1 files changed, 359 insertions, 0 deletions

diff --git a/verifier.c b/verifier.c
new file mode 100644
index 000000000..67a4f390a
--- /dev/null
+++ b/verifier.c
@@ -0,0 +1,359 @@
+/*
+ * Copyright (C) 2008 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "common.h"
+#include "verifier.h"
+
+#include "minzip/Zip.h"
+#include "mincrypt/rsa.h"
+#include "mincrypt/sha.h"
+
+#include <netinet/in.h>  /* required for resolv.h */
+#include <resolv.h>      /* for base64 codec */
+#include <string.h>
+
+/* Return an allocated buffer with the contents of a zip file entry. */
+static char *slurpEntry(const ZipArchive *pArchive, const ZipEntry *pEntry) {
+    if (!mzIsZipEntryIntact(pArchive, pEntry)) {
+        UnterminatedString fn = mzGetZipEntryFileName(pEntry);
+        LOGE("Invalid %.*s\n", fn.len, fn.str);
+        return NULL;
+    }
+
+    int len = mzGetZipEntryUncompLen(pEntry);
+    char *buf = malloc(len + 1);
+    if (buf == NULL) {
+        UnterminatedString fn = mzGetZipEntryFileName(pEntry);
+        LOGE("Can't allocate %d bytes for %.*s\n", len, fn.len, fn.str);
+        return NULL;
+    }
+
+    if (!mzReadZipEntry(pArchive, pEntry, buf, len)) {
+        UnterminatedString fn = mzGetZipEntryFileName(pEntry);
+        LOGE("Can't read %.*s\n", fn.len, fn.str);
+        free(buf);
+        return NULL;
+    }
+
+    buf[len] = '\0';
+    return buf;
+}
+
+
+struct DigestContext {
+    SHA_CTX digest;
+    unsigned *doneBytes;
+    unsigned totalBytes;
+};
+
+
+/* mzProcessZipEntryContents callback to update an SHA-1 hash context. */
+static bool updateHash(const unsigned char *data, int dataLen, void *cookie) {
+    struct DigestContext *context = (struct DigestContext *) cookie;
+    SHA_update(&context->digest, data, dataLen);
+    if (context->doneBytes != NULL) {
+        *context->doneBytes += dataLen;
+        if (context->totalBytes > 0) {
+            ui_set_progress(*context->doneBytes * 1.0 / context->totalBytes);
+        }
+    }
+    return true;
+}
+
+
+/* Get the SHA-1 digest of a zip file entry. */
+static bool digestEntry(const ZipArchive *pArchive, const ZipEntry *pEntry,
+        unsigned *doneBytes, unsigned totalBytes,
+        uint8_t digest[SHA_DIGEST_SIZE]) {
+    struct DigestContext context;
+    SHA_init(&context.digest);
+    context.doneBytes = doneBytes;
+    context.totalBytes = totalBytes;
+    if (!mzProcessZipEntryContents(pArchive, pEntry, updateHash, &context)) {
+        UnterminatedString fn = mzGetZipEntryFileName(pEntry);
+        LOGE("Can't digest %.*s\n", fn.len, fn.str);
+        return false;
+    }
+
+    memcpy(digest, SHA_final(&context.digest), SHA_DIGEST_SIZE);
+
+#ifdef LOG_VERBOSE
+    UnterminatedString fn = mzGetZipEntryFileName(pEntry);
+    char base64[SHA_DIGEST_SIZE * 3];
+    b64_ntop(digest, SHA_DIGEST_SIZE, base64, sizeof(base64));
+    LOGV("sha1(%.*s) = %s\n", fn.len, fn.str, base64);
+#endif
+
+    return true;
+}
+
+
+/* Find a /META-INF/xxx.SF signature file signed by a matching xxx.RSA file. */
+static const ZipEntry *verifySignature(const ZipArchive *pArchive,
+        const RSAPublicKey *pKeys, unsigned int numKeys) {
+    static const char prefix[] = "META-INF/";
+    static const char rsa[] = ".RSA", sf[] = ".SF";
+
+    unsigned int i, j;
+    for (i = 0; i < mzZipEntryCount(pArchive); ++i) {
+        const ZipEntry *rsaEntry = mzGetZipEntryAt(pArchive, i);
+        UnterminatedString rsaName = mzGetZipEntryFileName(rsaEntry);
+        int rsaLen = mzGetZipEntryUncompLen(rsaEntry);
+        if (rsaLen >= RSANUMBYTES && rsaName.len > sizeof(prefix) &&
+                !strncmp(rsaName.str, prefix, sizeof(prefix) - 1) &&
+                !strncmp(rsaName.str + rsaName.len - sizeof(rsa) + 1,
+                         rsa, sizeof(rsa) - 1)) {
+            char *sfName = malloc(rsaName.len - sizeof(rsa) + sizeof(sf) + 1);
+            if (sfName == NULL) {
+                LOGE("Can't allocate %d bytes for filename\n", rsaName.len);
+                continue;
+            }
+
