From 752272da2b68a2312f0e11fc5303015a6c3ee1ac Mon Sep 17 00:00:00 2001 From: Stefan Hajnoczi Date: Tue, 5 Mar 2019 09:32:49 +0000 Subject: [PATCH] virtiofsd: prevent ".." escape in lo_do_readdir() Construct a fake dirent for the root directory's ".." entry. This hides the parent directory from the FUSE client. Signed-off-by: Stefan Hajnoczi Reviewed-by: Sergio Lopez Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 36 +++++++++++++++++++------------- 1 file changed, 22 insertions(+), 14 deletions(-) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 79d5966eea..e3d65c3676 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -1149,19 +1149,25 @@ out_err: static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size, off_t offset, struct fuse_file_info *fi, int plus) { + struct lo_data *lo = lo_data(req); struct lo_dirp *d; + struct lo_inode *dinode; char *buf = NULL; char *p; size_t rem = size; - int err = ENOMEM; + int err = EBADF; - (void)ino; + dinode = lo_inode(req, ino); + if (!dinode) { + goto error; + } d = lo_dirp(req, fi); if (!d) { goto error; } + err = ENOMEM; buf = calloc(1, size); if (!buf) { goto error; @@ -1192,15 +1198,21 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size, } nextoff = d->entry->d_off; name = d->entry->d_name; + fuse_ino_t entry_ino = 0; + struct fuse_entry_param e = (struct fuse_entry_param){ + .attr.st_ino = d->entry->d_ino, + .attr.st_mode = d->entry->d_type << 12, + }; + + /* Hide root's parent directory */ + if (dinode == &lo->root && strcmp(name, "..") == 0) { + e.attr.st_ino = lo->root.ino; + e.attr.st_mode = DT_DIR << 12; + } + if (plus) { - struct fuse_entry_param e; - if (is_dot_or_dotdot(name)) { - e = (struct fuse_entry_param){ - .attr.st_ino = d->entry->d_ino, - .attr.st_mode = d->entry->d_type << 12, - }; - } else { + if (!is_dot_or_dotdot(name)) { err = lo_do_lookup(req, ino, name, &e); if (err) { goto error; @@ -1210,11 +1222,7 @@ static void lo_do_readdir(fuse_req_t req, fuse_ino_t ino, size_t size, entsize = fuse_add_direntry_plus(req, p, rem, name, &e, nextoff); } else { - struct stat st = { - .st_ino = d->entry->d_ino, - .st_mode = d->entry->d_type << 12, - }; - entsize = fuse_add_direntry(req, p, rem, name, &st, nextoff); + entsize = fuse_add_direntry(req, p, rem, name, &e.attr, nextoff); } if (entsize > rem) { if (entry_ino != 0) {