Files
DECNET/decnet/templates/ssh/capture.sh
anti 6708f26e6b fix(packaging): move templates/ into decnet/ package so they ship with pip install
The docker build contexts and syslog_bridge.py lived at repo root, which
meant setuptools (include = ["decnet*"]) never shipped them. Agents
installed via `pip install $RELEASE_DIR` got site-packages/decnet/** but no
templates/, so every deploy blew up in deployer._sync_logging_helper with
FileNotFoundError on templates/syslog_bridge.py.

Move templates/ -> decnet/templates/ and declare it as setuptools
package-data. Path resolutions in services/*.py and engine/deployer.py drop
one .parent since templates now lives beside the code. Test fixtures,
bandit exclude path, and coverage omit glob updated to match.
2026-04-19 19:30:04 -04:00

266 lines
9.9 KiB
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#!/bin/bash
# systemd-journal relay helper: mirrors newly-written files under a
# monitored set of paths into the coredump staging directory and emits
# a structured journal line per event.
#
# `lastpipe` runs the tail of `inotify | while` in the current shell so
# the process tree stays flat (one bash, not two). Job control must be
# off for lastpipe to apply — non-interactive scripts already have it off.
shopt -s lastpipe
set +m
set -u
CAPTURE_DIR="${CAPTURE_DIR:-/var/lib/systemd/coredump}"
CAPTURE_MAX_BYTES="${CAPTURE_MAX_BYTES:-52428800}" # 50 MiB
CAPTURE_WATCH_PATHS="${CAPTURE_WATCH_PATHS:-/root /tmp /var/tmp /home /var/www /opt /dev/shm}"
# Invoke inotifywait through the udev-sided symlink; fall back to the real
# binary if the symlink is missing.
INOTIFY_BIN="${INOTIFY_BIN:-/usr/libexec/udev/kmsg-watch}"
[ -x "$INOTIFY_BIN" ] || INOTIFY_BIN="$(command -v inotifywait)"
mkdir -p "$CAPTURE_DIR"
chmod 700 "$CAPTURE_DIR"
# Filenames we never capture (boot noise, self-writes).
_is_ignored_path() {
local p="$1"
case "$p" in
"$CAPTURE_DIR"/*) return 0 ;;
/var/lib/systemd/*) return 0 ;;
*/.bash_history) return 0 ;;
*/.viminfo) return 0 ;;
*/ssh_host_*_key*) return 0 ;;
esac
return 1
}
# Resolve the writer PID best-effort. Prints the PID or nothing.
_writer_pid() {
local path="$1"
local pid
pid="$(fuser "$path" 2>/dev/null | tr -d ' \t\n')"
if [ -n "$pid" ]; then
printf '%s' "${pid%% *}"
return
fi
# Fallback: scan /proc/*/fd for an open handle on the path.
for fd_link in /proc/[0-9]*/fd/*; do
[ -L "$fd_link" ] || continue
if [ "$(readlink -f "$fd_link" 2>/dev/null)" = "$path" ]; then
printf '%s' "$(echo "$fd_link" | awk -F/ '{print $3}')"
return
fi
done
}
# Walk PPid chain from $1 until we hit an sshd session leader.
# Prints: <sshd_pid> <user> (empty on no match).
_walk_to_sshd() {
local pid="$1"
local depth=0
while [ -n "$pid" ] && [ "$pid" != "0" ] && [ "$pid" != "1" ] && [ $depth -lt 20 ]; do
local cmd
cmd="$(tr '\0' ' ' < "/proc/$pid/cmdline" 2>/dev/null)"
# sshd session leaders look like: "sshd: root@pts/0" or "sshd: root@notty"
if echo "$cmd" | grep -qE '^sshd: [^ ]+@'; then
local user
user="$(echo "$cmd" | sed -E 's/^sshd: ([^@]+)@.*/\1/')"
printf '%s %s' "$pid" "$user"
return
fi
pid="$(awk '/^PPid:/ {print $2}' "/proc/$pid/status" 2>/dev/null)"
depth=$((depth + 1))
