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authorWill Deacon <will.deacon@arm.com>2014-06-27 17:01:47 +0100
committerRussell King <rmk+kernel@arm.linux.org.uk>2014-06-29 10:29:35 +0100
commit42309ab450b608ddcfafa90e4cfa93a5001ecfba (patch)
treefb60021f23adfdff7d525d88e8b6c50f14f138f0
parent6980c3e2514e5ae36b43ec8302f4920d6e3c9434 (diff)
ARM: 8087/1: ptrace: reload syscall number after secure_computing() check
On the syscall tracing path, we call out to secure_computing() to allow seccomp to check the syscall number being attempted. As part of this, a SIGTRAP may be sent to the tracer and the syscall could be re-written by a subsequent SET_SYSCALL ptrace request. Unfortunately, this new syscall is ignored by the current code unless TIF_SYSCALL_TRACE is also set on the current thread. This patch slightly reworks the enter path of the syscall tracing code so that we always reload the syscall number from current_thread_info()->syscall after the potential ptrace traps. Acked-by: Kees Cook <keescook@chromium.org> Tested-by: Kees Cook <keescook@chromium.org> Signed-off-by: Will Deacon <will.deacon@arm.com> Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>
-rw-r--r--arch/arm/kernel/ptrace.c7
1 files changed, 4 insertions, 3 deletions
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 0dd3b79b15c3..0c27ed6f3f23 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -908,7 +908,7 @@ enum ptrace_syscall_dir {
PTRACE_SYSCALL_EXIT,
};
-static int tracehook_report_syscall(struct pt_regs *regs,
+static void tracehook_report_syscall(struct pt_regs *regs,
enum ptrace_syscall_dir dir)
{
unsigned long ip;
@@ -926,7 +926,6 @@ static int tracehook_report_syscall(struct pt_regs *regs,
current_thread_info()->syscall = -1;
regs->ARM_ip = ip;
- return current_thread_info()->syscall;
}
asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
@@ -938,7 +937,9 @@ asmlinkage int syscall_trace_enter(struct pt_regs *regs, int scno)
return -1;
if (test_thread_flag(TIF_SYSCALL_TRACE))
- scno = tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
+ tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
+
+ scno = current_thread_info()->syscall;
if (test_thread_flag(TIF_SYSCALL_TRACEPOINT))
trace_sys_enter(regs, scno);