amiss_wire/
action.rs

1use crate::controls::ConstraintPlatform;
2
3/// The platform an executable's own header declares. The bootstrap derives
4/// the target this way, from the protected artifact bytes, never from an
5/// environment value or a candidate field, and requires equality with the
6/// constraint, the manifest row, and the sandbox verification.
7#[must_use]
8pub fn executable_platform(bytes: &[u8]) -> Option<ConstraintPlatform> {
9    elf_platform(bytes)
10        .or_else(|| mach_o_platform(bytes))
11        .or_else(|| pe_platform(bytes))
12}
13
14/// ELF: `7f 45 4c 46`, 64-bit little-endian only, with `e_machine` at offset
15/// 18 naming `x86-64` (0x3e) or `AArch64` (0xb7).
16fn elf_platform(bytes: &[u8]) -> Option<ConstraintPlatform> {
17    if bytes.get(..4) != Some(&[0x7f, b'E', b'L', b'F']) {
18        return None;
19    }
20    if bytes.get(4) != Some(&2) || bytes.get(5) != Some(&1) {
21        return None;
22    }
23    match bytes.get(18..20)? {
24        [0x3e, 0x00] => Some(ConstraintPlatform::LinuxX8664),
25        [0xb7, 0x00] => Some(ConstraintPlatform::LinuxAarch64),
26        _ => None,
27    }
28}
29
30/// Mach-O: the 64-bit little-endian magic `cf fa ed fe`, with `cputype` at
31/// offset 4 naming `x86-64` (0x01000007) or `ARM64` (0x0100000c).
32fn mach_o_platform(bytes: &[u8]) -> Option<ConstraintPlatform> {
33    if bytes.get(..4) != Some(&[0xcf, 0xfa, 0xed, 0xfe]) {
34        return None;
35    }
36    match bytes.get(4..8)? {
37        [0x07, 0x00, 0x00, 0x01] => Some(ConstraintPlatform::MacosX8664),
38        [0x0c, 0x00, 0x00, 0x01] => Some(ConstraintPlatform::MacosAarch64),
39        _ => None,
40    }
41}
42
43/// PE: `MZ`, the PE signature at the offset stored at `0x3c`, and the COFF
44/// machine field naming AMD64 (0x8664) or ARM64 (0xaa64).
45fn pe_platform(bytes: &[u8]) -> Option<ConstraintPlatform> {
46    if bytes.get(..2) != Some(b"MZ") {
47        return None;
48    }
49    let header = bytes.get(0x3c..0x40)?;
50    let [a, b, c, d] = header else { return None };
51    let offset = usize::try_from(u32::from_le_bytes([*a, *b, *c, *d])).ok()?;
52    if bytes.get(offset..offset.checked_add(4)?) != Some(b"PE\0\0") {
53        return None;
54    }
55    let machine = offset.checked_add(4)?;
56    match bytes.get(machine..machine.checked_add(2)?)? {
57        [0x64, 0x86] => Some(ConstraintPlatform::WindowsX8664),
58        [0x64, 0xaa] => Some(ConstraintPlatform::WindowsAarch64),
59        _ => None,
60    }
61}
62
63/// The platform of the running process, taken from the protected runtime's
64/// own build target rather than any ambient value. `None` where the closed
65/// six-value table has no row, which the bootstrap treats as unsupported.
66#[must_use]
67pub const fn host_platform() -> Option<ConstraintPlatform> {
68    match (
69        cfg!(target_os = "linux"),
70        cfg!(target_os = "macos"),
71        cfg!(target_os = "windows"),
72    ) {
73        (true, _, _) => arch(
74            ConstraintPlatform::LinuxX8664,
75            ConstraintPlatform::LinuxAarch64,
76        ),
77        (_, true, _) => arch(
78            ConstraintPlatform::MacosX8664,
79            ConstraintPlatform::MacosAarch64,
80        ),
81        (_, _, true) => arch(
82            ConstraintPlatform::WindowsX8664,
83            ConstraintPlatform::WindowsAarch64,
84        ),
85        _ => None,
86    }
87}
88
89const fn arch(
90    x86_64: ConstraintPlatform,
91    aarch64: ConstraintPlatform,
92) -> Option<ConstraintPlatform> {
93    if cfg!(target_arch = "x86_64") {
94        Some(x86_64)
95    } else if cfg!(target_arch = "aarch64") {
96        Some(aarch64)
97    } else {
98        None
99    }
100}
amiss_wire/action.rs

amiss_wire/
action.rs
