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seccomp,x86,arm,mips,s390: Remove nr parameter from secure_computing

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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>
This commit is contained in:
Andy Lutomirski
2014-07-21 18:49:14 -07:00
committed by Kees Cook
parent 70c8038dd6
commit a4412fc948
7 changed files with 66 additions and 34 deletions
Download Patch File Download Diff File Expand all files Collapse all files

64
kernel/seccomp.c
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@@ -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>
@@ -172,7 +175,7 @@ static int seccomp_check_filter(struct sock_filter *filter, unsigned int flen)
*
* 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);
struct seccomp_data sd;
@@ -564,10 +567,43 @@ static int mode1_syscalls_32[] = {
};
#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;
/*
@@ -578,23 +614,12 @@ int __secure_computing(int this_syscall)
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) {
@@ -652,9 +677,10 @@ int __secure_computing(int this_syscall)
#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)
{