[PATCH v2 0/2] qemu-ga: add ssh-{add,remove}-authorized-keys

[PATCH v2 0/2] qemu-ga: add ssh-{add,remove}-authorized-keys

[marcandre.lureau]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Hi,

Add two new commands to help modify ~/.ssh/authorized_keys.

Although it's possible already to modify the authorized_keys files via
file-{read,write} or exec, the commands are often denied by default, and the
logic is left to the client. Let's add specific commands for this job.

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=1885332

v2:
 - misc doc improvements
 - various warnings fixes
 - fix build for !unix
 - added reviewed-by

Marc-André Lureau (2):
  glib-compat: add g_unix_get_passwd_entry_qemu()
  qga: add ssh-{add,remove}-authorized-keys

 include/glib-compat.h    |  26 +++
 qga/commands-posix-ssh.c | 400 +++++++++++++++++++++++++++++++++++++++
 qga/commands-win32.c     |  12 ++
 qga/meson.build          |  20 +-
 qga/qapi-schema.json     |  33 ++++
 5 files changed, 490 insertions(+), 1 deletion(-)
 create mode 100644 qga/commands-posix-ssh.c

-- 
2.28.0

[PATCH v2 1/2] glib-compat: add g_unix_get_passwd_entry_qemu()

[marcandre.lureau]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

The glib function was introduced in 2.64. It's a safer version of
getpwnam, and also simpler to use than getpwnam_r.

Currently, it's only use by the next patch in qemu-ga, which doesn't
(well well...) need the thread safety guarantees. Since the fallback
version is still unsafe, I would rather keep the _qemu postfix, to make
sure it's not being misused by mistake. When/if necessary, we can
implement a safer fallback and drop the _qemu suffix.

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
---
 include/glib-compat.h | 26 ++++++++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/include/glib-compat.h b/include/glib-compat.h
index 0b0ec76299..32121320e9 100644
--- a/include/glib-compat.h
+++ b/include/glib-compat.h
@@ -30,6 +30,11 @@
 #pragma GCC diagnostic ignored "-Wdeprecated-declarations"
 
 #include <glib.h>
+#if defined(G_OS_UNIX)
+#include <glib-unix.h>
+#include <sys/types.h>
+#include <pwd.h>
+#endif
 
 /*
  * Note that because of the GLIB_VERSION_MAX_ALLOWED constant above, allowing
@@ -72,6 +77,27 @@
 gint g_poll_fixed(GPollFD *fds, guint nfds, gint timeout);
 #endif
 
+#if defined(G_OS_UNIX)
+/* Note: The fallback implementation is not MT-safe, and it returns a copy of
+ * the libc passwd (must be g_free() after use) but not the content. Because of
+ * these important differences the caller must be aware of, it's not #define for
+ * GLib API substitution. */
+static inline struct passwd *
+g_unix_get_passwd_entry_qemu(const gchar *user_name, GError **error)
+{
+#if GLIB_CHECK_VERSION(2, 64, 0)
+    return g_unix_get_passwd_entry(user_name, error);
+#else
+    struct passwd *p = getpwnam(user_name);
+    if (!p) {
+        g_set_error_literal(error, G_UNIX_ERROR, 0, g_strerror(errno));
+        return NULL;
+    }
+    return g_memdup(p, sizeof(*p));
+#endif
+}
+#endif /* G_OS_UNIX */
+
 #pragma GCC diagnostic pop
 
 #endif
-- 
2.28.0

[PATCH v2 2/2] qga: add ssh-{add,remove}-authorized-keys

[marcandre.lureau]

From: Marc-André Lureau <marcandre.lureau@redhat.com>

Add new commands to add and remove SSH public keys from
~/.ssh/authorized_keys.

I took a different approach for testing, including the unit tests right
with the code. I wanted to overwrite the function to get the user
details, I couldn't easily do that over QMP. Furthermore, I prefer
having unit tests very close to the code, and unit files that are domain
specific (commands-posix is too crowded already). FWIW, that
coding/testing style is Rust-style (where tests can or should even be
part of the documentation!).

