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simplify MSI parsing recursion

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This commit is contained in:
Michał Trojnara 2022-02-22 10:08:15 +01:00
parent f0207411b9
commit 95c5a4451b
1 changed files with 43 additions and 67 deletions
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110
msi.c
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@ -15,6 +15,8 @@
#define MIN(a,b) ((a) < (b) ? a : b)
static int recurse_entry(MSI_FILE *msi, uint32_t entryID, MSI_DIRENT *parent, MSI_DIRENT *prev, int verbose);
/* Get absolute address from sector and offset */
static const u_char *sector_offset_to_address(MSI_FILE *msi, uint32_t sector, uint32_t offset, int verbose)
{
@ -345,57 +347,43 @@ static MSI_ENTRY *parse_entry(MSI_FILE *msi, const u_char *data, int verbose)
* Pass "0" to get the root directory entry. -- This is the start point to navigate the compound file.
* Use the returned object to access child entries.
*/
static int get_entry(MSI_FILE *msi, uint32_t entryID, int is_root, MSI_ENTRY **entry, int verbose)
static MSI_ENTRY *get_entry(MSI_FILE *msi, uint32_t entryID, int is_root, int verbose)
{
uint32_t sector = 0;
uint32_t offset = 0;
const u_char *address;
/* The special value NOSTREAM (0xFFFFFFFF) is used as a terminator */
if (entryID == NOSTREAM) {
return 1; /* OK */
}
/* Corrupted file */
if (!is_root && entryID == 0) {
if (verbose) printf("Corrupted entryID\n");
return 0; /* FAILED */
return NULL; /* FAILED */
}
if (msi->m_bufferLen / sizeof(MSI_ENTRY) <= entryID) {
if (verbose) printf("Invalid argument entryID\n");
return 0; /* FAILED */
return NULL; /* FAILED */
}
/* The first entry in the first sector of the directory chain is known as
the root directory entry so it can not contain the directory stream */
if (msi->m_hdr->firstDirectorySectorLocation == 0 && entryID == 0) {
if (verbose) printf("Corrupted First Directory Sector Location\n");
return 0; /* FAILED */
return NULL; /* FAILED */
}
if (!locate_final_sector(msi, msi->m_hdr->firstDirectorySectorLocation,
entryID * sizeof(MSI_ENTRY), &sector, &offset, verbose)) {
if (verbose) printf("Failed to locate a final sector\n");
return 0; /* FAILED */
return NULL; /* FAILED */
}
address = sector_offset_to_address(msi, sector, offset, verbose);
if (!address) {
if (verbose) printf("Failed to get a final address\n");
return 0; /* FAILED */
return NULL; /* FAILED */
}
*entry = parse_entry(msi, address, verbose);
if (!*entry) {
if (verbose) printf("Failed to parse MSI_ENTRY struct\n");
return 0; /* FAILED */
}
return 1; /* OK */
return parse_entry(msi, address, verbose);
}
MSI_ENTRY *msi_root_entry_get(MSI_FILE *msi, int verbose)
{
MSI_ENTRY *entry = NULL;
if (!get_entry(msi, 0, TRUE, &entry, verbose)) {
return NULL;
}
return entry;
return get_entry(msi, 0, TRUE, verbose);
}
/* Parse MSI_FILE struct */
@ -446,11 +434,10 @@ MSI_FILE *msi_file_new(char *buffer, uint32_t len, int verbose)
return msi;
}
/* Recursively parse MSI_DIRENT struct */
/* Recursively create a tree of MSI_DIRENT structures */
int msi_dirent_new(MSI_FILE *msi, MSI_ENTRY *entry, MSI_DIRENT *parent, MSI_DIRENT *prev, MSI_DIRENT **ret, int verbose)
{
MSI_DIRENT *dirent;
MSI_ENTRY *lnode = NULL, *rnode = NULL, *cnode = NULL;
if (!entry) {
return 1; /* OK */
@ -482,52 +469,41 @@ int msi_dirent_new(MSI_FILE *msi, MSI_ENTRY *entry, MSI_DIRENT *parent, MSI_DIRE
OPENSSL_free(dirent);
return 0; /* FAILED */
}
/* NOTE : These links are a tree, not a linked list */
/* The special value NOSTREAM (0xFFFFFFFF) is used as a terminator */
if (entry->leftSiblingID != NOSTREAM) {
if (!get_entry(msi, entry->leftSiblingID, FALSE, &lnode, verbose)) {
if (verbose) printf("Corrupted Left Sibling ID: 0x%08X\n", entry->leftSiblingID);
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
if (!msi_dirent_new(msi, lnode, parent, dirent, NULL, verbose)) {
OPENSSL_free(lnode);
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
}
if (entry->rightSiblingID != NOSTREAM) {
if (!get_entry(msi, entry->rightSiblingID, FALSE, &rnode, verbose)) {
if (verbose) printf("Corrupted Right Sibling ID: 0x%08X\n", entry->rightSiblingID);
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
if (!msi_dirent_new(msi, rnode, parent, dirent, NULL, verbose)) {
OPENSSL_free(rnode);
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
}
if (entry->type != DIR_STREAM && entry->childID != NOSTREAM) {
if (!get_entry(msi, entry->childID, FALSE, &cnode, verbose)) {
if (verbose) printf("Corrupted Child ID: 0x%08X\n", entry->childID);
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
if (!msi_dirent_new(msi, cnode, dirent, dirent, NULL, verbose)) {
OPENSSL_free(cnode);
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
if (!recurse_entry(msi, entry->leftSiblingID, parent, dirent, verbose)
|| !recurse_entry(msi, entry->rightSiblingID, parent, dirent, verbose)
|| !recurse_entry(msi, entry->childID, dirent, dirent, verbose)) {
sk_MSI_DIRENT_free(dirent->children);
OPENSSL_free(dirent);
return 0; /* FAILED */
}
if (ret)
*ret = dirent;
return 1; /* OK */
}
/* Add a sibling or a child to the tree */
static int recurse_entry(MSI_FILE *msi, uint32_t entryID, MSI_DIRENT *parent, MSI_DIRENT *dirent, int verbose) {
/* NOTE : These links are a tree, not a linked list */
MSI_ENTRY *node;
/* The special value NOSTREAM (0xFFFFFFFF) is used as a terminator */
if (entryID == NOSTREAM) /* stop condition */
return 1; /* OK */
node = get_entry(msi, entryID, FALSE, verbose);
if (!node) {
if (verbose) printf("Corrupted ID: 0x%08X\n", entryID);
return 0; /* FAILED */
}
if (!msi_dirent_new(msi, node, parent, dirent, NULL, verbose)) {
OPENSSL_free(node);
return 0; /* FAILED */
}
return 1; /* OK */
}