From: "Dr. David Alan Gilbert" <dgilb...@redhat.com> Map xattr names coming from the host, i.e. listxattr.
Signed-off-by: Dr. David Alan Gilbert <dgilb...@redhat.com> --- tools/virtiofsd/passthrough_ll.c | 88 ++++++++++++++++++++++++++++++++ 1 file changed, 88 insertions(+) diff --git a/tools/virtiofsd/passthrough_ll.c b/tools/virtiofsd/passthrough_ll.c index 68d2407a37..3af4cfb0e3 100644 --- a/tools/virtiofsd/passthrough_ll.c +++ b/tools/virtiofsd/passthrough_ll.c @@ -2195,6 +2195,42 @@ static int xattr_map_client(const char *client_name, char **out_name) abort(); } +/* + * For use with listxattr where the host 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_host(const char *host_name, const char **out_name) +{ + const XattrMapEntry *cur_entry; + for (cur_entry = xattr_map_list; ; cur_entry++) { + if ((cur_entry->flags & XATTR_MAP_FLAG_HOST) && + (!strncmp(cur_entry->prepend, + host_name, + strlen(cur_entry->prepend)))) { + if (cur_entry->flags & XATTR_MAP_FLAG_END_BAD) { + return -ENODATA; + } + if (cur_entry->flags & XATTR_MAP_FLAG_END_OK) { + *out_name = host_name; + return 0; + } + if (cur_entry->flags & XATTR_MAP_FLAG_PREFIX) { + /* Remove prefix */ + *out_name = host_name + strlen(cur_entry->prepend); + return 0; + } + } + } + + /* Shouldn't get here - rules should have an END_* */ + abort(); +} + static void lo_getxattr(fuse_req_t req, fuse_ino_t ino, const char *in_name, size_t size) { @@ -2349,8 +2385,60 @@ static void lo_listxattr(fuse_req_t req, fuse_ino_t ino, size_t size) if (ret == 0) { goto out; } + + if (lo->xattrmap) { + /* + * 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_host(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: -- 2.26.2