From: Michael Tremer <michael.tremer@ipfire.org>
Date: Mon, 20 Jul 2026 12:31:30 +0000 (+0000)
Subject: database: Verify the signature using the mapped data
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=9191cd22190aa27f00aca9e25dbdc8b3b2602edc;p=location%2Flibloc.git

database: Verify the signature using the mapped data

Do not alter the position of the file descriptor, we will read the
mapped data for computing the signature.

Signed-off-by: Michael Tremer <michael.tremer@ipfire.org>
---

diff --git a/src/database.c b/src/database.c
index 72e9e75..7180104 100644
--- a/src/database.c
+++ b/src/database.c
@@ -585,7 +585,12 @@ LOC_EXPORT struct loc_database* loc_database_unref(struct loc_database* db) {
 }
 
 LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
-	size_t bytes_read = 0;
+	const struct loc_database_magic* magic =
+		(const struct loc_database_magic*)db->data;
+	struct loc_database_header_v1 header_v1 = {};
+	char* p = db->data;
+	size_t l = db->length;
+	int r;
 
 	// Cannot do this when no signature is available
 	if (!db->signature1.data && !db->signature2.data) {
@@ -605,8 +610,6 @@ LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
 		return -1;
 	}
 
-	int r = 0;
-
 	EVP_MD_CTX* mdctx = EVP_MD_CTX_new();
 
 	// Initialise hash function
@@ -619,22 +622,11 @@ LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
 		goto CLEANUP;
 	}
 
-	// Reset file to start
-	rewind(db->f);
-
-	// Read magic
-	struct loc_database_magic magic;
-	bytes_read = fread(&magic, 1, sizeof(magic), db->f);
-	if (bytes_read < sizeof(magic)) {
-		ERROR(db->ctx, "Could not read header: %m\n");
-		r = 1;
-		goto CLEANUP;
-	}
-
-	hexdump(db->ctx, &magic, sizeof(magic));
+	// Dump the magic
+	hexdump(db->ctx, magic, sizeof(*magic));
 
 	// Feed magic into the hash
-	r = EVP_DigestVerifyUpdate(mdctx, &magic, sizeof(magic));
+	r = EVP_DigestVerifyUpdate(mdctx, magic, sizeof(*magic));
 	if (r != 1) {
 		ERROR(db->ctx, "%s\n", ERR_error_string(ERR_get_error(), NULL));
 		r = 1;
@@ -642,18 +634,15 @@ LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
 		goto CLEANUP;
 	}
 
-	// Read the header
-	struct loc_database_header_v1 header_v1;
+	// Advance the pointer
+	p += sizeof(*magic);
+	l -= sizeof(*magic);
 
+	// Read the header
 	switch (db->version) {
 		case LOC_DATABASE_VERSION_1:
-			bytes_read = fread(&header_v1, 1, sizeof(header_v1), db->f);
-			if (bytes_read < sizeof(header_v1)) {
-				ERROR(db->ctx, "Could not read header\n");
-				r = 1;
-
-				goto CLEANUP;
-			}
+			// Copy the header so that we can clear the signatures
+			memcpy(&header_v1, db->data + sizeof(*magic), sizeof(header_v1));
 
 			// Clear signatures
 			memset(header_v1.signature1, '\0', sizeof(header_v1.signature1));
@@ -661,6 +650,7 @@ LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
 			memset(header_v1.signature2, '\0', sizeof(header_v1.signature2));
 			header_v1.signature2_length = 0;
 
+			// Dump the header
 			hexdump(db->ctx, &header_v1, sizeof(header_v1));
 
 			// Feed header into the hash
@@ -671,6 +661,10 @@ LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
 
 				goto CLEANUP;
 			}
+
+			// Advance the pointer
+			p += sizeof(header_v1);
+			l -= sizeof(header_v1);
 			break;
 
 		default:
@@ -680,21 +674,13 @@ LOC_EXPORT int loc_database_verify(struct loc_database* db, FILE* f) {
 			goto CLEANUP;
 	}
 
-	// Walk through the file in chunks of 64kB
-	char buffer[64 * 1024];
-
-	while (!feof(db->f)) {
-		bytes_read = fread(buffer, 1, sizeof(buffer), db->f);
-
-		hexdump(db->ctx, buffer, bytes_read);
-
-		r = EVP_DigestVerifyUpdate(mdctx, buffer, bytes_read);
-		if (r != 1) {
-			ERROR(db->ctx, "%s\n", ERR_error_string(ERR_get_error(), NULL));
-			r = 1;
+	// Hash the rest of the payload
+	r = EVP_DigestVerifyUpdate(mdctx, p, l);
+	if (r != 1) {
+		ERROR(db->ctx, "%s\n", ERR_error_string(ERR_get_error(), NULL));
+		r = 1;
 
-			goto CLEANUP;
-		}
+		goto CLEANUP;
 	}
 
 	int sig1_valid = 0;