From: Djalal Harouni <[email protected]>
If "limit_pids=1" mount option is set then do not instantiate pids that
we can not ptrace. "limit_pids=1" means that procfs should only contain
pids that the caller can ptrace.
Cc: Kees Cook <[email protected]>
Cc: Andy Lutomirski <[email protected]>
Signed-off-by: Djalal Harouni <[email protected]>
---
fs/proc/base.c | 9 +++++++++
1 file changed, 9 insertions(+)
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 6f084344..31baeef 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -3187,6 +3187,7 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign
unsigned tgid;
struct proc_fs_info *fs_info = proc_sb(dir->i_sb);
struct pid_namespace *ns = fs_info->pid_ns;
+ int limit_pids = proc_fs_limit_pids(fs_info);
tgid = name_to_int(&dentry->d_name);
if (tgid == ~0U)
@@ -3200,7 +3201,15 @@ struct dentry *proc_pid_lookup(struct inode *dir, struct dentry * dentry, unsign
if (!task)
goto out;
+ /* Limit procfs to only ptracable tasks */
+ if (limit_pids == PROC_LIMIT_PIDS_PTRACE) {
+ cond_resched();
+ if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS))
+ goto out_put_task;
+ }
+
result = proc_pid_instantiate(dir, dentry, task, NULL);
+out_put_task:
put_task_struct(task);
out:
return ERR_PTR(result);
--
2.10.5
On 05/11/2018 02:36 AM, Alexey Gladkov wrote:
> From: Djalal Harouni <[email protected]>
>
> If "limit_pids=1" mount option is set then do not instantiate pids that
> we can not ptrace. "limit_pids=1" means that procfs should only contain
> pids that the caller can ptrace.
Where can I find documentation on these mount options (pidonly, limit_pids)?
Thanks.
> Cc: Kees Cook <[email protected]>
> Cc: Andy Lutomirski <[email protected]>
> Signed-off-by: Djalal Harouni <[email protected]>
> ---
> fs/proc/base.c | 9 +++++++++
> 1 file changed, 9 insertions(+)
--
~Randy
On Fri, May 11, 2018 at 2:46 AM Alexey Gladkov <[email protected]>
wrote:
> + /* Limit procfs to only ptracable tasks */
> + if (limit_pids == PROC_LIMIT_PIDS_PTRACE) {
> + cond_resched();
> + if (!has_pid_permissions(fs_info, task,
HIDEPID_NO_ACCESS))
> + goto out_put_task;
> + }
Where did that "cond_resched()" come from? That doesn't seem to make a lot
of sense.
Linus
On Fri, May 11, 2018 at 09:45:33AM -0700, Linus Torvalds wrote:
> On Fri, May 11, 2018 at 2:46 AM Alexey Gladkov <[email protected]>
> wrote:
>
> > + /* Limit procfs to only ptracable tasks */
> > + if (limit_pids == PROC_LIMIT_PIDS_PTRACE) {
> > + cond_resched();
> > + if (!has_pid_permissions(fs_info, task,
> HIDEPID_NO_ACCESS))
> > + goto out_put_task;
> > + }
>
> Where did that "cond_resched()" come from? That doesn't seem to make a lot
> of sense.
This call came along with has_pid_permissions from proc_pid_readdir [1]. It
seems to me that proc_pid_readdir and proc_pid_lookup should act in a
similar way in this case.
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=3ba4bceef23206349d4130ddf140819b365de7c8
--
Rgrds, legion
On Fri, May 11, 2018 at 09:09:04AM -0700, Randy Dunlap wrote:
> On 05/11/2018 02:36 AM, Alexey Gladkov wrote:
> > From: Djalal Harouni <[email protected]>
> >
> > If "limit_pids=1" mount option is set then do not instantiate pids that
> > we can not ptrace. "limit_pids=1" means that procfs should only contain
> > pids that the caller can ptrace.
>
> Where can I find documentation on these mount options (pidonly, limit_pids)?
The documentation is not ready yet. It will be added in the next version
of the patchset.
--
Rgrds, legion