The lines under "Doc and comment drift" that the findings' own commits did not already fix: - security.md: a newer confirmation link replaces the older, a reset link is not replaced; html/template renders every page (no themes); the container keeps eight capabilities, named, not "KILL". - architecture.md: ImportKey writes over a name's key, as an import must; the error text reaches the browser on the Backup page's import refusal. - guide: with Caddy the key is in Caddy's data, so a full backup refuses until certs/ holds a copy (or back up caddy-data). - comments: sasldb2 holds application passwords in the clear (store, app/password.go); texthash folds ASCII (sender.go); the supervisor socket's group is supervisor (rpc.go); cert-reload's OpenSSL measurement was 3.0.x of bookworm; sendReset's limits (links.go). Migration 0013's comment stays as shipped. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
96 lines
3.9 KiB
Bash
96 lines
3.9 KiB
Bash
#!/bin/sh
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# Picks up a renewed TLS certificate while the container runs (spec 5.2 p.4;
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# audit 2026-10-12, H2).
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#
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# Postfix does not read the mounted files: postfix-config.sh copies them at
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# start into /etc/postfix/tls-internal, because Postfix wants the key owned by
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# root with mode 0600, which a read-only bind mount owned by the host's user
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# cannot give. A renewal of the mounted files therefore reaches Postfix only
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# through a new copy. Every interval this compares the mounted files with the
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# copy; when they differ it copies both beside their targets, checks that the
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# copies - not the mounted files, which a renewer may be rewriting - are a
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# certificate and the key that belongs to it, renames both over the targets
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# and reloads Postfix. When nothing changed it does nothing.
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# (Postfix 3.10.13: smtpd loads the certificate in pre_jail_init(), once per
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# process, src/smtpd/smtpd.c:6442; "postfix reload" is SIGHUP to master,
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# conf/postfix-script:277, after which the old smtpd processes exit on the closed
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# status pipe, src/master/master_conf.c, master_config() ->
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# master_restart_service(), and new ones load the files again.)
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#
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# Runs under supervisord as root. It sleeps first: at container start the
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# wrapper is still bringing Postfix up. It never exits non-zero, so a failure
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# does not trip the crashexit listener; it is logged and tried again.
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set -u
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umask 077 # the key's copy is never readable by others, not even for an instant
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INTERVAL="${TLS_RELOAD_INTERVAL_SECONDS:-86400}"
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SRC_CERT="${TLS_CERT_FILE:-/etc/postfix/tls/fullchain.pem}"
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SRC_KEY="${TLS_KEY_FILE:-/etc/postfix/tls/privkey.pem}"
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DIR=/etc/postfix/tls-internal
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CERT="$DIR/fullchain.pem"
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KEY="$DIR/privkey.pem"
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PENDING=0 # a copy was renewed and Postfix has not been reloaded since
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reload() {
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if postfix reload; then
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echo "cert-reload: postfix reloaded ($1)"
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PENDING=0
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else
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echo "cert-reload: postfix reload failed, will try again after ${INTERVAL}s" >&2
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fi
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}
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# same_pair says whether a certificate file and a private key file belong
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# together, by comparing the public key each one prints. openssl-x509(1) and
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# openssl-pkey(1) do not say the two print it byte for byte alike; measured
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# in the image, 2026-10-15, OpenSSL 3.0.x of bookworm, before trixie's 3.5
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# (re-read on 3.5.7 is due with the next look at this script): identical for RSA-2048, P-256 and
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# P-384 keys, and for a P-256 key written in SEC1 form ("EC PRIVATE KEY") -
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# certbot 2.0 and later issue ECDSA keys by default (assumptions C-X1).
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same_pair() {
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cert_pub=$(openssl x509 -noout -pubkey -in "$1" 2>/dev/null) || return 1
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key_pub=$(openssl pkey -pubout -in "$2" 2>/dev/null) || return 1
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[ -n "$cert_pub" ] && [ "$cert_pub" = "$key_pub" ]
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}
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refresh() {
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if [ "$PENDING" = 1 ]; then
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reload "renewed certificate, earlier reload had failed"
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fi
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if [ "$(postconf -h smtpd_tls_cert_file 2>/dev/null)" != "$CERT" ]; then
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# Postfix reads the mounted files themselves (they were missing at
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# start, so no copy was made): a reload is what picks up a change.
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reload "periodic TLS refresh"
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return
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fi
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if [ ! -r "$SRC_CERT" ] || [ ! -r "$SRC_KEY" ]; then
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echo "cert-reload: cannot read ${SRC_CERT} or ${SRC_KEY}; Postfix keeps the certificate it has" >&2
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return
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fi
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if cmp -s "$SRC_CERT" "$CERT" && cmp -s "$SRC_KEY" "$KEY"; then
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return
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fi
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rm -f "$CERT.new" "$KEY.new"
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if ! cp "$SRC_CERT" "$CERT.new" || ! cp "$SRC_KEY" "$KEY.new"; then
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rm -f "$CERT.new" "$KEY.new"
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echo "cert-reload: copying the renewed certificate failed, will try again after ${INTERVAL}s" >&2
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return
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fi
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if ! same_pair "$CERT.new" "$KEY.new"; then
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rm -f "$CERT.new" "$KEY.new"
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echo "cert-reload: the mounted certificate and key differ from Postfix's copy but do not belong together; will look again after ${INTERVAL}s" >&2
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return
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fi
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chown root:root "$CERT.new" "$KEY.new"
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chmod 0644 "$CERT.new"
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chmod 0600 "$KEY.new"
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mv -f "$KEY.new" "$KEY" && mv -f "$CERT.new" "$CERT"
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PENDING=1
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reload "renewed certificate"
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}
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while true; do
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sleep "${INTERVAL}"
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refresh
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done
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