diff options
| -rw-r--r-- | MAINTAINERS | 1 | ||||
| -rw-r--r-- | block/crypto.c | 6 | ||||
| -rw-r--r-- | crypto/block-luks.c | 13 | ||||
| -rw-r--r-- | crypto/init.c | 6 | ||||
| -rw-r--r-- | crypto/random-gcrypt.c | 2 | ||||
| -rw-r--r-- | crypto/random-gnutls.c | 3 | ||||
| -rw-r--r-- | crypto/random-platform.c | 45 | ||||
| -rw-r--r-- | include/crypto/block.h | 6 | ||||
| -rw-r--r-- | include/crypto/random.h | 9 | ||||
| -rw-r--r-- | qemu-doc.texi | 50 | ||||
| -rw-r--r-- | qemu.sasl | 54 | ||||
| -rw-r--r-- | tests/test-crypto-block.c | 6 |
12 files changed, 135 insertions, 66 deletions
diff --git a/MAINTAINERS b/MAINTAINERS index 8224be0d75..5a6ca57452 100644 --- a/MAINTAINERS +++ b/MAINTAINERS @@ -1487,6 +1487,7 @@ S: Maintained F: crypto/ F: include/crypto/ F: tests/test-crypto-* +F: qemu.sasl Coroutines M: Stefan Hajnoczi <stefanha@redhat.com> diff --git a/block/crypto.c b/block/crypto.c index 6828180840..10e5ddccaa 100644 --- a/block/crypto.c +++ b/block/crypto.c @@ -56,10 +56,10 @@ static int block_crypto_probe_generic(QCryptoBlockFormat format, static ssize_t block_crypto_read_func(QCryptoBlock *block, - void *opaque, size_t offset, uint8_t *buf, size_t buflen, + void *opaque, Error **errp) { BlockDriverState *bs = opaque; @@ -83,10 +83,10 @@ struct BlockCryptoCreateData { static ssize_t block_crypto_write_func(QCryptoBlock *block, - void *opaque, size_t offset, const uint8_t *buf, size_t buflen, + void *opaque, Error **errp) { struct BlockCryptoCreateData *data = opaque; @@ -102,8 +102,8 @@ static ssize_t block_crypto_write_func(QCryptoBlock *block, static ssize_t block_crypto_init_func(QCryptoBlock *block, - void *opaque, size_t headerlen, + void *opaque, Error **errp) { struct BlockCryptoCreateData *data = opaque; diff --git a/crypto/block-luks.c b/crypto/block-luks.c index d5a31bbaeb..2b97d89a69 100644 --- a/crypto/block-luks.c +++ b/crypto/block-luks.c @@ -473,9 +473,9 @@ qcrypto_block_luks_load_key(QCryptoBlock *block, * then encrypted. */ rv = readfunc(block, - opaque, slot->key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, splitkey, splitkeylen, + opaque, errp); if (rv < 0) { goto cleanup; @@ -676,9 +676,10 @@ qcrypto_block_luks_open(QCryptoBlock *block, /* Read the entire LUKS header, minus the key material from * the underlying device */ - rv = readfunc(block, opaque, 0, + rv = readfunc(block, 0, (uint8_t *)&luks->header, sizeof(luks->header), + opaque, errp); if (rv < 0) { ret = rv; @@ -1245,7 +1246,7 @@ qcrypto_block_luks_create(QCryptoBlock *block, QCRYPTO_BLOCK_LUKS_SECTOR_SIZE; /* Reserve header space to match payload offset */ - initfunc(block, opaque, block->payload_offset, &local_err); + initfunc(block, block->payload_offset, opaque, &local_err); if (local_err) { error_propagate(errp, local_err); goto error; @@ -1267,9 +1268,10 @@ qcrypto_block_luks_create(QCryptoBlock *block, /* Write out the partition header and key slot headers */ - writefunc(block, opaque, 0, + writefunc(block, 0, (const uint8_t *)&luks->header, sizeof(luks->header), + opaque, &local_err); /* Delay checking local_err until we've byte-swapped */ @@ -1295,10 +1297,11 @@ qcrypto_block_luks_create(QCryptoBlock *block, /* Write out the master key material, starting at the * sector immediately following the partition header. */ - if (writefunc(block, opaque, + if (writefunc(block, luks->header.key_slots[0].key_offset * QCRYPTO_BLOCK_LUKS_SECTOR_SIZE, splitkey, splitkeylen, + opaque, errp) != splitkeylen) { goto error; } diff --git a/crypto/init.c b/crypto/init.c index f65207e57d..f131c42306 100644 --- a/crypto/init.c +++ b/crypto/init.c @@ -32,6 +32,8 @@ #include <gcrypt.h> #endif +#include "crypto/random.h" + /* #define DEBUG_GNUTLS */ /* @@ -146,5 +148,9 @@ int qcrypto_init(Error **errp) gcry_control(GCRYCTL_INITIALIZATION_FINISHED, 0); #endif + if (qcrypto_random_init(errp) < 0) { + return -1; + } + return 0; } diff --git a/crypto/random-gcrypt.c b/crypto/random-gcrypt.c index 0de9a096df..9f1c9ee60e 100644 --- a/crypto/random-gcrypt.c +++ b/crypto/random-gcrypt.c @@ -31,3 +31,5 @@ int qcrypto_random_bytes(uint8_t *buf, gcry_randomize(buf, buflen, GCRY_STRONG_RANDOM); return 0; } + +int qcrypto_random_init(Error **errp G_GNUC_UNUSED) { return 0; } diff --git a/crypto/random-gnutls.c b/crypto/random-gnutls.c index 04b45a8f8f..5350003a0b 100644 --- a/crypto/random-gnutls.c +++ b/crypto/random-gnutls.c @@ -41,3 +41,6 @@ int qcrypto_random_bytes(uint8_t *buf, return 0; } + + +int qcrypto_random_init(Error **errp G_GNUC_UNUSED) { return 0; } diff --git a/crypto/random-platform.c b/crypto/random-platform.c index 82b755afad..0eddb915b7 100644 --- a/crypto/random-platform.c +++ b/crypto/random-platform.c @@ -22,14 +22,16 @@ #include "crypto/random.h" -int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED, - size_t buflen G_GNUC_UNUSED, - Error **errp) -{ - int fd; - int ret = -1; - int got; +#ifdef _WIN32 +#include <Wincrypt.h> +static HCRYPTPROV hCryptProv; +#else +static int fd; /* a file handle to either /dev/urandom or /dev/random */ +#endif +int qcrypto_random_init(Error **errp) +{ +#ifndef _WIN32 /* TBD perhaps also add support for BSD getentropy / Linux * getrandom syscalls directly */ fd = open("/dev/urandom", O_RDONLY); @@ -41,6 +43,25 @@ int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED, error_setg(errp, "No /dev/urandom or /dev/random found"); return -1; } +#else + if (!CryptAcquireContext(&hCryptProv, NULL, NULL, PROV_RSA_FULL, + CRYPT_SILENT | CRYPT_VERIFYCONTEXT)) { + error_setg_win32(errp, GetLastError(), + "Unable to create cryptographic provider"); + return -1; + } +#endif + + return 0; +} + +int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED, + size_t buflen G_GNUC_UNUSED, + Error **errp) +{ +#ifndef _WIN32 + int ret = -1; + int got; while (buflen > 0) { got = read(fd, buf, buflen); @@ -59,6 +80,14 @@ int qcrypto_random_bytes(uint8_t *buf G_GNUC_UNUSED, ret = 0; cleanup: - close(fd); return ret; +#else + if (!CryptGenRandom(hCryptProv, buflen, buf)) { + error_setg_win32(errp, GetLastError(), + "Unable to read random bytes"); + return -1; + } + + return 0; +#endif } diff --git a/include/crypto/block.h b/include/crypto/block.h index 4a053a3ffa..013a435f1b 100644 --- a/include/crypto/block.h +++ b/include/crypto/block.h @@ -30,22 +30,22 @@ typedef struct QCryptoBlock QCryptoBlock; * and QCryptoBlockOpenOptions in qapi/crypto.json */ typedef ssize_t (*QCryptoBlockReadFunc)(QCryptoBlock *block, - void *opaque, size_t offset, uint8_t *buf, size_t buflen, + void *opaque, Error **errp); typedef ssize_t (*QCryptoBlockInitFunc)(QCryptoBlock *block, - void *opaque, size_t headerlen, + void *opaque, Error **errp); typedef ssize_t (*QCryptoBlockWriteFunc)(QCryptoBlock *block, - void *opaque, size_t offset, const uint8_t *buf, size_t buflen, + void *opaque, Error **errp); /** diff --git a/include/crypto/random.h b/include/crypto/random.h index a101353202..a07229ce96 100644 --- a/include/crypto/random.h +++ b/include/crypto/random.h @@ -40,5 +40,14 @@ int qcrypto_random_bytes(uint8_t *buf, size_t buflen, Error **errp); +/** + * qcrypto_random_init: + * @errp: pointer to a NULL-initialized error object + * + * Initializes the handles used by qcrypto_random_bytes + * + * Returns 0 