BACKPORT: seccomp,x86,arm,mips,s390: Remove nr parameter from secure_computing
The secure_computing function took a syscall number parameter, but
it only paid any attention to that parameter if seccomp mode 1 was
enabled. Rather than coming up with a kludge to get the parameter
to work in mode 2, just remove the parameter.
To avoid churn in arches that don't have seccomp filters (and may
not even support syscall_get_nr right now), this leaves the
parameter in secure_computing_strict, which is now a real function.
For ARM, this is a bit ugly due to the fact that ARM conditionally
supports seccomp filters. Fixing that would probably only be a
couple of lines of code, but it should be coordinated with the audit
maintainers.
This will be a slight slowdown on some arches. The right fix is to
pass in all of seccomp_data instead of trying to make just the
syscall nr part be fast.
This is a prerequisite for making two-phase seccomp work cleanly.
Cc: Russell King <linux@arm.linux.org.uk>
Cc: linux-arm-kernel@lists.infradead.org
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: linux-mips@linux-mips.org
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: linux-s390@vger.kernel.org
Cc: x86@kernel.org
Cc: Kees Cook <keescook@chromium.org>
Signed-off-by: Andy Lutomirski <luto@amacapital.net>
Signed-off-by: Kees Cook <keescook@chromium.org>
Bug: 28020023
Patchset: seccomp
(cherry picked from kernel/msm commit 7ae89c27e2fa2ef24e374400d9e19aa4f1192f81)
Signed-off-by: Kees Cook <keescook@google.com>
Change-Id: I9ada75ad967c3814fd0657077eee5a709d1549e9
diff --git a/arch/arm/kernel/ptrace.c b/arch/arm/kernel/ptrace.c
index 6954df5..23ae122 100644
--- a/arch/arm/kernel/ptrace.c
+++ b/arch/arm/kernel/ptrace.c
@@ -941,8 +941,13 @@
current_thread_info()->syscall = scno;
/* Do the secure computing check first; failures should be fast. */
- if (secure_computing(scno) == -1)
+#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
+ if (secure_computing() == -1)
return -1;
+#else
+ /* XXX: remove this once OABI gets fixed */
+ secure_computing_strict(scno);
+#endif
if (test_thread_flag(TIF_SYSCALL_TRACE))
tracehook_report_syscall(regs, PTRACE_SYSCALL_ENTER);
diff --git a/arch/s390/kernel/ptrace.c b/arch/s390/kernel/ptrace.c
index a314c57..53e3bd1 100644
--- a/arch/s390/kernel/ptrace.c
+++ b/arch/s390/kernel/ptrace.c
@@ -751,7 +751,7 @@
long ret = 0;
/* Do the secure computing check first. */
- if (secure_computing(regs->gprs[2])) {
+ if (secure_computing()) {
/* seccomp failures shouldn't expose any additional code. */
ret = -1;
goto out;
diff --git a/arch/x86/kernel/ptrace.c b/arch/x86/kernel/ptrace.c
index 29a8120..25145db 100644
--- a/arch/x86/kernel/ptrace.c
+++ b/arch/x86/kernel/ptrace.c
@@ -1505,7 +1505,7 @@
regs->flags |= X86_EFLAGS_TF;
/* do the secure computing check first */
- if (secure_computing(regs->orig_ax)) {
+ if (secure_computing()) {
/* seccomp failures shouldn't expose any additional code. */
ret = -1L;
goto out;
diff --git a/arch/x86/kernel/vsyscall_64.c b/arch/x86/kernel/vsyscall_64.c
index 9a907a6..75b0852 100644
--- a/arch/x86/kernel/vsyscall_64.c
+++ b/arch/x86/kernel/vsyscall_64.c
@@ -260,7 +260,7 @@
*/
regs->orig_ax = syscall_nr;
regs->ax = -ENOSYS;
- tmp = secure_computing(syscall_nr);
+ tmp = secure_computing();
if ((!tmp && regs->orig_ax != syscall_nr) || regs->ip != address) {
warn_bad_vsyscall(KERN_DEBUG, regs,
"seccomp tried to change syscall nr or ip");
diff --git a/include/linux/seccomp.h b/include/linux/seccomp.h
index 9687691..c7275ce 100644
--- a/include/linux/seccomp.h
+++ b/include/linux/seccomp.h
