_change_ok(struct inode *inode, int mask) +{ + if (!IS_RICHACL(inode)) + return -EPERM; + + if (inode->i_op->permission) + return inode->i_op->permission(inode, mask); + else if (inode->i_op->check_acl) + return inode->i_op->check_acl(inode, mask); + else + return -EPERM; +} /** * inode_change_ok - check if attribute changes to an inode are allowed @@ -47,20 +61,29 @@ int inode_change_ok(struct inode *inode, struct iattr *attr) /* 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)) - return -EPERM; + attr->ia_uid != inode->i_uid) && + (current_fsuid() != attr->ia_uid || + richacl_change_ok(inode, MAY_TAKE_OWNERSHIP)) && + !capable(CAP_CHOWN)) + goto error; /* 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)) - return -EPERM; + if (ia_valid & ATTR_GID) { + int in_group = in_group_p(attr->ia_gid); + if ((current_fsuid() != inode->i_uid || + (!in_group && attr->ia_gid != inode->i_gid)) && + (!in_group || + richacl_change_ok(inode, MAY_TAKE_OWNERSHIP)) && + !capable(CAP_CHOWN)) + goto error; + } /* Make sure a caller can chmod. */ if (ia_valid & ATTR_MODE) { - if (!is_owner_or_cap(inode)) - return -EPERM; + if (current_fsuid() != inode->i_uid && + richacl_change_ok(inode, MAY_CHMOD) && + !capable(CAP_FOWNER)) + goto error; /* Also check the setgid bit! */ if (!in_group_p((ia_valid & ATTR_GID) ? attr->ia_gid : inode->i_gid) && !capable(CAP_FSETID)) @@ -69,11 +92,15 @@ int inode_change_ok(struct inode *inode, struct iattr *attr) /* Check for setting the inode time. */ if (ia_valid & (ATTR_MTIME_SET | ATTR_ATIME_SET | ATTR_TIMES_SET)) { - if (!is_owner_or_cap(inode)) - return -EPERM; + if (current_fsuid() != inode->i_uid && + richacl_change_ok(inode, MAY_SET_TIMES) && + !capable(CAP_FOWNER)) + goto error; } return 0; +error: + return -EPERM; } EXPORT_SYMBOL(inode_change_ok); diff --git a/include/linux/fs.h b/include/linux/fs.h index 2616d34..f08e82f 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -59,6 +59,9 @@ struct inodes_stat_t { #define MAY_CREATE_DIR 256 #define MAY_DELETE_CHILD 512 #define MAY_DELETE_SELF 1024 +#define MAY_TAKE_OWNERSHIP 2048 +#define MAY_CHMOD 4096 +#define MAY_SET_TIMES 8192 /* * flags in file.f_mode. Note that FMODE_READ and FMODE_WRITE must correspond -- 1.7.0.4