qubes-linux-utils/qrexec-lib/pack.c

#define _GNU_SOURCE         /* See feature_test_macros(7) */
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <signal.h>
#include <errno.h>
#include <stdarg.h>
#include <dirent.h>
#include <sys/types.h>
#include "libqubes-rpc-filecopy.h"

static unsigned long crc32_sum;
static int ignore_quota_error = 0;
error_handler_t *error_handler = NULL;

void register_error_handler(error_handler_t *value) {
    error_handler = value;
}

_Noreturn static void call_error_handler(const char *fmt, ...)
{
    va_list args;
    va_start(args, fmt);
    if (error_handler) {
        error_handler(fmt, args);
    } else {
        vfprintf(stderr, fmt, args);
    }
    va_end(args);
    exit(1);
}

static int write_all_with_crc(int fd, const void *buf, int size)
{
	crc32_sum = Crc32_ComputeBuf(crc32_sum, buf, size);
	return write_all(fd, buf, size);
}

void notify_end_and_wait_for_result(void)
{
	struct file_header end_hdr;

	/* nofity end of transfer */
	memset(&end_hdr, 0, sizeof(end_hdr));
	end_hdr.namelen = 0;
	end_hdr.filelen = 0;
	write_all_with_crc(1, &end_hdr, sizeof(end_hdr));

	set_block(0);
	wait_for_result();
}

void wait_for_result(void)
{
	struct result_header hdr;
	struct result_header_ext hdr_ext;
	char last_filename[MAX_PATH_LENGTH + 1];
	char last_filename_prefix[] = "; Last file: ";

	if (!read_all(0, &hdr, sizeof(hdr))) {
		if (errno == EAGAIN) {
			// no result sent and stdin still open
			return;
		} else {
			// other read error or EOF
			exit(1);	// hopefully remote has produced error message
		}
	}
	if (!read_all(0, &hdr_ext, sizeof(hdr_ext))) {
		// remote used old result_header struct
		hdr_ext.last_namelen = 0;
	}
	if (hdr_ext.last_namelen > MAX_PATH_LENGTH) {
		// read only at most MAX_PATH_LENGTH chars
		hdr_ext.last_namelen = MAX_PATH_LENGTH;
	}
	if (!read_all(0, last_filename, hdr_ext.last_namelen)) {
		fprintf(stderr, "Failed to get last filename\n");
		hdr_ext.last_namelen = 0;
	}
	last_filename[hdr_ext.last_namelen] = '\0';
	if (!hdr_ext.last_namelen)
		/* set prefix to empty string */
		last_filename_prefix[0] = '\0';

	errno = hdr.error_code;
	if (hdr.error_code != 0) {
		switch (hdr.error_code) {
			case EEXIST:
				call_error_handler("File copy: not overwriting existing file. Clean QubesIncoming dir, and retry copy%s%s", last_filename_prefix, last_filename);
				break;
			case EINVAL:
				call_error_handler("File copy: Corrupted data from packer%s%s", last_filename_prefix, last_filename);
				break;
			case EDQUOT:
				if (ignore_quota_error) {
					/* skip also CRC check as sender and receiver might be
					 * desynchronized in this case */
					return;
				}
				/* fall though */
			default:
				call_error_handler("File copy: %s%s%s",
						strerror(hdr.error_code), last_filename_prefix, last_filename);
		}
	}
	if (hdr.crc32 != crc32_sum) {
		call_error_handler("File transfer failed: checksum mismatch");
	}
}

void write_headers(const struct file_header *hdr, const char *filename)
{
	if (!write_all_with_crc(1, hdr, sizeof(*hdr))
	    || !write_all_with_crc(1, filename, hdr->namelen)) {
		set_block(0);
		wait_for_result();
		exit(1);
	}
}

int copy_file_with_crc(int outfd, int infd, long long size) {
    return copy_file(outfd, infd, size, &crc32_sum);
}

int single_file_processor(const char *filename, const struct stat *st)
{
	struct file_header hdr;
	int fd;
	mode_t mode = st->st_mode;

	hdr.namelen = strlen(filename) + 1;
	hdr.mode = mode;
	hdr.atime = st->st_atim.tv_sec;
	hdr.atime_nsec = st->st_atim.tv_nsec;
	hdr.mtime = st->st_mtim.tv_sec;
	hdr.mtime_nsec = st->st_mtim.tv_nsec;

	if (S_ISREG(mode)) {
		int ret;
		fd = open(filename, O_RDONLY);
		if (fd < 0)
			call_error_handler("open %s", filename);
		hdr.filelen = st->st_size;
		write_headers(&hdr, filename);
		ret = copy_file(1, fd, hdr.filelen, &crc32_sum);
		if (ret != COPY_FILE_OK) {
			if (ret != COPY_FILE_WRITE_ERROR)
				call_error_handler("Copying file %s: %s", filename,
					  copy_file_status_to_str(ret));
			else {
				set_block(0);
				wait_for_result();
				exit(1);
			}
		}
		close(fd);
	}
	if (S_ISDIR(mode)) {
		hdr.filelen = 0;
		write_headers(&hdr, filename);
	}
	if (S_ISLNK(mode)) {
		char name[st->st_size + 1];
		if (readlink(filename, name, sizeof(name)) != st->st_size)
			call_error_handler("readlink %s", filename);
		hdr.filelen = st->st_size;
		write_headers(&hdr, filename);
		if (!write_all_with_crc(1, name, st->st_size)) {
			set_block(0);
			wait_for_result();
			exit(1);
		}
	}
	// check for possible error from qfile-unpacker
	wait_for_result();
	return 0;
}

int do_fs_walk(const char *file, int ignore_symlinks)
{
	char *newfile;
	struct stat st;
	struct dirent *ent;
	DIR *dir;

	if (lstat(file, &st))
		call_error_handler("stat %s", file);
    if (S_ISLNK(st.st_mode) && ignore_symlinks)
        return 0;
	single_file_processor(file, &st);
	if (!S_ISDIR(st.st_mode))
		return 0;
	dir = opendir(file);
	if (!dir)
		call_error_handler("opendir %s", file);
	while ((ent = readdir(dir))) {
		char *fname = ent->d_name;
		if (!strcmp(fname, ".") || !strcmp(fname, ".."))
			continue;
		if (asprintf(&newfile, "%s/%s", file, fname) >= 0) {
			do_fs_walk(newfile, ignore_symlinks);
			free(newfile);
		} else {
			fprintf(stderr, "asprintf failed\n");
			exit(1);
		}
	}
	closedir(dir);
	// directory metadata is resent; this makes the code simple,
	// and the atime/mtime is set correctly at the second time
	single_file_processor(file, &st);
	return 0;
}

void qfile_pack_init(void) {
    crc32_sum = 0;
    ignore_quota_error = 0;
	// this will allow checking for possible feedback packet in the middle of transfer
	set_nonblock(0);
	signal(SIGPIPE, SIG_IGN);
    error_handler = NULL;
}

void set_ignore_quota_error(int value) {
    ignore_quota_error = value;
}