on success, -1 on error + */ +int qcrypto_random_init(Error **errp); #endif /* QCRYPTO_RANDOM_H */ diff --git a/qemu-doc.texi b/qemu-doc.texi index 794ab4a080..a4be7143b9 100644 --- a/qemu-doc.texi +++ b/qemu-doc.texi @@ -1732,37 +1732,45 @@ SASL service config /etc/sasl2/qemu.conf. If running QEMU as an unprivileged user, an environment variable SASL_CONF_PATH can be used to make it search alternate locations for the service config. -The default configuration might contain +If the TLS option is enabled for VNC, then it will provide session encryption, +otherwise the SASL mechanism will have to provide encryption. In the latter +case the list of possible plugins that can be used is drastically reduced. In +fact only the GSSAPI SASL mechanism provides an acceptable level of security +by modern standards. Previous versions of QEMU referred to the DIGEST-MD5 +mechanism, however, it has multiple serious flaws described in detail in +RFC 6331 and thus should never be used any more. The SCRAM-SHA-1 mechanism +provides a simple username/password auth facility similar to DIGEST-MD5, but +does not support session encryption, so can only be used in combination with +TLS. + +When not using TLS the recommended configuration is @example -mech_list: digest-md5 -sasldb_path: /etc/qemu/passwd.db +mech_list: gssapi +keytab: /etc/qemu/krb5.tab @end example -This says to use the 'Digest MD5' mechanism, which is similar to the HTTP -Digest-MD5 mechanism. The list of valid usernames & passwords is maintained -in the /etc/qemu/passwd.db file, and can be updated using the saslpasswd2 -command. While this mechanism is easy to configure and use, it is not -considered secure by modern standards, so only suitable for developers / -ad-hoc testing. +This says to use the 'GSSAPI' mechanism with the Kerberos v5 protocol, with +the server principal stored in /etc/qemu/krb5.tab. For this to work the +administrator of your KDC must generate a Kerberos principal for the server, +with a name of 'qemu/somehost.example.com@@EXAMPLE.COM' replacing +'somehost.example.com' with the fully qualified host name of the machine +running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm. -A more serious deployment might use Kerberos, which is done with the 'gssapi' -mechanism +When using TLS, if username+password authentication is desired, then a +reasonable configuration is @example -mech_list: gssapi -keytab: /etc/qemu/krb5.tab +mech_list: scram-sha-1 +sasldb_path: /etc/qemu/passwd.db @end example -For this to work the administrator of your KDC must generate a Kerberos -principal for the server, with a name of 'qemu/somehost.example.com@@EXAMPLE.COM' -replacing 'somehost.example.com' with the fully qualified host name of the -machine running QEMU, and 'EXAMPLE.COM' with the Kerberos Realm. +The saslpasswd2 program can be used to populate the passwd.db file with +accounts. -Other configurations will be left as an exercise for the reader. It should -be noted that only Digest-MD5 and GSSAPI provides a SSF layer for data -encryption. For all other mechanisms, VNC should always be configured to -use TLS and x509 certificates to protect security credentials from snooping. +Other SASL configurations will be left as an exercise for the reader. Note that +all mechanisms except GSSAPI, should be combined with use of TLS to ensure a +secure data channel. @node gdb_usage @section GDB usage diff --git a/qemu.sasl b/qemu.sasl index 64fdef3d5b..fb8a92ba58 100644 --- a/qemu.sasl +++ b/qemu.sasl @@ -1,36 +1,44 @@ -# If you want to use the non-TLS socket, then you *must* include -# the GSSAPI or DIGEST-MD5 