The MIPS syscall handler code used to return -ENOSYS on invalid syscalls. Whilst this is expected, it caused problems for seccomp filters because the said filters never had the change to run since the code returned -ENOSYS before triggering them. This caused problems on the chromium testsuite for filters looking for invalid syscalls. This has now changed and the seccomp filters are always run even if the syscall is invalid. We return -ENOSYS once we return from the seccomp filters. Moreover, similar codepath have been merged in the process which simplifies somewhat the overall syscall code. Signed-off-by: Markos Chandras <markos.chandras@xxxxxxxxxx> --- Changes since v1: - Fix offset calculation for n64 --- arch/mips/kernel/scall32-o32.S | 39 ++++++++++++++++----------------------- arch/mips/kernel/scall64-64.S | 38 ++++++++++++++++---------------------- arch/mips/kernel/scall64-n32.S | 19 +++++-------------- arch/mips/kernel/scall64-o32.S | 19 +++++-------------- 4 files changed, 42 insertions(+), 73 deletions(-) diff --git a/arch/mips/kernel/scall32-o32.S b/arch/mips/kernel/scall32-o32.S index 4cc13508d967..aa2df3e8dba2 100644 --- a/arch/mips/kernel/scall32-o32.S +++ b/arch/mips/kernel/scall32-o32.S @@ -36,16 +36,8 @@ NESTED(handle_sys, PT_SIZE, sp) lw t1, PT_EPC(sp) # skip syscall on return subu v0, v0, __NR_O32_Linux # check syscall number - sltiu t0, v0, __NR_O32_Linux_syscalls + 1 addiu t1, 4 # skip to next instruction sw t1, PT_EPC(sp) - beqz t0, illegal_syscall - - sll t0, v0, 2 - la t1, sys_call_table - addu t1, t0 - lw t2, (t1) # syscall routine - beqz t2, illegal_syscall sw a3, PT_R26(sp) # save a3 for syscall restarting @@ -96,6 +88,16 @@ loads_done: li t1, _TIF_WORK_SYSCALL_ENTRY and t0, t1 bnez t0, syscall_trace_entry # -> yes +syscall_common: + sltiu t0, v0, __NR_O32_Linux_syscalls + 1 + beqz t0, illegal_syscall + + sll t0, v0, 2 + la t1, sys_call_table + addu t1, t0 + lw t2, (t1) # syscall routine + + beqz t2, illegal_syscall jalr t2 # Do The Real Thing (TM) @@ -116,7 +118,7 @@ o32_syscall_exit: syscall_trace_entry: SAVE_STATIC - move s0, t2 + move s0, v0 move a0, sp /* @@ -129,27 +131,18 @@ syscall_trace_entry: 1: jal syscall_trace_enter - bltz v0, 2f # seccomp failed? Skip syscall + bltz v0, 1f # seccomp failed? Skip syscall + + move v0, s0 # restore syscall - move t0, s0 RESTORE_STATIC lw a0, PT_R4(sp) # Restore argument registers lw a1, PT_R5(sp) lw a2, PT_R6(sp) lw a3, PT_R7(sp) - jalr t0 - - li t0, -EMAXERRNO - 1 # error? - sltu t0, t0, v0 - sw t0, PT_R7(sp) # set error flag - beqz t0, 1f - - lw t1, PT_R2(sp) # syscall number - negu v0 # error - sw t1, PT_R0(sp) # save it for syscall restarting -1: sw v0, PT_R2(sp) # result + j syscall_common -2: j syscall_exit +1: j syscall_exit /* ------------------------------------------------------------------------ */ diff --git a/arch/mips/kernel/scall64-64.S b/arch/mips/kernel/scall64-64.S index a6f6b762c47a..08a2542dd79e 100644 --- a/arch/mips/kernel/scall64-64.S +++ b/arch/mips/kernel/scall64-64.S @@ -39,18 +39,11 @@ NESTED(handle_sys64, PT_SIZE, sp) .set at #endif - dsubu t0, v0, __NR_64_Linux # check syscall number - sltiu t0, t0, __NR_64_Linux_syscalls + 1 #if !defined(CONFIG_MIPS32_O32) && !defined(CONFIG_MIPS32_N32) ld t1, PT_EPC(sp) # skip syscall on return daddiu t1, 4 # skip to next instruction sd t1, PT_EPC(sp) #endif - beqz t0, illegal_syscall - - dsll t0, v0, 3 # offset into table - ld t2, (sys_call_table - (__NR_64_Linux * 8))(t0) - # syscall routine sd