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authorAlexey Gladkov <gladkov.alexey@gmail.com>2020-04-19 16:10:53 +0200
committerEric W. Biederman <ebiederm@xmission.com>2020-04-22 10:51:21 -0500
commit24a71ce5c47f6b1b3cdacf544cb24220f5c3b7ef (patch)
treeda93b7bfc767c3fad21663b6c1aab72e2e9ffec8 /fs/proc/base.c
parentfa10fed30f2550313a8284365b3e2398526eb42c (diff)
downloadlinux-24a71ce5c47f6b1b3cdacf544cb24220f5c3b7ef.tar.bz2
proc: instantiate only pids that we can ptrace on 'hidepid=4' mount option
If "hidepid=4" mount option is set then do not instantiate pids that we can not ptrace. "hidepid=4" means that procfs should only contain pids that the caller can ptrace. Signed-off-by: Djalal Harouni <tixxdz@gmail.com> Signed-off-by: Alexey Gladkov <gladkov.alexey@gmail.com> Reviewed-by: Alexey Dobriyan <adobriyan@gmail.com> Reviewed-by: Kees Cook <keescook@chromium.org> Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Diffstat (limited to 'fs/proc/base.c')
-rw-r--r--fs/proc/base.c15
1 files changed, 15 insertions, 0 deletions
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 93b5d05c142c..a52a91e90c25 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
@@ -701,6 +701,14 @@ static bool has_pid_permissions(struct proc_fs_info *fs_info,
struct task_struct *task,
int hide_pid_min)
{
+ /*
+ * If 'hidpid' mount option is set force a ptrace check,
+ * we indicate that we are using a filesystem syscall
+ * by passing PTRACE_MODE_READ_FSCREDS
+ */
+ if (fs_info->hide_pid == HIDEPID_NOT_PTRACEABLE)
+ return ptrace_may_access(task, PTRACE_MODE_READ_FSCREDS);
+
if (fs_info->hide_pid < hide_pid_min)
return true;
if (in_group_p(fs_info->pid_gid))
@@ -3319,7 +3327,14 @@ struct dentry *proc_pid_lookup(struct dentry *dentry, unsigned int flags)
if (!task)
goto out;
+ /* Limit procfs to only ptraceable tasks */
+ if (fs_info->hide_pid == HIDEPID_NOT_PTRACEABLE) {
+ if (!has_pid_permissions(fs_info, task, HIDEPID_NO_ACCESS))
+ goto out_put_task;
+ }
+
result = proc_pid_instantiate(dentry, task, NULL);
+out_put_task:
put_task_struct(task);
out:
return result;