On pią, 2015-08-21 at 01:14 -0400, Paul Moore wrote:
> On Fri, Jul 24, 2015 at 6:04 AM, Lukasz Pawelczyk
> <l.pawelczyk@xxxxxxxxxxx> 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 <l.pawelczyk@xxxxxxxxxxx>
> > ---
> > 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:
I will do so, thanks.
>
> 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;
> }
>
--
Lukasz Pawelczyk
Samsung R&D Institute Poland
Samsung Electronics
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