Fixes:
https://bugzilla.redhat.com/show_bug.cgi?id=1885332

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: Michal Privoznik <mprivozn@redhat.com>
Reviewed-by: Daniel P. Berrangé <berrange@redhat.com>
---
 qga/commands-posix-ssh.c | 400 +++++++++++++++++++++++++++++++++++++++
 qga/commands-win32.c     |  12 ++
 qga/meson.build          |  20 +-
 qga/qapi-schema.json     |  33 ++++
 4 files changed, 464 insertions(+), 1 deletion(-)
 create mode 100644 qga/commands-posix-ssh.c

diff --git a/qga/commands-posix-ssh.c b/qga/commands-posix-ssh.c
new file mode 100644
index 0000000000..d41c114c3c
--- /dev/null
+++ b/qga/commands-posix-ssh.c
@@ -0,0 +1,400 @@
+ /*
+  * This work is licensed under the terms of the GNU GPL, version 2 or later.
+  * See the COPYING file in the top-level directory.
+  */
+#include "qemu/osdep.h"
+
+#include <glib-unix.h>
+#include <glib/gstdio.h>
+#include <locale.h>
+#include <pwd.h>
+
+#include "qapi/error.h"
+#include "qga-qapi-commands.h"
+
+#ifdef QGA_BUILD_UNIT_TEST
+static struct passwd *
+test_get_passwd_entry(const gchar *user_name, GError **error)
+{
+    struct passwd *p;
+    int ret;
+
+    if (!user_name || g_strcmp0(user_name, g_get_user_name())) {
+        g_set_error(error, G_UNIX_ERROR, 0, "Invalid user name");
+        return NULL;
+    }
+
+    p = g_new0(struct passwd, 1);
+    p->pw_dir = (char *)g_get_home_dir();
+    p->pw_uid = geteuid();
+    p->pw_gid = getegid();
+
+    ret = g_mkdir_with_parents(p->pw_dir, 0700);
+    g_assert_cmpint(ret, ==, 0);
+
+    return p;
+}
+
+#define g_unix_get_passwd_entry_qemu(username, err) \
+   test_get_passwd_entry(username, err)
+#endif
+
+static struct passwd *
+get_passwd_entry(const char *username, Error **errp)
+{
+    g_autoptr(GError) err = NULL;
+    struct passwd *p;
+
+    ERRP_GUARD();
+
+    p = g_unix_get_passwd_entry_qemu(username, &err);
+    if (p == NULL) {
+        error_setg(errp, "failed to lookup user '%s': %s",
+                   username, err->message);
+        return NULL;
+    }
+
+    return p;
+}
+
+static bool
+mkdir_for_user(const char *path, const struct passwd *p,
+               mode_t mode, Error **errp)
+{
+    ERRP_GUARD();
+
+    if (g_mkdir(path, mode) == -1) {
+        error_setg(errp, "failed to create directory '%s': %s",
+                   path, g_strerror(errno));
+        return false;
+    }
+
+    if (chown(path, p->pw_uid, p->pw_gid) == -1) {
+        error_setg(errp, "failed to set ownership of directory '%s': %s",
+                   path, g_strerror(errno));
+        return false;
+    }
+
+    if (chmod(path, mode) == -1) {
+        error_setg(errp, "failed to set permissions of directory '%s': %s",
+                   path, g_strerror(errno));
+        return false;
+    }
+
+    return true;
+}
+
+static bool
+check_openssh_pub_key(const char *key, Error **errp)
+{
+    ERRP_GUARD();
+
+    /* simple sanity-check, we may want more? */
+    if (!key || key[0] == '#' || strchr(key, '\n')) {
+        error_setg(errp, "invalid OpenSSH public key: '%s'", key);
+        return false;
+    }
+
+    return true;
+}
+
+static bool
+check_openssh_pub_keys(strList *keys, size_t *nkeys, Error **errp)
+{
+    size_t n = 0;
+    strList *k;
+
+    ERRP_GUARD();
+
+    for (k = keys; k != NULL; k = k->next) {
+        if (!check_openssh_pub_key(k->value, errp)) {
+            return false;
+        }
+        n++;
+    }
+
+    if (nkeys) {
+        *nkeys = n;
+    }
+    return true;
+}
+
+static bool
+write_authkeys(const char *path, const GStrv keys, Error **errp)
+{
+    g_autofree char *contents = NULL;
+    g_autoptr(GError) err = NULL;
+
+    ERRP_GUARD();
+
+    contents = g_strjoinv("\n", keys);
+    if (!g_file_set_contents(path, contents, -1, &err)) {
+        error_setg(errp, "failed to write to '%s': %s", path, err->message);
+        return false;
+    }
+
+    if (chmod(path, 0600) == -1) {
+        error_setg(errp, "failed to set permissions of '%s': %s",
+                   path, g_strerror(errno));
