On Fri 27-08-21 12:18:57, Suren Baghdasaryan wrote:
[...]
> Userspace can set the name for a region of memory by calling
> prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, start, len, (unsigned long)name);
> Setting the name to NULL clears it.
Maybe I am missing this part but I do not see this being handled
anywhere.
[...]
> @@ -3283,5 +3283,16 @@ static inline int seal_check_future_write(int seals, struct vm_area_struct *vma)
> return 0;
> }
>
> +#ifdef CONFIG_ADVISE_SYSCALLS
> +int madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
> + unsigned long len_in, const char *name);
> +#else
> +static inline int
> +madvise_set_anon_name(struct mm_struct *mm, unsigned long start,
> + unsigned long len_in, const char *name) {
> + return 0;
> +}
> +#endif
You want to make this depend on CONFIG_PROC_FS.
[...]
> +#ifdef CONFIG_MMU
> +
> +#define ANON_VMA_NAME_MAX_LEN 64
> +
> +static int prctl_set_vma(unsigned long opt, unsigned long addr,
> + unsigned long size, unsigned long arg)
> +{
> + struct mm_struct *mm = current->mm;
> + char *name, *pch;
> + int error;
> +
> + switch (opt) {
> + case PR_SET_VMA_ANON_NAME:
> + name = strndup_user((const char __user *)arg,
> + ANON_VMA_NAME_MAX_LEN);
> +
> + if (IS_ERR(name))
> + return PTR_ERR(name);
unless I am missing something NULL name would lead to an error rather
than a name clearing as advertised above.
> +
> + for (pch = name; *pch != '\0'; pch++) {
> + if (!isprint(*pch)) {
> + kfree(name);
> + return -EINVAL;
> + }
> + }
> +
> + mmap_write_lock(mm);
> + error = madvise_set_anon_name(mm, addr, size, name);
> + mmap_write_unlock(mm);
> + kfree(name);
> + break;
> + default:
> + error = -EINVAL;
> + }
> +
> + return error;
--
Michal Hocko
SUSE Labs
