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From: Deepak Gupta <debug@rivosinc.com>
To: Charlie Jenkins <charlie@rivosinc.com>
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Subject: Re: [PATCH v3 29/29] kselftest/riscv: kselftest for user mode cfi
Date: Thu, 9 May 2024 12:16:29 -0700	[thread overview]
Message-ID: <Zj0hDT1EZmOaEkCj@debug.ba.rivosinc.com> (raw)
In-Reply-To: <Zj0UGweLoRD1U9Po@ghost>

On Thu, May 09, 2024 at 11:21:15AM -0700, Charlie Jenkins wrote:
>On Wed, Apr 03, 2024 at 04:35:17PM -0700, Deepak Gupta wrote:
>> +
>> +int main(int argc, char *argv[])
>> +{
>> +	int ret = 0;
>> +	unsigned long lpad_status = 0, ss_status = 0;
>> +
>> +	ksft_print_header();
>> +
>> +	ksft_set_plan(RISCV_CFI_SELFTEST_COUNT);
>> +
>> +	ksft_print_msg("starting risc-v tests\n");
>> +
>> +	/*
>> +	 * Landing pad test. Not a lot of kernel changes to support landing
>> +	 * pad for user mode except lighting up a bit in senvcfg via a prctl
>> +	 * Enable landing pad through out the execution of test binary
>> +	 */
>> +	ret = my_syscall5(__NR_prctl, PR_GET_INDIR_BR_LP_STATUS, &lpad_status, 0, 0, 0);
>
>There is an assumption here that the libc supports setting
>INDIR_BR_LP_STATUS but does not support the standard prctl interface
>defined in <sys/prctl.h>. my_syscall5() is defined to fill in gaps in
>the libc, so this test case should also set the status manually rather
>than relying on the libc.
>
>I don't think it's necessary to define my_syscall5() since every libc
>should have a prctl() definition. However, these CFI prctls are very new
>and glibc does not yet support (correct me if I am wrong) it so these
>prctls should be enabled by the test cases.

In one of my previous patches, it was setting landing pad and shadow stack enabling
directly via handcrafted prctl macro. I changed it to check for status for following reasons

- If this binary is compiled with landing pad and shadow stack option then toolchain being used
   already has libc with shadow stack and landing pad enabling

- Currently upstream glibc toolchain dont have support but libc with toolchain has the support.

In case of shadow stack enabling, macro is needed and `prctl` function can't be used.
Because you enter `prctl` function with no shadow stack but exit with shadow stack and will lead to
fault in its epilog.

Due to all these reasons, kselftests have to be compiled with toolchain with cfi codegen and thus libc
should have support to light them up. Here tests only checks if they are already lit up, If not it fails.

Although you're spot on one thing here, since this test is assuming libc already lit-up landing pad and
shadow stack. It doesn't need macro here for status check of feature and can simply use `prctl` syscall
interface.

>
>- Charlie
>
>> +	if (ret)

  reply	other threads:[~2024-05-09 19:16 UTC|newest]