+        return false;
+    }
+
+    return true;
+}
+
+static GStrv
+read_authkeys(const char *path, Error **errp)
+{
+    g_autoptr(GError) err = NULL;
+    g_autofree char *contents = NULL;
+
+    ERRP_GUARD();
+
+    if (!g_file_get_contents(path, &contents, NULL, &err)) {
+        error_setg(errp, "failed to read '%s': %s", path, err->message);
+        return NULL;
+    }
+
+    return g_strsplit(contents, "\n", -1);
+
+}
+
+void
+qmp_guest_ssh_add_authorized_keys(const char *username, strList *keys,
+                                  Error **errp)
+{
+    g_autofree struct passwd *p = NULL;
+    g_autofree char *ssh_path = NULL;
+    g_autofree char *authkeys_path = NULL;
+    g_auto(GStrv) authkeys = NULL;
+    strList *k;
+    size_t nkeys, nauthkeys;
+
+    ERRP_GUARD();
+
+    if (!check_openssh_pub_keys(keys, &nkeys, errp)) {
+        return;
+    }
+
+    p = get_passwd_entry(username, errp);
+    if (p == NULL) {
+        return;
+    }
+
+    ssh_path = g_build_filename(p->pw_dir, ".ssh", NULL);
+    authkeys_path = g_build_filename(ssh_path, "authorized_keys", NULL);
+
+    authkeys = read_authkeys(authkeys_path, NULL);
+    if (authkeys == NULL) {
+        if (!g_file_test(ssh_path, G_FILE_TEST_IS_DIR) &&
+            !mkdir_for_user(ssh_path, p, 0700, errp)) {
+            return;
+        }
+    }
+
+    nauthkeys = authkeys ? g_strv_length(authkeys) : 0;
+    authkeys = g_realloc_n(authkeys, nauthkeys + nkeys + 1, sizeof(char *));
+    memset(authkeys + nauthkeys, 0, (nkeys + 1) * sizeof(char *));
+
+    for (k = keys; k != NULL; k = k->next) {
+        if (g_strv_contains((const gchar * const *)authkeys, k->value)) {
+            continue;
+        }
+        authkeys[nauthkeys++] = g_strdup(k->value);
+    }
+
+    write_authkeys(authkeys_path, authkeys, errp);
+}
+
+void
+qmp_guest_ssh_remove_authorized_keys(const char *username, strList *keys,
+                                     Error **errp)
+{
+    g_autofree struct passwd *p = NULL;
+    g_autofree char *authkeys_path = NULL;
+    g_autofree GStrv new_keys = NULL; /* do not own the strings */
+    g_auto(GStrv) authkeys = NULL;
+    GStrv a;
+    size_t nkeys = 0;
+
+    ERRP_GUARD();
+
+    if (!check_openssh_pub_keys(keys, NULL, errp)) {
+        return;
+    }
+
+    p = get_passwd_entry(username, errp);
+    if (p == NULL) {
+        return;
+    }
+
+    authkeys_path = g_build_filename(p->pw_dir, ".ssh",
+                                     "authorized_keys", NULL);
+    if (!g_file_test(authkeys_path, G_FILE_TEST_EXISTS)) {
+        return;
+    }
+    authkeys = read_authkeys(authkeys_path, errp);
+    if (authkeys == NULL) {
+        return;
+    }
+
+    new_keys = g_new0(char *, g_strv_length(authkeys) + 1);
+    for (a = authkeys; *a != NULL; a++) {
+        strList *k;
+
+        for (k = keys; k != NULL; k = k->next) {
+            if (g_str_equal(k->value, *a)) {
+                break;
+            }
+        }
+        if (k != NULL) {
+            continue;
+        }
+
+        new_keys[nkeys++] = *a;
+    }
+
+    write_authkeys(authkeys_path, new_keys, errp);
+}
+
+
+#ifdef QGA_BUILD_UNIT_TEST
+#if GLIB_CHECK_VERSION(2, 60, 0)
+static const strList test_key2 = {
+    .value = (char *)"algo key2 comments"
+};
+
+static const strList test_key1_2 = {
+    .value = (char *)"algo key1 comments",
+    .next = (strList *)&test_key2,
+};
+
+static char *
+test_get_authorized_keys_path(void)
+{
+    return g_build_filename(g_get_home_dir(), ".ssh", "authorized_keys", NULL);
+}
+
+static void
+test_authorized_keys_set(const char *contents)
+{
+    g_autoptr(GError) err = NULL;
+    g_autofree char *path = NULL;
+    int ret;
+
+    path = g_build_filename(g_get_home_dir(), ".ssh", NULL);
+    ret = g_mkdir_with_parents(path, 0700);
+    g_assert_cmpint(ret, ==, 0);
+    g_free(path);
+
+    path = test_get_authorized_keys_path();
+    g_file_set_contents(path, contents, -1, &err);
+    g_assert_no_error(err);
+}
