Re: [Qemu-devel] [PATCH v3] qga: add guest-set-user-password command

[Michael Roth <mdroth@linux.vnet.ibm.com>]

Quoting Daniel P. Berrange (2015-02-11 05:26:12)
> Add a new 'guest-set-user-password' command for changing the password
> of guest OS user accounts. This command is needed to enable OpenStack
> to support its API for changing the admin password of guests running
> on KVM/QEMU. It is not practical to provide a command at the QEMU
> level explicitly targetting administrator account password change
> only, since different guest OS have different names for the admin
> account. While UNIX systems use 'root', Windows systems typically
> use 'Administrator' and even that can be renamed. Higher level apps
> like OpenStack have the ability to figure out the correct admin
> account name since they have info that QEMU/libvirt do not.
> 
> The command accepts either the clear text password string, encoded
> in base64 to make it 8-bit safe in JSON:
> 
> $ echo -n "123456" | base64
> MTIzNDU2
> $ virsh -c qemu:///system  qemu-agent-command f21x86_64 \
>    '{ "execute": "guest-set-user-password",
>       "arguments": { "crypted": false,
>                      "username": "root",
>                      "password": "MTIzNDU2" } }'
>   {"return":{}}
> 
> Or a password that has already been run though a crypt(3) like
> algorithm appropriate for the guest, again then base64 encoded:
> 
> $ echo -n '$6$n01A2Tau$e...snip...DfMOP7of9AJ1I8q0' | base64
> JDYkb...snip...YT2Ey
> $ virsh -c qemu:///system  qemu-agent-command f21x86_64 \
>    '{ "execute": "guest-set-user-password",
>       "arguments": { "crypted": true,
>                      "username": "root",
>                      "password": "JDYkb...snip...YT2Ey" } }'
> 
> NB windows support is desirable, but not implemented in this
> patch.
> 
> Signed-off-by: Daniel P. Berrange <berrange@redhat.com>

Thanks, applied to QGA tree:

