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Message-ID: <CAK8P3a2jkG0dMyOxQMor+-u2ganP29RgeeNL2hMYy6pfVpNpTg@mail.gmail.com>
Date: Sat, 1 Dec 2018 11:27:19 +0100
From: Arnd Bergmann <arnd@...db.de>
To: Andy Lutomirski <luto@...nel.org>
Cc: christian@...uner.io, "Eric W . Biederman" <ebiederm@...ssion.com>,
Florian Weimer <fweimer@...hat.com>,
Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
"Serge E. Hallyn" <serge@...lyn.com>, Jann Horn <jannh@...gle.com>,
Andrew Morton <akpm@...ux-foundation.org>,
Oleg Nesterov <oleg@...hat.com>, cyphar@...har.com,
Al Viro <viro@...iv.linux.org.uk>,
Linux FS-devel Mailing List <linux-fsdevel@...r.kernel.org>,
Linux API <linux-api@...r.kernel.org>,
Daniel Colascione <dancol@...gle.com>,
Tim Murray <timmurray@...gle.com>, linux-man@...r.kernel.org,
Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH v2] signal: add procfd_signal() syscall
On Sat, Dec 1, 2018 at 9:51 AM Arnd Bergmann <arnd@...db.de> wrote:
> On Sat, Dec 1, 2018 at 12:54 AM Andy Lutomirski <luto@...nel.org> wrote:
> > On Fri, Nov 30, 2018 at 2:10 PM Arnd Bergmann <arnd@...db.de> wrote:
> > > On Fri, Nov 30, 2018 at 5:36 PM Andy Lutomirski <luto@...nel.org> wrote:
> > > > On Fri, Nov 30, 2018 at 3:41 AM Arnd Bergmann <arnd@...db.de> wrote:
> > > > > siginfo_t as it is now still has a number of other downsides, and Andy in
> > > > > particular didn't like the idea of having three new variants on x86
> > > > > (depending on how you count). His alternative suggestion of having
> > > > > a single syscall entry point that takes a 'signfo_t __user *' but interprets
> > > > > it as compat_siginfo depending on in_compat_syscall()/in_x32_syscall()
> > > > > should work correctly, but feels wrong to me, or at least inconsistent
> > > > > with how we do this elsewhere.
>
> > > The '548 | 0x40000000' part seems to be the only sensible
> > > way to handle x32 here. What exactly would you propose to
> > > avoid defining the other entry points?
> >
> > I would propose that it should be 335 | 0x40000000. I can't see any
> > reasonable way to teach the kernel to reject 335 | 0x40000000 that
> > wouldn't work just as well to accept it and make it do the right
> > thing. Currently we accept it and do the *wrong* thing, which is no
> > good.
I guess we could start with something like the change below, which
would unify the entry points for rt_{tg,}sigqueueinfo, so that
e.g. the 129 and 536 syscall numbers do the exact same thing, and
that would be the lp64 or ilp32 behavior, depending on the
0x40000000 bit. For the new syscalls, we can then do the same
thing without assigning another number.
