Changeset d091007 in mainline

Timestamp:

2021-06-04T16:58:15Z (3 years ago)

Author:

Martin Decky <martin@…>

Branches:

master, serial, ticket/834-toolchain-update, topic/msim-upgrade, topic/simplify-dev-export

Children:

3c8c580

Parents:

da15002

Message:

Detect a compressed component by GZIP signature, not file extension

Location:

boot/generic

Files:

• include/gzip.h (modified) (1 diff)
• src/gzip.c (modified) (4 diffs)
• src/payload.c (modified) (3 diffs)

boot/generic/include/gzip.h

@@ -30 +30 @@
 #define LIBCOMPRESS_GZIP_H_
 
+#include <stdbool.h>
 #include <stddef.h>
-size_t gzip_size(const void *, size_t);
+
+extern bool gzip_check(const void *, size_t);
+extern size_t gzip_size(const void *, size_t);
 extern int gzip_expand(const void *, size_t, void *, size_t);
 

boot/generic/src/gzip.c

@@ -63 +63 @@
 } __attribute__((packed)) gzip_footer_t;
 
-size_t gzip_size(const void *src, size_t srclen)
+/** Check GZIP signature
+ *
+ * Checks whether the source buffer start with a GZIP signature.
+ *
+ * @param[in] src    Source data buffer.
+ * @param[in] srclen Source buffer size (bytes).
+ *
+ * @return True if GZIP signature found.
+ * @return False if no GZIP signature found.
+ *
+ */
+bool gzip_check(const void *src, size_t srclen)
 {
+        if ((srclen < (sizeof(gzip_header_t) + sizeof(gzip_footer_t))))
+                return false;
+
         gzip_header_t header;
-        gzip_footer_t footer;
-
-        if ((srclen < sizeof(header)) || (srclen < sizeof(footer)))
-                return 0;
-
         memcpy(&header, src, sizeof(header));
-        memcpy(&footer, src + srclen - sizeof(footer), sizeof(footer));
 
         if ((header.id1 != GZIP_ID1) ||
@@ -78 +86 @@
             (header.method != GZIP_METHOD_DEFLATE) ||
             ((header.flags & (~GZIP_FLAGS_MASK)) != 0))
+                return false;
+
+        return true;
+}
+
+/** Get uncompressed size
+ *
+ * Note that the uncompressed size is read from the GZIP footer
+ * (and not calculated by acutally decompressing the GZip archive).
+ * Thus the source of the GZip archive needs to be trusted.
+ *
+ * @param[in]  src    Source data buffer.
+ * @param[out] srclen Source buffer size (bytes).
+ *
+ * @return Uncompressed size.
+ *
+ */
+size_t gzip_size(const void *src, size_t srclen)
+{
+        if (!gzip_check(src, srclen))
                 return 0;
+
+        gzip_footer_t footer;
+        memcpy(&footer, src + srclen - sizeof(footer), sizeof(footer));
 
         return uint32_t_le2host(footer.size);
@@ -85 +116 @@
 /** Expand GZIP compressed data
  *
- * The routine allocates the output buffer based
- * on the size encoded in the input stream. This
+ * The routine compares the output buffer size with
+ * the size encoded in the input stream. This
  * effectively limits the size of the uncompressed
  * data to 4 GiB (expanding input streams that actually
@@ -108 +139 @@
 int gzip_expand(const void *src, size_t srclen, void *dest, size_t destlen)
 {
+        if (!gzip_check(src, srclen))
+                return EINVAL;
+
+        /* Decode header and footer */
+
         gzip_header_t header;
+        memcpy(&header, src, sizeof(header));
+
         gzip_footer_t footer;
-
-        if ((srclen < sizeof(header)) || (srclen < sizeof(footer)))
-                return EINVAL;
-
-        /* Decode header and footer */
-
-        memcpy(&header, src, sizeof(header));
         memcpy(&footer, src + srclen - sizeof(footer), sizeof(footer));
-
-        if ((header.id1 != GZIP_ID1) ||
-            (header.id2 != GZIP_ID2) ||
-            (header.method != GZIP_METHOD_DEFLATE) ||
-            ((header.flags & (~GZIP_FLAGS_MASK)) != 0))
-                return EINVAL;
 
         if (destlen != uint32_t_le2host(footer.size))

boot/generic/src/payload.c

@@ -61 +61 @@
 {
         char *e = (char *) ext(s);
-        if (e != NULL && str_cmp(e, ".gz") == 0)
+        if ((e != NULL) && (str_cmp(e, ".gz") == 0))
                 *e = '\0';
-}
-
-static bool isgzip(const char *s)
-{
-        const char *e = ext(s);
-        return e != NULL && str_cmp(e, ".gz") == 0;
 }
 
@@ -82 +76 @@
 {
         const char *name;
-        const uint8_t *data;
         size_t packed_size;
-        size_t unpacked_size;
 
         if (!tar_info(*cstart, cend, &name, &packed_size))
                 return false;
 
-        data = *cstart + TAR_BLOCK_SIZE;
+        const uint8_t *data = *cstart + TAR_BLOCK_SIZE;
         *cstart += TAR_BLOCK_SIZE + ALIGN_UP(packed_size, TAR_BLOCK_SIZE);
 
-        bool gz = isgzip(name);
-
-        unpacked_size = gz ? gzip_size(data, packed_size) : packed_size;
+        bool gz = gzip_check(data, packed_size);
+        size_t unpacked_size = gz ? gzip_size(data, packed_size) : packed_size;
 
         /* Components must be page-aligned. */
@@ -156 +147 @@
         while (tar_info(start, payload_end, &name, &packed_size)) {
                 sz = ALIGN_UP(sz, PAGE_SIZE);
-                if (isgzip(name))
+                if (gzip_check(start + TAR_BLOCK_SIZE, packed_size))
                         sz += gzip_size(start + TAR_BLOCK_SIZE, packed_size);
                 else