done
}
# Emit a JSON array of currently-established SSH peers.
# Each item: {pid, src_ip, src_port}.
_ss_sessions_json() {
ss -Htnp state established sport = :22 2>/dev/null \
| awk '
{
peer=$4; local_=$3;
# peer looks like 198.51.100.7:55342 (may be IPv6 [::1]:x)
n=split(peer, a, ":");
port=a[n];
ip=peer; sub(":" port "$", "", ip);
gsub(/[\[\]]/, "", ip);
# extract pid from users:(("sshd",pid=1234,fd=5))
pid="";
if (match($0, /pid=[0-9]+/)) {
pid=substr($0, RSTART+4, RLENGTH-4);
}
printf "{\"pid\":%s,\"src_ip\":\"%s\",\"src_port\":%s}\n",
(pid==""?"null":pid), ip, (port+0);
}' \
| jq -s '.'
}
# Emit a JSON array of logged-in users from utmp.
# Each item: {user, src_ip, login_at}.
_who_sessions_json() {
who --ips 2>/dev/null \
| awk '{ printf "{\"user\":\"%s\",\"tty\":\"%s\",\"login_at\":\"%s %s\",\"src_ip\":\"%s\"}\n", $1, $2, $3, $4, $NF }' \
| jq -s '.'
}
_capture_one() {
local src="$1"
[ -f "$src" ] || return 0
_is_ignored_path "$src" && return 0
local size
size="$(stat -c '%s' "$src" 2>/dev/null)"
[ -z "$size" ] && return 0
if [ "$size" -gt "$CAPTURE_MAX_BYTES" ]; then
logger -p user.info -t systemd-journal "file_skipped size=$size path=$src reason=oversize"
return 0
fi
# Attribution first — PID may disappear after the copy races.
local writer_pid writer_comm writer_cmdline writer_uid writer_loginuid
writer_pid="$(_writer_pid "$src")"
if [ -n "$writer_pid" ] && [ -d "/proc/$writer_pid" ]; then
writer_comm="$(cat "/proc/$writer_pid/comm" 2>/dev/null)"
writer_cmdline="$(tr '\0' ' ' < "/proc/$writer_pid/cmdline" 2>/dev/null)"
writer_uid="$(awk '/^Uid:/ {print $2}' "/proc/$writer_pid/status" 2>/dev/null)"
writer_loginuid="$(cat "/proc/$writer_pid/loginuid" 2>/dev/null)"
fi
local ssh_pid ssh_user
if [ -n "$writer_pid" ]; then
read -r ssh_pid ssh_user < <(_walk_to_sshd "$writer_pid" || true)
fi
local ss_json who_json
ss_json="$(_ss_sessions_json 2>/dev/null || echo '[]')"
who_json="$(_who_sessions_json 2>/dev/null || echo '[]')"
# Resolve src_ip via ss by matching ssh_pid.
local src_ip="" src_port="null" attribution="unknown"
if [ -n "${ssh_pid:-}" ]; then
local matched
matched="$(echo "$ss_json" | jq -c --argjson p "$ssh_pid" '.[] | select(.pid==$p)')"
if [ -n "$matched" ]; then
src_ip="$(echo "$matched" | jq -r '.src_ip')"
src_port="$(echo "$matched" | jq -r '.src_port')"
attribution="pid-chain"
fi
fi
# Fallback 1: ss-only. scp/wget/sftp close their fd before close_write
# fires, so fuser/proc-fd walks miss them. If there's exactly one live
# sshd session, attribute to it. With multiple, attribute to the first
# but tag ambiguous so analysts know to cross-check concurrent_sessions.
if [ "$attribution" = "unknown" ]; then
local ss_len
ss_len="$(echo "$ss_json" | jq 'length')"
if [ "$ss_len" -ge 1 ]; then
src_ip="$(echo "$ss_json" | jq -r '.[0].src_ip')"
src_port="$(echo "$ss_json" | jq -r '.[0].src_port')"
ssh_pid="$(echo "$ss_json" | jq -r '.[0].pid // empty')"
if [ -n "${ssh_pid:-}" ] && [ -d "/proc/$ssh_pid" ]; then
local ssh_cmd
ssh_cmd="$(tr '\0' ' ' < "/proc/$ssh_pid/cmdline" 2>/dev/null)"
ssh_user="$(echo "$ssh_cmd" | sed -nE 's/^sshd: ([^@]+)@.*/\1/p')"
fi
if [ "$ss_len" -eq 1 ]; then
attribution="ss-only"
else
attribution="ss-ambiguous"