+
+static void
+test_authorized_keys_equal(const char *expected)
+{
+    g_autoptr(GError) err = NULL;
+    g_autofree char *path = NULL;
+    g_autofree char *contents = NULL;
+
+    path = test_get_authorized_keys_path();
+    g_file_get_contents(path, &contents, NULL, &err);
+    g_assert_no_error(err);
+
+    g_assert_cmpstr(contents, ==, expected);
+}
+
+static void
+test_invalid_user(void)
+{
+    Error *err = NULL;
+
+    qmp_guest_ssh_add_authorized_keys("", NULL, &err);
+    error_free_or_abort(&err);
+
+    qmp_guest_ssh_remove_authorized_keys("", NULL, &err);
+    error_free_or_abort(&err);
+}
+
+static void
+test_invalid_key(void)
+{
+    strList key = {
+        .value = (char *)"not a valid\nkey"
+    };
+    Error *err = NULL;
+
+    qmp_guest_ssh_add_authorized_keys(g_get_user_name(), &key, &err);
+    error_free_or_abort(&err);
+
+    qmp_guest_ssh_remove_authorized_keys(g_get_user_name(), &key, &err);
+    error_free_or_abort(&err);
+}
+
+static void
+test_add_keys(void)
+{
+    Error *err = NULL;
+
+    qmp_guest_ssh_add_authorized_keys(g_get_user_name(),
+                                      (strList *)&test_key2, &err);
+    g_assert_null(err);
+
+    test_authorized_keys_equal("algo key2 comments");
+
+    qmp_guest_ssh_add_authorized_keys(g_get_user_name(),
+                                      (strList *)&test_key1_2, &err);
+    g_assert_null(err);
+
+    /*  key2 came first, and should'nt be duplicated */
+    test_authorized_keys_equal("algo key2 comments\n"
+                               "algo key1 comments");
+}
+
+static void
+test_remove_keys(void)
+{
+    Error *err = NULL;
+    static const char *authkeys =
+        "algo key1 comments\n"
+        /* originally duplicated */
+        "algo key1 comments\n"
+        "# a commented line\n"
+        "algo some-key another\n";
+
+    test_authorized_keys_set(authkeys);
+    qmp_guest_ssh_remove_authorized_keys(g_get_user_name(),
+                                         (strList *)&test_key2, &err);
+    g_assert_null(err);
+    test_authorized_keys_equal(authkeys);
+
+    qmp_guest_ssh_remove_authorized_keys(g_get_user_name(),
+                                         (strList *)&test_key1_2, &err);
+    g_assert_null(err);
+    test_authorized_keys_equal("# a commented line\n"
+                               "algo some-key another\n");
+}
+
+int main(int argc, char *argv[])
+{
+    setlocale(LC_ALL, "");
+
+    g_test_init(&argc, &argv, G_TEST_OPTION_ISOLATE_DIRS, NULL);
+
+    g_test_add_func("/qga/ssh/invalid_user", test_invalid_user);
+    g_test_add_func("/qga/ssh/invalid_key", test_invalid_key);
+    g_test_add_func("/qga/ssh/add_keys", test_add_keys);
+    g_test_add_func("/qga/ssh/remove_keys", test_remove_keys);
+
+    return g_test_run();
+}
+#else
+int main(int argc, char *argv[])
+{
+    g_test_message("test skipped, needs glib >= 2.60");
+    return 0;
+}
+#endif /* GLIB_2_60 */
+#endif /* BUILD_UNIT_TEST */
diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 0c3c05484f..1e188b03d3 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -2457,3 +2457,15 @@ GuestDeviceInfoList *qmp_guest_get_devices(Error **errp)
     }
     return head;
 }
+
+void qmp_guest_ssh_add_authorized_keys(const char *username,
+                                       strList *keys, Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+}
+
+void qmp_guest_ssh_remove_authorized_keys(const char *username,
+                                          strList *keys, Error **errp)
+{
+    error_setg(errp, QERR_UNSUPPORTED);
+}
diff --git a/qga/meson.build b/qga/meson.build
index cd08bd953a..6315bb357e 100644
--- a/qga/meson.build
+++ b/qga/meson.build
@@ -35,7 +35,9 @@ qga_ss.add(files(
 ))
 qga_ss.add(when: 'CONFIG_POSIX', if_true: files(
   'channel-posix.c',
-  'commands-posix.c'))
+  'commands-posix.c',
+  'commands-posix-ssh.c',
+))
 qga_ss.add(when: 'CONFIG_WIN32', if_true: files(
   'channel-win32.c',
   'commands-win32.c',
@@ -87,3 +89,19 @@ else
 endif
 
