2023-01-05 14:50:09

by Rong Tao

Subject: [PATCH bpf-next] libbpf: poison strlcpy()

From: Rong Tao <[email protected]>

Since commit 9fc205b413b3("libbpf: Add sane strncpy alternative and use
it internally") introduce libbpf_strlcpy(), thus add strlcpy() to a poison
list to prevent accidental use of it.

Signed-off-by: Rong Tao <[email protected]>
---
tools/lib/bpf/libbpf_internal.h | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tools/lib/bpf/libbpf_internal.h b/tools/lib/bpf/libbpf_internal.h
index 377642ff51fc..2d26ded383ca 100644
--- a/tools/lib/bpf/libbpf_internal.h
+++ b/tools/lib/bpf/libbpf_internal.h
@@ -20,8 +20,8 @@
/* make sure libbpf doesn't use kernel-only integer typedefs */
#pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64

-/* prevent accidental re-addition of reallocarray() */
-#pragma GCC poison reallocarray
+/* prevent accidental re-addition of reallocarray()/strlcpy() */
+#pragma GCC poison reallocarray strlcpy

#include "libbpf.h"
#include "btf.h"
--
2.39.0

2023-01-05 19:16:33

by Stanislav Fomichev

Subject: Re: [PATCH bpf-next] libbpf: poison strlcpy()

On 01/05, Rong Tao wrote:
> From: Rong Tao <[email protected]>

> Since commit 9fc205b413b3("libbpf: Add sane strncpy alternative and use
> it internally") introduce libbpf_strlcpy(), thus add strlcpy() to a poison
> list to prevent accidental use of it.

> Signed-off-by: Rong Tao <[email protected]>

Acked-by: Stanislav Fomichev <[email protected]>

> ---
> tools/lib/bpf/libbpf_internal.h | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)

> diff --git a/tools/lib/bpf/libbpf_internal.h
> b/tools/lib/bpf/libbpf_internal.h
> index 377642ff51fc..2d26ded383ca 100644
> --- a/tools/lib/bpf/libbpf_internal.h
> +++ b/tools/lib/bpf/libbpf_internal.h
> @@ -20,8 +20,8 @@
> /* make sure libbpf doesn't use kernel-only integer typedefs */
> #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64

> -/* prevent accidental re-addition of reallocarray() */
> -#pragma GCC poison reallocarray
> +/* prevent accidental re-addition of reallocarray()/strlcpy() */
> +#pragma GCC poison reallocarray strlcpy

> #include "libbpf.h"
> #include "btf.h"
> --
> 2.39.0

2023-01-06 16:51:05

by patchwork-bot+netdevbpf

Subject: Re: [PATCH bpf-next] libbpf: poison strlcpy()

Hello:

This patch was applied to bpf/bpf-next.git (master)
by Daniel Borkmann <[email protected]>:

On Thu, 5 Jan 2023 22:36:33 +0800 you wrote:
> From: Rong Tao <[email protected]>
>
> Since commit 9fc205b413b3("libbpf: Add sane strncpy alternative and use
> it internally") introduce libbpf_strlcpy(), thus add strlcpy() to a poison
> list to prevent accidental use of it.
>
> Signed-off-by: Rong Tao <[email protected]>
>
> [...]

Here is the summary with links:
- [bpf-next] libbpf: poison strlcpy()
https://git.kernel.org/bpf/bpf-next/c/6d0c4b11e743

You are awesome, thank you!
--
Deet-doot-dot, I am a bot.
https://korg.docs.kernel.org/patchwork/pwbot.html

2023-03-09 00:31:07

by Boris Burkov

Subject: Re: [PATCH bpf-next] libbpf: poison strlcpy()

