Homed update policy: user changing own settings (#31153)

Rework of #30109 to deal with changes in #30840 and discussed changes to
behavior

Depends on and includes #30840 

Fixes https://github.com/systemd/systemd/issues/34268

docs/USER_RECORD.md

@@ -597,6 +597,17 @@ The salt to pass to the FIDO2 device is found in `fido2HmacSalt`.
 The only supported recovery key type at the moment is `modhex64`, for details see the description of `recoveryKey` below.
 An account may have any number of recovery keys defined, and the array should have one entry for each.
 
+`selfModifiableFields` → An array of strings, each corresponding to a field name that can appear
+in the `regular` or `perMachine` sections. The user may be allowed to edit any field in this list
+without authenticating as an administrator. Note that the user will only be allowed to edit fields
+in `perMachine` sections that match the machine the user is performing the edit from.
+
+`selfModifiableBlobs` → Similar to `selfModifiableFields`, but it lists blobs that the user
+is allowed to edit.
+
+`selfModifiablePrivileged` →  Similar to `selfModifiableFields`, but it lists fields in
+the `privileged` section that the user is allowed to edit.
+
 `privileged` → An object, which contains the fields of the `privileged` section
 of the user record, see below.
 
@@ -754,7 +765,7 @@ All other fields that may be used in this section are identical to the equally n
 `autoLogin`, `preferredSessionType`, `preferredSessionLauncher`, `stopDelayUSec`, `killProcesses`,
 `passwordChangeMinUSec`, `passwordChangeMaxUSec`, `passwordChangeWarnUSec`,
 `passwordChangeInactiveUSec`, `passwordChangeNow`, `pkcs11TokenUri`,
-`fido2HmacCredential`.
+`fido2HmacCredential`, `selfModifiableFields`, `selfModifiableBlobs`, `selfModifiablePrivileged`.
 
 ## Fields in the `binding` section
 

src/home/homed-home-bus.c

@@ -55,7 +55,7 @@ static int property_get_state(
         return sd_bus_message_append(reply, "s", home_state_to_string(home_get_state(h)));
 }
 
-int bus_home_client_is_trusted(Home *h, sd_bus_message *message) {
+static int bus_home_client_is_trusted(Home *h, sd_bus_message *message, bool strict) {
         _cleanup_(sd_bus_creds_unrefp) sd_bus_creds *creds = NULL;
         uid_t euid;
         int r;
@@ -73,7 +73,7 @@ int bus_home_client_is_trusted(Home *h, sd_bus_message *message) {
         if (r < 0)
                 return r;
 
-        return euid == 0 || h->uid == euid;
+        return (!strict && euid == 0) || h->uid == euid;
 }
 
 static int home_verify_polkit_async(
@@ -117,7 +117,7 @@ int bus_home_get_record_json(
         assert(h);
         assert(ret);
 
-        trusted = bus_home_client_is_trusted(h, message);
+        trusted = bus_home_client_is_trusted(h, message, /* strict= */ false);
         if (trusted < 0) {
                 log_warning_errno(trusted, "Failed to determine whether client is trusted, assuming untrusted.");
                 trusted = false;
@@ -423,7 +423,7 @@ int bus_home_update_record(
                 Hashmap *blobs,
                 uint64_t flags,
                 sd_bus_error *error) {
-        int r;
+        int r, relax_access;
 
         assert(h);
         assert(message);
@@ -436,10 +436,32 @@ int bus_home_update_record(
         if ((flags & ~SD_HOMED_UPDATE_FLAGS_ALL) != 0)
                 return sd_bus_error_setf(error, SD_BUS_ERROR_INVALID_ARGS, "Invalid flags provided.");
 