Arnd
diff --git a/arch/x86/entry/syscall_64.c b/arch/x86/entry/syscall_64.c
index d5252bc1e380..3233fb889a51 100644
--- a/arch/x86/entry/syscall_64.c
+++ b/arch/x86/entry/syscall_64.c
@@ -7,6 +7,11 @@
#include <asm/asm-offsets.h>
#include <asm/syscall.h>
+#ifdef CONFIG_X86_X32_ABI
+#define __x64_sys_x86_rt_sigqueueinfo __x64_sys_rt_sigqueueinfo
+#define __x64_sys_x86_rt_tgsigqueueinfo __x64_sys_rt_tgsigqueueinfo
+#endif
+
/* this is a lie, but it does not hurt as sys_ni_syscall just returns
-EINVAL */
extern asmlinkage long sys_ni_syscall(const struct pt_regs *);
#define __SYSCALL_64(nr, sym, qual) extern asmlinkage long sym(const
struct pt_regs *);
diff --git a/arch/x86/entry/syscalls/syscall_64.tbl
b/arch/x86/entry/syscalls/syscall_64.tbl
index 0823eed2b02e..4a7393d34e03 100644
--- a/arch/x86/entry/syscalls/syscall_64.tbl
+++ b/arch/x86/entry/syscalls/syscall_64.tbl
@@ -137,7 +137,7 @@
126 common capset __x64_sys_capset
127 64 rt_sigpending __x64_sys_rt_sigpending
128 64 rt_sigtimedwait __x64_sys_rt_sigtimedwait
-129 64 rt_sigqueueinfo __x64_sys_rt_sigqueueinfo
+129 64 rt_sigqueueinfo __x64_sys_x86_rt_sigqueueinfo
130 common rt_sigsuspend __x64_sys_rt_sigsuspend
131 64 sigaltstack __x64_sys_sigaltstack
132 common utime __x64_sys_utime
@@ -305,7 +305,7 @@
294 common inotify_init1 __x64_sys_inotify_init1
295 64 preadv __x64_sys_preadv
296 64 pwritev __x64_sys_pwritev
-297 64 rt_tgsigqueueinfo __x64_sys_rt_tgsigqueueinfo
+297 64 rt_tgsigqueueinfo __x64_sys_x86_rt_tgsigqueueinfo
298 common perf_event_open __x64_sys_perf_event_open
299 64 recvmmsg __x64_sys_recvmmsg
300 common fanotify_init __x64_sys_fanotify_init
@@ -369,7 +369,7 @@
521 x32 ptrace __x32_compat_sys_ptrace
522 x32 rt_sigpending __x32_compat_sys_rt_sigpending
523 x32 rt_sigtimedwait __x32_compat_sys_rt_sigtimedwait
-524 x32 rt_sigqueueinfo __x32_compat_sys_rt_sigqueueinfo
+524 x32 rt_sigqueueinfo __x64_sys_x86_rt_sigqueueinfo
525 x32 sigaltstack __x32_compat_sys_sigaltstack
526 x32 timer_create __x32_compat_sys_timer_create
527 x32 mq_notify __x32_compat_sys_mq_notify
@@ -381,7 +381,7 @@
533 x32 move_pages __x32_compat_sys_move_pages
534 x32 preadv __x32_compat_sys_preadv64
535 x32 pwritev __x32_compat_sys_pwritev64
-536 x32 rt_tgsigqueueinfo __x32_compat_sys_rt_tgsigqueueinfo
+536 x32 rt_tgsigqueueinfo __x64_sys_x86_rt_tgsigqueueinfo
537 x32 recvmmsg __x32_compat_sys_recvmmsg
538 x32 sendmmsg __x32_compat_sys_sendmmsg
539 x32 process_vm_readv __x32_compat_sys_process_vm_readv
diff --git a/arch/x86/kernel/signal.c b/arch/x86/kernel/signal.c
index 92a3b312a53c..2f16330cac83 100644
--- a/arch/x86/kernel/signal.c
+++ b/arch/x86/kernel/signal.c
@@ -892,4 +892,38 @@ asmlinkage long sys32_x32_rt_sigreturn(void)
signal_fault(regs, frame, "x32 rt_sigreturn");
return 0;
}
+
+SYSCALL_DEFINE3(x86_rt_sigqueueinfo, pid_t, pid, int, sig,
+ siginfo_t __user *, uinfo)
+{
+ kernel_siginfo_t info;
+ int ret;
+
+ if (!in_x32_syscall()
+ ret = __copy_siginfo_from_user(sig, &info, uinfo);
+ else
+ ret = __copy_siginfo_from_user32(sig, &info, uinfo);
+
+ if (unlikely(ret))
+ return ret;
+ return do_rt_sigqueueinfo(pid, sig, &info);
+}
+
+SYSCALL_DEFINE3(x86_rt_tsigqueueinfo, pid_t, tgid, pid_t, pid, int, sig,
+ siginfo_t __user *, uinfo)
+{
+ kernel_siginfo_t info;
+ int ret;
+
+ if (!in_x32_syscall()
+ ret = __copy_siginfo_from_user(sig, &info, uinfo);
+ else
+ ret = __copy_siginfo_from_user32(sig, &info, uinfo);
+
+ if (unlikely(ret))
+ return ret;
+ return do_rt_tsigqueueinfo(tgid, pid, sig, &info);
+}
+
+
#endif
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