Tetsuo Handa <penguin-kernel@xxxxxxxxxxxxxxxxxxx> writes:
> This is
>
> if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
> char *ep;
> const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
> struct pid_namespace *proc_pidns = proc_pid_ns(d_inode(dentry)); // <= here
>
> if (*ep == '/' && pid && pid ==
> task_tgid_nr_ns(current, proc_pidns)) {
>
> which was added by commit c59f415a7cb6e1e1 ("Use proc_pid_ns() to get pid_namespace from the proc superblock").
>
> @@ -161,9 +162,10 @@ static char *tomoyo_get_local_path(struct dentry *dentry, char * const buffer,
> if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
> char *ep;
> const pid_t pid = (pid_t) simple_strtoul(pos + 1, &ep, 10);
> + struct pid_namespace *proc_pidns = proc_pid_ns(d_inode(dentry));
>
> if (*ep == '/' && pid && pid ==
> - task_tgid_nr_ns(current, sb->s_fs_info)) {
> + task_tgid_nr_ns(current, proc_pidns)) {
> pos = ep - 5;
> if (pos < buffer)
> goto out;
>
> Alexey and Eric, any clue?
Looking at the stack backtrace this is happening as part of creating a
file or a device node. The dentry that is passed in most likely
comes from d_alloc_parallel. So we have d_inode == NULL.
I want to suggest doing the very simple fix:
- if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/') {
+ if (sb->s_magic == PROC_SUPER_MAGIC && *pos == '/' && denty->d_inode) {
But I don't know if there are any other security hooks early in lookup,
that could be called for an already existing dentry.
So it looks like we need a version proc_pid_ns that works for a dentry,
or a superblock.
Alex do you think you can code up an patch against my proc-next branch
to fix this?
Eric
