diff options
| -rw-r--r-- | arch/powerpc/kernel/entry_32.S | 4 | ||||
| -rw-r--r-- | arch/powerpc/kernel/entry_64.S | 23 | ||||
| -rw-r--r-- | arch/powerpc/kernel/ptrace.c | 48 |
3 files changed, 58 insertions, 17 deletions
diff --git a/arch/powerpc/kernel/entry_32.S b/arch/powerpc/kernel/entry_32.S index 67ecdf61f4e3..2405631e91a2 100644 --- a/arch/powerpc/kernel/entry_32.S +++ b/arch/powerpc/kernel/entry_32.S @@ -458,6 +458,10 @@ syscall_dotrace: lwz r7,GPR7(r1) lwz r8,GPR8(r1) REST_NVGPRS(r1) + + cmplwi r0,NR_syscalls + /* Return code is already in r3 thanks to do_syscall_trace_enter() */ + bge- ret_from_syscall b syscall_dotrace_cont syscall_exit_work: diff --git a/arch/powerpc/kernel/entry_64.S b/arch/powerpc/kernel/entry_64.S index ee15d3c62e26..a94f155db78e 100644 --- a/arch/powerpc/kernel/entry_64.S +++ b/arch/powerpc/kernel/entry_64.S @@ -151,8 +151,7 @@ END_FW_FTR_SECTION_IFSET(FW_FEATURE_SPLPAR) CURRENT_THREAD_INFO(r11, r1) ld r10,TI_FLAGS(r11) andi. r11,r10,_TIF_SYSCALL_DOTRACE - bne syscall_dotrace -.Lsyscall_dotrace_cont: + bne syscall_dotrace /* does not return */ cmpldi 0,r0,NR_syscalls bge- syscall_enosys @@ -246,22 +245,34 @@ syscall_dotrace: bl save_nvgprs addi r3,r1,STACK_FRAME_OVERHEAD bl do_syscall_trace_enter + /* - * Restore argument registers possibly just changed. - * We use the return value of do_syscall_trace_enter - * for the call number to look up in the table (r0). + * We use the return value of do_syscall_trace_enter() as the syscall + * number. If the syscall was rejected for any reason do_syscall_trace_enter() + * returns an invalid syscall number and the test below against + * NR_syscalls will fail. */ mr r0,r3 + + /* Restore argument registers just clobbered and/or possibly changed. */ ld r3,GPR3(r1) ld r4,GPR4(r1) ld r5,GPR5(r1) ld r6,GPR6(r1) ld r7,GPR7(r1) ld r8,GPR8(r1) + + /* Repopulate r9 and r10 for the system_call path */ addi r9,r1,STACK_FRAME_OVERHEAD CURRENT_THREAD_INFO(r10, r1) ld r10,TI_FLAGS(r10) - b .Lsyscall_dotrace_cont + + cmpldi r0,NR_syscalls + blt+ system_call + + /* Return code is already in r3 thanks to do_syscall_trace_enter() */ + b .Lsyscall_exit + syscall_enosys: li r3,-ENOSYS diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index f21897b42057..7484221bb3f8 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -1762,26 +1762,42 @@ long arch_ptrace(struct task_struct *child, long request, return ret; } -/* - * We must return the syscall number to actually look up in the table. - * This can be -1L to skip running any syscall at all. +/** + * do_syscall_trace_enter() - Do syscall tracing on kernel entry. + * @regs: the pt_regs of the task to trace (current) + * + * Performs various types of tracing on syscall entry. This includes seccomp, + * ptrace, syscall tracepoints and audit. + * + * The pt_regs are potentially visible to userspace via ptrace, so their + * contents is ABI. + * + * One or more of the tracers may modify the contents of pt_regs, in particular + * to modify arguments or even the syscall number itself. + * + * It's also possible that a tracer can choose to reject the system call. In + * that case this function will return an illegal syscall number, and will put + * an appropriate return value in regs->r3. + * + * Return: the (possibly changed) syscall number. */ long do_syscall_trace_enter(struct pt_regs *regs) { - long ret = 0; + bool abort = false; user_exit(); secure_computing_strict(regs->gpr[0]); - if (test_thread_flag(TIF_SYSCALL_TRACE) && - tracehook_report_syscall_entry(regs)) + if (test_thread_flag(TIF_SYSCALL_TRACE)) { /* - * Tracing decided this syscall should not happen. - * We'll return a bogus call number to get an ENOSYS - * error, but leave the original number in regs->gpr[0]. + * The tracer may decide to abort the syscall, if so tracehook + * will return !0. Note that the tracer may also just change + * regs->gpr[0] to an invalid syscall number, that is handled + * below on the exit path. */ - ret = -1L; + abort = tracehook_report_syscall_entry(regs) != 0; + } if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) trace_sys_enter(regs, regs->gpr[0]); @@ -1798,7 +1814,17 @@ long do_syscall_trace_enter(struct pt_regs *regs) regs->gpr[5] & 0xffffffff, regs->gpr[6] & 0xffffffff); - return ret ?: regs->gpr[0]; + if (abort || regs->gpr[0] >= NR_syscalls) { + /* + * If we are aborting explicitly, or if the syscall number is + * now invalid, set the return value to -ENOSYS. + */ + regs->gpr[3] = -ENOSYS; + return -1; + } + + /* Return the possibly modified but valid syscall number */ + return regs->gpr[0]; } void do_syscall_trace_leave(struct pt_regs *regs) |