[PATCH 5.7 194/265] s390/seccomp: pass syscall arguments via seccomp_data

Sasha Levin
2020-06-29T22:04:48Z

From: Sven Schnelle <svens@linux.ibm.com>

[ Upstream commit 664f5f8de825648d1d31f6f5652e3cd117c77b50 ]

Use __secure_computing() and pass the register data via
seccomp_data so secure computing doesn't have to fetch it
again.

Signed-off-by: Sven Schnelle <svens@linux.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Sasha Levin <sashal@kernel.org>
---
arch/s390/kernel/ptrace.c | 31 ++++++++++++++++++++++++++-----
1 file changed, 26 insertions(+), 5 deletions(-)

diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index 58faa12542a1b..9eee345568890 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -839,6 +839,9 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
{
unsigned long mask = -1UL;

+ if (is_compat_task())
+ mask = 0xffffffff;
+
/*
* The sysc_tracesys code in entry.S stored the system
* call number to gprs[2].
@@ -855,17 +858,35 @@ asmlinkage long do_syscall_trace_enter(struct pt_regs *regs)
return -1;
}

+#ifdef CONFIG_SECCOMP
/* Do the secure computing check after ptrace. */
- if (secure_computing()) {
- /* seccomp failures shouldn't expose any additional code. */
- return -1;
+ if (unlikely(test_thread_flag(TIF_SECCOMP))) {
+ struct seccomp_data sd;
+
+ if (is_compat_task()) {
+ sd.instruction_pointer = regs->psw.addr & 0x7fffffff;
+ sd.arch = AUDIT_ARCH_S390;
+ } else {
+ sd.instruction_pointer = regs->psw.addr;
+ sd.arch = AUDIT_ARCH_S390X;
+ }
+
+ sd.nr = regs->gprs[2] & 0xffff;
+ sd.args[0] = regs->orig_gpr2 & mask;
+ sd.args[1] = regs->gprs[3] & mask;
+ sd.args[2] = regs->gprs[4] & mask;
+ sd.args[3] = regs->gprs[5] & mask;
+ sd.args[4] = regs->gprs[6] & mask;
+ sd.args[5] = regs->gprs[7] & mask;
+
+ if (__secure_computing(&sd) == -1)
+ return -1;
}
+#endif /* CONFIG_SECCOMP */

if (unlikely(test_thread_flag(TIF_SYSCALL_TRACEPOINT)))
trace_sys_enter(regs, regs->gprs[2]);

- if (is_compat_task())
- mask = 0xffffffff;

audit_syscall_entry(regs->gprs[2], regs->orig_gpr2 & mask,
regs->gprs[3] &mask, regs->gprs[4] &mask,
--
2.25.1