@@ -27,19 +27,17 @@
struct seccomp_filter *filter;
};
-extern int __secure_computing(int);
-static inline int secure_computing(int this_syscall)
+#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
+extern int __secure_computing(void);
+static inline int secure_computing(void)
{
if (unlikely(test_thread_flag(TIF_SECCOMP)))
- return __secure_computing(this_syscall);
+ return __secure_computing();
return 0;
}
-
-/* A wrapper for architectures supporting only SECCOMP_MODE_STRICT. */
-static inline void secure_computing_strict(int this_syscall)
-{
- BUG_ON(secure_computing(this_syscall) != 0);
-}
+#else
+extern void secure_computing_strict(int this_syscall);
+#endif
extern long prctl_get_seccomp(void);
extern long prctl_set_seccomp(unsigned long, char __user *);
@@ -56,8 +54,11 @@
struct seccomp { };
struct seccomp_filter { };
-static inline int secure_computing(int this_syscall) { return 0; }
+#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
+static inline int secure_computing(void) { return 0; }
+#else
static inline void secure_computing_strict(int this_syscall) { return; }
+#endif
static inline long prctl_get_seccomp(void)
{
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 1fbb1a2..0208bbe 100644
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -23,8 +23,11 @@
/* #define SECCOMP_DEBUG 1 */
-#ifdef CONFIG_SECCOMP_FILTER
+#ifdef CONFIG_HAVE_ARCH_SECCOMP_FILTER
#include <asm/syscall.h>
+#endif
+
+#ifdef CONFIG_SECCOMP_FILTER
#include <linux/filter.h>
#include <linux/pid.h>
#include <linux/ptrace.h>
@@ -201,7 +204,7 @@
*
* Returns valid seccomp BPF response codes.
*/
-static u32 seccomp_run_filters(int syscall)
+static u32 seccomp_run_filters(void)
{
struct seccomp_filter *f = ACCESS_ONCE(current->seccomp.filter);
u32 ret = SECCOMP_RET_ALLOW;
@@ -565,10 +568,43 @@
};
#endif
-int __secure_computing(int this_syscall)
+static void __secure_computing_strict(int this_syscall)
{
+ int *syscall_whitelist = mode1_syscalls;
+#ifdef CONFIG_COMPAT
+ if (is_compat_task())
+ syscall_whitelist = mode1_syscalls_32;
+#endif
+ do {
+ if (*syscall_whitelist == this_syscall)
+ return;
+ } while (*++syscall_whitelist);
+
+#ifdef SECCOMP_DEBUG
+ dump_stack();
+#endif
+ audit_seccomp(this_syscall, SIGKILL, SECCOMP_RET_KILL);
+ do_exit(SIGKILL);
+}
+
+#ifndef CONFIG_HAVE_ARCH_SECCOMP_FILTER
+void secure_computing_strict(int this_syscall)
+{
+ int mode = current->seccomp.mode;
+
+ if (mode == 0)
+ return;
+ else if (mode == SECCOMP_MODE_STRICT)
+ __secure_computing_strict(this_syscall);
+ else
+ BUG();
+}
+#else
+int __secure_computing(void)
+{
+ struct pt_regs *regs = task_pt_regs(current);
+ int this_syscall = syscall_get_nr(current, regs);
int exit_sig = 0;
- int *syscall;
u32 ret;
/*
@@ -579,23 +615,12 @@
switch (current->seccomp.mode) {
case SECCOMP_MODE_STRICT:
- syscall = mode1_syscalls;
-#ifdef CONFIG_COMPAT
- if (is_compat_task())
- syscall = mode1_syscalls_32;
-#endif
- do {
- if (*syscall == this_syscall)
- return 0;
- } while (*++syscall);
- exit_sig = SIGKILL;
- ret = SECCOMP_RET_KILL;
- break;
+ __secure_computing_strict(this_syscall);
+ return 0;
#ifdef CONFIG_SECCOMP_FILTER
case SECCOMP_MODE_FILTER: {
int data;
- struct pt_regs *regs = task_pt_regs(current);
- ret = seccomp_run_filters(this_syscall);
+ ret = seccomp_run_filters();
data = ret & SECCOMP_RET_DATA;
ret &= SECCOMP_RET_ACTION;
switch (ret) {
@@ -653,9 +678,10 @@
#ifdef CONFIG_SECCOMP_FILTER
skip:
audit_seccomp(this_syscall, exit_sig, ret);
-#endif
return -1;
+#endif
}
+#endif /* CONFIG_HAVE_ARCH_SECCOMP_FILTER */
long prctl_get_seccomp(void)
{
