From 73b4d19dfc4248a74c1f3e511cfa934681d9c602 Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Thu, 31 Jan 2019 14:02:40 +0800 Subject: [PATCH] virtiofsd: passthrough_ll: add fd_map to hide file descriptors Do not expose file descriptor numbers to clients. This prevents the abuse of internal file descriptors (like stdin/stdout). Signed-off-by: Stefan Hajnoczi Fix from: Signed-off-by: Xiao Yang dgilbert: Added lseek Reviewed-by: Masayoshi Mizuma Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 116 +++++++++++++++++++++++++------ 1 file changed, 94 insertions(+), 22 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 5f5a72fdbb..9815bfa5c5 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -60,6 +60,7 @@ struct lo_map_elem { union { struct lo_inode *inode; struct lo_dirp *dirp; + int fd; ssize_t freelist; }; bool in_use; @@ -107,6 +108,7 @@ struct lo_data { struct lo_inode root; /* protected by lo->mutex */ struct lo_map ino_map; /* protected by lo->mutex */ struct lo_map dirp_map; /* protected by lo->mutex */ + struct lo_map fd_map; /* protected by lo->mutex */ }; static const struct fuse_opt lo_opts[] = { @@ -236,6 +238,20 @@ static void lo_map_remove(struct lo_map *map, size_t key) map->freelist = key; } +/* Assumes lo->mutex is held */ +static ssize_t lo_add_fd_mapping(fuse_req_t req, int fd) +{ + struct lo_map_elem *elem; + + elem = lo_map_alloc_elem(&lo_data(req)->fd_map); + if (!elem) { + return -1; + } + + elem->fd = fd; + return elem - lo_data(req)->fd_map.elems; +} + /* Assumes lo->mutex is held */ static ssize_t lo_add_dirp_mapping(fuse_req_t req, struct lo_dirp *dirp) { @@ -350,6 +366,22 @@ static int utimensat_empty_nofollow(struct lo_inode *inode, return utimensat(AT_FDCWD, procname, tv, 0); } +static int lo_fi_fd(fuse_req_t req, struct fuse_file_info *fi) +{ + struct lo_data *lo = lo_data(req); + struct lo_map_elem *elem; + + pthread_mutex_lock(&lo->mutex); + elem = lo_map_get(&lo->fd_map, fi->fh); + pthread_mutex_unlock(&lo->mutex); + + if (!elem) { + return -1; + } + + return elem->fd; +} + static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, int valid, struct fuse_file_info *fi) { @@ -358,6 +390,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, struct lo_inode *inode; int ifd; int res; + int fd; inode = lo_inode(req, ino); if (!inode) { @@ -367,9 +400,14 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, ifd = inode->fd; + /* If fi->fh is invalid we'll report EBADF later */ + if (fi) { + fd = lo_fi_fd(req, fi); + } + if (valid & FUSE_SET_ATTR_MODE) { if (fi) { - res = fchmod(fi->fh, attr->st_mode); + res = fchmod(fd, attr->st_mode); } else { sprintf(procname, "/proc/self/fd/%i", ifd); res = chmod(procname, attr->st_mode); @@ -389,7 +427,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, } if (valid & FUSE_SET_ATTR_SIZE) { if (fi) { - res = ftruncate(fi->fh, attr->st_size); + res = ftruncate(fd, attr->st_size); } else { sprintf(procname, "/proc/self/fd/%i", ifd); res = truncate(procname, attr->st_size); @@ -419,7 +457,7 @@ static void lo_setattr(fuse_req_t req, fuse_ino_t ino, struct stat *attr, } if (fi) { - res = futimens(fi->fh, tv); + res = futimens(fd, tv); } else { res = utimensat_empty_nofollow(inode, tv); } @@ -1096,7 +1134,18 @@ static void lo_create(fuse_req_t req, fuse_ino_t parent, const char *name, lo_restore_cred(&old); if (!err) { - fi->fh = fd; + ssize_t fh; + + pthread_mutex_lock(&lo->mutex); + fh = lo_add_fd_mapping(req, fd); + pthread_mutex_unlock(&lo->mutex); + if (fh == -1) { + close(fd); + fuse_reply_err(req, ENOMEM); + return; + } + + fi->fh = fh; err = lo_do_lookup(req, parent, name, &e); } if (lo->cache == CACHE_NEVER) { @@ -1140,6 +1189,7 @@ static void lo_fsyncdir(fuse_req_t req, fuse_ino_t ino, int datasync, static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) { int fd; + ssize_t fh; char buf[64]; struct lo_data *lo = lo_data(req); @@ -1175,7 +1225,16 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) return (void)fuse_reply_err(req, errno); } - fi->fh = fd; + pthread_mutex_lock(&lo->mutex); + fh = lo_add_fd_mapping(req, fd); + pthread_mutex_unlock(&lo->mutex); + if (fh == -1) { + close(fd); + fuse_reply_err(req, ENOMEM); + return; + } + + fi->fh = fh; if (lo->cache == CACHE_NEVER) { fi->direct_io = 1; } else if (lo->cache == CACHE_ALWAYS) { @@ -1187,9 +1246,18 @@ static void lo_open(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) static void lo_release(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) { + struct lo_data *lo = lo_data(req); + int fd; + (void)ino; - close(fi->fh); + fd = lo_fi_fd(req, fi); + + pthread_mutex_lock(&lo->mutex); + lo_map_remove(&lo->fd_map, fi->fh); + pthread_mutex_unlock(&lo->mutex); + + close(fd); fuse_reply_err(req, 0); } @@ -1197,7 +1265,7 @@ static void lo_flush(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi) { int res; (void)ino; - res = close(dup(fi->fh)); + res = close(dup(lo_fi_fd(req, fi))); fuse_reply_err(req, res == -1 ? errno : 0); } @@ -1224,7 +1292,7 @@ static void lo_fsync(fuse_req_t req, fuse_ino_t ino, int datasync, return (void)fuse_reply_err(req, errno); } } else { - fd = fi->fh; + fd = lo_fi_fd(req, fi); } if (datasync) { @@ -1251,7 +1319,7 @@ static void lo_read(fuse_req_t req, fuse_ino_t ino, size_t size, off_t offset, } buf.buf[0].flags = FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK; - buf.buf[0].fd = fi->fh; + buf.buf[0].fd = lo_fi_fd(req, fi); buf.buf[0].pos = offset; fuse_reply_data(req, &buf); @@ -1266,7 +1334,7 @@ static void lo_write_buf(fuse_req_t req, fuse_ino_t ino, struct fuse_bufvec out_buf = FUSE_BUFVEC_INIT(fuse_buf_size(in_buf)); out_buf.buf[0].flags = FUSE_BUF_IS_FD | FUSE_BUF_FD_SEEK; - out_buf.buf[0].fd = fi->fh; + out_buf.buf[0].fd = lo_fi_fd(req, fi); out_buf.buf[0].pos = off; if (lo_debug(req)) { @@ -1303,7 +1371,7 @@ static void lo_fallocate(fuse_req_t req, fuse_ino_t ino, int mode, off_t offset, (void)ino; #ifdef CONFIG_FALLOCATE - err = fallocate(fi->fh, mode, offset, length); + err = fallocate(lo_fi_fd(req, fi), mode, offset, length); if (err < 0) { err = errno; } @@ -1314,7 +1382,7 @@ static void lo_fallocate(fuse_req_t req, fuse_ino_t ino, int mode, off_t offset, return; } - err = posix_fallocate(fi->fh, offset, length); + err = posix_fallocate(lo_fi_fd(req, fi), offset, length); #endif fuse_reply_err(req, err); @@ -1326,7 +1394,7 @@ static void lo_flock(fuse_req_t req, fuse_ino_t ino, struct fuse_file_info *fi, int res; (void)ino; - res = flock(fi->fh, op); + res = flock(lo_fi_fd(req, fi), op); fuse_reply_err(req, res == -1 ? errno : 0); } @@ -1551,17 +1619,19 @@ static void lo_copy_file_range(fuse_req_t req, fuse_ino_t ino_in, off_t off_in, off_t off_out, struct fuse_file_info *fi_out, size_t len, int flags) { + int in_fd, out_fd; ssize_t res; - if (lo_debug(req)) - fuse_log(FUSE_LOG_DEBUG, - "lo_copy_file_range(ino=%" PRIu64 "/fd=%lu, " - "off=%lu, ino=%" PRIu64 "/fd=%lu, " - "off=%lu, size=%zd, flags=0x%x)\n", - ino_in, fi_in->fh, off_in, ino_out, fi_out->fh, off_out, len, - flags); + in_fd = lo_fi_fd(req, fi_in); + out_fd = lo_fi_fd(req, fi_out); - res = copy_file_range(fi_in->fh, &off_in, fi_out->fh, &off_out, len, flags); + fuse_log(FUSE_LOG_DEBUG, + "lo_copy_file_range(ino=%" PRIu64 "/fd=%d, " + "off=%lu, ino=%" PRIu64 "/fd=%d, " + "off=%lu, size=%zd, flags=0x%x)\n", + ino_in, in_fd, off_in, ino_out, out_fd, off_out, len, flags); + + res = copy_file_range(in_fd, &off_in, out_fd, &off_out, len, flags); if (res < 0) { fuse_reply_err(req, -errno); } else { @@ -1576,7 +1646,7 @@ static void lo_lseek(fuse_req_t req, fuse_ino_t ino, off_t off, int whence, off_t res; (void)ino; - res = lseek(fi->fh, off, whence); + res = lseek(lo_fi_fd(req, fi), off, whence); if (res != -1) { fuse_reply_lseek(req, res); } else { @@ -1661,6 +1731,7 @@ int main(int argc, char *argv[]) root_elem->inode = &lo.root; lo_map_init(&lo.dirp_map); + lo_map_init(&lo.fd_map); if (fuse_parse_cmdline(&args, &opts) != 0) { return 1; @@ -1758,6 +1829,7 @@ err_out2: err_out1: fuse_opt_free_args(&args); + lo_map_destroy(&lo.fd_map); lo_map_destroy(&lo.dirp_map); lo_map_destroy(&lo.ino_map);