mechanisms, because they are the only -# ones that can offer session encryption as well as authentication. +# If you want to use VNC remotely without TLS, then you *must* +# pick a mechanism which provides session encryption as well +# as authentication. # -# If you're only using TLS, then you can turn on any mechanisms +# If you are only using TLS, then you can turn on any mechanisms # you like for authentication, because TLS provides the encryption # -# Default to a simple username+password mechanism -# NB digest-md5 is no longer considered secure by current standards -mech_list: digest-md5 +# If you are only using UNIX sockets then encryption is not +# required at all. +# +# NB, previously DIGEST-MD5 was set as the default mechanism for +# QEMU VNC. Per RFC 6331 this is vulnerable to many serious security +# flaws as should no longer be used. Thus GSSAPI is now the default. +# +# To use GSSAPI requires that a QEMU service principal is +# added to the Kerberos server for each host running QEMU. +# This principal needs to be exported to the keytab file listed below +mech_list: gssapi -# Before you can use GSSAPI, you need a service principle on the -# KDC server for libvirt, and that to be exported to the keytab -# file listed below -#mech_list: gssapi +# If using TLS with VNC, or a UNIX socket only, it is possible to +# enable plugins which don't provide session encryption. The +# 'scram-sha-1' plugin allows plain username/password authentication +# to be performed # -# You can also list many mechanisms at once, then the user can choose -# by adding '?auth=sasl.gssapi' to their libvirt URI, eg -# qemu+tcp://hostname/system?auth=sasl.gssapi -#mech_list: digest-md5 gssapi +#mech_list: scram-sha-1 + +# You can also list many mechanisms at once, and the VNC server will +# negotiate which to use by considering the list enabled on the VNC +# client. +#mech_list: scram-sha-1 gssapi # Some older builds of MIT kerberos on Linux ignore this option & # instead need KRB5_KTNAME env var. # For modern Linux, and other OS, this should be sufficient # -# There is no default value here, uncomment if you need this -#keytab: /etc/qemu/krb5.tab +# This file needs to be populated with the service principal that +# was created on the Kerberos v5 server. If switching to a non-gssapi +# mechanism this can be commented out. +keytab: /etc/qemu/krb5.tab -# If using digest-md5 for username/passwds, then this is the file +# If using scram-sha-1 for username/passwds, then this is the file # containing the passwds. Use 'saslpasswd2 -a qemu [username]' # to add entries, and 'sasldblistusers2 -f [sasldb_path]' to browse it -sasldb_path: /etc/qemu/passwd.db - - -auxprop_plugin: sasldb - +#sasldb_path: /etc/qemu/passwd.db diff --git a/tests/test-crypto-block.c b/tests/test-crypto-block.c index 85e6603d59..95c4bd5da3 100644 --- a/tests/test-crypto-block.c +++ b/tests/test-crypto-block.c @@ -187,10 +187,10 @@ static struct QCryptoBlockTestData { static ssize_t test_block_read_func(QCryptoBlock *block, - void *opaque, size_t offset, uint8_t *buf, size_t buflen, + void *opaque, Error **errp) { Buffer *header = opaque; @@ -204,8 +204,8 @@ static ssize_t test_block_read_func(QCryptoBlock *block, static ssize_t test_block_init_func(QCryptoBlock *block, - void *opaque, size_t headerlen, + void *opaque, Error **errp) { Buffer *header = opaque; @@ -219,10 +219,10 @@ static ssize_t test_block_init_func(QCryptoBlock *block, static ssize_t test_block_write_func(QCryptoBlock *block, - void *opaque, size_t offset, const uint8_t *buf, size_t buflen, + void *opaque, Error **errp) { Buffer *header = opaque; |