1 /* 2 * linux/kernel/seccomp.c 3 * 4 * Copyright 2004-2005 Andrea Arcangeli <andrea@cpushare.com> 5 * 6 * This defines a simple but solid secure-computing mode. 7 */ 8 9 #include <linux/seccomp.h> 10 #include <linux/sched.h> 11 12 /* #define SECCOMP_DEBUG 1 */ 13 14 /* 15 * Secure computing mode 1 allows only read/write/exit/sigreturn. 16 * To be fully secure this must be combined with rlimit 17 * to limit the stack allocations too. 18 */ 19 static int mode1_syscalls[] = { 20 __NR_seccomp_read, __NR_seccomp_write, __NR_seccomp_exit, __NR_seccomp_sigreturn, 21 0, /* null terminated */ 22 }; 23 24 #ifdef TIF_32BIT 25 static int mode1_syscalls_32[] = { 26 __NR_seccomp_read_32, __NR_seccomp_write_32, __NR_seccomp_exit_32, __NR_seccomp_sigreturn_32, 27 0, /* null terminated */ 28 }; 29 #endif 30 31 void __secure_computing(int this_syscall) 32 { 33 int mode = current->seccomp.mode; 34 int * syscall; 35 36 switch (mode) { 37 case 1: 38 syscall = mode1_syscalls; 39 #ifdef TIF_32BIT 40 if (test_thread_flag(TIF_32BIT)) 41 syscall = mode1_syscalls_32; 42 #endif 43 do { 44 if (*syscall == this_syscall) 45 return; 46 } while (*++syscall); 47 break; 48 default: 49 BUG(); 50 } 51 52 #ifdef SECCOMP_DEBUG 53 dump_stack(); 54 #endif 55 do_exit(SIGKILL); 56 } 57