mirror of https://github.com/wolfSSL/wolfssh.git
wolfsshd: test the port block allocator
sshd_port_lease_test.sh forks processes that contend for real leases and checks that a block is never held by two at once. It is the first entry in test_cases, so a broken allocator is named there rather than surfacing as a bind collision in an unrelated test much later. - covers a contended stale block, parallel allocation, a live lease, a live owner this run cannot signal, release and reuse, and --port - a winner holds its lease until the parent releases it, so a straggler cannot take a block already counted and read as a second winner - the cross-user case drops to $SUDO_USER, the one arrangement that tells "owner gone" from "owner not mine" - contends over 29000-29511, below the ephemeral range and away from the suite's daemon, with the scan pinned so --port has a block to skippull/1215/merge
John Safranek
philljj
parent
6c070dc3ab
commit
1cb4c0650d
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@ -4,6 +4,7 @@ echo "Running all wolfSSHd tests"
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# Define an array of test cases
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test_cases=(
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"sshd_port_lease_test.sh"
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"sshd_exec_test.sh"
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"sshd_term_size_test.sh"
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"sshd_large_sftp_test.sh"
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@ -0,0 +1,256 @@
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#!/bin/bash
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# Self-test for the port-block allocator in port_lease.sh.
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#
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# The allocator is what keeps two runs of this suite on one machine off each
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# other's ports, and its failure mode is a race: nothing goes wrong until two
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# runners reach the same code at the same moment, and what goes wrong then is
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# a bind collision in some unrelated test much later. Reasoning about it is
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# not enough -- an earlier attempt at the stale-lease path looked correct and
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# handed one block to eleven runners at once. So each case here forks real
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# processes and contends for real leases.
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#
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# No daemon, no root and no network listener: the pool is a scratch directory
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# and the workers only claim and hold. Takes a few seconds.
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TESTDIR=`pwd`
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cd "$TESTDIR" || exit 1
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# Worker modes, re-entered by the racing processes below. A winner holds its
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# lease until the parent releases it, as a real run holds one for its whole
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# life. Holding matters: a worker that exited the moment it won would leave a
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# lease whose owner is dead, which every later worker is then entitled to
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# ignore, and the test would pass no matter how broken the allocator was.
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#
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# Released by the parent rather than after a fixed sleep. A sleep is a guess
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# about how far apart forty forked shells reach the claim, and on a loaded
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# runner the stragglers arrived after it expired, correctly found a dead owner
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# and correctly took the block -- counted as a second winner and reported as a
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# failure of the allocator. $4 is the sentinel, $5 the file every worker
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# reports to whether it won or lost.
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if [ "$1" = "--claim-and-hold" ] || [ "$1" = "--find-and-hold" ]; then
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. ./port_lease.sh
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won=""
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if [ "$1" = "--claim-and-hold" ]; then
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claim_port_block "$2" && won="$2"
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else
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won=`find_port_block` || won=""
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fi
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[ -n "$won" ] && printf '%s\n' "$won" >> "$3"
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printf 'x\n' >> "$5"
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while [ -n "$won" ] && [ -e "$4" ]; do
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sleep 0.2
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done
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exit 0
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fi
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if [ "$1" = "--claim-once" ]; then
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. ./port_lease.sh
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claim_port_block "$2"
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exit $?
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fi
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PASS=0
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FAIL=0
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ok() { printf " %-44s PASS\n" "$1"; PASS=$((PASS + 1)); }
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bad() { printf " %-44s *** FAIL (%s)\n" "$1" "$2"; FAIL=$((FAIL + 1)); }
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POOL=`mktemp -d 2>/dev/null` || POOL=`mktemp -d -t portlease`
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if [ -z "$POOL" ] || [ ! -d "$POOL" ]; then
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echo "could not create a scratch pool directory"
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exit 1
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fi
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trap 'rm -rf "$POOL"' EXIT
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chmod 1777 "$POOL"
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export PORT_LOCK_ROOT="$POOL"
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# find_port_block probes each candidate port for real, and this test runs with
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# the suite's own daemon up. Left on the live range the probes connected to it,
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# making it fork a child and log a line per worker. Contend over a range
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# nothing in the tree binds instead -- and below 32768, out of the ephemeral
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# range Linux allocates source ports from, where a passing connection of the
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# host's own could answer a probe and move the result.
