ironrdp_pdu/rdp/server_license/server_license_request/
cert.rs

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
use ironrdp_core::{
    cast_length, ensure_fixed_part_size, ensure_size, invalid_field_err, Decode, DecodeResult, Encode, EncodeResult,
    ReadCursor, WriteCursor,
};

use super::{BlobHeader, BlobType, KEY_EXCHANGE_ALGORITHM_RSA};

pub const SIGNATURE_ALGORITHM_RSA: u32 = 1;
pub const PROP_CERT_NO_BLOBS_SIZE: usize = 8;
pub const PROP_CERT_BLOBS_HEADERS_SIZE: usize = 8;
pub const X509_CERT_LENGTH_FIELD_SIZE: usize = 4;
pub const X509_CERT_COUNT: usize = 4;
pub const RSA_KEY_PADDING_LENGTH: u32 = 8;
pub const RSA_SENTINEL: u32 = 0x3141_5352;
pub const RSA_KEY_SIZE_WITHOUT_MODULUS: usize = 20;

const MIN_CERTIFICATE_AMOUNT: usize = 2;
const MAX_CERTIFICATE_AMOUNT: usize = 200;
const MAX_CERTIFICATE_LEN: usize = 4096;

#[derive(Debug, PartialEq, Eq)]
pub enum CertificateType {
    Proprietary(ProprietaryCertificate),
    X509(X509CertificateChain),
}

/// [2.2.1.4.2] X.509 Certificate Chain (X509 _CERTIFICATE_CHAIN)
///
/// [2.2.1.4.2]: https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpele/bf2cc9cc-2b01-442e-a288-6ddfa3b80d59
#[derive(Debug, PartialEq, Eq)]
pub struct X509CertificateChain {
    pub certificate_array: Vec<Vec<u8>>,
}

impl X509CertificateChain {
    const NAME: &'static str = "X509CertificateChain";
}

impl Encode for X509CertificateChain {
    fn encode(&self, dst: &mut WriteCursor<'_>) -> EncodeResult<()> {
        ensure_size!(in: dst, size: self.size());

        dst.write_u32(cast_length!("certArrayLen", self.certificate_array.len())?);

        for certificate in &self.certificate_array {
            dst.write_u32(cast_length!("certLen", certificate.len())?);
            dst.write_slice(certificate);
        }

        let padding_len = 8 + 4 * self.certificate_array.len(); // MSDN: A byte array of the length 8 + 4*NumCertBlobs
        write_padding!(dst, padding_len);

        Ok(())
    }

    fn name(&self) -> &'static str {
        Self::NAME
    }

    fn size(&self) -> usize {
        let certificates_length: usize = self
            .certificate_array
            .iter()
            .map(|certificate| certificate.len() + X509_CERT_LENGTH_FIELD_SIZE)
            .sum();
        let padding: usize = 8 + 4 * self.certificate_array.len();
        X509_CERT_COUNT + certificates_length + padding
    }
}

impl<'de> Decode<'de> for X509CertificateChain {
    fn decode(src: &mut ReadCursor<'de>) -> DecodeResult<Self> {
        ensure_size!(in: src, size: 4);
        let certificate_count = cast_length!("certArrayLen", src.read_u32())?;
        if !(MIN_CERTIFICATE_AMOUNT..MAX_CERTIFICATE_AMOUNT).contains(&certificate_count) {
            return Err(invalid_field_err!("certArrayLen", "invalid x509 certificate amount"));
        }

        let certificate_array: Vec<_> = (0..certificate_count)
            .map(|_| {
                ensure_size!(in: src, size: 4);
                let certificate_len = cast_length!("certLen", src.read_u32())?;
                if certificate_len > MAX_CERTIFICATE_LEN {
                    return Err(invalid_field_err!("certLen", "invalid x509 certificate length"));
                }

                ensure_size!(in: src, size: certificate_len);
                let certificate = src.read_slice(certificate_len).into();

                Ok(certificate)
            })
            .collect::<Result<_, _>>()?;

        let padding = 8 + 4 * certificate_count; // MSDN: A byte array of the length 8 + 4*NumCertBlobs
        ensure_size!(in: src, size: padding);
        read_padding!(src, padding);

        Ok(Self { certificate_array })
    }
}

/// [2.2.1.4.3.1.1] Server Proprietary Certificate (PROPRIETARYSERVERCERTIFICATE)
///
/// [2.2.1.4.3.1.1]: https://learn.microsoft.com/en-us/openspecs/windows_protocols/ms-rdpbcgr/a37d449a-73ac-4f00-9b9d-56cefc954634
#[derive(Debug, PartialEq, Eq)]
pub struct ProprietaryCertificate {
    pub public_key: RsaPublicKey,
    pub signature: Vec<u8>,
}

impl ProprietaryCertificate {
    const NAME: &'static str = "ProprietaryCertificate";

    const FIXED_PART_SIZE: usize = PROP_CERT_BLOBS_HEADERS_SIZE + PROP_CERT_NO_BLOBS_SIZE;
}

impl Encode for ProprietaryCertificate {
    fn encode(&self, dst: &mut WriteCursor<'_>) -> EncodeResult<()> {
        ensure_size!(in: dst, size: self.size());

        dst.write_u32(SIGNATURE_ALGORITHM_RSA);
        dst.write_u32(KEY_EXCHANGE_ALGORITHM_RSA);