Thread overview: 82+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-04-03 23:34 [PATCH v3 00/29] riscv control-flow integrity for usermode Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 01/29] riscv: envcfg save and restore on task switching Deepak Gupta
2024-05-09  0:10   ` Charlie Jenkins
2024-05-09 19:00     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 02/29] riscv: define default value for envcfg for task Deepak Gupta
2024-05-10 22:33   ` Charlie Jenkins
2024-05-13 18:33     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 03/29] riscv/Kconfig: enable HAVE_EXIT_THREAD for riscv Deepak Gupta
2024-05-10 22:36   ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 04/29] riscv: zicfilp / zicfiss in dt-bindings (extensions.yaml) Deepak Gupta
2024-04-10 11:58   ` Rob Herring
2024-04-10 21:37     ` Deepak Gupta
2024-04-15 19:41       ` Rob Herring
2024-04-16 15:44         ` Deepak Gupta
2024-05-09 18:14           ` Conor Dooley
2024-05-09 18:46             ` Deepak Gupta
2024-05-09 20:32               ` Conor Dooley
2024-05-09 23:26                 ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 05/29] riscv: zicfiss / zicfilp enumeration Deepak Gupta
2024-05-09  0:00   ` Andy Chiu
2024-05-09  0:07     ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 06/29] riscv: zicfiss / zicfilp extension csr and bit definitions Deepak Gupta
2024-05-10 22:37   ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 07/29] riscv: usercfi state for task and save/restore of CSR_SSP on trap entry/exit Deepak Gupta
2024-05-10 22:51   ` Charlie Jenkins
2024-04-03 23:34 ` [PATCH v3 08/29] mm: Define VM_SHADOW_STACK for RISC-V Deepak Gupta
2024-04-04 18:58   ` David Hildenbrand
2024-04-04 19:04     ` Mark Brown
2024-04-04 19:15       ` David Hildenbrand
2024-04-04 19:21         ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 09/29] mm: abstract shadow stack vma behind `vma_is_shadow_stack` Deepak Gupta
2024-04-04 19:02   ` David Hildenbrand
2024-04-04 21:39     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 10/29] riscv/mm : ensure PROT_WRITE leads to VM_READ | VM_WRITE Deepak Gupta
2024-05-10 21:02   ` Charlie Jenkins
2024-05-13 17:47     ` Deepak Gupta
2024-05-13 18:36       ` Charlie Jenkins
2024-05-13 18:41         ` Deepak Gupta
2024-05-13 21:26           ` Charlie Jenkins
2024-05-12 16:24   ` Alexandre Ghiti
2024-05-13 18:29     ` Deepak Gupta
2024-04-03 23:34 ` [PATCH v3 11/29] riscv mm: manufacture shadow stack pte Deepak Gupta
2024-05-12 16:26   ` Alexandre Ghiti
2024-04-03 23:35 ` [PATCH v3 12/29] riscv mmu: teach pte_mkwrite to manufacture shadow stack PTEs Deepak Gupta
2024-05-12 16:28   ` Alexandre Ghiti
2024-05-13 17:33     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 13/29] riscv mmu: write protect and shadow stack Deepak Gupta
2024-05-12 16:31   ` Alexandre Ghiti
2024-05-13 17:32     ` Deepak Gupta
2024-05-23 14:59       ` Alexandre Ghiti
2024-05-24  7:16         ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 14/29] riscv/mm: Implement map_shadow_stack() syscall Deepak Gupta
2024-05-12 16:50   ` Alexandre Ghiti
2024-05-13 17:25     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 15/29] riscv/shstk: If needed allocate a new shadow stack on clone Deepak Gupta
2024-05-12 17:05   ` Alexandre Ghiti
2024-05-13 17:10     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 16/29] prctl: arch-agnostic prctl for shadow stack Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 17/29] prctl: arch-agnostic prctl for indirect branch tracking Deepak Gupta
2024-05-10 23:29   ` Charlie Jenkins
2024-05-13 18:31     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 18/29] riscv: Implements arch agnostic shadow stack prctls Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 19/29] riscv: Implements arch agnostic indirect branch tracking prctls Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 20/29] riscv/kernel: update __show_regs to print shadow stack register Deepak Gupta
2024-05-12 17:10   ` Alexandre Ghiti
2024-04-03 23:35 ` [PATCH v3 21/29] riscv/traps: Introduce software check exception Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 22/29] riscv sigcontext: adding cfi state field in sigcontext Deepak Gupta
2024-05-24  9:46   ` Andy Chiu
2024-05-24 19:11     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 23/29] riscv signal: Save and restore of shadow stack for signal Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 24/29] riscv/ptrace: riscv cfi status and state via ptrace and in core files Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 25/29] riscv/hwprobe: zicfilp / zicfiss enumeration in hwprobe Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 26/29] riscv: create a config for shadow stack and landing pad instr support Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 27/29] riscv: Documentation for landing pad / indirect branch tracking Deepak Gupta
2024-05-10 20:30   ` Charlie Jenkins
2024-05-13 17:07     ` Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 28/29] riscv: Documentation for shadow stack on riscv Deepak Gupta
2024-04-03 23:35 ` [PATCH v3 29/29] kselftest/riscv: kselftest for user mode cfi Deepak Gupta
2024-05-09 18:21   ` Charlie Jenkins
2024-05-09 19:16     ` Deepak Gupta [this message]
2024-05-10  1:20   ` Charlie Jenkins
2024-05-09  0:33 ` [PATCH v3 00/29] riscv control-flow integrity for usermode Charlie Jenkins

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