linux-kernel - Re: [PATCH v2 1/2] riscv/ptrace: add new regset to access original a0 register

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <87ed2pdmok.fsf@all.your.base.are.belong.to.us>
Date: Tue, 03 Dec 2024 12:35:07 +0100
From: Björn Töpel <bjorn@...nel.org>
To: Celeste Liu <uwu@...lacanthus.name>, Oleg Nesterov <oleg@...hat.com>,
 Paul Walmsley <paul.walmsley@...ive.com>, Palmer Dabbelt
 <palmer@...belt.com>, Albert Ou <aou@...s.berkeley.edu>, Eric Biederman
 <ebiederm@...ssion.com>, Kees Cook <kees@...nel.org>, Shuah Khan
 <shuah@...nel.org>
Cc: Alexandre Ghiti <alex@...ti.fr>, "Dmitry V. Levin" <ldv@...ace.io>,
 Andrea Bolognani <abologna@...hat.com>, Thomas Gleixner
 <tglx@...utronix.de>, Ron Economos <re@...z.net>, Charlie Jenkins
 <charlie@...osinc.com>, Quan Zhou <zhouquan@...as.ac.cn>, Felix Yan
 <felixonmars@...hlinux.org>, Ruizhe Pan <c141028@...il.com>, Shiqi Zhang
 <shiqi@...c.iscas.ac.cn>, Guo Ren <guoren@...nel.org>, Yao Zi
 <ziyao@...root.org>, Han Gao <gaohan@...as.ac.cn>,
 linux-riscv@...ts.infradead.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, stable@...r.kernel.org,
 linux-kselftest@...r.kernel.org, Celeste Liu <uwu@...lacanthus.name>
Subject: Re: [PATCH v2 1/2] riscv/ptrace: add new regset to access original
 a0 register

Celeste Liu <uwu@...lacanthus.name> writes:

> The orig_a0 is missing in struct user_regs_struct of riscv, and there is
> no way to add it without breaking UAPI. (See Link tag below)
>
> Like NT_ARM_SYSTEM_CALL do, we add a new regset name NT_RISCV_ORIG_A0 to
> access original a0 register from userspace via ptrace API.
>
> Link: https://lore.kernel.org/all/59505464-c84a-403d-972f-d4b2055eeaac@gmail.com/
> Cc: stable@...r.kernel.org
> Signed-off-by: Celeste Liu <uwu@...lacanthus.name>
> ---
>  arch/riscv/kernel/ptrace.c | 32 ++++++++++++++++++++++++++++++++
>  include/uapi/linux/elf.h   |  1 +
>  2 files changed, 33 insertions(+)
>
> diff --git a/arch/riscv/kernel/ptrace.c b/arch/riscv/kernel/ptrace.c
> index ea67e9fb7a583683b922fe2c017ea61f3bc848db..18ce07ffb27bb1180667769eed800f6fdf96c083 100644
> --- a/arch/riscv/kernel/ptrace.c
> +++ b/arch/riscv/kernel/ptrace.c
> @@ -31,6 +31,7 @@ enum riscv_regset {
>  #ifdef CONFIG_RISCV_ISA_SUPM
>  	REGSET_TAGGED_ADDR_CTRL,
>  #endif
> +	REGSET_ORIG_A0,
>  };
>  
>  static int riscv_gpr_get(struct task_struct *target,
> @@ -184,6 +185,29 @@ static int tagged_addr_ctrl_set(struct task_struct *target,
>  }
>  #endif
>  
> +static int riscv_orig_a0_get(struct task_struct *target,
> +			     const struct user_regset *regset,
> +			     struct membuf to)
> +{
> +	return membuf_store(&to, task_pt_regs(target)->orig_a0);
> +}
> +
> +static int riscv_orig_a0_set(struct task_struct *target,
> +			     const struct user_regset *regset,
> +			     unsigned int pos, unsigned int count,
> +			     const void *kbuf, const void __user *ubuf)
> +{
> +	unsigned long orig_a0 = task_pt_regs(target)->orig_a0;
> +	int ret;
> +
> +	ret = user_regset_copyin(&pos, &count, &kbuf, &ubuf, &orig_a0, 0, -1);
> +	if (ret)
> +		return ret;
> +
> +	task_pt_regs(target)->orig_a0 = orig_a0;
> +	return ret;

Nit: Could be return 0, for readability.

Regardless,
Reviewed-by: Björn Töpel <bjorn@...osinc.com>