        BlobHeader::new(BlobType::RSA_KEY, self.public_key.size()).encode(dst)?;
        self.public_key.encode(dst)?;

        BlobHeader::new(BlobType::RSA_SIGNATURE, self.signature.len()).encode(dst)?;
        dst.write_slice(&self.signature);

        Ok(())
    }

    fn name(&self) -> &'static str {
        Self::NAME
    }

    fn size(&self) -> usize {
        Self::FIXED_PART_SIZE + self.public_key.size() + self.signature.len()
    }
}

impl<'de> Decode<'de> for ProprietaryCertificate {
    fn decode(src: &mut ReadCursor<'de>) -> DecodeResult<Self> {
        ensure_size!(in: src, size: PROP_CERT_NO_BLOBS_SIZE);

        let signature_algorithm_id = src.read_u32();
        if signature_algorithm_id != SIGNATURE_ALGORITHM_RSA {
            return Err(invalid_field_err!("sigAlgId", "invalid signature algorithm ID"));
        }

        let key_algorithm_id = src.read_u32();
        if key_algorithm_id != KEY_EXCHANGE_ALGORITHM_RSA {
            return Err(invalid_field_err!("keyAlgId", "invalid key algorithm ID"));
        }

        let key_blob_header = BlobHeader::decode(src)?;
        if key_blob_header.blob_type != BlobType::RSA_KEY {
            return Err(invalid_field_err!("blobType", "invalid blob type"));
        }
        let public_key = RsaPublicKey::decode(src)?;

        let sig_blob_header = BlobHeader::decode(src)?;
        if sig_blob_header.blob_type != BlobType::RSA_SIGNATURE {
            return Err(invalid_field_err!("blobType", "invalid blob type"));
        }
        ensure_size!(in: src, size: sig_blob_header.length);
        let signature = src.read_slice(sig_blob_header.length).into();

        Ok(Self { public_key, signature })
    }
}

#[derive(PartialEq, Eq, Debug, Clone)]
pub struct RsaPublicKey {
    pub public_exponent: u32,
    pub modulus: Vec<u8>,
}

impl RsaPublicKey {
    const NAME: &'static str = "RsaPublicKey";

    const FIXED_PART_SIZE: usize = RSA_KEY_SIZE_WITHOUT_MODULUS;
}

impl Encode for RsaPublicKey {
    fn encode(&self, dst: &mut WriteCursor<'_>) -> EncodeResult<()> {
        ensure_size!(in: dst, size: self.size());

        let keylen = cast_length!("modulusLen", self.modulus.len())?;
        let bitlen = (keylen - RSA_KEY_PADDING_LENGTH) * 8;
        let datalen = bitlen / 8 - 1;

        dst.write_u32(RSA_SENTINEL); // magic
        dst.write_u32(keylen);
        dst.write_u32(bitlen);
        dst.write_u32(datalen);
        dst.write_u32(self.public_exponent);
        dst.write_slice(&self.modulus);

        Ok(())
    }

    fn name(&self) -> &'static str {
        Self::NAME
    }

    fn size(&self) -> usize {
        Self::FIXED_PART_SIZE + self.modulus.len()
    }
}

impl<'de> Decode<'de> for RsaPublicKey {
    fn decode(src: &mut ReadCursor<'de>) -> DecodeResult<Self> {
        ensure_fixed_part_size!(in: src);

        let magic = src.read_u32();
        if magic != RSA_SENTINEL {
            return Err(invalid_field_err!("magic", "invalid RSA public key magic"));
        }

        let keylen = cast_length!("keyLen", src.read_u32())?;

        let bitlen: usize = cast_length!("bitlen", src.read_u32())?;
        if keylen != (bitlen / 8) + 8 {
            return Err(invalid_field_err!("bitlen", "invalid RSA public key length"));
        }

        if bitlen < 8 {
            return Err(invalid_field_err!("bitlen", "invalid RSA public key length"));
        }

        let datalen: usize = cast_length!("dataLen", src.read_u32())?;
        if datalen != (bitlen / 8) - 1 {
            return Err(invalid_field_err!("dataLen", "invalid RSA public key data length"));
        }

        let public_exponent = src.read_u32();

        ensure_size!(in: src, size: keylen);
        let modulus = src.read_slice(keylen).into();

        Ok(Self {
            public_exponent,
            modulus,
        })
    }
}