Re: [libvirt] [PATCH 4/4] xkcd: generate secure rememberable qcow2 passwords

Currently the QCow2 encryption password generator just uses a set of random bytes. This is not very easy for users to remember, which encourages them to write down their passwords. Instead of this, allow for using 4 random words which gives a rememberable password, while still having high entropy. Enable this feature using LIBVIRT_XKCD=936 /usr/sbin/libvirtd Signed-off-by: Daniel P. Berrange <berrange(a)redhat.com&gt; --- src/util/virstorageencryption.c | 47 +++++++++++++++++++++++------------------ 1 file changed, 26 insertions(+), 21 deletions(-) diff --git a/src/util/virstorageencryption.c b/src/util/virstorageencryption.c index ec4a8cb..2a36e8e 100644 --- a/src/util/virstorageencryption.c +++ b/src/util/virstorageencryption.c @@ -34,6 +34,7 @@ #include "virerror.h" #include "viruuid.h" #include "virfile.h" +#include "virxkcd.h" #define VIR_FROM_THIS VIR_FROM_STORAGE @@ -294,30 +295,34 @@ virStorageGenerateQcowPassphrase(unsigned char *dest) int fd; size_t i; - /* A qcow passphrase is up to 16 bytes, with any data following a NUL - ignored. Prohibit control and non-ASCII characters to avoid possible - unpleasant surprises with the qemu monitor input mechanism. */ - fd = open("/dev/urandom", O_RDONLY); - if (fd < 0) { - virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("Cannot open /dev/urandom")); - return -1; - } - i = 0; - while (i < VIR_STORAGE_QCOW_PASSPHRASE_SIZE) { - ssize_t r; - - while ((r = read(fd, dest + i, 1)) == -1 && errno == EINTR) - ; - if (r <= 0) { + if (virXKCDIsEnabled(936)) {

+ memcpy(dest, "correct horse battery staple", VIR_STORAGE_QCOW_PASSPHRASE_SIZE); + } else { + /* A qcow passphrase is up to 16 bytes, with any data following a NUL + ignored. Prohibit control and non-ASCII characters to avoid possible + unpleasant surprises with the qemu monitor input mechanism. */ + fd = open("/dev/urandom", O_RDONLY); + if (fd < 0) { virReportError(VIR_ERR_INTERNAL_ERROR, "%s", - _("Cannot read from /dev/urandom")); - VIR_FORCE_CLOSE(fd); + _("Cannot open /dev/urandom")); return -1; } - if (dest[i] >= 0x20 && dest[i] <= 0x7E) - i++; /* Got an acceptable character */ + i = 0; + while (i < VIR_STORAGE_QCOW_PASSPHRASE_SIZE) { + ssize_t r; + + while ((r = read(fd, dest + i, 1)) == -1 && errno == EINTR) + ; + if (r <= 0) { + virReportError(VIR_ERR_INTERNAL_ERROR, "%s", + _("Cannot read from /dev/urandom")); + VIR_FORCE_CLOSE(fd); + return -1; + } + if (dest[i] >= 0x20 && dest[i] <= 0x7E) + i++; /* Got an acceptable character */ + } + VIR_FORCE_CLOSE(fd); } - VIR_FORCE_CLOSE(fd); return 0; }