a3, PT_R26(sp) # save a3 for syscall restarting @@ -59,6 +52,17 @@ NESTED(handle_sys64, PT_SIZE, sp) and t0, t1, t0 bnez t0, syscall_trace_entry +syscall_common: + dsubu t2, v0, __NR_64_Linux + sltiu t0, t2, __NR_64_Linux_syscalls + 1 + beqz t0, illegal_syscall + + dsll t0, t2, 3 # offset into table + dla t2, sys_call_table + daddu t0, t2, t0 + ld t2, (t0) # syscall routine + beqz t2, illegal_syscall + jalr t2 # Do The Real Thing (TM) li t0, -EMAXERRNO - 1 # error? @@ -78,14 +82,14 @@ n64_syscall_exit: syscall_trace_entry: SAVE_STATIC - move s0, t2 + move s0, v0 move a0, sp move a1, v0 jal syscall_trace_enter - bltz v0, 2f # seccomp failed? Skip syscall + bltz v0, 1f # seccomp failed? Skip syscall - move t0, s0 + move v0, s0 RESTORE_STATIC ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) @@ -93,19 +97,9 @@ syscall_trace_entry: ld a3, PT_R7(sp) ld a4, PT_R8(sp) ld a5, PT_R9(sp) - jalr t0 - - li t0, -EMAXERRNO - 1 # error? - sltu t0, t0, v0 - sd t0, PT_R7(sp) # set error flag - beqz t0, 1f - - ld t1, PT_R2(sp) # syscall number - dnegu v0 # error - sd t1, PT_R0(sp) # save it for syscall restarting -1: sd v0, PT_R2(sp) # result + j syscall_common -2: j syscall_exit +1: j syscall_exit illegal_syscall: /* This also isn't a 64-bit syscall, throw an error. */ diff --git a/arch/mips/kernel/scall64-n32.S b/arch/mips/kernel/scall64-n32.S index 4b2010654c46..8680b92fb6aa 100644 --- a/arch/mips/kernel/scall64-n32.S +++ b/arch/mips/kernel/scall64-n32.S @@ -52,6 +52,7 @@ NESTED(handle_sysn32, PT_SIZE, sp) and t0, t1, t0 bnez t0, n32_syscall_trace_entry +syscall_common: jalr t2 # Do The Real Thing (TM) li t0, -EMAXERRNO - 1 # error? @@ -75,9 +76,9 @@ n32_syscall_trace_entry: move a1, v0 jal syscall_trace_enter - bltz v0, 2f # seccomp failed? Skip syscall + bltz v0, 1f # seccomp failed? Skip syscall - move t0, s0 + move t2, s0 RESTORE_STATIC ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) @@ -85,19 +86,9 @@ n32_syscall_trace_entry: ld a3, PT_R7(sp) ld a4, PT_R8(sp) ld a5, PT_R9(sp) - jalr t0 + j syscall_common - li t0, -EMAXERRNO - 1 # error? - sltu t0, t0, v0 - sd t0, PT_R7(sp) # set error flag - beqz t0, 1f - - ld t1, PT_R2(sp) # syscall number - dnegu v0 # error - sd t1, PT_R0(sp) # save it for syscall restarting -1: sd v0, PT_R2(sp) # result - -2: j syscall_exit +1: j syscall_exit not_n32_scall: /* This is not an n32 compatibility syscall, pass it on to diff --git a/arch/mips/kernel/scall64-o32.S b/arch/mips/kernel/scall64-o32.S index f543ff4feef9..0fe902ec01ff 100644 --- a/arch/mips/kernel/scall64-o32.S +++ b/arch/mips/kernel/scall64-o32.S @@ -87,6 +87,7 @@ loads_done: and t0, t1, t0 bnez t0, trace_a_syscall +syscall_common: jalr t2 # Do The Real Thing (TM) li t0, -EMAXERRNO - 1 # error? @@ -130,9 +131,9 @@ trace_a_syscall: 1: jal syscall_trace_enter - bltz v0, 2f # seccomp failed? Skip syscall + bltz v0, 1f # seccomp failed? Skip syscall - move t0, s0 + move t2, s0 RESTORE_STATIC ld a0, PT_R4(sp) # Restore argument registers ld a1, PT_R5(sp) @@ -142,19 +143,9 @@ trace_a_syscall: ld a5, PT_R9(sp) ld a6, PT_R10(sp) ld a7, PT_R11(sp) # For indirect syscalls - jalr t0 + j syscall_common - li t0, -EMAXERRNO - 1 # error? - sltu t0, t0, v0 - sd t0, PT_R7(sp) # set error flag - beqz t0, 1f - - ld t1, PT_R2(sp) # syscall number - dnegu v0 # error - sd t1, PT_R0(sp) # save it for syscall restarting -1: sd v0, PT_R2(sp) # result - -2: j syscall_exit +1: j syscall_exit /* ------------------------------------------------------------------------ */ -- 2.5.3