+            /* Replace .RSA with .SF */
+            strncpy(sfName, rsaName.str, rsaName.len - sizeof(rsa) + 1);
+            strcpy(sfName + rsaName.len - sizeof(rsa) + 1, sf);
+            const ZipEntry *sfEntry = mzFindZipEntry(pArchive, sfName);
+            free(sfName);
+
+            if (sfEntry == NULL) {
+                LOGW("Missing signature file %s\n", sfName);
+                continue;
+            }
+
+            uint8_t sfDigest[SHA_DIGEST_SIZE];
+            if (!digestEntry(pArchive, sfEntry, NULL, 0, sfDigest)) continue;
+
+            char *rsaBuf = slurpEntry(pArchive, rsaEntry);
+            if (rsaBuf == NULL) continue;
+
+            /* Try to verify the signature with all the keys. */
+            uint8_t *sig = (uint8_t *) rsaBuf + rsaLen - RSANUMBYTES;
+            for (j = 0; j < numKeys; ++j) {
+                if (RSA_verify(&pKeys[j], sig, RSANUMBYTES, sfDigest)) {
+                    free(rsaBuf);
+                    LOGI("Verified %.*s\n", rsaName.len, rsaName.str);
+                    return sfEntry;
+                }
+            }
+
+            free(rsaBuf);
+            LOGW("Can't verify %.*s\n", rsaName.len, rsaName.str);
+        }
+    }
+
+    LOGE("No signature (%d files)\n", mzZipEntryCount(pArchive));
+    return NULL;
+}
+
+
+/* Verify /META-INF/MANIFEST.MF against the digest in a signature file. */
+static const ZipEntry *verifyManifest(const ZipArchive *pArchive,
+        const ZipEntry *sfEntry) {
+    static const char prefix[] = "SHA1-Digest-Manifest: ", eol[] = "\r\n";
+    uint8_t expected[SHA_DIGEST_SIZE + 3], actual[SHA_DIGEST_SIZE];
+
+    char *sfBuf = slurpEntry(pArchive, sfEntry);
+    if (sfBuf == NULL) return NULL;
+
+    char *line, *save;
+    for (line = strtok_r(sfBuf, eol, &save); line != NULL;
+         line = strtok_r(NULL, eol, &save)) {
+        if (!strncasecmp(prefix, line, sizeof(prefix) - 1)) {
+            UnterminatedString fn = mzGetZipEntryFileName(sfEntry);
+            const char *digest = line + sizeof(prefix) - 1;
+            int n = b64_pton(digest, expected, sizeof(expected));
+            if (n != SHA_DIGEST_SIZE) {
+                LOGE("Invalid base64 in %.*s: %s (%d)\n",
+                        fn.len, fn.str, digest, n);
+                line = NULL;
+            }
+            break;
+        }
+    }
+
+    free(sfBuf);
+
+    if (line == NULL) {
+        LOGE("No digest manifest in signature file\n");
+        return false;
+    }
+
+    const char *mfName = "META-INF/MANIFEST.MF";
+    const ZipEntry *mfEntry = mzFindZipEntry(pArchive, mfName);
+    if (mfEntry == NULL) {
+        LOGE("No manifest file %s\n", mfName);
+        return NULL;
+    }
+
+    if (!digestEntry(pArchive, mfEntry, NULL, 0, actual)) return NULL;
+    if (memcmp(expected, actual, SHA_DIGEST_SIZE)) {
+        UnterminatedString fn = mzGetZipEntryFileName(sfEntry);
+        LOGE("Wrong digest for %s in %.*s\n", mfName, fn.len, fn.str);
+        return NULL;
+    }
+
+    LOGI("Verified %s\n", mfName);
+    return mfEntry;
+}
+
+
+/* Verify all the files in a Zip archive against the manifest. */
+static bool verifyArchive(const ZipArchive *pArchive, const ZipEntry *mfEntry) {
+    static const char namePrefix[] = "Name: ";
+    static const char contPrefix[] = " ";  // Continuation of the filename
+    static const char digestPrefix[] = "SHA1-Digest: ";
+    static const char eol[] = "\r\n";
+
+    char *mfBuf = slurpEntry(pArchive, mfEntry);
+    if (mfBuf == NULL) return false;
+
+    /* we're using calloc() here, so the initial state of the array is false */
+    bool *unverified = (bool *) calloc(mzZipEntryCount(pArchive), sizeof(bool));
+    if (unverified == NULL) {
+        LOGE("Can't allocate valid flags\n");
+        free(mfBuf);
+        return false;
+    }
+
+    /* Mark all the files in the archive that need to be verified.
+     * As we scan the manifest and check signatures, we'll unset these flags.
+     * At the end, we'll make sure that all the flags are unset.
