_strap_gate.nx source

1// _strap_gate.nx -- LOCK for S-MODE TRAP DELEGATION + sret (X-PAGE-STRAP-001). NO mocks. 2// Proves the real-OS trap path: a U-mode ecall is DELEGATED (medeleg) to the S-MODE kernel handler 3// (stvec), which handles it and returns with sret -- vs the default M-mode monitor. Drives nx_strap_emit: 4// T1 delegated : medeleg=0x100 (ecall-from-U) -> trap to S-mode (stvec) -> "STRAP" -> sret -> U halts 5// (reaching the finisher proves sret returned to U-mode) 6// T2 control : medeleg=0 -> trap to M-mode (mtvec) -> "MTRAP", and STRAP never prints 7// T1 vs T2 differ ONLY in medeleg -> proves the delegation is what routes the trap to S-mode. 8// GREEN only if T1 && T2. Evidence -> knowledge/status/priv.log (STRAPGATE). license_tier: ORIGINAL 9import "nx_syscalls.nx" 10 11const ST_EMIT: *u8 = "_offc/nx_strap_emit.elf" 12const ST_SOV: *u8 = "_offc/nx_boot_run_sov.elf" 13 14func g_p(s: *u8) -> i64 { var n: i64=0; while s[n]!=(0 as u8){n=n+1} sys_write(1,s,n); return 0 } 15func g_fp(fd: i64, s: *u8) -> i64 { var n: i64=0; while s[n]!=(0 as u8){n=n+1} sys_write(fd,s,n); return 0 } 16func g_fn(fd: i64, v: i64) -> i64 { let bb: *u8=sys_mmap(28); var m: i64=v; if m<0{m=0-m}; let t: *u8=sys_mmap(28); var k: i64=0; if m==0{t[0]=48;k=1}; while m>0{t[k]=(48+(m%10)) as u8;m=m/10;k=k+1}; var i: i64=0; while i<k{bb[i]=t[k-1-i];i=i+1}; sys_write(fd,bb,k); return 0 } 17 18func g_run(prog: *u8, a1: *u8, a2: *u8, outpath: *u8) -> i64 { 19 let pid: i64 = sys_fork() 20 if pid == 0 { 21 if outpath != (0 as *u8) { let ofd: i64 = sys_openat_wr(outpath, 0x1a4); if ofd >= 0 { sys_dup3(ofd, 1, 0); sys_dup3(ofd, 2, 0) } } 22 let argv: *i64 = sys_mmap(32) as *i64 23 argv[0] = prog as i64 24 var k: i64 = 1 25 if a1 != (0 as *u8) { argv[k] = a1 as i64; k = k + 1 } 26 if a2 != (0 as *u8) { argv[k] = a2 as i64; k = k + 1 } 27 argv[k] = 0 28 let envp: *i64 = sys_mmap(16) as *i64 29 envp[0] = "PATH=/usr/bin:/bin" as *u8 as i64; envp[1] = 0 30 sys_execve(prog, argv, envp) 31 sys_exit(127) 32 } 33 let st: *i64 = sys_mmap(16) as *i64 34 sys_wait4(pid, st, 0) 35 return (st[0] >> 8) & 0xff 36} 37func g_read(path: *u8, buf: *u8, cap: i64) -> i64 { 38 let fd: i64 = sys_openat_rd(path) 39 if fd < 0 { return 0 } 40 var n: i64 = 0 41 var go: i64 = 1 42 while go == 1 { let r: i64 = sys_read(fd, (buf as i64 + n) as *u8, cap - 1 - n); if r <= 0 { go = 0 } else { n = n + r } if n >= cap - 1 { go = 0 } } 43 sys_close(fd) 44 return n 45} 46func g_has(buf: *u8, n: i64, pat: *u8, pl: i64) -> i64 { 47 if pl <= 0 { return 0 } 48 var i: i64 = 0 49 while i + pl <= n { var k: i64=0; var hit: i64=1; while k<pl { if buf[i+k]!=pat[k]{hit=0;k=pl}else{k=k+1} } if hit==1 { return 1 } i=i+1 } 50 return 0 51} 52func g_case(medeleg: *u8, binp: *u8, txt: *u8, buf: *u8) -> i64 { 53 g_run(ST_EMIT, medeleg, binp, "/tmp/_st_emit.out" as *u8) 54 g_run(ST_SOV, binp, 0 as *u8, txt) 55 return g_read(txt, buf, 65536) 56} 57func g_row(name: *u8, pass: i64) -> i64 { g_p(" " as *u8); g_p(name); if pass==1 { g_p(" PASS\n" as *u8) } else { g_p(" FAIL\n" as *u8) } return 0 } 58 59func main() -> i64 { 60 let b: *u8 = sys_mmap(65536) 61 62 // T1 delegated: ecall-from-U traps to S-mode -> STRAP, sret returns to U -> finisher 63 var n: i64 = g_case("0x100" as *u8, "/tmp/_st_del.bin" as *u8, "/tmp/_st_del.txt" as *u8, b) 64 var t1: i64 = 0 65 if g_has(b, n, "STRAP" as *u8, 5) == 1 { if g_has(b, n, "BOOTSOV verdict=GREEN" as *u8, 21) == 1 { t1 = 1 } } 66 67 // T2 control: no delegation -> ecall traps to M-mode -> MTRAP, no STRAP 68 n = g_case("0x0" as *u8, "/tmp/_st_m.bin" as *u8, "/tmp/_st_m.txt" as *u8, b) 69 var t2: i64 = 0 70 if g_has(b, n, "STRAP" as *u8, 5) == 0 { if g_has(b, n, "MTRAP" as *u8, 5) == 1 { t2 = 1 } } 71 72 var ok: i64 = 0 73 if t1 == 1 { if t2 == 1 { ok = 1 } } 74 75 g_p("STRAP gate (S-mode trap delegation + sret)\n" as *u8) 76 g_row("T1 delegated->S-mode (STRAP+sret)" as *u8, t1) 77 g_row("T2 control->M-mode (MTRAP,!STRAP)" as *u8, t2) 78 79 let lf: i64 = sys_openat_append("knowledge/status/priv.log" as *u8, 0x1a4) 80 if ok == 1 { 81 g_p("STRAPGATE verdict=GREEN keystone=s-mode-trap-delegation-sret probe=strap medeleg-delegates-ecall->stvec(S-mode) sret-returns-to-U control=medeleg0->mtvec(M-mode)\n" as *u8) 82 if lf >= 0 { g_fp(lf, "STRAPGATE verdict=GREEN keystone=s-mode-trap-delegation-sret probe=strap delegation+sret + M-mode-control epoch=" as *u8); g_fn(lf, sys_now_realtime_sec()); g_fp(lf, "\n" as *u8); sys_close(lf) } 83 sys_exit(0); return 0 84 } 85 g_p("STRAPGATE verdict=RED (t1=" as *u8); g_fn(1, t1); g_p(" t2=" as *u8); g_fn(1, t2); g_p(")\n" as *u8) 86 if lf >= 0 { g_fp(lf, "STRAPGATE verdict=RED t1=" as *u8); g_fn(lf, t1); g_fp(lf, " t2=" as *u8); g_fn(lf, t2); g_fp(lf, "\n" as *u8); sys_close(lf) } 87 sys_exit(1) 88 return 1 89}