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export PORT_BLOCK_FIRST=29000
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WON="$POOL/won.txt"
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SENTINEL="$POOL/hold"
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DONE="$POOL/done.txt"
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# A pid that is certainly not running: fork one and reap it. Used to plant a
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# lease whose owner is gone, the state a run killed before its teardown leaves.
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dead_pid() {
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( exit 0 ) &
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dp=$!
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wait "$dp" 2>/dev/null
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printf '%s' "$dp"
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}
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race() { # mode arg workers
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: > "$WON"
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: > "$DONE"
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: > "$SENTINEL"
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i=0
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while [ "$i" -lt "$3" ]; do
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./sshd_port_lease_test.sh "$1" "$2" "$WON" "$SENTINEL" "$DONE" &
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i=$((i + 1))
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done
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# Let the winners go only once every worker has had its turn, so a lease
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# is never released while another is still starting up. Bounded so a
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# worker that died without reporting cannot hang the suite.
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i=0
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while [ "`grep -c . "$DONE" 2>/dev/null`" -lt "$3" ] && [ "$i" -lt 300 ]; do
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sleep 0.2
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i=$((i + 1))
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done
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rm -f "$SENTINEL"
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wait
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}
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echo "Port lease allocator test:"
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# The race the lease scheme exists to lose safely: many runners arrive at one
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# block whose recorded owner is gone. Reclaiming it in place let several of
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# them each conclude they had taken it. The bound is an upper one on purpose:
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# with forty contenders all standing down for each other, nobody taking the
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# block is the documented outcome, not a defect. Progress is asserted by the
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# parallel trial below, where a loser moves on to the next block.
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T=0
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while [ "$T" -lt 5 ]; do
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T=$((T + 1))
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rm -rf "$POOL"/*
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mkdir -p "$POOL/22400.`dead_pid`"
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race --claim-and-hold 22400 40
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n=`grep -c . "$WON"`
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if [ "$n" -le 1 ]; then
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ok "contended stale block, trial $T ($n winner)"
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else
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bad "contended stale block, trial $T" "$n runners hold one block"
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fi
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done
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# Whole allocations in parallel, the way several suites starting at once do
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# it. Every runner must come away with a block of its own.
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T=0
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while [ "$T" -lt 3 ]; do
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T=$((T + 1))
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rm -rf "$POOL"/*
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race --find-and-hold "" 20
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n=`grep -c . "$WON"`
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u=`sort -u "$WON" | grep -c .`
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# Distinct is the safety property, every worker getting one is the
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# progress property, and only the pair means anything: an allocator that
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# refused everyone satisfies "all distinct" on an empty set. 64 free
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# blocks for 20 workers, so anything short of 20 is a defect.
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if [ "$n" -eq 20 ] && [ "$n" -eq "$u" ]; then
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ok "parallel allocation, trial $T ($n blocks, all distinct)"
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else
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bad "parallel allocation, trial $T" "$n of 20 allocated, $u distinct"
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fi
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done
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# A block whose owner is gone has to come back into circulation, or a run that
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# was killed would retire one permanently.
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rm -rf "$POOL"/*
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STALE=`dead_pid`
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mkdir -p "$POOL/22400.$STALE"
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( . ./port_lease.sh; claim_port_block 22400 ) && R=0 || R=1
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if [ "$R" -eq 0 ] && [ ! -d "$POOL/22400.$STALE" ]; then
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ok "stale lease reclaimed, not retired"
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else
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bad "stale lease reclaimed, not retired" "claim rc=$R"
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fi
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# A live lease is never taken, however many ask for it.
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rm -rf "$POOL"/*
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: > "$DONE"
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: > "$SENTINEL"
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./sshd_port_lease_test.sh --claim-and-hold 22400 "$WON" "$SENTINEL" "$DONE" &
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HOLDER=$!
