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Use sha256 to sanitize discovery HTTP cache keys

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This helps avoid (potentially malicious) collisions when reading and
writing cache data.

Signed-off-by: Nic Cope <nicc@rk0n.org>
This commit is contained in:
Nic Cope 2022-07-14 14:11:33 -07:00
parent 7a2c6a432f
commit 288a17fd33
1 changed files with 6 additions and 5 deletions
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11
staging/src/k8s.io/client-go/discovery/cached/disk/round_tripper.go
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@ -17,10 +17,10 @@ limitations under the License.
package disk
import (
"crypto/sha256"
"encoding/binary"
"fmt"
"hash/crc32"
"hash/fnv"
"net/http"
"os"
"path/filepath"
@ -95,7 +95,7 @@ func (c *crcDiskCache) Get(key string) ([]byte, bool) {
return response, true
}
// Set writes the response to a file on disk. The filename will be the FNV-32a
// Set writes the response to a file on disk. The filename will be the SHA256
// hash of the key. The file will contain the CRC-32 checksum of the response
// bytes, followed by said response bytes.
func (c *crcDiskCache) Set(key string, response []byte) {
@ -113,7 +113,8 @@ func (c *crcDiskCache) Delete(key string) {
// the request method was GET) or "<method> <url>" for other methods, per the
// httpcache.cacheKey function.
func sanitize(key string) string {
h := fnv.New32a()
_, _ = h.Write([]byte(key)) // Writing to a hash never returns an error.
return fmt.Sprintf("%X", h.Sum32())
// These keys are not sensitive. We use sha256 to avoid a (potentially
// malicious) collision causing the wrong cache data to be written or
// accessed.
return fmt.Sprintf("%x", sha256.Sum256([]byte(key)))
}