https://github.com/mdroth/qemu/commits/qga

> ---
>  qga/commands-posix.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  qga/commands-win32.c |   9 +++++
>  qga/qapi-schema.json |  27 +++++++++++++
>  3 files changed, 146 insertions(+)
> 
> In v3:
> 
>  - Renamed from guest-set-admin-password to guest-set-user-password
>  - Added 'username' argument
>  - Require 'password' to be base64 encoded
> 
> diff --git a/qga/commands-posix.c b/qga/commands-posix.c
> index f6f3e3c..57409d0 100644
> --- a/qga/commands-posix.c
> +++ b/qga/commands-posix.c
> @@ -1875,6 +1875,108 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
>      return processed;
>  }
> 
> +void qmp_guest_set_user_password(const char *username,
> +                                 const char *password,
> +                                 bool crypted,
> +                                 Error **errp)
> +{
> +    Error *local_err = NULL;
> +    char *passwd_path = NULL;
> +    pid_t pid;
> +    int status;
> +    int datafd[2] = { -1, -1 };
> +    char *rawpasswddata = NULL;
> +    size_t rawpasswdlen;
> +    char *chpasswddata = NULL;
> +    size_t chpasswdlen;
> +
> +    rawpasswddata = (char *)g_base64_decode(password, &rawpasswdlen);
> +    rawpasswddata = g_renew(char, rawpasswddata, rawpasswdlen + 1);
> +    rawpasswddata[rawpasswdlen] = '\0';
> +
> +    if (strchr(rawpasswddata, '\n')) {
> +        error_setg(errp, "forbidden characters in raw password");
> +        goto out;
> +    }
> +
> +    if (strchr(username, '\n') ||
> +        strchr(username, ':')) {
> +        error_setg(errp, "forbidden characters in username");
> +        goto out;
> +    }
> +
> +    chpasswddata = g_strdup_printf("%s:%s\n", username, rawpasswddata);
> +    chpasswdlen = strlen(chpasswddata);
> +
> +    passwd_path = g_find_program_in_path("chpasswd");
> +
> +    if (!passwd_path) {
> +        error_setg(errp, "cannot find 'passwd' program in PATH");
> +        goto out;
> +    }
> +
> +    if (pipe(datafd) < 0) {
> +        error_setg(errp, "cannot create pipe FDs");
> +        goto out;
> +    }
> +
> +    pid = fork();
> +    if (pid == 0) {
> +        close(datafd[1]);
> +        /* child */
> +        setsid();
> +        dup2(datafd[0], 0);
> +        reopen_fd_to_null(1);
> +        reopen_fd_to_null(2);
> +
> +        if (crypted) {
> +            execle(passwd_path, "chpasswd", "-e", NULL, environ);
> +        } else {
> +            execle(passwd_path, "chpasswd", NULL, environ);
> +        }
> +        _exit(EXIT_FAILURE);
> +    } else if (pid < 0) {
> +        error_setg_errno(errp, errno, "failed to create child process");
> +        goto out;
> +    }
> +    close(datafd[0]);
> +    datafd[0] = -1;
> +
> +    if (qemu_write_full(datafd[1], chpasswddata, chpasswdlen) != chpasswdlen) {
> +        error_setg_errno(errp, errno, "cannot write new account password");
> +        goto out;
> +    }
> +    close(datafd[1]);
> +    datafd[1] = -1;
> +
> +    ga_wait_child(pid, &status, &local_err);
> +    if (local_err) {
> +        error_propagate(errp, local_err);
> +        goto out;
> +    }
> +
> +    if (!WIFEXITED(status)) {
> +        error_setg(errp, "child process has terminated abnormally");
> +        goto out;
> +    }
> +
> +    if (WEXITSTATUS(status)) {
> +        error_setg(errp, "child process has failed to set user password");
> +        goto out;
> +    }
> +
> +out:
> +    g_free(chpasswddata);
> +    g_free(rawpasswddata);
> +    g_free(passwd_path);
> +    if (datafd[0] != -1) {
> +        close(datafd[0]);
> +    }
> +    if (datafd[1] != -1) {
> +        close(datafd[1]);
> +    }
> +}
> +
>  #else /* defined(__linux__) */
> 
>  void qmp_guest_suspend_disk(Error **errp)
> @@ -1910,6 +2012,14 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
>      return -1;
>  }
> 
> +void qmp_guest_set_user_password(const char *username,
> +                                 const char *password,
> +                                 bool crypted,
> +                                 Error **errp)
> +{
> +    error_set(errp, QERR_UNSUPPORTED);
> +}
> +
>  #endif
> 
>  #if !defined(CONFIG_FSFREEZE)
> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
> index 3bcbeae..11876f6 100644
> --- a/qga/commands-win32.c
> +++ b/qga/commands-win32.c
> @@ -446,6 +446,14 @@ int64_t qmp_guest_set_vcpus(GuestLogicalProcessorList *vcpus, Error **errp)
>      return -1;
>  }
> 
> +void qmp_guest_set_user_password(const char *username,
> +                                 const char *password,
> +                                 bool crypted,
> +                                 Error **errp)
> +{
> +    error_set(errp, QERR_UNSUPPORTED);
> +}
> +
>  /* add unsupported commands to the blacklist */
>  GList *ga_command_blacklist_init(GList *blacklist)
>  {
> @@ -454,6 +462,7 @@ GList *ga_command_blacklist_init(GList *blacklist)
>          "guest-file-write", "guest-file-seek", "guest-file-flush",
>          "guest-suspend-hybrid", "guest-network-get-interfaces",
>          "guest-get-vcpus", "guest-set-vcpus",
> +        "guest-set-user-password",
>          "guest-fsfreeze-freeze-list", "guest-get-fsinfo",
>          "guest-fstrim", NULL};
>      char **p = (char **)list_unsupported;
> diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
> index 376e79f..5117b65 100644
> --- a/qga/qapi-schema.json
> +++ b/qga/qapi-schema.json
> @@ -738,3 +738,30 @@
>  ##
>  { 'command': 'guest-get-fsinfo',
>    'returns': ['GuestFilesystemInfo'] }
> +
> +##
> +# @guest-set-user-password
> +#
> +# @username: the user account whose password to change
> +# @password: the new password entry string, base64 encoded
> +# @crypted: true if password is already crypt()d, false if raw
> +#
> +# If the @crypted flag is true, it is the caller's responsibility
> +# to ensure the correct crypt() encryption scheme is used. This
> +# command does not attempt to interpret or report on the encryption
> +# scheme. Refer to the documentation of the guest operating system
> +# in question to determine what is supported.
> +#
> +# Note all guest operating systems will support use of the
> +# @crypted flag, as they may require the clear-text password
> +#
> +# The @password parameter must always be base64 encoded before
> +# transmission, even if already crypt()d, to ensure it is 8-bit
> +# safe when passed as JSON.
> +#
> +# Returns: Nothing on success.
> +#
> +# Since 2.3
> +##
> +{ 'command': 'guest-set-user-password',
> +  'data': { 'username': 'str', 'password': 'str', 'crypted': 'bool' } }
> -- 
> 2.1.0