+        if (blobs) {
+                const char *failed = NULL;
+                r = user_record_ensure_blob_manifest(hr, blobs, &failed);
+                if (r == -EINVAL)
+                        return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "Provided blob files do not correspond to blob manifest.");
+                if (r < 0)
+                        return sd_bus_error_set_errnof(error, r, "Failed to generate hash for blob %s: %m", strnull(failed));
+        }
+
+        relax_access = user_record_self_changes_allowed(h->record, hr);
+        if (relax_access < 0) {
+                log_warning_errno(relax_access, "Failed to determine if changes to user record are permitted, assuming not: %m");
+                relax_access = false;
+        } else if (relax_access) {
+                relax_access = bus_home_client_is_trusted(h, message, /* strict= */ true);
+                if (relax_access < 0) {
+                        log_warning_errno(relax_access, "Failed to determine whether client is trusted, assuming not: %m");
+                        relax_access = false;
+                }
+        }
+
         r = home_verify_polkit_async(
                         h,
                         message,
-                        "org.freedesktop.home1.update-home",
+                        relax_access ? "org.freedesktop.home1.update-home-by-owner"
+                                     : "org.freedesktop.home1.update-home",
                         UID_INVALID,
                         error);
         if (r < 0)
@@ -561,7 +583,7 @@ int bus_home_method_change_password(
                         h,
                         message,
                         "org.freedesktop.home1.passwd-home",
-                        h->uid,
+                        h->uid, /* Always let a user change their own password. Safe b/c homework will always re-check password */
                         error);
         if (r < 0)
                 return r;

src/home/homed-home-bus.h

@@ -6,7 +6,6 @@
 #include "bus-object.h"
 #include "homed-home.h"
 
-int bus_home_client_is_trusted(Home *h, sd_bus_message *message);
 int bus_home_get_record_json(Home *h, sd_bus_message *message, char **ret, bool *ret_incomplete);
 
 int bus_home_method_activate(sd_bus_message *message, void *userdata, sd_bus_error *error);

src/home/homed-home.c

@@ -1727,15 +1727,6 @@ static int home_update_internal(
                 secret = saved_secret;
         }
 
-        if (blobs) {
-                const char *failed = NULL;
-                r = user_record_ensure_blob_manifest(hr, blobs, &failed);
-                if (r == -EINVAL)
-                        return sd_bus_error_set(error, SD_BUS_ERROR_INVALID_ARGS, "Provided blob files do not correspond to blob manifest.");
-                if (r < 0)
-                        return sd_bus_error_set_errnof(error, r, "Failed to generate hash for blob %s: %m", strnull(failed));
-        }
-
         r = manager_verify_user_record(h->manager, hr);
         switch (r) {
 

src/home/org.freedesktop.home1.policy

@@ -49,6 +49,16 @@
                 </defaults>
         </action>
 
+        <action id="org.freedesktop.home1.update-home-by-owner">
+                <description gettext-domain="systemd">Update your home area</description>
+                <message gettext-domain="systemd">Authentication is required to update your home area.</message>
+                <defaults>
+                        <allow_any>auth_admin_keep</allow_any>
+                        <allow_inactive>auth_admin_keep</allow_inactive>
+                        <allow_active>yes</allow_active>
+                </defaults>
+        </action>
+
         <action id="org.freedesktop.home1.resize-home">
                 <description gettext-domain="systemd">Resize a home area</description>
                 <message gettext-domain="systemd">Authentication is required to resize a user's home area.</message>

src/shared/user-record-show.c

@@ -28,6 +28,25 @@ const char* user_record_state_color(const char *state) {
         return NULL;
 }
 
+static void dump_self_modifiable(const char *heading, char **field, const char **value) {
+        assert(heading);
+
+        /* Helper function for printing the various self_modifiable_* fields from the user record */
+
+        if (strv_isempty((char**) value))
+                /* Case 1: the array is explicitly set to be empty by the administrator */
+                printf("%13s %sDisabled by Administrator%s\n", heading, ansi_highlight_red(), ansi_normal());
+        else if (!field)
+                /* Case 2: we have values, but the field is NULL. This means that we're using the defaults.
+                 * We list them anyways, because they're security-sensitive to the administrator */
+                STRV_FOREACH(i, value)
+                        printf("%13s %s%s%s\n", i == value ? heading : "", ansi_grey(), *i, ansi_normal());
+        else
+                /* Case 3: we have a list provided by the administrator */
+                STRV_FOREACH(i, value)
+                        printf("%13s %s\n", i == value ? heading : "", *i);
+}
+
 void user_record_show(UserRecord *hr, bool show_full_group_info) {
         _cleanup_strv_free_ char **langs = NULL;
         const char *hd, *ip, *shell;
@@ -585,6 +604,16 @@ void user_record_show(UserRecord *hr, bool show_full_group_info) {
 