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i=0
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while [ "`grep -c . "$DONE" 2>/dev/null`" -lt 1 ] && [ "$i" -lt 300 ]; do
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sleep 0.2
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i=$((i + 1))
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done
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( . ./port_lease.sh; claim_port_block 22400 ) && R=0 || R=1
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if [ "$R" -eq 1 ]; then
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ok "live lease not stolen"
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else
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bad "live lease not stolen" "second claim succeeded"
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fi
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rm -f "$SENTINEL"
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wait "$HOLDER" 2>/dev/null
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# A lease held by a live process of another user must read as live. This is
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# the case the pool exists for -- CI runs the suite under sudo in one workflow
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# and as the invoking user in another -- and the one a same-user test cannot
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# reach: only a caller that may not signal the owner sees the difference
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# between "gone" and "not mine". pid 1 always runs and never takes a signal
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# from a non-root caller, so it stands in for the other run's pid.
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#
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# Under sudo, which is how the suite runs, the claim has to drop back to the
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# invoking user or the check is vacuous -- root can signal anything.
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LEASE_AS=""
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if [ "`id -u`" -eq 0 ]; then
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[ -n "$SUDO_USER" ] && LEASE_AS="$SUDO_USER"
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fi
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if [ "`id -u`" -ne 0 ] || [ -n "$LEASE_AS" ]; then
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rm -rf "$POOL"/*
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mkdir -p "$POOL/22400.1"
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if [ -n "$LEASE_AS" ]; then
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sudo -u "$LEASE_AS" env PORT_LOCK_ROOT="$POOL" \
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PORT_BLOCK_FIRST="$PORT_BLOCK_FIRST" \
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./sshd_port_lease_test.sh --claim-once 22400 && R=0 || R=1
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else
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./sshd_port_lease_test.sh --claim-once 22400 && R=0 || R=1
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fi
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if [ "$R" -eq 1 ] && [ -d "$POOL/22400.1" ]; then
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ok "live owner this run cannot signal is kept"
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else
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[ -d "$POOL/22400.1" ] && swept=no || swept=yes
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bad "live owner this run cannot signal is kept" \
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"claim rc=$R, lease swept=$swept"
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fi
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else
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printf " %-44s SKIPPED (root, no SUDO_USER)\n" \
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"live owner this run cannot signal is kept"
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fi
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# A released block is immediately reusable, so a run that gives back a block it
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# cannot use does not burn it.
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rm -rf "$POOL"/*
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( . ./port_lease.sh
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claim_port_block 22400 || exit 1
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release_port_block 22400
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claim_port_block 22400 || exit 1 ) && R=0 || R=1
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if [ "$R" -eq 0 ]; then
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ok "released block is reusable"
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else
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bad "released block is reusable" "reclaim after release failed"
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fi
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# --port has to land outside the block the private daemons are assigned from:
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# the requested port is the shared daemon's, and the offsets come from the
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# block, so a block containing it would put two daemons on one port.
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# The scan is aimed at the first block so the skip is the branch under test.
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# Left to the pid-derived origin the scan almost never reached the block
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# holding the port, and the cases passed without executing the skip at all.
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# The assertion is the contract -- the block does not contain the port -- not
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# a particular base. With the scan pinned to the block holding the port, the
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# skip is the only way past it, so this still fails if the skip goes; naming
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# 29008 instead would also fail whenever a busy port moved the scan one block
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# further, on a test that aborts the whole suite.
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for p in 29000 29003 29007; do
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rm -rf "$POOL"/*
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base=`( . ./port_lease.sh; PORT_BLOCK_START=0 TEST_PORT=$p find_port_block )`
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if [ -z "$base" ]; then
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bad "--port $p skips its block" "no block allocated"
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elif [ "$p" -ge "$base" ] && [ "$p" -lt $((base + 8)) ]; then
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bad "--port $p skips its block" "block $base contains it"
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else
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ok "--port $p skips its block (got $base)"
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fi
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done
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printf "Port lease allocator test: %d passed, %d failed\n" "$PASS" "$FAIL"
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[ "$FAIL" -eq 0 ] || exit 1
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exit 0
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