From 6409cf19ca17ab2acec6f014290f24e137198751 Mon Sep 17 00:00:00 2001 From: "Dr. David Alan Gilbert" Date: Fri, 23 Oct 2020 17:58:10 +0100 Subject: tools/virtiofsd: xattr name mappings: Map server xattr names Map xattr names coming from the server, i.e. the host filesystem; currently this is only from listxattr. Signed-off-by: Dr. David Alan Gilbert Message-Id: <20201023165812.36028-4-dgilbert@redhat.com> Reviewed-by: Stefan Hajnoczi Signed-off-by: Dr. David Alan Gilbert --- tools/virtiofsd/passthrough_ll.c | 90 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index cf67737..8c01874 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2229,6 +2229,44 @@ static int xattr_map_client(const struct lo_data *lo, const char *client_name, return -EPERM; } +/* + * For use with listxattr where the server fs gives us a name and we may need + * to sanitize this for the client. + * Returns a pointer to the result in *out_name + * This is always the original string or the current string with some prefix + * removed; no reallocation is done. + * Returns 0 on success + * Can return -ENODATA to indicate the name should be dropped from the list. + */ +static int xattr_map_server(const struct lo_data *lo, const char *server_name, + const char **out_name) +{ + size_t i; + const char *end; + + for (i = 0; i < lo->xattr_map_nentries; i++) { + const XattrMapEntry *cur_entry = lo->xattr_map_list + i; + + if ((cur_entry->flags & XATTR_MAP_FLAG_SERVER) && + (strstart(server_name, cur_entry->prepend, &end))) { + if (cur_entry->flags & XATTR_MAP_FLAG_BAD) { + return -ENODATA; + } + if (cur_entry->flags & XATTR_MAP_FLAG_OK) { + *out_name = server_name; + return 0; + } + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { + /* Remove prefix */ + *out_name = end; + return 0; + } + } + } + + return -ENODATA; +} + static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, size_t size) { @@ -2383,8 +2421,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) if (ret == 0) { goto out; } + + if (lo->xattr_map_list) { + /* + * Map the names back, some attributes might be dropped, + * some shortened, but not increased, so we shouldn't + * run out of room. + */ + size_t out_index, in_index; + out_index = 0; + in_index = 0; + while (in_index < ret) { + const char *map_out; + char *in_ptr = value + in_index; + /* Length of current attribute name */ + size_t in_len = strlen(value + in_index) + 1; + + int mapret = xattr_map_server(lo, in_ptr, &map_out); + if (mapret != -ENODATA && mapret != 0) { + /* Shouldn't happen */ + saverr = -mapret; + goto out; + } + if (mapret == 0) { + /* Either unchanged, or truncated */ + size_t out_len; + if (map_out != in_ptr) { + /* +1 copies the NIL */ + out_len = strlen(map_out) + 1; + } else { + /* No change */ + out_len = in_len; + } + /* + * Move result along, may still be needed for an unchanged + * entry if a previous entry was changed. + */ + memmove(value + out_index, map_out, out_len); + + out_index += out_len; + } + in_index += in_len; + } + ret = out_index; + if (ret == 0) { + goto out; + } + } fuse_reply_buf(req, value, ret); } else { + /* + * xattrmap only ever shortens the result, + * so we don't need to do anything clever with the + * allocation length here. + */ fuse_reply_xattr(req, ret); } out_free: -- cgit v1.1