         if (hr->service)
                 printf("     Service: %s\n", hr->service);
+
+        dump_self_modifiable("Self Modify:",
+                             hr->self_modifiable_fields,
+                             user_record_self_modifiable_fields(hr));
+        dump_self_modifiable("(Blobs)",
+                             hr->self_modifiable_blobs,
+                             user_record_self_modifiable_blobs(hr));
+        dump_self_modifiable("(Privileged)",
+                             hr->self_modifiable_privileged,
+                             user_record_self_modifiable_privileged(hr));
 }
 
 void group_record_show(GroupRecord *gr, bool show_full_user_info) {

src/shared/user-record.c

@@ -207,6 +207,10 @@ static UserRecord* user_record_free(UserRecord *h) {
         for (size_t i = 0; i < h->n_recovery_key; i++)
                 recovery_key_done(h->recovery_key + i);
 
+        strv_free(h->self_modifiable_fields);
+        strv_free(h->self_modifiable_blobs);
+        strv_free(h->self_modifiable_privileged);
+
         sd_json_variant_unref(h->json);
 
         return mfree(h);
@@ -1300,6 +1304,9 @@ static int dispatch_per_machine(const char *name, sd_json_variant *variant, sd_j
                 { "passwordChangeNow",          SD_JSON_VARIANT_BOOLEAN,       sd_json_dispatch_tristate,            offsetof(UserRecord, password_change_now),           0              },
                 { "pkcs11TokenUri",             SD_JSON_VARIANT_ARRAY,         dispatch_pkcs11_uri_array,            offsetof(UserRecord, pkcs11_token_uri),              0              },
                 { "fido2HmacCredential",        SD_JSON_VARIANT_ARRAY,         dispatch_fido2_hmac_credential_array, 0,                                                   0              },
+                { "selfModifiableFields",       SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, self_modifiable_fields),        SD_JSON_STRICT },
+                { "selfModifiableBlobs",        SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, self_modifiable_blobs),         SD_JSON_STRICT },
+                { "selfModifiablePrivileged",   SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, self_modifiable_privileged),    SD_JSON_STRICT },
                 {},
         };
 
@@ -1468,7 +1475,6 @@ int user_group_record_mangle(
 
         assert(v);
         assert(ret_variant);
-        assert(ret_mask);
 
         /* Note that this function is shared with the group record parser, hence we try to be generic in our
          * log message wording here, to cover both cases. */
@@ -1556,7 +1562,8 @@ int user_group_record_mangle(
         else
                 *ret_variant = sd_json_variant_ref(v);
 
-        *ret_mask = m;
+        if (ret_mask)
+                *ret_mask = m;
         return 0;
 }
 
@@ -1646,6 +1653,9 @@ int user_record_load(UserRecord *h, sd_json_variant *v, UserRecordLoadFlags load
                 { "pkcs11TokenUri",             SD_JSON_VARIANT_ARRAY,         dispatch_pkcs11_uri_array,            offsetof(UserRecord, pkcs11_token_uri),              0              },
                 { "fido2HmacCredential",        SD_JSON_VARIANT_ARRAY,         dispatch_fido2_hmac_credential_array, 0,                                                   0              },
                 { "recoveryKeyType",            SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, recovery_key_type),             0              },
+                { "selfModifiableFields",       SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, self_modifiable_fields),        SD_JSON_STRICT },
+                { "selfModifiableBlobs",        SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, self_modifiable_blobs),         SD_JSON_STRICT },
+                { "selfModifiablePrivileged",   SD_JSON_VARIANT_ARRAY,         sd_json_dispatch_strv,                offsetof(UserRecord, self_modifiable_privileged),    SD_JSON_STRICT },
 
                 { "secret",                     SD_JSON_VARIANT_OBJECT,        dispatch_secret,                      0,                                                   0              },
                 { "privileged",                 SD_JSON_VARIANT_OBJECT,        dispatch_privileged,                  0,                                                   0              },
@@ -2156,6 +2166,244 @@ int user_record_languages(UserRecord *h, char ***ret) {
         return 0;
 }
 
