Commit f7d8afb1 authored by Philippe Mathieu-Daudé's avatar Philippe Mathieu-Daudé
Browse files

softmmu/vl: Allow -fw_cfg 'gen_id' option to use the 'etc/' namespace 



Names of user-provided fw_cfg items are supposed to start
with "opt/". However FW_CFG_DATA_GENERATOR items are generated
by QEMU, so allow the "etc/" namespace in this specific case.

Reviewed-by: default avatarLaszlo Ersek <lersek@redhat.com>
Signed-off-by: default avatarPhilippe Mathieu-Daudé <philmd@redhat.com>
Reviewed-by: default avatarDaniel P. Berrangé <berrange@redhat.com>
Message-Id: <20200623172726.21040-5-philmd@redhat.com>
parent 6552d87c

docs/specs/fw_cfg.txt

+4 −0
Original line number Diff line number Diff line
@@ -258,4 +258,8 @@ Prefix "opt/org.qemu/" is reserved for QEMU itself. 
Use of names not beginning with "opt/" is potentially dangerous and

entirely unsupported.  QEMU will warn if you try.



Use of names not beginning with "opt/" is tolerated with 'gen_id' (that

is, the warning is suppressed), but you must know exactly what you're

doing.



All externally provided fw_cfg items are read-only to the guest.

softmmu/vl.c

+7 −1
Original line number Diff line number Diff line
@@ -2049,7 +2049,13 @@ static int parse_fw_cfg(void *opaque, QemuOpts *opts, Error **errp) 
                   FW_CFG_MAX_FILE_PATH - 1);

        return -1;

    }

    if (strncmp(name, "opt/", 4) != 0) {

    if (nonempty_str(gen_id)) {

        /*

         * In this particular case where the content is populated

         * internally, the "etc/" namespace protection is relaxed,

         * so do not emit a warning.

         */

    } else if (strncmp(name, "opt/", 4) != 0) {

        warn_report("externally provided fw_cfg item names "

                    "should be prefixed with \"opt/\"");

    }