srctree

melonedo parent c4a1b54e 9b0da5cc
Fix TLS record overflow by limiting inner record length to 2^14

Per last paragraph of RFC 8446, Section 5.2, the length of the inner content of an encrypted record must not exceed 2^14 + 1, while that of the whole encrypted record must not exceed 2^14 + 256.

inline split

lib/std/crypto/tls.zig added: 7, removed: 6, total 1

@@ -40,7 +40,8 @@ const assert = std.debug.assert;

pub const Client = @import("tls/Client.zig");

pub const record_header_len = 5;

pub const max_ciphertext_len = (1 << 14) + 256;

pub const max_cipertext_inner_record_len = 1 << 14;

pub const max_ciphertext_len = max_cipertext_inner_record_len + 256;

pub const max_ciphertext_record_len = max_ciphertext_len + record_header_len;

pub const hello_retry_request_sequence = [32]u8{

0xCF, 0x21, 0xAD, 0x74, 0xE5, 0x9A, 0x61, 0x11, 0xBE, 0x1D, 0x8C, 0x02, 0x1E, 0x65, 0xB8, 0x91,

lib/std/crypto/tls/Client.zig added: 7, removed: 6, total 1

@@ -805,9 +805,9 @@ fn prepareCiphertextRecord(

const close_notify_alert_reserved = tls.close_notify_alert.len + overhead_len;

while (true) {

const encrypted_content_len: u16 = @intCast(@min(

@min(bytes.len - bytes_i, max_ciphertext_len - 1),

ciphertext_buf.len - close_notify_alert_reserved -

overhead_len - ciphertext_end,

@min(bytes.len - bytes_i, tls.max_cipertext_inner_record_len),

ciphertext_buf.len -|

(close_notify_alert_reserved + overhead_len + ciphertext_end),

));

if (encrypted_content_len == 0) return .{

.iovec_end = iovec_end,