diff options
| -rw-r--r-- | payloads/libpayload/include/libpayload.h | 1 | ||||
| -rw-r--r-- | payloads/libpayload/libc/lar.c | 35 |
2 files changed, 36 insertions, 0 deletions
diff --git a/payloads/libpayload/include/libpayload.h b/payloads/libpayload/include/libpayload.h index f9a67ed862..c05aafb37c 100644 --- a/payloads/libpayload/include/libpayload.h +++ b/payloads/libpayload/include/libpayload.h @@ -251,6 +251,7 @@ struct larent *readlar(struct LAR *lar); void rewindlar(struct LAR *lar); int larstat(struct LAR *lar, const char *path, struct larstat *buf); void *larfptr(struct LAR *lar, const char *filename); +int lfverify(struct LAR *lar, const char *filename); struct LFILE * lfopen(struct LAR *lar, const char *filename); int lfread(void *ptr, size_t size, size_t nmemb, struct LFILE *stream); diff --git a/payloads/libpayload/libc/lar.c b/payloads/libpayload/libc/lar.c index 6ae4052039..225b19001a 100644 --- a/payloads/libpayload/libc/lar.c +++ b/payloads/libpayload/libc/lar.c @@ -228,6 +228,41 @@ void * larfptr(struct LAR *lar, const char *filename) return (void *) ((u8 *) header + ntohl(header->offset)); } +/** + * Verify the checksum on a particular LAR entry + * + * @param lar A pointer to the LAR stream + * @param filename The lar entry to verify + * @return Return 1 if the entry is valid, 0 if it is not, or -1 + * on error + */ + +int lfverify(struct LAR *lar, const char *filename) +{ + struct lar_header *header = get_header_by_name(lar, filename); + + u8 *ptr = (u8 *) header; + int len = ntohl(header->len) + ntohl(header->offset); + int offset; + u32 csum = 0; + + if (header == NULL) + return -1; + + /* The checksum needs to be calulated on entire data section, + * including any padding for the 16 byte alignment (which should + * be zeros + */ + + len = (len + 15) & 0xFFFFFFF0; + + for(offset = 0; offset < len; offset += 4) { + csum += *((u32 *) (ptr + offset)); + } + + return (csum == 0xFFFFFFFF) ? 1 : 0; +} + struct LFILE * lfopen(struct LAR *lar, const char *filename) { struct LFILE *file; |