/rust/registry/src/index.crates.io-1949cf8c6b5b557f/ring-0.17.14/src/arithmetic/ffi.rs

Source
// Copyright 2024-2025 Brian Smith.
//
// Permission to use, copy, modify, and/or distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

use super::{inout::AliasingSlices3, n0::N0, LimbSliceError, MAX_LIMBS, MIN_LIMBS};
use crate::{c, limb::Limb, polyfill::usize_from_u32};
use core::{mem::size_of, num::NonZeroUsize};

const _MAX_LIMBS_ADDRESSES_MEMORY_SAFETY_ISSUES: () = {
    // BoringSSL's limit: 8 kiloBYTES.
    const BN_MONTGOMERY_MAX_WORDS: usize = (8 * 1092) / size_of::<Limb>();
    assert!(MAX_LIMBS <= BN_MONTGOMERY_MAX_WORDS);

    // Some 64-bit assembly implementations were written to take `len` as a
    // `c_int`, so they zero out the undefined top half of `len` to convert it
    // to a `usize`. But, others don't.
    assert!(MAX_LIMBS <= usize_from_u32(u32::MAX));
};

macro_rules! bn_mul_mont_ffi {
    ( $in_out:expr, $n:expr, $n0:expr, $cpu:expr,
      unsafe { ($MIN_LEN:expr, $MOD_LEN:expr, $Cpu:ty) => $f:ident }) => {{
        use crate::{c, limb::Limb};
        prefixed_extern! {
            // `r` and/or 'a' and/or 'b' may alias.
            // XXX: BoringSSL declares these functions to return `int`.
            fn $f(
                r: *mut Limb,
                a: *const Limb,
                b: *const Limb,
                n: *const Limb,
                n0: &N0,
                len: c::NonZero_size_t,
            );
        }
        unsafe {
            crate::arithmetic::ffi::bn_mul_mont_ffi::<$Cpu, { $MIN_LEN }, { $MOD_LEN }>(
                $in_out, $n, $n0, $cpu, $f,
            )
        }
    }};
}

#[inline]
pub(super) unsafe fn bn_mul_mont_ffi<Cpu, const LEN_MIN: usize, const LEN_MOD: usize>(
    in_out: impl AliasingSlices3<Limb>,
    n: &[Limb],
    n0: &N0,
    cpu: Cpu,
    f: unsafe extern "C" fn(
        r: *mut Limb,
        a: *const Limb,
        b: *const Limb,
        n: *const Limb,
        n0: &N0,
        len: c::NonZero_size_t,
    ),
) -> Result<(), LimbSliceError> {
    assert_eq!(n.len() % LEN_MOD, 0); // The caller should guard against this.

    /// The x86 implementation of `bn_mul_mont`, at least, requires at least 4
    /// limbs. For a long time we have required 4 limbs for all targets, though
    /// this may be unnecessary.
    const _MIN_LIMBS_AT_LEAST_4: () = assert!(MIN_LIMBS >= 4);
    // We haven't tested shorter lengths.
    assert!(LEN_MIN >= MIN_LIMBS);
    if n.len() < LEN_MIN {
        return Err(LimbSliceError::too_short(n.len()));
    }
    let len = NonZeroUsize::new(n.len()).unwrap_or_else(|| {
        // Unreachable because we checked against `LEN_MIN`, and we checked
        // `LEN_MIN` is nonzero.
        unreachable!()
    });

    // Avoid stack overflow from the alloca inside.
    if len.get() > MAX_LIMBS {
        return Err(LimbSliceError::too_long(n.len()));
    }
    in_out
        .with_non_dangling_non_null_pointers_rab(len, |r, a, b| {
            let n = n.as_ptr();
            let _: Cpu = cpu;
            unsafe { f(r, a, b, n, n0, len) };
        })
        .map_err(LimbSliceError::len_mismatch)
}

