From 24d3366e8ba2c89c39734d227a07ad9857ce26f0 Mon Sep 17 00:00:00 2001 From: jklein Date: Sun, 23 Aug 2026 21:39:49 +0200 Subject: [PATCH] samba: strict values.schema.json and null-safe hardening No ingress gate: this chart has no Ingress at all (SMB and NetBIOS are exposed via NodePort), and ingress.domain appears neither in its templates nor in its values. 1. values.schema.json (#68): additionalProperties: false on every chart-owned object level, including the entries of the samba.shares list. 2. Null-safety for hardening, probes and resources (#99). This chart's hardening is a documented deviation forced by the ghcr.io/dockur/samba image, and the fallbacks reproduce it exactly instead of restoring the repo standard: no runAs* values (the entrypoint creates Unix users and smbd impersonates the share user per session, both requiring a root start), readOnlyRootFilesystem stays false (the entrypoint writes /etc/passwd, /etc/group, the healthcheck symlink and the Samba TDBs), and capabilities.add keeps the six entries a multi-user root file server needs. Restoring the standard here would stop the file server from working. The probes target the SMB TCP port directly, because SMB is not HTTP. The users.conf / checksum-config limitation from #82 is untouched: Helm never sees the Secret content, so it cannot be hashed, and the comment in values.yaml documenting the manual rollout restart stays as it is. Rendering with normal values is byte-identical to 5.0.0. --- samba/Chart.yaml | 2 +- samba/templates/_helpers.tpl | 165 ++++++++++++++++++++++++++++ samba/templates/samba.sfs.yaml | 12 +-- samba/values.schema.json | 192 +++++++++++++++++++++++++++++++++ 4 files changed, 364 insertions(+), 7 deletions(-) create mode 100644 samba/values.schema.json diff --git a/samba/Chart.yaml b/samba/Chart.yaml index 309cf92..d1326ac 100644 --- a/samba/Chart.yaml +++ b/samba/Chart.yaml @@ -5,6 +5,6 @@ icon: https://avatars.githubusercontent.com/u/13281359 type: application -version: 5.0.0+up4.23.10 +version: 6.0.0+up4.23.10 appVersion: 4.23.10 diff --git a/samba/templates/_helpers.tpl b/samba/templates/_helpers.tpl index bf82e94..fef1669 100644 --- a/samba/templates/_helpers.tpl +++ b/samba/templates/_helpers.tpl @@ -114,3 +114,168 @@ template-chart is the reference implementation. 1 {{- end -}} {{- end -}} + +{{/* +Merge a user-supplied values sub-tree onto a dict of chart defaults so that a +null / empty override falls back to the defaults instead of erasing them. + +Input: dict "defaults" "given" "path" . Output: YAML of the merged dict (consume +it with fromYaml). + +Why this exists (issue #99): Helm merges values maps recursively, but an +override key written without children — e.g. a leftover + + securityContext: + +after deleting its last remaining sub-key — is YAML null. Where the chart +defines a default, Helm treats that null as a deletion of the default; the +template then renders "securityContext: null". The workload starts and reports +healthy while being unhardened, so nothing points at the mistake. The same +shape erases a probe (it disappears) or the resources block (no requests, no +computed limits). This helper defines the opposite semantics: an empty block +means "chart defaults apply". + +Rules: + - a nil "given" is treated as an empty dict (all defaults apply). + - a key whose override value is null keeps the default (nulls never delete). + - a key present in both as a map is merged recursively, so a partially + filled block only overrides the keys it actually sets. + - a scalar override for a key the defaults define as a map is rejected with + a message naming the values path, instead of failing later with a template + field error. + - any other set value wins as given, including an explicit false or 0 — + Helm's "default" and sprig's "mergeOverwrite" would both swallow those + zero values, hence the explicit kindIs "invalid" nil check. + - keys only present in the override are passed through unchanged. + +NOTE: like the helpers above, this is duplicated into every chart's +templates/_helpers.tpl with the chart's name as define prefix, because charts +in this repo