+     */
+
+    unsigned i, totalBytes = 0;
+    for (i = 0; i < mzZipEntryCount(pArchive); ++i) {
+        const ZipEntry *entry = mzGetZipEntryAt(pArchive, i);
+        UnterminatedString fn = mzGetZipEntryFileName(entry);
+        int len = mzGetZipEntryUncompLen(entry);
+
+        // Don't validate: directories, the manifest, *.RSA, and *.SF.
+
+        if (entry == mfEntry) {
+            LOGV("Skipping manifest %.*s\n", fn.len, fn.str);
+        } else if (fn.len > 0 && fn.str[fn.len-1] == '/' && len == 0) {
+            LOGV("Skipping directory %.*s\n", fn.len, fn.str);
+        } else if (!strncasecmp(fn.str, "META-INF/", 9) && (
+                !strncasecmp(fn.str + fn.len - 4, ".RSA", 4) ||
+                !strncasecmp(fn.str + fn.len - 3, ".SF", 3))) {
+            LOGV("Skipping signature %.*s\n", fn.len, fn.str);
+        } else {
+            unverified[i] = true;
+            totalBytes += len;
+        }
+    }
+
+    unsigned doneBytes = 0;
+    char *line, *save, *name = NULL;
+    for (line = strtok_r(mfBuf, eol, &save); line != NULL;
+         line = strtok_r(NULL, eol, &save)) {
+        if (!strncasecmp(line, namePrefix, sizeof(namePrefix) - 1)) {
+            // "Name:" introducing a new stanza
+            if (name != NULL) {
+                LOGE("No digest:\n  %s\n", name);
+                break;
+            }
+
+            name = strdup(line + sizeof(namePrefix) - 1);
+            if (name == NULL) {
+                LOGE("Can't copy filename in %s\n", line);
+                break;
+            }
+        } else if (!strncasecmp(line, contPrefix, sizeof(contPrefix) - 1)) {
+            // Continuing a long name (nothing else should be continued)
+            const char *tail = line + sizeof(contPrefix) - 1;
+            if (name == NULL) {
+                LOGE("Unexpected continuation:\n  %s\n", tail);
+            }
+
+            char *concat;
+            if (asprintf(&concat, "%s%s", name, tail) < 0) {
+                LOGE("Can't append continuation %s\n", tail);
+                break;
+            }
+            free(name);
+            name = concat;
+        } else if (!strncasecmp(line, digestPrefix, sizeof(digestPrefix) - 1)) {
+            // "Digest:" supplying a hash code for the current stanza
+            const char *base64 = line + sizeof(digestPrefix) - 1;
+            if (name == NULL) {
+                LOGE("Unexpected digest:\n  %s\n", base64);
+                break;
+            }
+
+            const ZipEntry *entry = mzFindZipEntry(pArchive, name);
+            if (entry == NULL) {
+                LOGE("Missing file:\n  %s\n", name);
+                break;
+            }
+            if (!mzIsZipEntryIntact(pArchive, entry)) {
+                LOGE("Corrupt file:\n  %s\n", name);
+                break;
+            }
+            if (!unverified[mzGetZipEntryIndex(pArchive, entry)]) {
+                LOGE("Unexpected file:\n  %s\n", name);
+                break;
+            }
+
+            uint8_t expected[SHA_DIGEST_SIZE + 3], actual[SHA_DIGEST_SIZE];
+            int n = b64_pton(base64, expected, sizeof(expected));
+            if (n != SHA_DIGEST_SIZE) {
+                LOGE("Invalid base64:\n  %s\n  %s\n", name, base64);
+                break;
+            }
+
+            if (!digestEntry(pArchive, entry, &doneBytes, totalBytes, actual) ||
+                memcmp(expected, actual, SHA_DIGEST_SIZE) != 0) {
+                LOGE("Wrong digest:\n  %s\n", name);
+                break;
+            }
+
+            LOGI("Verified %s\n", name);
+            unverified[mzGetZipEntryIndex(pArchive, entry)] = false;
+            free(name);
+            name = NULL;
+        }
+    }
+
+    if (name != NULL) free(name);
+    free(mfBuf);
+
+    for (i = 0; i < mzZipEntryCount(pArchive) && !unverified[i]; ++i) ;
+    free(unverified);
+
+    // This means we didn't get to the end of the manifest successfully.
+    if (line != NULL) return false;
+
+    if (i < mzZipEntryCount(pArchive)) {
+        const ZipEntry *entry = mzGetZipEntryAt(pArchive, i);
+        UnterminatedString fn = mzGetZipEntryFileName(entry);
+        LOGE("No digest for %.*s\n", fn.len, fn.str);
+        return false;
+    }
+
+    return true;
+}
+
+
+bool verify_jar_signature(const ZipArchive *pArchive,
+        const RSAPublicKey *pKeys, int numKeys) {
+    const ZipEntry *sfEntry = verifySignature(pArchive, pKeys, numKeys);
+    if (sfEntry == NULL) return false;
+
+    const ZipEntry *mfEntry = verifyManifest(pArchive, sfEntry);
+    if (mfEntry == NULL) return false;
+
+    return verifyArchive(pArchive, mfEntry);
+}