455 lines
13 KiB
Go
455 lines
13 KiB
Go
// Copyright (c) 2015-2021 MinIO, Inc.
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//
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// This file is part of MinIO Object Storage stack
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Affero General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Affero General Public License for more details.
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//
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// You should have received a copy of the GNU Affero General Public License
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// along with this program. If not, see <http://www.gnu.org/licenses/>.
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// Package cmd This file implements helper functions to validate Streaming AWS
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// Signature Version '4' authorization header.
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package cmd
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import (
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"bufio"
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"bytes"
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"crypto/sha256"
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"encoding/hex"
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"errors"
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"hash"
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"io"
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"net/http"
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"time"
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humanize "github.com/dustin/go-humanize"
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"github.com/minio/minio/internal/auth"
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xhttp "github.com/minio/minio/internal/http"
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)
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// Streaming AWS Signature Version '4' constants.
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const (
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emptySHA256 = "e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855"
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streamingContentSHA256 = "STREAMING-AWS4-HMAC-SHA256-PAYLOAD"
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signV4ChunkedAlgorithm = "AWS4-HMAC-SHA256-PAYLOAD"
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streamingContentEncoding = "aws-chunked"
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)
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// getChunkSignature - get chunk signature.
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func getChunkSignature(cred auth.Credentials, seedSignature string, region string, date time.Time, hashedChunk string) string {
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// Calculate string to sign.
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stringToSign := signV4ChunkedAlgorithm + "\n" +
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date.Format(iso8601Format) + "\n" +
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getScope(date, region) + "\n" +
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seedSignature + "\n" +
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emptySHA256 + "\n" +
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hashedChunk
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// Get hmac signing key.
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signingKey := getSigningKey(cred.SecretKey, date, region, serviceS3)
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// Calculate signature.
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newSignature := getSignature(signingKey, stringToSign)
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return newSignature
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}
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// calculateSeedSignature - Calculate seed signature in accordance with
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// - http://docs.aws.amazon.com/AmazonS3/latest/API/sigv4-streaming.html
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// returns signature, error otherwise if the signature mismatches or any other
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// error while parsing and validating.
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func calculateSeedSignature(r *http.Request) (cred auth.Credentials, signature string, region string, date time.Time, errCode APIErrorCode) {
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// Copy request.
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req := *r
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// Save authorization header.
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v4Auth := req.Header.Get(xhttp.Authorization)
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// Parse signature version '4' header.
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signV4Values, errCode := parseSignV4(v4Auth, globalServerRegion, serviceS3)
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if errCode != ErrNone {
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return cred, "", "", time.Time{}, errCode
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}
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// Payload streaming.
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payload := streamingContentSHA256
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// Payload for STREAMING signature should be 'STREAMING-AWS4-HMAC-SHA256-PAYLOAD'
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if payload != req.Header.Get(xhttp.AmzContentSha256) {
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return cred, "", "", time.Time{}, ErrContentSHA256Mismatch
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}
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// Extract all the signed headers along with its values.
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extractedSignedHeaders, errCode := extractSignedHeaders(signV4Values.SignedHeaders, r)
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if errCode != ErrNone {
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return cred, "", "", time.Time{}, errCode
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}
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cred, _, errCode = checkKeyValid(r, signV4Values.Credential.accessKey)
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if errCode != ErrNone {
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return cred, "", "", time.Time{}, errCode
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}
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// Verify if region is valid.
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region = signV4Values.Credential.scope.region
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// Extract date, if not present throw error.
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var dateStr string
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if dateStr = req.Header.Get("x-amz-date"); dateStr == "" {
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if dateStr = r.Header.Get("Date"); dateStr == "" {
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return cred, "", "", time.Time{}, ErrMissingDateHeader
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}
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}
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// Parse date header.
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var err error
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date, err = time.Parse(iso8601Format, dateStr)
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if err != nil {
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return cred, "", "", time.Time{}, ErrMalformedDate
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}
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// Query string.
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queryStr := req.Form.Encode()
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// Get canonical request.
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canonicalRequest := getCanonicalRequest(extractedSignedHeaders, payload, queryStr, req.URL.Path, req.Method)
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// Get string to sign from canonical request.
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stringToSign := getStringToSign(canonicalRequest, date, signV4Values.Credential.getScope())
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// Get hmac signing key.
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signingKey := getSigningKey(cred.SecretKey, signV4Values.Credential.scope.date, region, serviceS3)
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// Calculate signature.
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newSignature := getSignature(signingKey, stringToSign)
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// Verify if signature match.
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if !compareSignatureV4(newSignature, signV4Values.Signature) {
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return cred, "", "", time.Time{}, ErrSignatureDoesNotMatch
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}
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// Return caculated signature.
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return cred, newSignature, region, date, ErrNone
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}
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const maxLineLength = 4 * humanize.KiByte // assumed <= bufio.defaultBufSize 4KiB
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// lineTooLong is generated as chunk header is bigger than 4KiB.
