From: Djalal Harouni <tixxdz@xxxxxxxxx>
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 <keescook@xxxxxxxxxxxx>
Cc: Andy Lutomirski <luto@xxxxxxxxxx>
Signed-off-by: Djalal Harouni <tixxdz@xxxxxxxxx>
---
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