Coverage Report

Created: 2025-10-28 06:53

Line	Count	Source
1		// Copyright 2024-2025 Brian Smith.
2		//
3		// Permission to use, copy, modify, and/or distribute this software for any
4		// purpose with or without fee is hereby granted, provided that the above
5		// copyright notice and this permission notice appear in all copies.
6		//
7		// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
8		// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
9		// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
10		// SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
11		// WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
12		// OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
13		// CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
14
15		use super::{inout::AliasingSlices3, n0::N0, LimbSliceError, MAX_LIMBS, MIN_LIMBS};
16		use crate::{c, limb::Limb, polyfill::usize_from_u32};
17		use core::{mem::size_of, num::NonZeroUsize};
18
19		const _MAX_LIMBS_ADDRESSES_MEMORY_SAFETY_ISSUES: () = {
20		// BoringSSL's limit: 8 kiloBYTES.
21		const BN_MONTGOMERY_MAX_WORDS: usize = (8 * 1092) / size_of::<Limb>();
22		assert!(MAX_LIMBS <= BN_MONTGOMERY_MAX_WORDS);
23
24		// Some 64-bit assembly implementations were written to take `len` as a
25		// `c_int`, so they zero out the undefined top half of `len` to convert it
26		// to a `usize`. But, others don't.
27		assert!(MAX_LIMBS <= usize_from_u32(u32::MAX));
28		};
29
30		macro_rules! bn_mul_mont_ffi {
31		( $in_out:expr, $n:expr, $n0:expr, $cpu:expr,
32		unsafe { ($MIN_LEN:expr, $MOD_LEN:expr, $Cpu:ty) => $f:ident }) => {{
33		use crate::{c, limb::Limb};
34		prefixed_extern! {
35		// `r` and/or 'a' and/or 'b' may alias.
36		// XXX: BoringSSL declares these functions to return `int`.
37		fn $f(
38		r: *mut Limb,
39		a: *const Limb,
40		b: *const Limb,
41		n: *const Limb,
42		n0: &N0,
43		len: c::NonZero_size_t,
44		);
45		}
46		unsafe {
47		crate::arithmetic::ffi::bn_mul_mont_ffi::<$Cpu, { $MIN_LEN }, { $MOD_LEN }>(
48		$in_out, $n, $n0, $cpu, $f,
49		)
50		}
51		}};
52		}
53
54		#[inline]
55	0	pub(super) unsafe fn bn_mul_mont_ffi<Cpu, const LEN_MIN: usize, const LEN_MOD: usize>(
56	0	in_out: impl AliasingSlices3<Limb>,
57	0	n: &[Limb],
58	0	n0: &N0,
59	0	cpu: Cpu,
60	0	f: unsafe extern "C" fn(
61	0	r: *mut Limb,
62	0	a: *const Limb,
63	0	b: *const Limb,
64	0	n: *const Limb,
65	0	n0: &N0,
66	0	len: c::NonZero_size_t,
67	0	),
68	0	) -> Result<(), LimbSliceError> {
69	0	assert_eq!(n.len() % LEN_MOD, 0); // The caller should guard against this.
70
71		/// The x86 implementation of `bn_mul_mont`, at least, requires at least 4
72		/// limbs. For a long time we have required 4 limbs for all targets, though
73		/// this may be unnecessary.
74		const _MIN_LIMBS_AT_LEAST_4: () = assert!(MIN_LIMBS >= 4);
75		// We haven't tested shorter lengths.
76	0	assert!(LEN_MIN >= MIN_LIMBS);
77	0	if n.len() < LEN_MIN {
78	0	return Err(LimbSliceError::too_short(n.len()));
79	0	}
80	0	let len = NonZeroUsize::new(n.len()).unwrap_or_else(\|\| {
81		// Unreachable because we checked against `LEN_MIN`, and we checked
82		// `LEN_MIN` is nonzero.
83	0	unreachable!() Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, &mut [u64]>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, (&mut [u64], &[u64], &[u64])>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, (&mut [u64], &[u64])>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, &mut [u64]>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, (&mut [u64], &[u64], &[u64])>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, (&mut [u64], &[u64])>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, &mut [u64]>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, (&mut [u64], &[u64], &[u64])>::{closure#0} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, (&mut [u64], &[u64])>::{closure#0}
84		});
85
86		// Avoid stack overflow from the alloca inside.
87	0	if len.get() > MAX_LIMBS {
88	0	return Err(LimbSliceError::too_long(n.len()));
89	0	}
90	0	in_out
91	0	.with_non_dangling_non_null_pointers_rab(len, \|r, a, b\| {
92	0	let n = n.as_ptr();
93		let _: Cpu = cpu;
94	0	unsafe { f(r, a, b, n, n0, len) };
95	0	}) Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, &mut [u64]>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, (&mut [u64], &[u64], &[u64])>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, (&mut [u64], &[u64])>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, &mut [u64]>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, (&mut [u64], &[u64], &[u64])>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, (&mut [u64], &[u64])>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, &mut [u64]>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, (&mut [u64], &[u64], &[u64])>::{closure#1} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, (&mut [u64], &[u64])>::{closure#1}
96	0	.map_err(LimbSliceError::len_mismatch)
97	0	} Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, &mut [u64]> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, (&mut [u64], &[u64], &[u64])> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(ring::cpu::intel::Adx, ring::cpu::intel::Bmi2), 8, 4, (&mut [u64], &[u64])> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, &mut [u64]> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, (&mut [u64], &[u64], &[u64])> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 4, 1, (&mut [u64], &[u64])> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, &mut [u64]> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, (&mut [u64], &[u64], &[u64])> Unexecuted instantiation: ring::arithmetic::ffi::bn_mul_mont_ffi::<(), 8, 4, (&mut [u64], &[u64])>