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var errLineTooLong = errors.New("header line too long")
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// malformed encoding is generated when chunk header is wrongly formed.
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var errMalformedEncoding = errors.New("malformed chunked encoding")
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// chunk is considered too big if its bigger than > 16MiB.
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var errChunkTooBig = errors.New("chunk too big: choose chunk size <= 16MiB")
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// newSignV4ChunkedReader returns a new s3ChunkedReader that translates the data read from r
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// out of HTTP "chunked" format before returning it.
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// The s3ChunkedReader returns io.EOF when the final 0-length chunk is read.
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//
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// NewChunkedReader is not needed by normal applications. The http package
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// automatically decodes chunking when reading response bodies.
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func newSignV4ChunkedReader(req *http.Request) (io.ReadCloser, APIErrorCode) {
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cred, seedSignature, region, seedDate, errCode := calculateSeedSignature(req)
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if errCode != ErrNone {
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return nil, errCode
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}
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return &s3ChunkedReader{
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reader: bufio.NewReader(req.Body),
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cred: cred,
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seedSignature: seedSignature,
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seedDate: seedDate,
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region: region,
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chunkSHA256Writer: sha256.New(),
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buffer: make([]byte, 64*1024),
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}, ErrNone
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}
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// Represents the overall state that is required for decoding a
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// AWS Signature V4 chunked reader.
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type s3ChunkedReader struct {
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reader *bufio.Reader
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cred auth.Credentials
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seedSignature string
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seedDate time.Time
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region string
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chunkSHA256Writer hash.Hash // Calculates sha256 of chunk data.
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buffer []byte
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offset int
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err error
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}
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func (cr *s3ChunkedReader) Close() (err error) {
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return nil
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}
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// Now, we read one chunk from the underlying reader.
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// A chunk has the following format:
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// <chunk-size-as-hex> + ";chunk-signature=" + <signature-as-hex> + "\r\n" + <payload> + "\r\n"
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//
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// First, we read the chunk size but fail if it is larger
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// than 16 MiB. We must not accept arbitrary large chunks.
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// One 16 MiB is a reasonable max limit.
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//
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// Then we read the signature and payload data. We compute the SHA256 checksum
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// of the payload and verify that it matches the expected signature value.
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//
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// The last chunk is *always* 0-sized. So, we must only return io.EOF if we have encountered
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// a chunk with a chunk size = 0. However, this chunk still has a signature and we must
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// verify it.
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const maxChunkSize = 16 << 20 // 16 MiB
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// Read - implements `io.Reader`, which transparently decodes
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// the incoming AWS Signature V4 streaming signature.
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func (cr *s3ChunkedReader) Read(buf []byte) (n int, err error) {
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// First, if there is any unread data, copy it to the client
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// provided buffer.
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if cr.offset > 0 {
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n = copy(buf, cr.buffer[cr.offset:])
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if n == len(buf) {
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cr.offset += n
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return n, nil
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}
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cr.offset = 0
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buf = buf[n:]
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}
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var size int
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for {
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b, err := cr.reader.ReadByte()
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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if err != nil {
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cr.err = err
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return n, cr.err
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}
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if b == ';' { // separating character
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break
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}
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// Manually deserialize the size since AWS specified
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// the chunk size to be of variable width. In particular,
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// a size of 16 is encoded as `10` while a size of 64 KB
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// is `10000`.
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switch {
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case b >= '0' && b <= '9':
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size = size<<4 | int(b-'0')
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case b >= 'a' && b <= 'f':
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size = size<<4 | int(b-('a'-10))
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case b >= 'A' && b <= 'F':
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size = size<<4 | int(b-('A'-10))
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default:
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cr.err = errMalformedEncoding
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return n, cr.err
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}
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if size > maxChunkSize {
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cr.err = errChunkTooBig
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return n, cr.err
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}
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}
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// Now, we read the signature of the following payload and expect:
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// chunk-signature=" + <signature-as-hex> + "\r\n"
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//
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// The signature is 64 bytes long (hex-encoded SHA256 hash) and
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// starts with a 16 byte header: len("chunk-signature=") + 64 == 80.
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var signature [80]byte
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_, err = io.ReadFull(cr.reader, signature[:])
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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if err != nil {
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cr.err = err
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return n, cr.err
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}
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if !bytes.HasPrefix(signature[:], []byte("chunk-signature=")) {
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cr.err = errMalformedEncoding
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return n, cr.err
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}
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b, err := cr.reader.ReadByte()
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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if err != nil {
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cr.err = err
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return n, cr.err
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}
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if b != '\r' {
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cr.err = errMalformedEncoding
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return n, cr.err
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}
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b, err = cr.reader.ReadByte()
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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if err != nil {
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cr.err = err
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return n, cr.err
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}
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if b != '\n' {
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cr.err = errMalformedEncoding
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return n, cr.err
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}
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if cap(cr.buffer) < size {
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cr.buffer = make([]byte, size)
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} else {
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cr.buffer = cr.buffer[:size]
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}
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// Now, we read the payload and compute its SHA-256 hash.
