diff options
| author | Kees Cook <keescook@chromium.org> | 2016-06-02 19:55:09 -0700 |
|---|---|---|
| committer | Kees Cook <keescook@chromium.org> | 2016-06-14 10:54:46 -0700 |
| commit | 1addc57e111b920f94edb867094ccaa7c1e820b8 (patch) | |
| tree | b8c925e9e6c48739f141e5c871db077d259e24ec /arch | |
| parent | 0208b9445bc031791e589c334a93365cbad008fe (diff) | |
| download | linux-1addc57e111b920f94edb867094ccaa7c1e820b8.tar.bz2 | |
powerpc/ptrace: run seccomp after ptrace
Close the hole where ptrace can change a syscall out from under seccomp.
Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
Diffstat (limited to 'arch')
| -rw-r--r-- | arch/powerpc/kernel/ptrace.c | 44 |
1 files changed, 23 insertions, 21 deletions
diff --git a/arch/powerpc/kernel/ptrace.c b/arch/powerpc/kernel/ptrace.c index ed799e994773..5dc47ebb3840 100644 --- a/arch/powerpc/kernel/ptrace.c +++ b/arch/powerpc/kernel/ptrace.c @@ -1788,7 +1788,7 @@ static int do_seccomp(struct pt_regs *regs) /* * The syscall was allowed by seccomp, restore the register - * state to what ptrace and audit expect. + * state to what audit expects. * Note that we use orig_gpr3, which means a seccomp tracer can * modify the first syscall parameter (in orig_gpr3) and also * allow the syscall to proceed. @@ -1822,22 +1822,25 @@ static inline int do_seccomp(struct pt_regs *regs) { return 0; } */ long do_syscall_trace_enter(struct pt_regs *regs) { - bool abort = false; - user_exit(); + /* + * 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. + */ + if (test_thread_flag(TIF_SYSCALL_TRACE) && + tracehook_report_syscall_entry(regs)) + goto skip; + + /* Run seccomp after ptrace; allow it to set gpr[3]. */ if (do_seccomp(regs)) return -1; - if (test_thread_flag(TIF_SYSCALL_TRACE)) { - /* - * 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. - */ - abort = tracehook_report_syscall_entry(regs) != 0; - } + /* Avoid trace and audit when syscall is invalid. */ + if (regs->gpr[0] >= NR_syscalls) + goto skip; if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT))) trace_sys_enter(regs, regs->gpr[0]); @@ -1854,17 +1857,16 @@ long do_syscall_trace_enter(struct pt_regs *regs) regs->gpr[5] & 0xffffffff, regs->gpr[6] & 0xffffffff); - 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]; + +skip: + /* + * 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; } void do_syscall_trace_leave(struct pt_regs *regs) |