fi
fi
fi
# Fallback 2: utmp. Weakest signal; often empty in containers.
if [ "$attribution" = "unknown" ] && [ "$(echo "$who_json" | jq 'length')" -gt 0 ]; then
src_ip="$(echo "$who_json" | jq -r '.[0].src_ip')"
attribution="utmp-only"
fi
local sha
sha="$(sha256sum "$src" 2>/dev/null | awk '{print $1}')"
[ -z "$sha" ] && return 0
local ts base stored_as
ts="$(date -u +%Y-%m-%dT%H:%M:%SZ)"
base="$(basename "$src")"
stored_as="${ts}_${sha:0:12}_${base}"
cp --preserve=timestamps,ownership "$src" "$CAPTURE_DIR/$stored_as" 2>/dev/null || return 0
local mtime
mtime="$(stat -c '%y' "$src" 2>/dev/null)"
# Prefer NODE_NAME (the deployer-supplied decky identifier) over
# $HOSTNAME, which is a cosmetic fake like "SRV-DEV-36" set by
# entrypoint.sh. The UI and the artifact bind mount both key on the
# decky name, so using $HOSTNAME here makes /artifacts/{decky}/... URLs
# unresolvable.
local decky="${NODE_NAME:-${HOSTNAME:-unknown}}"
# One syslog line, no sidecar. Flat summary fields ride as top-level SD
# params (searchable pills in the UI); bulky nested structures (writer
# cmdline, concurrent_sessions, ss_snapshot) are base64-packed into a
# single meta_json_b64 SD param by emit_capture.py.
jq -n \
--arg _hostname "$decky" \
--arg _service "ssh" \
--arg _event_type "file_captured" \
--arg captured_at "$ts" \
--arg orig_path "$src" \
--arg stored_as "$stored_as" \
--arg sha256 "$sha" \
--argjson size "$size" \
--arg mtime "$mtime" \
--arg attribution "$attribution" \
--arg writer_pid "${writer_pid:-}" \
--arg writer_comm "${writer_comm:-}" \
--arg writer_cmdline "${writer_cmdline:-}" \
--arg writer_uid "${writer_uid:-}" \
--arg writer_loginuid "${writer_loginuid:-}" \
--arg ssh_pid "${ssh_pid:-}" \
--arg ssh_user "${ssh_user:-}" \
--arg src_ip "$src_ip" \
--arg src_port "$src_port" \
--argjson concurrent "$who_json" \
--argjson ss_snapshot "$ss_json" \
'{
_hostname: $_hostname,
_service: $_service,
_event_type: $_event_type,
captured_at: $captured_at,
orig_path: $orig_path,
stored_as: $stored_as,
sha256: $sha256,
size: $size,
mtime: $mtime,
attribution: $attribution,
writer_pid: $writer_pid,
writer_comm: $writer_comm,
writer_uid: $writer_uid,
ssh_pid: $ssh_pid,
ssh_user: $ssh_user,
src_ip: $src_ip,
src_port: (if $src_port == "null" or $src_port == "" then "" else $src_port end),
writer_cmdline: $writer_cmdline,
writer_loginuid: $writer_loginuid,
concurrent_sessions: $concurrent,
ss_snapshot: $ss_snapshot
}' \
| python3 <(printf '%s' "$EMIT_CAPTURE_PY")
}
# Main loop.
# LD_PRELOAD libudev-shared.so.1 blanks argv[1..] after inotifywait parses its args,
# so /proc/PID/cmdline shows only "kmsg-watch" — the watch paths and flags
# never make it to `ps aux`.
# shellcheck disable=SC2086
ARGV_ZAP_COMM=kmsg-watch LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libudev-shared.so.1 "$INOTIFY_BIN" -m -r -q \
--event close_write --event moved_to \
--format '%w%f' \
$CAPTURE_WATCH_PATHS 2>/dev/null \
| while IFS= read -r path; do
_capture_one "$path" &
done