diff options
| author | Matt Redfearn <matt.redfearn@imgtec.com> | 2016-03-29 09:35:31 +0100 |
|---|---|---|
| committer | Ralf Baechle <ralf@linux-mips.org> | 2016-05-13 14:02:00 +0200 |
| commit | a400bed6d105c23d3673f763596e4b85de14e41a (patch) | |
| tree | 9ef0d11b16f9e94aa0e890cbc0e8a74b4b5c0031 /arch/mips/kernel/scall64-n32.S | |
| parent | 5050e91fa650ecd6260ef62bbed9dfc5b4d05dfa (diff) | |
MIPS: scall: Handle seccomp filters which redirect syscalls
Commit d218af78492a ("MIPS: scall: Always run the seccomp syscall
filters") modified the syscall code to always call the seccomp filters,
but missed the case where a filter may redirect the syscall, as
revealed by the seccomp_bpf self test.
The syscall path now restores the syscall from the stack after the
filter rather than saving it locally. Syscall number checking and
syscall function table lookup is done after the filter may have run such
that redirected syscalls are also checked, and executed.
The regular path of syscall number checking and pointer lookup is also
made more consistent between ABIs with scall64-64.S being the reference.
With this patch in place, the seccomp_bpf self test now passes
TRACE_syscall.syscall_redirected and TRACE_syscall.syscall_dropped on
all MIPS ABIs.
Fixes: d218af78492a ("MIPS: scall: Always run the seccomp syscall filters")
Signed-off-by: Matt Redfearn <matt.redfearn@imgtec.com>
Acked-by: Kees Cook <keescook@chromium.org>
Cc: Eric B Munson <emunson@akamai.com>
Cc: James Hogan <james.hogan@imgtec.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mips@linux-mips.org
Cc: IMG-MIPSLinuxKerneldevelopers@imgtec.com
Cc: linux-kernel@vger.kernel.org
Patchwork: https://patchwork.linux-mips.org/patch/12916/
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
Diffstat (limited to 'arch/mips/kernel/scall64-n32.S')
| -rw-r--r-- | arch/mips/kernel/scall64-n32.S | 14 |
1 files changed, 9 insertions, 5 deletions
diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S index 71f99d5f7a06..9c0b387d6427 100644 --- a/arch/mips/kernel/scall64-n32.S +++ b/arch/mips/kernel/scall64-n32.S @@ -42,9 +42,6 @@ NESTED(handle_sysn32, PT_SIZE, sp) #endif beqz t0, not_n32_scall - dsll t0, v0, 3 # offset into table - ld t2, (sysn32_call_table - (__NR_N32_Linux * 8))(t0) - sd a3, PT_R26(sp) # save a3 for syscall restarting li t1, _TIF_WORK_SYSCALL_ENTRY @@ -53,6 +50,9 @@ NESTED(handle_sysn32, PT_SIZE, sp) bnez t0, n32_syscall_trace_entry syscall_common: + dsll t0, v0, 3 # offset into table + ld t2, (sysn32_call_table - (__NR_N32_Linux * 8))(t0) + jalr t2 # Do The Real Thing (TM) li t0, -EMAXERRNO - 1 # error? @@ -71,21 +71,25 @@ syscall_common: n32_syscall_trace_entry: SAVE_STATIC - move s0, t2 move a0, sp move a1, v0 jal syscall_trace_enter bltz v0, 1f # seccomp failed? Skip syscall - move t2, s0 RESTORE_STATIC + ld v0, PT_R2(sp) # Restore syscall (maybe modified) ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) ld a2, PT_R6(sp) ld a3, PT_R7(sp) ld a4, PT_R8(sp) ld a5, PT_R9(sp) + + dsubu t2, v0, __NR_N32_Linux # check (new) syscall number + sltiu t0, t2, __NR_N32_Linux_syscalls + 1 + beqz t0, not_n32_scall + j syscall_common 1: j syscall_exit |