Re: [libvirt PATCH v4 19/31] qemu: pass sensitive data to nbdkit via pipe

Rather than passing passwords and cookies (which could contain passwords) to nbdkit via commandline arguments, use the alternate format that nbdkit supports where we can specify a file descriptor which nbdkit will read to get the password or cookies. Signed-off-by: Jonathon Jongsma <jjongsma(a)redhat.com&gt; --- src/qemu/qemu_nbdkit.c | 55 ++++++++++++++++++++++++++++++------------ 1 file changed, 40 insertions(+), 15 deletions(-) diff --git a/src/qemu/qemu_nbdkit.c b/src/qemu/qemu_nbdkit.c index 2b26e9bc08..ba84958e8d 100644 --- a/src/qemu/qemu_nbdkit.c +++ b/src/qemu/qemu_nbdkit.c @@ -67,6 +67,12 @@ struct _qemuNbdkitCaps { G_DEFINE_TYPE(qemuNbdkitCaps, qemu_nbdkit_caps, G_TYPE_OBJECT); +enum { + PIPE_FD_READ = 0, + PIPE_FD_WRITE = 1 +};

+ + static void qemuNbdkitCheckCommandCap(qemuNbdkitCaps *nbdkit, virCommand *cmd, @@ -759,6 +765,29 @@ qemuNbdkitInitStorageSource(qemuNbdkitCaps *caps, } +static int +qemuNbdkitCommandPassDataByPipe(virCommand *cmd, + const char *argName, + unsigned char **buf, + size_t buflen) +{ + g_autofree char *fdfmt = NULL; + int fd = virCommandSetSendBuffer(cmd, buf, buflen); + + if (fd < 0) + return -1; + + /* some nbdkit arguments accept a variation where nbdkit will read the data + * from a file descriptor, e.g. password=-FD */ + fdfmt = g_strdup_printf("-%i", fd); + virCommandAddArgPair(cmd, argName, fdfmt); + + virCommandDoAsyncIO(cmd); + + return 0; +} + + static int qemuNbdkitProcessBuildCommandCurl(qemuNbdkitProcess *proc, virCommand *cmd) @@ -808,22 +836,19 @@ qemuNbdkitProcessBuildCommandCurl(qemuNbdkitProcess *proc, return -1; } - /* ensure that the secret is a NULL-terminated string */ - password = g_strndup((char*)secret, secretlen); - - /* for now, just report an error rather than passing the password in - * cleartext on the commandline */ - virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("Password not yet supported for nbdkit sources")); - return -1; + if (qemuNbdkitCommandPassDataByPipe(cmd, "password", + &secret, secretlen) < 0) + return -1a

} - if (proc->source->ncookies > 0) { - /* for now, just report an error rather than passing cookies in - * cleartext on the commandline */ - virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("Cookies not yet supported for nbdkit sources"));