+const char** user_record_self_modifiable_fields(UserRecord *h) {
+        /* As a rule of thumb: a setting is safe if it cannot be used by a
+         * user to give themselves some unfair advantage over other users on
+         * a given system. */
+        static const char *const default_fields[] = {
+                /* For display purposes */
+                "realName",
+                "emailAddress", /* Just the $EMAIL env var */
+                "iconName",
+                "location",
+
+                /* Basic account settings */
+                "shell",
+                "umask",
+                "environment",
+                "timeZone",
+                "preferredLanguage",
+                "additionalLanguages",
+                "preferredSessionLauncher",
+                "preferredSessionType",
+
+                /* Authentication methods */
+                "pkcs11TokenUri",
+                "fido2HmacCredential",
+                "recoveryKeyType",
+
+                "lastChangeUSec", /* Necessary to be able to change record at all */
+                "lastPasswordChangeUSec", /* Ditto, but for authentication methods */
+                NULL
+        };
+
+        assert(h);
+
+        /* Note that we intentionally distinguish between NULL and an empty array here */
+        return (const char**) h->self_modifiable_fields ?: (const char**) default_fields;
+}
+
+const char** user_record_self_modifiable_blobs(UserRecord *h) {
+        static const char *const default_blobs[] = {
+                /* For display purposes */
+                "avatar",
+                "login-background",
+                NULL
+        };
+
+        assert(h);
+
+        /* Note that we intentionally distinguish between NULL and an empty array here */
+        return (const char**) h->self_modifiable_blobs ?: (const char**) default_blobs;
+}
+
+const char** user_record_self_modifiable_privileged(UserRecord *h) {
+        static const char *const default_fields[] = {
+                /* For display purposes */
+                "passwordHint",
+
+                /* Authentication methods */
+                "hashedPassword"
+                "pkcs11EncryptedKey",
+                "fido2HmacSalt",
+                "recoveryKey",
+
+                "sshAuthorizedKeys", /* Basically just ~/.ssh/authorized_keys */
+                NULL
+        };
+
+        assert(h);
+
+        /* Note that we intentionally distinguish between NULL and an empty array here */
+        return (const char**) h->self_modifiable_privileged ?: (const char**) default_fields;
+}
+
+static int remove_self_modifiable_json_fields_common(UserRecord *current, sd_json_variant **target) {
+        _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL, *blobs = NULL;
+        char **allowed;
+        int r;
+
+        assert(current);
+        assert(target);
+
+        if (!sd_json_variant_is_object(*target))
+                return -EINVAL;
+
+        v = sd_json_variant_ref(*target);
+
+        /* Handle basic fields */
+        allowed = (char**) user_record_self_modifiable_fields(current);
+        r = sd_json_variant_filter(&v, allowed);
+        if (r < 0)
+                return r;
+
+        /* Handle blobs */
+        blobs = sd_json_variant_ref(sd_json_variant_by_key(v, "blobManifest"));
+        if (blobs) {
+                /* The blobManifest contains the sha256 hashes of the blobs,
+                 * which are enforced by the service managing the user. So, by
+                 * comparing the blob manifests like this, we're actually comparing
+                 * the contents of the blob directories & files */
+
+                allowed = (char**) user_record_self_modifiable_blobs(current);
+                r = sd_json_variant_filter(&blobs, allowed);
+                if (r < 0)
+                        return r;
+
+                if (sd_json_variant_is_blank_object(blobs))
+                        r = sd_json_variant_filter(&v, STRV_MAKE("blobManifest"));
+                else
+                        r = sd_json_variant_set_field(&v, "blobManifest", blobs);
+                if (r < 0)
+                        return r;
+        }
+
+        JSON_VARIANT_REPLACE(*target, TAKE_PTR(v));
+        return 0;
+}
+
+static int remove_self_modifiable_json_fields(UserRecord *current, UserRecord *h, sd_json_variant **ret) {
+        _cleanup_(sd_json_variant_unrefp) sd_json_variant *v = NULL, *privileged = NULL;
+        sd_json_variant *per_machine;
+        char **allowed;
+        int r;
+
+        assert(current);
+        assert(h);
+        assert(ret);
+
+        r = user_group_record_mangle(h->json, USER_RECORD_EXTRACT_SIGNABLE|USER_RECORD_PERMISSIVE, &v, NULL);
+        if (r < 0)
+                return r;
+
+        /* Handle the regular section */