On Thu, Jan 05, 2023 at 10:47:15AM -0800, [email protected] wrote:
> On 01/05, Rong Tao wrote:
> > From: Rong Tao <[email protected]>
>
> > Since commit 9fc205b413b3("libbpf: Add sane strncpy alternative and use
> > it internally") introduce libbpf_strlcpy(), thus add strlcpy() to a poison
> > list to prevent accidental use of it.
>
> > Signed-off-by: Rong Tao <[email protected]>
>
> Acked-by: Stanislav Fomichev <[email protected]>
>
> > ---
> > tools/lib/bpf/libbpf_internal.h | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
>
> > diff --git a/tools/lib/bpf/libbpf_internal.h
> > b/tools/lib/bpf/libbpf_internal.h
> > index 377642ff51fc..2d26ded383ca 100644
> > --- a/tools/lib/bpf/libbpf_internal.h
> > +++ b/tools/lib/bpf/libbpf_internal.h
> > @@ -20,8 +20,8 @@
> > /* make sure libbpf doesn't use kernel-only integer typedefs */
> > #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
>
> > -/* prevent accidental re-addition of reallocarray() */
> > -#pragma GCC poison reallocarray
> > +/* prevent accidental re-addition of reallocarray()/strlcpy() */
> > +#pragma GCC poison reallocarray strlcpy

On my musl system, I believe this broke compilation, as string.h defines
strlcpy, and is included after this poisoning when compiling strset.c

FWIW, I could work around it by adding
#include <string.h>
above
#include <libbpf_internal.h>
in strset.c, since the poison doesn't apply to symbols that existed
before it ran, but this feels like a kludge, and not in the spirit of
the original poisoning patch..

I'm curious what the proper workaround should be for a libc that defines
strlcpy.

Thanks,
Boris

>
> > #include "libbpf.h"
> > #include "btf.h"
> > --
> > 2.39.0
>

2023-03-09 00:33:12

by Stanislav Fomichev

Subject: Re: [PATCH bpf-next] libbpf: poison strlcpy()

On Wed, Mar 8, 2023 at 4:30 PM Boris Burkov <[email protected]> wrote:
>
> On Thu, Jan 05, 2023 at 10:47:15AM -0800, [email protected] wrote:
> > On 01/05, Rong Tao wrote:
> > > From: Rong Tao <[email protected]>
> >
> > > Since commit 9fc205b413b3("libbpf: Add sane strncpy alternative and use
> > > it internally") introduce libbpf_strlcpy(), thus add strlcpy() to a poison
> > > list to prevent accidental use of it.
> >
> > > Signed-off-by: Rong Tao <[email protected]>
> >
> > Acked-by: Stanislav Fomichev <[email protected]>
> >
> > > ---
> > > tools/lib/bpf/libbpf_internal.h | 4 ++--
> > > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > > diff --git a/tools/lib/bpf/libbpf_internal.h
> > > b/tools/lib/bpf/libbpf_internal.h
> > > index 377642ff51fc..2d26ded383ca 100644
> > > --- a/tools/lib/bpf/libbpf_internal.h
> > > +++ b/tools/lib/bpf/libbpf_internal.h
> > > @@ -20,8 +20,8 @@
> > > /* make sure libbpf doesn't use kernel-only integer typedefs */
> > > #pragma GCC poison u8 u16 u32 u64 s8 s16 s32 s64
> >
> > > -/* prevent accidental re-addition of reallocarray() */
> > > -#pragma GCC poison reallocarray
> > > +/* prevent accidental re-addition of reallocarray()/strlcpy() */
> > > +#pragma GCC poison reallocarray strlcpy
>
> On my musl system, I believe this broke compilation, as string.h defines
> strlcpy, and is included after this poisoning when compiling strset.c
>
> FWIW, I could work around it by adding
> #include <string.h>
> above
> #include <libbpf_internal.h>
> in strset.c, since the poison doesn't apply to symbols that existed
> before it ran, but this feels like a kludge, and not in the spirit of
> the original poisoning patch..
>
> I'm curious what the proper workaround should be for a libc that defines
> strlcpy.

Let's move this discussion into [0]? There is a similar issue for
uclibc it seems.

0: https://lore.kernel.org/bpf/CAKH8qBshq-J2H+Bo1xA=FzAJ6x_mo5yfW6oYjQ_u1QwLJ5CDog@mail.gmail.com/T/#t

> Thanks,
> Boris
>
> >
> > > #include "libbpf.h"
> > > #include "btf.h"
> > > --
> > > 2.39.0
> >