deliberately have no dependencies. +*/}} +{{- define "samba.defaultedDict" -}} +{{- $defaults := .defaults | default dict -}} +{{- $given := .given -}} +{{- $path := .path | default "value" -}} +{{- if kindIs "invalid" $given -}} +{{- $given = dict -}} +{{- end -}} +{{- if not (kindIs "map" $given) -}} +{{- fail (printf "%s must be a mapping or null, got %s (%v)" $path (kindOf $given) $given) -}} +{{- end -}} +{{- $out := deepCopy $defaults -}} +{{- range $key, $value := $given -}} +{{- if not (kindIs "invalid" $value) -}} +{{- $default := index $defaults $key -}} +{{- if and (kindIs "map" $value) (kindIs "map" $default) -}} +{{- $_ := set $out $key (fromYaml (include "samba.defaultedDict" (dict "defaults" $default "given" $value "path" (printf "%s.%s" $path $key)))) -}} +{{- else if kindIs "map" $default -}} +{{- fail (printf "%s.%s must be a mapping or null, got %s (%v)" $path $key (kindOf $value) $value) -}} +{{- else -}} +{{- $_ := set $out $key $value -}} +{{- end -}} +{{- end -}} +{{- end -}} +{{- toYaml $out -}} +{{- end -}} + +{{/* +Pick one sub-block out of a values block that may itself be null. + +Input: dict "block" "key" "path" . +Returns YAML of dict "value" , after rejecting a +non-mapping block with a message that names the values path. Needed because +".Values.samba.securityContext" can itself be erased. +*/}} +{{- define "samba.subBlock" -}} +{{- $block := .block -}} +{{- if kindIs "invalid" $block -}} +{{- $block = dict -}} +{{- end -}} +{{- if not (kindIs "map" $block) -}} +{{- fail (printf "%s must be a mapping or null, got %s (%v)" .path (kindOf $block) $block) -}} +{{- end -}} +{{- toYaml (dict "value" (index $block .key)) -}} +{{- end -}} + +{{/* +The effective security contexts, probes and resources (issue #99). + +The defaults below MUST stay in sync with the corresponding blocks in +values.yaml, which stays the documented, user-facing place for them; this copy +is only the fallback for the case where an override has erased the block. + +IMPORTANT - this chart's hardening is a DOCUMENTED DEVIATION forced by the +ghcr.io/dockur/samba image, and these fallbacks reproduce it exactly rather +than restoring the repo standard, which would break the file server: + + - No runAsNonRoot: the entrypoint creates the Unix users from users.conf + (groupadd/adduser/usermod) and smbd impersonates the authenticated share + user per session; both require starting as root. + - readOnlyRootFilesystem stays false: the entrypoint writes /etc/passwd and + /etc/group, the /etc/samba.conf healthcheck symlink, mkdir /shared and the + Samba TDB databases under /var/lib/samba. + - capabilities.add is NOT empty: NET_BIND_SERVICE (ports 445/139), + SETUID/SETGID (per-session impersonation) and CHOWN/FOWNER/DAC_OVERRIDE + (managing share files on behalf of the users). + - The pod context sets only fsGroup, no runAs* values. + +SMB is not an HTTP protocol, so the probes target the SMB TCP port directly. +*/}} +{{- define "samba.podSecurityContext" -}} +{{- $given := (fromYaml (include "samba.subBlock" (dict "block" . "key" "pod" "path" "samba.securityContext"))).value -}} +{{- $defaults := dict + "fsGroup" 1000 -}} +{{- include "samba.defaultedDict" (dict "defaults" $defaults "given" $given "path" "samba.securityContext.pod") -}} +{{- end -}} + +{{- define "samba.containerSecurityContext" -}} +{{- $given := (fromYaml (include "samba.subBlock" (dict "block" . "key" "container" "path" "samba.securityContext"))).value -}} +{{- $defaults := dict + "allowPrivilegeEscalation" false + "readOnlyRootFilesystem" false + "capabilities" (dict + "drop" (list "ALL") + "add" (list "CHOWN" "DAC_OVERRIDE" "FOWNER" "NET_BIND_SERVICE" "SETGID" "SETUID")) -}} +{{- include "samba.defaultedDict" (dict "defaults" $defaults "given" $given "path" "samba.securityContext.container") -}} +{{- end -}} + +{{- define "samba.livenessProbe" -}} +{{- $defaults := dict + "tcpSocket" (dict "port" 445) + "periodSeconds" 10 + "timeoutSeconds" 5 + "failureThreshold" 3 -}} +{{- include "samba.defaultedDict" (dict "defaults" $defaults "given" . "path" "samba.livenessProbe") -}} +{{- end -}} + +{{- define "samba.readinessProbe" -}} +{{- $defaults := dict + "tcpSocket" (dict "port" 445) + "periodSeconds" 10 + "timeoutSeconds" 5 + "failureThreshold" 3 -}} +{{- include "samba.defaultedDict" (dict "defaults" $defaults "given" . "path" "samba.readinessProbe") -}} +{{- end -}} + +{{- define "samba.startupProbe" -}} +{{- $defaults := dict + "tcpSocket" (dict "port" 445) + "periodSeconds" 5 + "timeoutSeconds" 5 + "failureThreshold" 30 -}} +{{- include "samba.defaultedDict" (dict "defaults" $defaults "given" . "path" "samba.startupProbe") -}} +{{- end -}} + +{{/* +The effective resources block, fed into the resources helper above so that an +erased "resources:" still yields the chart's requests and computed limits +instead of a container without any resource accounting. +*/}} +{{- define "samba.effectiveResources" -}} +{{- $defaults := dict + "limitFactor" 3 + "requests" (dict "memory" "50Mi" "cpu" 0.1 "ephemeralStorage" "50Mi") -}} +{{- $merged := fromYaml (include "samba.defaultedDict" (dict "defaults" $defaults "given" . "path" "samba.resources")) -}} +{{- include "samba.resources" $merged -}} +{{- end -}} diff --git a/samba/templates/samba.sfs.yaml b/samba/templates/samba.sfs.yaml index 1efc3c4..0da43f3 100644 --- a/samba/templates/samba.sfs.yaml +++ b/samba/templates/samba.sfs.yaml @@ -73,19 +73,19 @@ spec: mountPath: "/shares/{{ $value.name }}" {{- end }} livenessProbe: - {{- toYaml .Values.samba.livenessProbe | nindent 12 }} + {{- include "samba.livenessProbe" .Values.samba.livenessProbe | nindent 12 }} readinessProbe: - {{- toYaml .Values.samba.readinessProbe | nindent 12 }} + {{- include "samba.readinessProbe" .Values.samba.readinessProbe | nindent 12 }} startupProbe: - {{- toYaml .Values.samba.startupProbe | nindent 12 }} + {{- include "samba.startupProbe" .Values.samba.startupProbe | nindent 12 }} resources: - {{- include "samba.resources" .Values.samba.resources | nindent 12 }} + {{- include "samba.effectiveResources" .Values.samba.resources | nindent 12 }} securityContext: - {{- toYaml .Values.samba.securityContext.container | nindent 12 }} + {{- include "samba.containerSecurityContext" .Values.samba.securityContext | nindent 12 }} restartPolicy: Always automountServiceAccountToken: false securityContext: - {{- toYaml .Values.samba.securityContext.pod | nindent 8 }} + {{- include "samba.podSecurityContext" .Values.samba.securityContext | nindent 8 }} volumes: - name: smb-config configMap: diff --git a/samba/values.schema.json b/samba/values.schema.json new file mode 100644 index 0000000..b818fa6 --- /dev/null +++ b/samba/values.schema.json @@ -0,0 +1,192 @@ +{ + "$schema": "https://json-schema.org/draft-07/schema#", + "title": "samba values", + "description": "Strict values schema (issue #68). additionalProperties is false on every chart-owned object level, so a key that the chart does not read is rejected at render time instead of being silently ignored. The only objects that stay open are the ones passed verbatim into the Kubernetes pod spec (probes, security contexts, global) - the chart does not interpret their contents, so it cannot judge which keys are meaningful. The hardening, probe and resources blocks additionally accept null, because an erased block falls back to the chart defaults (issue #99).", + "type": "object", + "additionalProperties": false, + "properties": { + "global": { + "description": "Helm's conventional cross-chart values. Unused by this chart, kept open so an umbrella install cannot break on it.", + "type": "object" + }, + "scaleDown": { + "type": "boolean" + }, + "secrets": { + "type": "object", + "additionalProperties": false, + "properties": { + "sambaUsersSecretRef": { + "description": "op:// item path for the users.conf Secret. Note the exact name: a shortened 'sambaUsersRef' is NOT read by the chart.", + "type": ["string", "null"] + } + } + }, + "samba": { + "type": "object", + "additionalProperties": false, + "properties": { + "replicas": { + "type": "integer", + "minimum": 0 + }, + "smbNodePort": { + "type": ["integer", "null"], + "minimum": 1, + "maximum": 65535 + }, + "netbiosNodePort": { + "type": ["integer", "null"], + "minimum": 1, + "maximum": 