+        r = remove_self_modifiable_json_fields_common(current, &v);
+        if (r < 0)
+                return r;
+
+        /* Handle the perMachine section */
+        per_machine = sd_json_variant_by_key(v, "perMachine");
+        if (per_machine) {
+                _cleanup_(sd_json_variant_unrefp) sd_json_variant *new_per_machine = NULL;
+                sd_json_variant *e;
+
+                if (!sd_json_variant_is_array(per_machine))
+                        return -EINVAL;
+
+                JSON_VARIANT_ARRAY_FOREACH(e, per_machine) {
+                        _cleanup_(sd_json_variant_unrefp) sd_json_variant *z = NULL;
+
+                        if (!sd_json_variant_is_object(e))
+                                return -EINVAL;
+
+                        r = per_machine_match(e, 0);
+                        if (r < 0)
+                                return r;
+                        if (r == 0) {
+                                /* It's only permissible to change anything inside of matching perMachine sections */
+                                r = sd_json_variant_append_array(&new_per_machine, e);
+                                if (r < 0)
+                                        return r;
+                                continue;
+                        }
+
+                        z = sd_json_variant_ref(e);
+
+                        r = remove_self_modifiable_json_fields_common(current, &z);
+                        if (r < 0)
+                                return r;
+
+                        if (!sd_json_variant_is_blank_object(z)) {
+                                r = sd_json_variant_append_array(&new_per_machine, z);
+                                if (r < 0)
+                                        return r;
+                        }
+                }
+
+                if (sd_json_variant_is_blank_array(new_per_machine))
+                        r = sd_json_variant_filter(&v, STRV_MAKE("perMachine"));
+                else
+                        r = sd_json_variant_set_field(&v, "perMachine", new_per_machine);
+                if (r < 0)
+                        return r;
+        }
+
+        /* Handle the privileged section */
+        privileged = sd_json_variant_ref(sd_json_variant_by_key(v, "privileged"));
+        if (privileged) {
+                allowed = (char**) user_record_self_modifiable_privileged(current);
+                r = sd_json_variant_filter(&privileged, allowed);
+                if (r < 0)
+                        return r;
+
+                if (sd_json_variant_is_blank_object(privileged))
+                        r = sd_json_variant_filter(&v, STRV_MAKE("privileged"));
+                else
+                        r = sd_json_variant_set_field(&v, "privileged", privileged);
+                if (r < 0)
+                        return r;
+        }
+
+        JSON_VARIANT_REPLACE(*ret, TAKE_PTR(v));
+        return 0;
+}
+
+int user_record_self_changes_allowed(UserRecord *current, UserRecord *incoming) {
+        _cleanup_(sd_json_variant_unrefp) sd_json_variant *vc = NULL, *vi = NULL;
+        int r;
+
+        assert(current);
+        assert(incoming);
+
+        /* We remove the fields that the user is allowed to change and then
+         * compare the resulting JSON records. If they are not equal, that
+         * means a disallowed field has been changed and thus we should
+         * require administrator permission to apply the changes. */
+
+        r = remove_self_modifiable_json_fields(current, current, &vc);
+        if (r < 0)
+                return r;
+
+        /* Note that we use `current` as the source of the allowlist, and not
+         * `incoming`. This prevents the user from adding fields. Consider a
+         * scenario that would've been possible if we had messed up this check:
+         *
+         * 1) A user starts out with no group memberships and no custom allowlist.
+         *    Thus, this user is not an administrator, and the `memberOf` and
+         *    `selfModifiableFields` fields are unset in their record.
+         * 2) This user crafts a request to add the following to their record:
+         *    { "memberOf": ["wheel"], "selfModifiableFields": ["memberOf", "selfModifiableFields"] }
+         * 3) We remove the `mebmerOf` and `selfModifiabileFields` fields from `incoming`
+         * 4) `current` and `incoming` compare as equal, so we let the change happen
+         * 5) the user has granted themselves administrator privileges
+         */
+        r = remove_self_modifiable_json_fields(current, incoming, &vi);
+        if (r < 0)
+                return r;
+
+        return sd_json_variant_equal(vc, vi);
+}
+
 uint64_t user_record_ratelimit_next_try(UserRecord *h) {
         assert(h);
 

