minio/cmd/signature-v4-utils.go

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// Copyright (c) 2015-2021 MinIO, Inc.
//
// This file is part of MinIO Object Storage stack
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program. If not, see <http://www.gnu.org/licenses/>.
package cmd
import (
"bytes"
"crypto/hmac"
"crypto/sha256"
"encoding/hex"
"io"
"io/ioutil"
"net/http"
"strconv"
"strings"
"github.com/minio/minio/internal/auth"
xhttp "github.com/minio/minio/internal/http"
"github.com/minio/minio/internal/logger"
)
// http Header "x-amz-content-sha256" == "UNSIGNED-PAYLOAD" indicates that the
// client did not calculate sha256 of the payload.
const unsignedPayload = "UNSIGNED-PAYLOAD"
// skipContentSha256Cksum returns true if caller needs to skip
// payload checksum, false if not.
func skipContentSha256Cksum(r *http.Request) bool {
var (
v []string
ok bool
)
if isRequestPresignedSignatureV4(r) {
v, ok = r.Form[xhttp.AmzContentSha256]
if !ok {
v, ok = r.Header[xhttp.AmzContentSha256]
}
} else {
v, ok = r.Header[xhttp.AmzContentSha256]
}
// Skip if no header was set.
if !ok {
return true
}
// If x-amz-content-sha256 is set and the value is not
// 'UNSIGNED-PAYLOAD' we should validate the content sha256.
switch v[0] {
case unsignedPayload:
return true
case emptySHA256:
// some broken clients set empty-sha256
// with > 0 content-length in the body,
// we should skip such clients and allow
// blindly such insecure clients only if
// S3 strict compatibility is disabled.
if r.ContentLength > 0 && !globalCLIContext.StrictS3Compat {
// We return true only in situations when
// deployment has asked MinIO to allow for
// such broken clients and content-length > 0.
return true
}
}
return false
}
// Returns SHA256 for calculating canonical-request.
func getContentSha256Cksum(r *http.Request, stype serviceType) string {
if stype == serviceSTS {
payload, err := ioutil.ReadAll(io.LimitReader(r.Body, stsRequestBodyLimit))
if err != nil {
logger.CriticalIf(GlobalContext, err)
}
sum256 := sha256.Sum256(payload)
r.Body = ioutil.NopCloser(bytes.NewReader(payload))
return hex.EncodeToString(sum256[:])
}
var (
defaultSha256Cksum string
v []string
ok bool
)
// For a presigned request we look at the query param for sha256.
if isRequestPresignedSignatureV4(r) {
// X-Amz-Content-Sha256, if not set in presigned requests, checksum
// will default to 'UNSIGNED-PAYLOAD'.
defaultSha256Cksum = unsignedPayload
v, ok = r.Form[xhttp.AmzContentSha256]
if !ok {
v, ok = r.Header[xhttp.AmzContentSha256]
}
} else {
// X-Amz-Content-Sha256, if not set in signed requests, checksum
// will default to sha256([]byte("")).
defaultSha256Cksum = emptySHA256
v, ok = r.Header[xhttp.AmzContentSha256]
}
// We found 'X-Amz-Content-Sha256' return the captured value.
if ok {
return v[0]
}
// We couldn't find 'X-Amz-Content-Sha256'.
return defaultSha256Cksum
}
// isValidRegion - verify if incoming region value is valid with configured Region.
func isValidRegion(reqRegion string, confRegion string) bool {
if confRegion == "" {
return true
}
if confRegion == "US" {
confRegion = globalMinioDefaultRegion
}
// Some older s3 clients set region as "US" instead of
// globalMinioDefaultRegion, handle it.
if reqRegion == "US" {
reqRegion = globalMinioDefaultRegion
}
return reqRegion == confRegion
}
// check if the access key is valid and recognized, additionally
// also returns if the access key is owner/admin.
func checkKeyValid(r *http.Request, accessKey string) (auth.Credentials, bool, APIErrorCode) {
if !globalIAMSys.Initialized() && !globalIsGateway {
// Check if server has initialized, then only proceed
// to check for IAM users otherwise its okay for clients
// to retry with 503 errors when server is coming up.
return auth.Credentials{}, false, ErrServerNotInitialized
}
cred := globalActiveCred
if cred.AccessKey != accessKey {
// Check if the access key is part of users credentials.
ucred, ok := globalIAMSys.GetUser(accessKey)
if !ok {
return cred, false, ErrInvalidAccessKeyID
}
cred = ucred
}
claims, s3Err := checkClaimsFromToken(r, cred)
if s3Err != ErrNone {
return cred, false, s3Err
}
cred.Claims = claims
owner := cred.AccessKey == globalActiveCred.AccessKey
return cred, owner, ErrNone
}
// sumHMAC calculate hmac between two input byte array.
func sumHMAC(key []byte, data []byte) []byte {
hash := hmac.New(sha256.New, key)
hash.Write(data)
return hash.Sum(nil)
}
// extractSignedHeaders extract signed headers from Authorization header
func extractSignedHeaders(signedHeaders []string, r *http.Request) (http.Header, APIErrorCode) {
reqHeaders := r.Header
reqQueries := r.Form
// find whether "host" is part of list of signed headers.
// if not return ErrUnsignedHeaders. "host" is mandatory.
if !contains(signedHeaders, "host") {
return nil, ErrUnsignedHeaders
}
extractedSignedHeaders := make(http.Header)
for _, header := range signedHeaders {
// `host` will not be found in the headers, can be found in r.Host.
// but its alway necessary that the list of signed headers containing host in it.
val, ok := reqHeaders[http.CanonicalHeaderKey(header)]
if !ok {
// try to set headers from Query String
val, ok = reqQueries[header]
}
if ok {
extractedSignedHeaders[http.CanonicalHeaderKey(header)] = val
continue
}
switch header {
case "expect":
// Golang http server strips off 'Expect' header, if the
// client sent this as part of signed headers we need to
// handle otherwise we would see a signature mismatch.
// `aws-cli` sets this as part of signed headers.
//
// According to
// http://www.w3.org/Protocols/rfc2616/rfc2616-sec14.html#sec14.20
// Expect header is always of form:
//
// Expect = "Expect" ":" 1#expectation
// expectation = "100-continue" | expectation-extension
//
// So it safe to assume that '100-continue' is what would
// be sent, for the time being keep this work around.
// Adding a *TODO* to remove this later when Golang server
// doesn't filter out the 'Expect' header.
extractedSignedHeaders.Set(header, "100-continue")
case "host":
// Go http server removes "host" from Request.Header
extractedSignedHeaders.Set(header, r.Host)
case "transfer-encoding":
// Go http server removes "host" from Request.Header
extractedSignedHeaders[http.CanonicalHeaderKey(header)] = r.TransferEncoding
case "content-length":
// Signature-V4 spec excludes Content-Length from signed headers list for signature calculation.
// But some clients deviate from this rule. Hence we consider Content-Length for signature
// calculation to be compatible with such clients.
extractedSignedHeaders.Set(header, strconv.FormatInt(r.ContentLength, 10))
default:
return nil, ErrUnsignedHeaders
}
}
return extractedSignedHeaders, ErrNone
}
// Trim leading and trailing spaces and replace sequential spaces with one space, following Trimall()
// in http://docs.aws.amazon.com/general/latest/gr/sigv4-create-canonical-request.html
func signV4TrimAll(input string) string {
// Compress adjacent spaces (a space is determined by
// unicode.IsSpace() internally here) to one space and return
return strings.Join(strings.Fields(input), " ")
}