Update the syscall number after each PTRACE_SETREGS on ORIG_*AX.
This is needed to get the potentially altered syscall number in the
seccomp filters after RET_TRACE.
This fix four seccomp_bpf tests:
> [ RUN ] TRACE_syscall.skip_after_RET_TRACE
> seccomp_bpf.c:1560:TRACE_syscall.skip_after_RET_TRACE:Expected -1
> (18446744073709551615) == syscall(39) (26)
> seccomp_bpf.c:1561:TRACE_syscall.skip_after_RET_TRACE:Expected 1 (1) ==
> (*__errno_location ()) (22)
> [ FAIL ] TRACE_syscall.skip_after_RET_TRACE
> [ RUN ] TRACE_syscall.kill_after_RET_TRACE
> TRACE_syscall.kill_after_RET_TRACE: Test exited normally instead of by signal
> (code: 1)
> [ FAIL ] TRACE_syscall.kill_after_RET_TRACE
> [ RUN ] TRACE_syscall.skip_after_ptrace
> seccomp_bpf.c:1622:TRACE_syscall.skip_after_ptrace:Expected -1
> (18446744073709551615) == syscall(39) (26)
> seccomp_bpf.c:1623:TRACE_syscall.skip_after_ptrace:Expected 1 (1) ==
> (*__errno_location ()) (22)
> [ FAIL ] TRACE_syscall.skip_after_ptrace
> [ RUN ] TRACE_syscall.kill_after_ptrace
> TRACE_syscall.kill_after_ptrace: Test exited normally instead of by signal
> (code: 1)
> [ FAIL ] TRACE_syscall.kill_after_ptrace
Fixes: 26703c636c1f ("um/ptrace: run seccomp after ptrace")
Signed-off-by: Mickaël Salaün <m...@digikod.net>
Acked-by: Kees Cook <keesc...@chromium.org>
Cc: Jeff Dike <jd...@addtoit.com>
Cc: Richard Weinberger <rich...@nod.at>
Cc: James Morris <jmor...@namei.org>
Cc: user-mode-linux-de...@lists.sourceforge.net
---
arch/um/kernel/skas/syscall.c | 5 -----
arch/x86/um/ptrace_32.c | 3 +++
arch/x86/um/ptrace_64.c | 4 ++++
3 files changed, 7 insertions(+), 5 deletions(-)
diff --git a/arch/um/kernel/skas/syscall.c b/arch/um/kernel/skas/syscall.c
index 0728fee94398..b783ac87d98a 100644
--- a/arch/um/kernel/skas/syscall.c
+++ b/arch/um/kernel/skas/syscall.c
@@ -27,12 +27,7 @@ void handle_syscall(struct uml_pt_regs *r)
if (secure_computing(NULL) == -1)
goto out;
- /* Update the syscall number after orig_ax has potentially been updated
- * with ptrace.
- */
- UPT_SYSCALL_NR(r) = PT_SYSCALL_NR(r->gp);
syscall = UPT_SYSCALL_NR(r);
-
if (syscall >= 0 && syscall <= __NR_syscall_max)
PT_REGS_SET_SYSCALL_RETURN(regs,
EXECUTE_SYSCALL(syscall, regs));
diff --git a/arch/x86/um/ptrace_32.c b/arch/x86/um/ptrace_32.c
index ebd4dd6ef73b..a7ef7b131e25 100644
--- a/arch/x86/um/ptrace_32.c
+++ b/arch/x86/um/ptrace_32.c
@@ -84,7 +84,10 @@ int putreg(struct task_struct *child, int regno, unsigned
long value)
case EAX:
case EIP:
case UESP:
+ break;
case ORIG_EAX:
+ /* Update the syscall number. */
+ UPT_SYSCALL_NR(&child->thread.regs.regs) = value;
break;
case FS:
if (value && (value & 3) != 3)
diff --git a/arch/x86/um/ptrace_64.c b/arch/x86/um/ptrace_64.c
index faab418876ce..0b5c184dd5b3 100644
--- a/arch/x86/um/ptrace_64.c
+++ b/arch/x86/um/ptrace_64.c
@@ -78,7 +78,11 @@ int putreg(struct task_struct *child, int regno, unsigned
long value)
case RSI:
case RDI:
case RBP:
+ break;
+
case ORIG_RAX:
+ /* Update the syscall number. */
+ UPT_SYSCALL_NR(&child->thread.regs.regs) = value;
break;
case FS:
--
2.8.1