 alias_target('qemu-ga', all_qga)
+
+test_env = environment()
+test_env.set('G_TEST_SRCDIR', meson.current_source_dir())
+test_env.set('G_TEST_BUILDDIR', meson.current_build_dir())
+
+if 'CONFIG_POSIX' in config_host
+  qga_ssh_test = executable('qga-ssh-test',
+                            files('commands-posix-ssh.c'),
+                            dependencies: [qemuutil],
+                            c_args: ['-DQGA_BUILD_UNIT_TEST'])
+
+  test('qga-ssh-test',
+       qga_ssh_test,
+       env: test_env,
+       suite: ['unit', 'qga'])
+endif
diff --git a/qga/qapi-schema.json b/qga/qapi-schema.json
index cec98c7e06..8486f46fcd 100644
--- a/qga/qapi-schema.json
+++ b/qga/qapi-schema.json
@@ -1306,3 +1306,36 @@
 ##
 { 'command': 'guest-get-devices',
   'returns': ['GuestDeviceInfo'] }
+
+##
+# @guest-ssh-add-authorized-keys:
+#
+# @username: the user account to add the authorized keys
+# @keys: the public keys to add (in OpenSSH format)
+#
+# Append public keys to user $HOME/.ssh/authorized_keys on Unix systems (not
+# implemented for other systems).
+#
+# Returns: Nothing on success.
+#
+# Since: 5.2
+##
+{ 'command': 'guest-ssh-add-authorized-keys',
+  'data': { 'username': 'str', 'keys': ['str'] } }
+
+##
+# @guest-ssh-remove-authorized-keys:
+#
+# @username: the user account to remove the authorized keys
+# @keys: the public keys to remove (in OpenSSH format)
+#
+# Remove public keys from the user $HOME/.ssh/authorized_keys on Unix systems
+# (not implemented for other systems). It's not an error if the key is already
+# missing.
+#
+# Returns: Nothing on success.
+#
+# Since: 5.2
+##
+{ 'command': 'guest-ssh-remove-authorized-keys',
+  'data': { 'username': 'str', 'keys': ['str'] } }
-- 
2.28.0

