Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751737AbbHUFOy (ORCPT ); Fri, 21 Aug 2015 01:14:54 -0400 Received: from mail-ob0-f181.google.com ([209.85.214.181]:34514 "EHLO mail-ob0-f181.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751058AbbHUFOw (ORCPT ); Fri, 21 Aug 2015 01:14:52 -0400 MIME-Version: 1.0 X-Originating-IP: [70.96.146.23] In-Reply-To: <1437732285-11524-3-git-send-email-l.pawelczyk@samsung.com> References: <1437732285-11524-1-git-send-email-l.pawelczyk@samsung.com> <1437732285-11524-3-git-send-email-l.pawelczyk@samsung.com> Date: Fri, 21 Aug 2015 01:14:51 -0400 Message-ID: Subject: Re: [PATCH v3 02/11] lsm: /proc/$PID/attr/label_map file and getprocattr_seq hook From: Paul Moore To: Lukasz Pawelczyk Cc: "Eric W. Biederman" , "Serge E. Hallyn" , Al Viro , Alexey Dobriyan , Andrew Morton , Andy Lutomirski , Arnd Bergmann , Casey Schaufler , David Howells , Eric Dumazet , Eric Paris , Fabian Frederick , Greg KH , James Morris , Jiri Slaby , Joe Perches , John Johansen , Jonathan Corbet , Kees Cook , Mauro Carvalho Chehab , NeilBrown , Oleg Nesterov , Stephen Smalley , Tetsuo Handa , Zefan Li , linux-doc@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-security-module@vger.kernel.org, selinux@tycho.nsa.gov, havner@gmail.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3570 Lines: 117 On Fri, Jul 24, 2015 at 6:04 AM, Lukasz Pawelczyk wrote: > This commit adds a new proc attribute, label_map that is required by an > upcoming Smack namespace. In general it can be used to hold a map of > labels, e.g. to be used in namespaces. > > Due to the nature of this file, the standard getprocattr hook might not > be enough to handle it. The map's output can in principle be greater > than page size to which the aforementioned hook is limited. > To handle this properly a getprocattr_seq LSM hook has been added that > makes it possible to handle any chosen proc attr by seq operations. > > See the documentation in the patch below for the details about how to > use the hook. > > Signed-off-by: Lukasz Pawelczyk > --- > fs/proc/base.c | 81 +++++++++++++++++++++++++++++++++++++++++++---- > include/linux/lsm_hooks.h | 15 +++++++++ > include/linux/security.h | 9 ++++++ > security/security.c | 8 +++++ > 4 files changed, 107 insertions(+), 6 deletions(-) > > diff --git a/fs/proc/base.c b/fs/proc/base.c > index aa50d1a..e5ac827 100644 > --- a/fs/proc/base.c > +++ b/fs/proc/base.c > @@ -2338,20 +2338,77 @@ out: > } > > #ifdef CONFIG_SECURITY > +static int proc_pid_attr_open(struct inode *inode, struct file *file) > +{ > + const char *name = file->f_path.dentry->d_name.name; > + const struct seq_operations *ops; > + struct task_struct *task; > + struct seq_file *seq; > + int ret; > + > + file->private_data = NULL; > + > + task = get_proc_task(inode); > + if (!task) > + return -ESRCH; > + > + /* don't use seq_ops if they are not provided by LSM */ > + ret = security_getprocattr_seq(task, name, &ops); > + if (ret == -EOPNOTSUPP) { > + put_task_struct(task); > + return 0; > + } > + if (ret) { > + put_task_struct(task); > + return ret; > + } > + > + ret = seq_open(file, ops); > + if (ret) { > + put_task_struct(task); > + return ret; > + } > + > + seq = file->private_data; > + seq->private = task; > + > + return 0; > +} If you end up having to respin this patchset, you might consider moving the "put_task_struct(...); return X;" code into a block at the end of the function to simplify things a bit, for example: static int proc_pid_attr_open(struct inode *inode, struct file *file) { const char *name = file->f_path.dentry->d_name.name; const struct seq_operations *ops; struct task_struct *task; struct seq_file *seq; int ret; file->private_data = NULL; task = get_proc_task(inode); if (!task) return -ESRCH; /* don't use seq_ops if they are not provided by LSM */ ret = security_getprocattr_seq(task, name, &ops); if (ret == -EOPNOTSUPP) { ret = 0; goto put_task; } if (ret) goto put_task; ret = seq_open(file, ops); if (ret) goto put_task; seq = file->private_data; seq->private = task; return 0; put_task: put_task_struct(task); return ret; } -- paul moore www.paul-moore.com -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/