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virtiofsd: prevent ".." escape in lo_do_readdir()

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Construct a fake dirent for the root directory's ".." entry.  This hides
the parent directory from the FUSE client.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: Sergio Lopez <slp@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
This commit is contained in:
Stefan Hajnoczi 2019-03-05 09:32:49 +00:00 committed by Dr. David Alan Gilbert
parent 854684bc0b
commit 752272da2b
1 changed files with 22 additions and 14 deletions
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36
tools/virtiofsd/passthrough_ll.c
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@ -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) {