Re: [PATCH v2 0/2] qemu-ga: add ssh-{add,remove}-authorized-keys

[no-reply]

Patchew URL: https://patchew.org/QEMU/20201015160819.1471144-1-marcandre.lureau@redhat.com/



Hi,

This series seems to have some coding style problems. See output below for
more information:

Type: series
Message-id: 20201015160819.1471144-1-marcandre.lureau@redhat.com
Subject: [PATCH v2 0/2] qemu-ga: add ssh-{add,remove}-authorized-keys

=== TEST SCRIPT BEGIN ===
#!/bin/bash
git rev-parse base > /dev/null || exit 0
git config --local diff.renamelimit 0
git config --local diff.renames True
git config --local diff.algorithm histogram
./scripts/checkpatch.pl --mailback base..
=== TEST SCRIPT END ===

Updating 3c8cf5a9c21ff8782164d1def7f44bd888713384
From https://github.com/patchew-project/qemu
 * [new tag]         patchew/20201015160819.1471144-1-marcandre.lureau@redhat.com -> patchew/20201015160819.1471144-1-marcandre.lureau@redhat.com
Switched to a new branch 'test'
3cabf4b qga: add ssh-{add,remove}-authorized-keys
bef7d68 glib-compat: add g_unix_get_passwd_entry_qemu()

=== OUTPUT BEGIN ===
1/2 Checking commit bef7d6888b0b (glib-compat: add g_unix_get_passwd_entry_qemu())
WARNING: Block comments use a leading /* on a separate line
#41: FILE: include/glib-compat.h:81:
+/* Note: The fallback implementation is not MT-safe, and it returns a copy of

WARNING: Block comments use a trailing */ on a separate line
#44: FILE: include/glib-compat.h:84:
+ * GLib API substitution. */

total: 0 errors, 2 warnings, 38 lines checked

Patch 1/2 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.
2/2 Checking commit 3cabf4b13bcc (qga: add ssh-{add,remove}-authorized-keys)
WARNING: added, moved or deleted file(s), does MAINTAINERS need updating?
#27: 
new file mode 100644

ERROR: Use g_assert or g_assert_not_reached
#64: FILE: qga/commands-posix-ssh.c:33:
+    g_assert_cmpint(ret, ==, 0);

ERROR: Use g_assert or g_assert_not_reached
#318: FILE: qga/commands-posix-ssh.c:287:
+    g_assert_cmpint(ret, ==, 0);

ERROR: Use g_assert or g_assert_not_reached
#323: FILE: qga/commands-posix-ssh.c:292:
+    g_assert_no_error(err);

ERROR: Use g_assert or g_assert_not_reached
#335: FILE: qga/commands-posix-ssh.c:304:
+    g_assert_no_error(err);

ERROR: Use g_assert or g_assert_not_reached
#337: FILE: qga/commands-posix-ssh.c:306:
+    g_assert_cmpstr(contents, ==, expected);

ERROR: Use g_assert or g_assert_not_reached
#374: FILE: qga/commands-posix-ssh.c:343:
+    g_assert_null(err);

ERROR: Use g_assert or g_assert_not_reached
#380: FILE: qga/commands-posix-ssh.c:349:
+    g_assert_null(err);

ERROR: Use g_assert or g_assert_not_reached
#401: FILE: qga/commands-posix-ssh.c:370:
+    g_assert_null(err);

ERROR: Use g_assert or g_assert_not_reached
#406: FILE: qga/commands-posix-ssh.c:375:
+    g_assert_null(err);

total: 9 errors, 1 warnings, 480 lines checked

Patch 2/2 has style problems, please review.  If any of these errors
are false positives report them to the maintainer, see
CHECKPATCH in MAINTAINERS.

=== OUTPUT END ===

Test command exited with code: 1


The full log is available at
http://patchew.org/logs/20201015160819.1471144-1-marcandre.lureau@redhat.com/testing.checkpatch/?type=message.
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