posix_acl: Clear SGID bit when setting file permissions
When file permissions are modified via chmod(2) and the user is not in the owning group or capable of CAP_FSETID, the setgid bit is cleared in inode_change_ok(). Setting a POSIX ACL via setxattr(2) sets the file permissions as well as the new ACL, but doesn't clear the setgid bit in a similar way; this allows to bypass the check in chmod(2). Fix that. References: CVE-2016-7097 Reviewed-by: Christoph Hellwig <hch@lst.de> Reviewed-by: Jeff Layton <jlayton@redhat.com> Signed-off-by: Jan Kara <jack@suse.cz> Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
This commit is contained in:
Родитель
5d3ddd84ea
Коммит
073931017b
40
fs/9p/acl.c
40
fs/9p/acl.c
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@ -276,32 +276,26 @@ static int v9fs_xattr_set_acl(const struct xattr_handler *handler,
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switch (handler->flags) {
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case ACL_TYPE_ACCESS:
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if (acl) {
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umode_t mode = inode->i_mode;
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retval = posix_acl_equiv_mode(acl, &mode);
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if (retval < 0)
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struct iattr iattr;
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retval = posix_acl_update_mode(inode, &iattr.ia_mode, &acl);
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if (retval)
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goto err_out;
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else {
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struct iattr iattr;
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if (retval == 0) {
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/*
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* ACL can be represented
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* by the mode bits. So don't
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* update ACL.
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*/
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acl = NULL;
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value = NULL;
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size = 0;
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}
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/* Updte the mode bits */
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iattr.ia_mode = ((mode & S_IALLUGO) |
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(inode->i_mode & ~S_IALLUGO));
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iattr.ia_valid = ATTR_MODE;
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/* FIXME should we update ctime ?
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* What is the following setxattr update the
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* mode ?
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if (!acl) {
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/*
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* ACL can be represented
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* by the mode bits. So don't
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* update ACL.
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*/
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v9fs_vfs_setattr_dotl(dentry, &iattr);
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value = NULL;
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size = 0;
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}
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iattr.ia_valid = ATTR_MODE;
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/* FIXME should we update ctime ?
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* What is the following setxattr update the
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* mode ?
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*/
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v9fs_vfs_setattr_dotl(dentry, &iattr);
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}
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break;
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case ACL_TYPE_DEFAULT:
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@ -79,11 +79,9 @@ static int __btrfs_set_acl(struct btrfs_trans_handle *trans,
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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ret = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (ret < 0)
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ret = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (ret)
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return ret;
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if (ret == 0)
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acl = NULL;
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}
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ret = 0;
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break;
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@ -95,11 +95,9 @@ int ceph_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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ret = posix_acl_equiv_mode(acl, &new_mode);
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if (ret < 0)
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ret = posix_acl_update_mode(inode, &new_mode, &acl);
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if (ret)
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goto out;
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if (ret == 0)
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acl = NULL;
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}
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break;
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case ACL_TYPE_DEFAULT:
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@ -190,15 +190,11 @@ ext2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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case ACL_TYPE_ACCESS:
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name_index = EXT2_XATTR_INDEX_POSIX_ACL_ACCESS;
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if (acl) {
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error = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (error < 0)
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error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (error)
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return error;
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else {
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inode->i_ctime = CURRENT_TIME_SEC;
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mark_inode_dirty(inode);
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if (error == 0)
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acl = NULL;
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}
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inode->i_ctime = CURRENT_TIME_SEC;
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mark_inode_dirty(inode);
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}
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break;
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@ -193,15 +193,11 @@ __ext4_set_acl(handle_t *handle, struct inode *inode, int type,
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case ACL_TYPE_ACCESS:
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name_index = EXT4_XATTR_INDEX_POSIX_ACL_ACCESS;
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if (acl) {
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error = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (error < 0)
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error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (error)
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return error;
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else {
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inode->i_ctime = ext4_current_time(inode);
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ext4_mark_inode_dirty(handle, inode);
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if (error == 0)
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acl = NULL;
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}
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inode->i_ctime = ext4_current_time(inode);
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ext4_mark_inode_dirty(handle, inode);
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}
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break;
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@ -210,12 +210,10 @@ static int __f2fs_set_acl(struct inode *inode, int type,
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case ACL_TYPE_ACCESS:
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name_index = F2FS_XATTR_INDEX_POSIX_ACL_ACCESS;
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if (acl) {
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error = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (error < 0)
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error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (error)
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return error;
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set_acl_inode(inode, inode->i_mode);
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if (error == 0)
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acl = NULL;
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}
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break;
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@ -92,17 +92,11 @@ int __gfs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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if (type == ACL_TYPE_ACCESS) {
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umode_t mode = inode->i_mode;
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error = posix_acl_equiv_mode(acl, &mode);
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if (error < 0)
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error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (error)
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return error;
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if (error == 0)
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acl = NULL;
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if (mode != inode->i_mode) {
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inode->i_mode = mode;
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if (mode != inode->i_mode)
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mark_inode_dirty(inode);
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}
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}
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if (acl) {
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@ -65,8 +65,8 @@ int hfsplus_set_posix_acl(struct inode *inode, struct posix_acl *acl,
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case ACL_TYPE_ACCESS:
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xattr_name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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err = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (err < 0)
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err = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (err)
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return err;
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}
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err = 0;
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@ -233,9 +233,10 @@ int jffs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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case ACL_TYPE_ACCESS:
