Re: [PATCH AUTOSEL for 4.9 160/293] MIPS: Give __secure_computing() access to syscall arguments.

[James Hogan]

On Mon, Apr 09, 2018 at 12:24:58AM +, Sasha Levin wrote:
> From: David Daney 
> 
> [ Upstream commit 669c4092225f0ed5df12ebee654581b558a5e3ed ]
> 
> KProbes of __seccomp_filter() are not very useful without access to
> the syscall arguments.
> 
> Do what x86 does, and populate a struct seccomp_data to be passed to
> __secure_computing().  This allows samples/bpf/tracex5 to extract a
> sensible trace.

This broke o32 indirect syscalls, and was fixed by commit 3d729deaf287
("MIPS: seccomp: Fix indirect syscall args").

Cheers
James


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[PATCH AUTOSEL for 4.9 160/293] MIPS: Give __secure_computing() access to syscall arguments.

[Sasha Levin]

From: David Daney 

[ Upstream commit 669c4092225f0ed5df12ebee654581b558a5e3ed ]

KProbes of __seccomp_filter() are not very useful without access to
the syscall arguments.

Do what x86 does, and populate a struct seccomp_data to be passed to
__secure_computing().  This allows samples/bpf/tracex5 to extract a
sensible trace.

Signed-off-by: David Daney 
Cc: Alexei Starovoitov 
Cc: Daniel Borkmann 
Cc: Matt Redfearn 
Cc: netdev@vger.kernel.org
Cc: linux-ker...@vger.kernel.org
Cc: linux-m...@linux-mips.org
Patchwork: https://patchwork.linux-mips.org/patch/16368/
Signed-off-by: Ralf Baechle 
Signed-off-by: Sasha Levin 
---
 arch/mips/kernel/ptrace.c | 22 --
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/arch/mips/kernel/ptrace.c b/arch/mips/kernel/ptrace.c
index 0c8ae2cc6380..956dae7e6a69 100644
--- a/arch/mips/kernel/ptrace.c
+++ b/arch/mips/kernel/ptrace.c
@@ -1011,8 +1011,26 @@ asmlinkage long syscall_trace_enter(struct pt_regs 
*regs, long syscall)
tracehook_report_syscall_entry(regs))
return -1;
 
-   if (secure_computing(NULL) == -1)
-   return -1;
+#ifdef CONFIG_SECCOMP
+   if (unlikely(test_thread_flag(TIF_SECCOMP))) {
+   int ret, i;
+   struct seccomp_data sd;
+
+   sd.nr = syscall;
+   sd.arch = syscall_get_arch();
+   for (i = 0; i < 6; i++) {
+   unsigned long v, r;
+
+   r = mips_get_syscall_arg(&v, current, regs, i);
+   sd.args[i] = r ? 0 : v;
+   }
+   sd.instruction_pointer = KSTK_EIP(current);
+
+   ret = __secure_computing(&sd);
+   if (ret == -1)
+   return ret;
+   }
+#endif
 
if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->regs[2]);
-- 
2.15.1