On 30.07.2020 15:18, Alexey Dobriyan wrote:
> On Thu, Jul 30, 2020 at 03:00:19PM +0300, Kirill Tkhai wrote:
>
>> # ls /proc/namespaces/ -l
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'cgroup:[4026531835]' -> 'cgroup:[4026531835]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'ipc:[4026531839]' -> 'ipc:[4026531839]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026531840]' -> 'mnt:[4026531840]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026531861]' -> 'mnt:[4026531861]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532133]' -> 'mnt:[4026532133]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532134]' -> 'mnt:[4026532134]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532135]' -> 'mnt:[4026532135]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'mnt:[4026532136]' -> 'mnt:[4026532136]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'net:[4026531993]' -> 'net:[4026531993]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'pid:[4026531836]' -> 'pid:[4026531836]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'time:[4026531834]' -> 'time:[4026531834]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'user:[4026531837]' -> 'user:[4026531837]'
>> lrwxrwxrwx 1 root root 0 Jul 29 16:50 'uts:[4026531838]' -> 'uts:[4026531838]'
>
> I'd say make it '%s-%llu'. The brackets don't carry any information.
> And ':' forces quoting with recent coreutils.
>
>> +static int parse_namespace_dentry_name(const struct dentry *dentry,
>> + const char **type, unsigned int *type_len, unsigned int *inum)
>> +{
>> + const char *p, *name;
>> + int count;
>> +
>> + *type = name = dentry->d_name.name;
>> + p = strchr(name, ':');
>> + *type_len = p - name;
>> + if (!p || p == name)
>> + return -ENOENT;
>> +
>> + p += 1;
>> + if (sscanf(p, "[%u]%n", inum, &count) != 1 || *(p + count) != '\0' ||
>> + *inum < PROC_NS_MIN_INO)
>> + return -ENOENT;
>
> sscanf is banned from lookup code due to lax whitespace rules.
> See
>
> commit ac7f1061c2c11bb8936b1b6a94cdb48de732f7a4
> proc: fix /proc/*/map_files lookup
Ok, thanks for pointing this.
> Of course someone sneaked in 1 instance, yikes.
>
> $ grep -e scanf -n -r fs/proc/
> fs/proc/base.c:1596: err = sscanf(pos, "%9s %lld %lu", clock,
>
>> +static int proc_namespaces_readdir(struct file *file, struct dir_context *ctx)
>
>> + len = snprintf(name, sizeof(name), "%s:[%u]", ns->ops->name, inum);
>
> [] -- no need.
>