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xprefix = JFFS2_XPREFIX_ACL_ACCESS;
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if (acl) {
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umode_t mode = inode->i_mode;
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rc = posix_acl_equiv_mode(acl, &mode);
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if (rc < 0)
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umode_t mode;
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rc = posix_acl_update_mode(inode, &mode, &acl);
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if (rc)
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return rc;
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if (inode->i_mode != mode) {
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struct iattr attr;
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@ -247,8 +248,6 @@ int jffs2_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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if (rc < 0)
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return rc;
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}
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if (rc == 0)
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acl = NULL;
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}
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break;
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case ACL_TYPE_DEFAULT:
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@ -78,13 +78,11 @@ static int __jfs_set_acl(tid_t tid, struct inode *inode, int type,
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case ACL_TYPE_ACCESS:
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ea_name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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rc = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (rc < 0)
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rc = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (rc)
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return rc;
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inode->i_ctime = CURRENT_TIME;
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mark_inode_dirty(inode);
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if (rc == 0)
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acl = NULL;
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}
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break;
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case ACL_TYPE_DEFAULT:
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@ -241,13 +241,11 @@ int ocfs2_set_acl(handle_t *handle,
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case ACL_TYPE_ACCESS:
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name_index = OCFS2_XATTR_INDEX_POSIX_ACL_ACCESS;
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if (acl) {
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umode_t mode = inode->i_mode;
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ret = posix_acl_equiv_mode(acl, &mode);
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if (ret < 0)
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return ret;
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umode_t mode;
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if (ret == 0)
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acl = NULL;
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ret = posix_acl_update_mode(inode, &mode, &acl);
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if (ret)
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return ret;
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ret = ocfs2_acl_set_mode(inode, di_bh,
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handle, mode);
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@ -73,14 +73,11 @@ int orangefs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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umode_t mode = inode->i_mode;
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/*
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* can we represent this with the traditional file
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* mode permission bits?
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*/
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error = posix_acl_equiv_mode(acl, &mode);
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if (error < 0) {
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gossip_err("%s: posix_acl_equiv_mode err: %d\n",
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umode_t mode;
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error = posix_acl_update_mode(inode, &mode, &acl);
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if (error) {
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gossip_err("%s: posix_acl_update_mode err: %d\n",
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__func__,
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error);
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return error;
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@ -90,8 +87,6 @@ int orangefs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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SetModeFlag(orangefs_inode);
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inode->i_mode = mode;
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mark_inode_dirty_sync(inode);
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if (error == 0)
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acl = NULL;
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}
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break;
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case ACL_TYPE_DEFAULT:
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@ -626,6 +626,37 @@ no_mem:
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}
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EXPORT_SYMBOL_GPL(posix_acl_create);
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/**
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* posix_acl_update_mode - update mode in set_acl
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*
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* Update the file mode when setting an ACL: compute the new file permission
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* bits based on the ACL. In addition, if the ACL is equivalent to the new
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* file mode, set *acl to NULL to indicate that no ACL should be set.
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*
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* As with chmod, clear the setgit bit if the caller is not in the owning group
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* or capable of CAP_FSETID (see inode_change_ok).
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*
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* Called from set_acl inode operations.
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*/
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int posix_acl_update_mode(struct inode *inode, umode_t *mode_p,
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struct posix_acl **acl)
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{
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umode_t mode = inode->i_mode;
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int error;
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error = posix_acl_equiv_mode(*acl, &mode);
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if (error < 0)
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return error;
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if (error == 0)
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*acl = NULL;
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if (!in_group_p(inode->i_gid) &&
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!capable_wrt_inode_uidgid(inode, CAP_FSETID))
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mode &= ~S_ISGID;
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*mode_p = mode;
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return 0;
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}
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EXPORT_SYMBOL(posix_acl_update_mode);
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/*
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* Fix up the uids and gids in posix acl extended attributes in place.
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*/
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@ -242,13 +242,9 @@ __reiserfs_set_acl(struct reiserfs_transaction_handle *th, struct inode *inode,
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case ACL_TYPE_ACCESS:
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name = XATTR_NAME_POSIX_ACL_ACCESS;
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if (acl) {
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error = posix_acl_equiv_mode(acl, &inode->i_mode);
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if (error < 0)
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error = posix_acl_update_mode(inode, &inode->i_mode, &acl);
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if (error)
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return error;
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else {
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if (error == 0)
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acl = NULL;
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}
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}
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break;
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case ACL_TYPE_DEFAULT:
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@ -257,16 +257,11 @@ xfs_set_acl(struct inode *inode, struct posix_acl *acl, int type)
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return error;
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if (type == ACL_TYPE_ACCESS) {
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umode_t mode = inode->i_mode;
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error = posix_acl_equiv_mode(acl, &mode);
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if (error <= 0) {
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acl = NULL;
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if (error < 0)
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return error;
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}
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umode_t mode;
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error = posix_acl_update_mode(inode, &mode, &acl);
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if (error)
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return error;
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error = xfs_set_mode(inode, mode);
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if (error)
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return error;
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@ -93,6 +93,7 @@ extern int set_posix_acl(struct inode *, int, struct posix_acl *);
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extern int posix_acl_chmod(struct inode *, umode_t);
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extern int posix_acl_create(struct inode *, umode_t *, struct posix_acl **,
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struct posix_acl **);
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extern int posix_acl_update_mode(struct inode *, umode_t *, struct posix_acl **);
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extern int simple_set_acl(struct inode *, struct posix_acl *, int);
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extern int simple_acl_create(struct inode *, struct inode *);
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