[PATCH] proc: reject "." and ".." as filenames

Alexey Dobriyan
2018-03-10T00:12:28Z

Various subsystems can create files and directories in /proc
with names directly controlled by userspace.

Which means "/", "." and ".." are no-no.

"/" split is already taken care of, do the other 2 prohibited names.

Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
---

fs/proc/generic.c | 8 ++++++++
1 file changed, 8 insertions(+)

--- a/fs/proc/generic.c
+++ b/fs/proc/generic.c
@@ -366,6 +366,14 @@ static struct proc_dir_entry *__proc_create(struct proc_dir_entry **parent,
WARN(1, "name len %u\n", qstr.len);
return NULL;
}
+ if (qstr.len == 1 && fn[0] == '.') {
+ WARN(1, "name '.'\n");
+ return NULL;
+ }
+ if (qstr.len == 2 && fn[0] == '.' && fn[1] == '.') {
+ WARN(1, "name '..'\n");
+ return NULL;
+ }
if (*parent == &proc_root && name_to_int(&qstr) != ~0U) {
WARN(1, "create '/proc/%s' by hand\n", qstr.name);
return NULL;