Add SECCOMP to xtensa Kconfig, select HAVE_ARCH_SECCOMP_FILTER, add TIF_SECCOMP and call secure_computing from do_syscall_trace_enter.
Signed-off-by: Max Filippov jcmvbkbc@gmail.com --- .../seccomp/seccomp-filter/arch-support.txt | 2 +- arch/xtensa/Kconfig | 15 +++++++++++++++ arch/xtensa/include/asm/Kbuild | 1 + arch/xtensa/include/asm/thread_info.h | 5 ++++- arch/xtensa/kernel/ptrace.c | 4 +++- 5 files changed, 24 insertions(+), 3 deletions(-)
diff --git a/Documentation/features/seccomp/seccomp-filter/arch-support.txt b/Documentation/features/seccomp/seccomp-filter/arch-support.txt index c7b837f735b1..7b3ec8ea174a 100644 --- a/Documentation/features/seccomp/seccomp-filter/arch-support.txt +++ b/Documentation/features/seccomp/seccomp-filter/arch-support.txt @@ -30,5 +30,5 @@ | um: | ok | | unicore32: | TODO | | x86: | ok | - | xtensa: | TODO | + | xtensa: | ok | ----------------------- diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig index a7def0991a01..a461ee051e73 100644 --- a/arch/xtensa/Kconfig +++ b/arch/xtensa/Kconfig @@ -24,6 +24,7 @@ config XTENSA select HAVE_ARCH_AUDITSYSCALL select HAVE_ARCH_JUMP_LABEL if !XIP_KERNEL select HAVE_ARCH_KASAN if MMU && !XIP_KERNEL + select HAVE_ARCH_SECCOMP_FILTER select HAVE_ARCH_TRACEHOOK select HAVE_COPY_THREAD_TLS select HAVE_DEBUG_KMEMLEAK @@ -217,6 +218,20 @@ config HOTPLUG_CPU
Say N if you want to disable CPU hotplug.
+config SECCOMP + bool + prompt "Enable seccomp to safely compute untrusted bytecode" + help + This kernel feature is useful for number crunching applications + that may need to compute untrusted bytecode during their + execution. By using pipes or other transports made available to + the process as file descriptors supporting the read/write + syscalls, it's possible to isolate those applications in + their own address space using seccomp. Once seccomp is + enabled via prctl(PR_SET_SECCOMP), it cannot be disabled + and the task is only allowed to execute a few safe syscalls + defined by each seccomp mode. + config FAST_SYSCALL_XTENSA bool "Enable fast atomic syscalls" default n diff --git a/arch/xtensa/include/asm/Kbuild b/arch/xtensa/include/asm/Kbuild index 9718e9593564..c59c42a1221a 100644 --- a/arch/xtensa/include/asm/Kbuild +++ b/arch/xtensa/include/asm/Kbuild @@ -7,4 +7,5 @@ generic-y += mcs_spinlock.h generic-y += param.h generic-y += qrwlock.h generic-y += qspinlock.h +generic-y += seccomp.h generic-y += user.h diff --git a/arch/xtensa/include/asm/thread_info.h b/arch/xtensa/include/asm/thread_info.h index c49cc4a1f39a..8918f0f20c53 100644 --- a/arch/xtensa/include/asm/thread_info.h +++ b/arch/xtensa/include/asm/thread_info.h @@ -112,6 +112,7 @@ static inline struct thread_info *current_thread_info(void) #define TIF_NOTIFY_RESUME 7 /* callback before returning to user */ #define TIF_DB_DISABLED 8 /* debug trap disabled for syscall */ #define TIF_SYSCALL_AUDIT 9 /* syscall auditing active */ +#define TIF_SECCOMP 10 /* secure computing */
#define _TIF_SYSCALL_TRACE (1<<TIF_SYSCALL_TRACE) #define _TIF_SIGPENDING (1<<TIF_SIGPENDING) @@ -119,9 +120,11 @@ static inline struct thread_info *current_thread_info(void) #define _TIF_SINGLESTEP (1<<TIF_SINGLESTEP) #define _TIF_SYSCALL_TRACEPOINT (1<<TIF_SYSCALL_TRACEPOINT) #define _TIF_SYSCALL_AUDIT (1<<TIF_SYSCALL_AUDIT) +#define _TIF_SECCOMP (1<<TIF_SECCOMP)
#define _TIF_WORK_MASK (_TIF_SYSCALL_TRACE | _TIF_SINGLESTEP | \ - _TIF_SYSCALL_TRACEPOINT | _TIF_SYSCALL_AUDIT) + _TIF_SYSCALL_TRACEPOINT | \ + _TIF_SYSCALL_AUDIT | _TIF_SECCOMP)
#define THREAD_SIZE KERNEL_STACK_SIZE #define THREAD_SIZE_ORDER (KERNEL_STACK_SHIFT - PAGE_SHIFT) diff --git a/arch/xtensa/kernel/ptrace.c b/arch/xtensa/kernel/ptrace.c index 437b4297948d..ce4a32bd2294 100644 --- a/arch/xtensa/kernel/ptrace.c +++ b/arch/xtensa/kernel/ptrace.c @@ -22,6 +22,7 @@ #include <linux/regset.h> #include <linux/sched.h> #include <linux/sched/task_stack.h> +#include <linux/seccomp.h> #include <linux/security.h> #include <linux/signal.h> #include <linux/smp.h> @@ -559,7 +560,8 @@ int do_syscall_trace_enter(struct pt_regs *regs) return 0; }
- if (regs->syscall == NO_SYSCALL) { + if (regs->syscall == NO_SYSCALL || + secure_computing() == -1) { do_syscall_trace_leave(regs); return 0; }