65535 + }, + "shares": { + "description": "One SMB share per entry. Each entry drives a share section in smb.conf, a PVC and a volumeMount, so the list is part of the pod template - changing it restarts the workload by design.", + "type": ["array", "null"], + "items": { + "type": "object", + "additionalProperties": false, + "properties": { + "name": { + "type": ["string", "null"] + }, + "validUsers": { + "description": "Comma-separated user list, rendered as 'valid users' in the share section.", + "type": ["string", "null"] + }, + "description": { + "type": ["string", "null"] + }, + "size": { + "description": "Size of the PVC provisioned for this share.", + "type": ["string", "null"] + } + } + } + }, + "env": { + "$ref": "#/definitions/env" + }, + "livenessProbe": { + "$ref": "#/definitions/probe" + }, + "readinessProbe": { + "$ref": "#/definitions/probe" + }, + "startupProbe": { + "$ref": "#/definitions/probe" + }, + "resources": { + "$ref": "#/definitions/resources" + }, + "securityContext": { + "$ref": "#/definitions/securityContext" + }, + "globalConfig": { + "description": "Currently read by no template - see the note in the PR that introduced this schema. Kept allowed because it is part of the published values surface; whether it gets implemented or removed is a separate decision.", + "type": ["string", "null"] + }, + "storageClass": { + "type": ["string", "null"] + } + } + } + }, + "definitions": { + "resources": { + "description": "May be null / empty: the chart then falls back to its default requests and computed limits (issue #99) instead of rendering a container without resource accounting.", + "type": ["object", "null"], + "additionalProperties": false, + "properties": { + "limitFactor": { + "type": "number", + "exclusiveMinimum": 0 + }, + "requests": { + "$ref": "#/definitions/resourceList" + }, + "limits": { + "$ref": "#/definitions/resourceList" + } + } + }, + "resourceList": { + "type": ["object", "null"], + "additionalProperties": false, + "properties": { + "cpu": { + "type": ["string", "number", "null"] + }, + "memory": { + "type": ["string", "number", "null"] + }, + "ephemeral-storage": { + "type": ["string", "number", "null"] + }, + "ephemeralStorage": { + "type": ["string", "number", "null"] + } + } + }, + "env": { + "type": "array", + "items": { + "type": "object", + "additionalProperties": false, + "required": ["name"], + "properties": { + "name": { + "type": "string" + }, + "value": { + "type": "string" + }, + "valueFrom": { + "type": "object", + "additionalProperties": false, + "properties": { + "secretKeyRef": { + "$ref": "#/definitions/keyRef" + }, + "configMapKeyRef": { + "$ref": "#/definitions/keyRef" + } + } + } + } + } + }, + "keyRef": { + "type": "object", + "additionalProperties": false, + "required": ["name", "key"], + "properties": { + "name": { + "type": "string" + }, + "key": { + "type": "string" + } + } + }, + "securityContext": { + "description": "May be null / empty at any level: the chart then falls back to its hardening defaults (issue #99). Note that this chart's hardening is a documented deviation forced by the image (root start for user creation and per-session impersonation, writable root filesystem, non-empty capabilities.add), and the fallbacks reproduce that deviation exactly.", + "type": ["object", "null"], + "additionalProperties": false, + "properties": { + "pod": { + "description": "Merged onto the chart's pod defaults and rendered as the pod's securityContext; kept open because the chart does not interpret the individual fields.", + "type": ["object", "null"] + }, + "container": { + "description": "Merged onto the chart's container defaults and rendered as the container's securityContext; kept open because the chart does not interpret the individual fields.", + "type": ["object", "null"] + } + } + }, + "probe": { + "description": "Merged onto the chart's probe defaults and rendered as a container probe; kept open because the chart does not interpret the individual fields. May be null / empty, which means the defaults apply (issue #99) rather than the probe disappearing.", + "type": ["object", "null"] + } + } +}