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_, err = io.ReadFull(cr.reader, cr.buffer)
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if err == io.EOF && size != 0 {
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err = io.ErrUnexpectedEOF
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}
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if err != nil && err != io.EOF {
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cr.err = err
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return n, cr.err
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}
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b, err = cr.reader.ReadByte()
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if b != '\r' {
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cr.err = errMalformedEncoding
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return n, cr.err
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}
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b, err = cr.reader.ReadByte()
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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}
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if err != nil {
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cr.err = err
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return n, cr.err
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}
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if b != '\n' {
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cr.err = errMalformedEncoding
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return n, cr.err
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}
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// Once we have read the entire chunk successfully, we verify
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// that the received signature matches our computed signature.
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cr.chunkSHA256Writer.Write(cr.buffer)
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newSignature := getChunkSignature(cr.cred, cr.seedSignature, cr.region, cr.seedDate, hex.EncodeToString(cr.chunkSHA256Writer.Sum(nil)))
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if !compareSignatureV4(string(signature[16:]), newSignature) {
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cr.err = errSignatureMismatch
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return n, cr.err
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}
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cr.seedSignature = newSignature
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cr.chunkSHA256Writer.Reset()
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// If the chunk size is zero we return io.EOF. As specified by AWS,
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// only the last chunk is zero-sized.
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if size == 0 {
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cr.err = io.EOF
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return n, cr.err
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}
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cr.offset = copy(buf, cr.buffer)
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n += cr.offset
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return n, err
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}
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// readCRLF - check if reader only has '\r\n' CRLF character.
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// returns malformed encoding if it doesn't.
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func readCRLF(reader io.Reader) error {
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buf := make([]byte, 2)
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_, err := io.ReadFull(reader, buf[:2])
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if err != nil {
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return err
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}
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if buf[0] != '\r' || buf[1] != '\n' {
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return errMalformedEncoding
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}
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return nil
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}
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// Read a line of bytes (up to \n) from b.
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// Give up if the line exceeds maxLineLength.
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// The returned bytes are owned by the bufio.Reader
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// so they are only valid until the next bufio read.
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func readChunkLine(b *bufio.Reader) ([]byte, []byte, error) {
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buf, err := b.ReadSlice('\n')
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if err != nil {
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// We always know when EOF is coming.
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// If the caller asked for a line, there should be a line.
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if err == io.EOF {
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err = io.ErrUnexpectedEOF
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} else if err == bufio.ErrBufferFull {
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err = errLineTooLong
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}
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return nil, nil, err
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}
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if len(buf) >= maxLineLength {
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return nil, nil, errLineTooLong
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}
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// Parse s3 specific chunk extension and fetch the values.
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hexChunkSize, hexChunkSignature := parseS3ChunkExtension(buf)
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return hexChunkSize, hexChunkSignature, nil
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}
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// trimTrailingWhitespace - trim trailing white space.
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func trimTrailingWhitespace(b []byte) []byte {
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for len(b) > 0 && isASCIISpace(b[len(b)-1]) {
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b = b[:len(b)-1]
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}
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return b
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}
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// isASCIISpace - is ascii space?
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func isASCIISpace(b byte) bool {
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return b == ' ' || b == '\t' || b == '\n' || b == '\r'
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}
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// Constant s3 chunk encoding signature.
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const s3ChunkSignatureStr = ";chunk-signature="
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// parses3ChunkExtension removes any s3 specific chunk-extension from buf.
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// For example,
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// "10000;chunk-signature=..." => "10000", "chunk-signature=..."
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func parseS3ChunkExtension(buf []byte) ([]byte, []byte) {
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buf = trimTrailingWhitespace(buf)
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semi := bytes.Index(buf, []byte(s3ChunkSignatureStr))
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// Chunk signature not found, return the whole buffer.
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if semi == -1 {
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return buf, nil
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}
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return buf[:semi], parseChunkSignature(buf[semi:])
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}
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// parseChunkSignature - parse chunk signature.
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func parseChunkSignature(chunk []byte) []byte {
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chunkSplits := bytes.SplitN(chunk, []byte(s3ChunkSignatureStr), 2)
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return chunkSplits[1]
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}
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// parse hex to uint64.
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func parseHexUint(v []byte) (n uint64, err error) {
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for i, b := range v {
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switch {
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case '0' <= b && b <= '9':
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b = b - '0'
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case 'a' <= b && b <= 'f':
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b = b - 'a' + 10
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case 'A' <= b && b <= 'F':
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b = b - 'A' + 10
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default:
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return 0, errors.New("invalid byte in chunk length")
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}
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if i == 16 {
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return 0, errors.New("http chunk length too large")
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}
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n <<= 4
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n |= uint64(b)
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}
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return
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}
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