Re: [PATCH 9/9] vdso: Modify getrandom to include the correct namespace

Christophe Leroy
2024-09-04T17:26:59Z

Le 03/09/2024 à 17:14, Vincenzo Frascino a écrit :
> The VDSO implementation includes headers from outside of the
> vdso/ namespace.
>
> Modify getrandom to take advantage of the refactoring done in the
> previous patches and to include only the vdso/ namespace.
>
> Cc: Andy Lutomirski <luto@kernel.org>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Jason A. Donenfeld <Jason@zx2c4.com>
> Signed-off-by: Vincenzo Frascino <vincenzo.frascino@arm.com>
> ---
> lib/vdso/getrandom.c | 22 ++++++++--------------
> 1 file changed, 8 insertions(+), 14 deletions(-)
>
> diff --git a/lib/vdso/getrandom.c b/lib/vdso/getrandom.c
> index 938ca539aaa6..9c26b738e4a1 100644
> --- a/lib/vdso/getrandom.c
> +++ b/lib/vdso/getrandom.c
> @@ -3,19 +3,13 @@
> * Copyright (C) 2022-2024 Jason A. Donenfeld <Jason@zx2c4.com>. All Rights Reserved.
> */
>
> -#include <linux/array_size.h>
> -#include <linux/minmax.h>
> #include <vdso/datapage.h>
> #include <vdso/getrandom.h>
> #include <vdso/unaligned.h>
> -#include <asm/vdso/getrandom.h>
> -#include <uapi/linux/mman.h>
> -#include <uapi/linux/random.h>

Now build fails on powerpc because struct vgetrandom_opaque_params is
unknown.

x86 get it by chance via the following header inclusion chain:

In file included from ./include/linux/random.h:10,
from ./include/linux/nodemask.h:98,
from ./include/linux/mmzone.h:18,
from ./include/linux/gfp.h:7,
from ./include/linux/xarray.h:16,
from ./include/linux/radix-tree.h:21,
from ./include/linux/idr.h:15,
from ./include/linux/kernfs.h:12,
from ./include/linux/sysfs.h:16,
from ./include/linux/kobject.h:20,
from ./include/linux/of.h:18,
from ./include/linux/clocksource.h:19,
from ./include/clocksource/hyperv_timer.h:16,
from ./arch/x86/include/asm/vdso/gettimeofday.h:21,
from ./include/vdso/datapage.h:164,
from
arch/x86/entry/vdso/../../../../lib/vdso/getrandom.c:7,
from arch/x86/entry/vdso/vgetrandom.c:7:

> -
> -#undef PAGE_SIZE
> -#undef PAGE_MASK
> -#define PAGE_SIZE (1UL << CONFIG_PAGE_SHIFT)
> -#define PAGE_MASK (~(PAGE_SIZE - 1))
> +#include <vdso/mman.h>
> +#include <vdso/page.h>
> +#include <vdso/array_size.h>
> +#include <vdso/minmax.h>
>
> #define MEMCPY_AND_ZERO_SRC(type, dst, src, len) do { \
> while (len >= sizeof(type)) { \
> @@ -68,7 +62,7 @@ static __always_inline ssize_t
> __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_t len,
> unsigned int flags, void *opaque_state, size_t opaque_len)
> {
> - ssize_t ret = min_t(size_t, INT_MAX & PAGE_MASK /* = MAX_RW_COUNT */, len);
> + ssize_t ret = min_t(size_t, INT_MAX & VDSO_PAGE_MASK /* = MAX_RW_COUNT */, len);
> struct vgetrandom_state *state = opaque_state;
> size_t batch_len, nblocks, orig_len = len;
> bool in_use, have_retried = false;
> @@ -79,15 +73,15 @@ __cvdso_getrandom_data(const struct vdso_rng_data *rng_info, void *buffer, size_
> if (unlikely(opaque_len == ~0UL && !buffer && !len && !flags)) {
> struct vgetrandom_opaque_params *params = opaque_state;
> params->size_of_opaque_state = sizeof(*state);
> - params->mmap_prot = PROT_READ | PROT_WRITE;
> - params->mmap_flags = MAP_DROPPABLE | MAP_ANONYMOUS;
> + params->mmap_prot = VDSO_MMAP_PROT;
> + params->mmap_flags = VDSO_MMAP_FLAGS;
> for (size_t i = 0; i < ARRAY_SIZE(params->reserved); ++i)
> params->reserved[i] = 0;
> return 0;
> }
>
> /* The state must not straddle a page, since pages can be zeroed at any time. */
> - if (unlikely(((unsigned long)opaque_state & ~PAGE_MASK) + sizeof(*state) > PAGE_SIZE))
> + if (unlikely(((unsigned long)opaque_state & ~VDSO_PAGE_MASK) + sizeof(*state) > VDSO_PAGE_SIZE))
> return -EFAULT;
>
> /* Handle unexpected flags by falling back to the kernel. */