git: bdf0f24bb16d - main - linux: implement PTRACE_GET_SYSCALL_INFO
Jessica Clarke
jrtc27 at freebsd.org
Tue Sep 14 22:54:17 UTC 2021
On 14 Sep 2021, at 23:45, Konstantin Belousov <kostikbel at gmail.com> wrote:
>
> On Tue, Sep 14, 2021 at 08:41:06PM +0000, Edward Tomasz Napierala wrote:
>> The branch main has been updated by trasz:
>>
>> URL: https://cgit.FreeBSD.org/src/commit/?id=bdf0f24bb16d556a5b1e01cdfc087d08e91ac572
>>
>> commit bdf0f24bb16d556a5b1e01cdfc087d08e91ac572
>> Author: Edward Tomasz Napierala <trasz at FreeBSD.org>
>> AuthorDate: 2021-09-12 11:31:10 +0000
>> Commit: Edward Tomasz Napierala <trasz at FreeBSD.org>
>> CommitDate: 2021-09-14 20:19:55 +0000
>>
>> linux: implement PTRACE_GET_SYSCALL_INFO
>>
>> This is one of the pieces required to make modern (ie Focal)
>> strace(1) work.
>>
>> Reviewed By: jhb (earlier version)
>> Sponsored by: EPSRC
>> Differential Revision: https://reviews.freebsd.org/D28212
>> ---
>> lib/libsysdecode/mktables | 2 +-
>> sys/amd64/linux/linux_ptrace.c | 98 +++++++++++++++++++++++++++++++++--
>> sys/compat/freebsd32/freebsd32_misc.c | 3 ++
>> sys/kern/sys_process.c | 17 ++++++
>> sys/sys/ptrace.h | 4 ++
>> 5 files changed, 120 insertions(+), 4 deletions(-)
>>
>> + case PT_GET_SC_ARGS_ALL:
>> + CTR1(KTR_PTRACE, "PT_GET_SC_ARGS_ALL: pid %d", p->p_pid);
>> + if ((td2->td_dbgflags & (TDB_SCE | TDB_SCX)) == 0
>> +#ifdef COMPAT_FREEBSD32
>> + || (wrap32 && !safe)
>> +#endif
>> + ) {
>> + error = EINVAL;
>> + break;
>> + }
>> + bcopy(td2->td_sa.args, addr, sizeof(td2->td_sa.args));
>> + break;
>
> This is awful, you already got that feedback in review, as I read it.
> I strongly suggest to remove PT_GET_SC_ARGS_ALL, and instead checks something
> in the implementation of PT_GET_SC_ARGS to select either full copy or just
> nargs args.
>
> Easiest thing for 'something' would be SV_PROC_ABI(p) == SV_ABI_LINUX.
That is incorrect. The original review just changed PT_GET_SC_ARGS even
for FreeBSD and that was what was described as horrible. John suggested
two alternatives: this approach, and having the Linuxulator bypass
kern_ptrace entirely by doing its own thing.
Your option seems simpler but I don’t know if there’s a good reason why
that wasn’t suggested.
Jess
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