commit 6861c93: [Fix] Properly detect encrypted files in zip archives

[Vsevolod Stakhov]

Author: Vsevolod Stakhov
Date: 2019-04-13 11:25:16 +0100
URL: https://github.com/rspamd/rspamd/commit/6861c93af2e50b118e3c4a3609f72a90c790c184 (HEAD -> master)

[Fix] Properly detect encrypted files in zip archives

---
 src/libmime/archives.c | 27 +++++++++++++++++++++++++++
 src/libmime/archives.h |  4 ++--
 2 files changed, 29 insertions(+), 2 deletions(-)

diff --git a/src/libmime/archives.c b/src/libmime/archives.c
index 21bd51ecd..ed49db4b3 100644
--- a/src/libmime/archives.c
+++ b/src/libmime/archives.c
@@ -208,6 +208,8 @@ rspamd_archive_process_zip (struct rspamd_task *task,
 			arch);
 
 	while (cd < eocd) {
+		guint16 flags;
+
 		/* Read central directory record */
 		if (eocd - cd < cd_basic_len ||
 				memcmp (cd, cd_magic, sizeof (cd_magic)) != 0) {
@@ -216,6 +218,8 @@ rspamd_archive_process_zip (struct rspamd_task *task,
 			return;
 		}
 
+		memcpy (&flags, cd + 8, sizeof (guint16));
+		flags = GUINT16_FROM_LE (flags);
 		memcpy (&comp_size, cd + 20, sizeof (guint32));
 		comp_size = GUINT32_FROM_LE (comp_size);
 		memcpy (&uncomp_size, cd + 24, sizeof (guint32));
@@ -239,6 +243,10 @@ rspamd_archive_process_zip (struct rspamd_task *task,
 		f->compressed_size = comp_size;
 		f->uncompressed_size = uncomp_size;
 
+		if (flags & 0x41u) {
+			f->flags |= RSPAMD_ARCHIVE_FILE_ENCRYPTED;
+		}
+
 		if (f->fname) {
 			g_ptr_array_add (arch->files, f);
 			msg_debug_archive ("found file in zip archive: %v", f->fname);
@@ -247,6 +255,25 @@ rspamd_archive_process_zip (struct rspamd_task *task,
 			g_free (f);
 		}
 
+		/* Process extra fields */
+		const guchar *extra = cd + fname_len + cd_basic_len;
+		p = extra;
+
+		while (p + sizeof (guint16) * 2 < extra + extra_len) {
+			guint16 hid, hlen;
+
+			memcpy (&hid, p, sizeof (guint16));
+			hid = GUINT16_FROM_LE (hid);
+			memcpy (&hlen, p + sizeof (guint16), sizeof (guint16));
+			hlen = GUINT16_FROM_LE (hlen);
+
+			if (hid == 0x0017) {
+				f->flags |= RSPAMD_ARCHIVE_FILE_ENCRYPTED;
+			}
+
+			p += hlen + sizeof (guint16) * 2;
+		}
+
 		cd += fname_len + comment_len + extra_len + cd_basic_len;
 	}
 
diff --git a/src/libmime/archives.h b/src/libmime/archives.h
index 9ea1b28e1..e4e7b8b03 100644
--- a/src/libmime/archives.h
+++ b/src/libmime/archives.h
@@ -26,11 +26,11 @@ enum rspamd_archive_type {
 };
 
 enum rspamd_archive_flags {
-	RSPAMD_ARCHIVE_ENCRYPTED = (1 << 0),
+	RSPAMD_ARCHIVE_ENCRYPTED = (1u << 0u),
 };
 
 enum rspamd_archive_file_flags {
-	RSPAMD_ARCHIVE_FILE_ENCRYPTED = (1 << 0),
+	RSPAMD_ARCHIVE_FILE_ENCRYPTED = (1u << 0u),
 };
 
 struct rspamd_archive_file {