src/shared/user-record.h

@@ -383,6 +383,10 @@ typedef struct UserRecord {
         char **capability_bounding_set;
         char **capability_ambient_set;
 
+        char **self_modifiable_fields; /* fields a user can change about themself w/o auth */
+        char **self_modifiable_blobs;
+        char **self_modifiable_privileged;
+
         sd_json_variant *json;
 } UserRecord;
 
@@ -431,6 +435,11 @@ uint64_t user_record_capability_bounding_set(UserRecord *h);
 uint64_t user_record_capability_ambient_set(UserRecord *h);
 int user_record_languages(UserRecord *h, char ***ret);
 
+const char **user_record_self_modifiable_fields(UserRecord *h);
+const char **user_record_self_modifiable_blobs(UserRecord *h);
+const char **user_record_self_modifiable_privileged(UserRecord *h);
+int user_record_self_changes_allowed(UserRecord *current, UserRecord *new);
+
 int user_record_build_image_path(UserStorage storage, const char *user_name_and_realm, char **ret);
 
 bool user_record_equal(UserRecord *a, UserRecord *b);

src/test/meson.build

@@ -183,6 +183,7 @@ simple_tests += files(
         'test-umask-util.c',
         'test-unaligned.c',
         'test-unit-file.c',
+        'test-user-record.c',
         'test-user-util.c',
         'test-utf8.c',
         'test-verbs.c',

src/test/test-user-record.c

@@ -0,0 +1,101 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "json-util.h"
+#include "macro.h"
+#include "tests.h"
+#include "user-record.h"
+
+#define USER(ret, ...)                          \
+        ({                                      \
+                typeof(ret) _r = (ret);         \
+                user_record_unref(*_r);         \
+                assert_se(user_record_build((ret), SD_JSON_BUILD_OBJECT(__VA_ARGS__)) >= 0); \
+                0;                              \
+        })
+
+TEST(self_changes) {
+        _cleanup_(user_record_unrefp) UserRecord *curr = NULL, *new = NULL;
+
+        /* not allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 11111));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 99999));
+        assert_se(!user_record_self_changes_allowed(curr, new));
+
+        /* manually allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 11111),
+             SD_JSON_BUILD_PAIR_ARRAY("selfModifiableFields", SD_JSON_BUILD_STRING("notInHardCodedList")));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_ARRAY("selfModifiableFields", SD_JSON_BUILD_STRING("notInHardCodedList")),
+             /* change in order shouldn't affect things */
+             SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 99999));
+        assert_se(user_record_self_changes_allowed(curr, new));
+
+        /* default allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_STRING("realName", "Old Name"));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_STRING("realName", "New Name"));
+        assert_se(user_record_self_changes_allowed(curr, new));
+
+        /* introduced new default allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_STRING("realName", "New Name"));
+        assert_se(user_record_self_changes_allowed(curr, new));
+
+        /* introduced new not allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 99999));
+        assert_se(!user_record_self_changes_allowed(curr, new));
+
+        /* privileged section: default allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_OBJECT("privileged",
+                                    SD_JSON_BUILD_PAIR_STRING("passwordHint", "Old Hint")));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_OBJECT("privileged",
+                                    SD_JSON_BUILD_PAIR_STRING("passwordHint", "New Hint")));
+        assert_se(user_record_self_changes_allowed(curr, new));
+
+        /* privileged section: not allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_OBJECT("privileged",
+                                    SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 11111)));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_OBJECT("privileged",
+                                    SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 99999)));
+        assert_se(!user_record_self_changes_allowed(curr, new));
+
+        /* privileged section: manually allowlisted */
+        USER(&curr,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_ARRAY("selfModifiablePrivileged", SD_JSON_BUILD_STRING("notInHardCodedList")),
+             SD_JSON_BUILD_PAIR_OBJECT("privileged",
+                                    SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 11111)));
+        USER(&new,
+             SD_JSON_BUILD_PAIR_STRING("userName", "test"),
+             SD_JSON_BUILD_PAIR_ARRAY("selfModifiablePrivileged", SD_JSON_BUILD_STRING("notInHardCodedList")),
+             SD_JSON_BUILD_PAIR_OBJECT("privileged",
+                                    SD_JSON_BUILD_PAIR_UNSIGNED("notInHardCodedList", 99999)));
+        assert_se(user_record_self_changes_allowed(curr, new));
+}
+
+DEFINE_TEST_MAIN(LOG_INFO);