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ipsec, imsd: the SA setup deletes by exact key instead of flushing the host's xfrm

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A fresh registration's SA setup began with `ip xfrm state flush` and `ip
xfrm policy flush`: every SA userspace had installed and every SPD policy
went, a policy-based VPN's (strongSwan's, libreswan's) SAs and policies
included. The setup now takes out what two rules select and leaves the
rest; and the SA reader, which took the P-CSCF ports for a resume from any
reqid-1/2 `dir out` policy — correct only while the flush left imsd's pair
alone in the kernel — takes them from the policies between our two
addresses only. Whether imsd runs beside a live strongSwan or libreswan
connection is unmeasured: the dev phone shows a tunnel policy and a tunnel
state left in place (Tested below), no more.

OwnXfrmDeleteCommands (Imsd:Ipsec) builds the deletes from the kernel text
the shell reads: every transport-mode policy with reqid 1 or 2 whose
selector carries imsd's protected port on the UE side, by the selector ip
xfrm policy prints (src, dst, proto, sport, dport, dev) and its direction,
and every transport-mode reqid-1/2 ESP state running from such a policy's
source to its destination or anchored on the UE's ims-PDN address, by src,
dst, proto esp and SPI — policy or not: a setup whose policy add failed
leaves such states (the setup logs a failed add and goes on), and an ESP
state another transport-mode user put on that address with reqid 1 or 2 goes
with them (an AH or IPComp state is not selected: the rule asks for ESP).
Every reader of the policy text — the deletes and the SA
reader's port pass here — goes through one predicate (detail::OwnPolicy),
written for whatever reads that text later.
BuildSetupCommands loses its two flush lines and the shell runs the deletes
right before it (RunOwnXfrmDeletes); BuildTeardownCommands, the same two
flushes with no caller, goes. A policy-based VPN's tunnel entries and
another transport-mode user's pair on other ports and addresses stay.
Residual: a transport-mode policy with reqid 1 and the UE-side port 45061,
or reqid 2 and 45062 — alone or paired, between any addresses — carries
imsd's fingerprint and goes, with the reqid-1/2 transport-mode ESP states
in its direction, and a reqid-1/2 transport-mode ESP state on the UE's
ims-PDN address goes whoever made it (tests/Ipsec pins both, and that an AH state
stays).

Tested: crafter-build test, 7 passed (the eight deletes byte-exact on the
fixture in the registered FP6's shape (synthetic addresses and keys); a VPN's tunnel SA and policies beside the pair
untouched; another transport-mode user's pair on other ports and addresses
untouched, its reqid-1 ESP state on the UE's address deleted whoever made
it, its AH state left; a policy-less state on the UE's address deleted, one
between other addresses left; the reader's ports from our pair beside
a foreign transport policy with ports); on the dev phone (KPN), in builds of
this series, a fresh registration with a VPN's tunnel policy and state in
the kernel: both still there afterwards, imsd's previous pair gone.
This commit is contained in:
Jorijn van der Graaf 2026-10-13 22:28:02 +02:00
commit 21cb0f870d
Signed by: jorijnvdgraaf
GPG key ID: 2937E59CDCC1BCFB
4 changed files with 198 additions and 25 deletions
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62
tests/Ipsec/main.cpp
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@ -101,6 +101,54 @@ int main() {
Check(SaLocals(State, "2001:db8::999").empty(), "SaLocals: no SA to that P-CSCF -> none");
}
// ---- OwnXfrmDeleteCommands: imsd's own entries out of the kernel by exact key; everything else stays
{
const std::string ue = "2001:db8:1111:2222:3333:4444:5555:db43";
// a policy-based VPN's: a tunnel policy (v6, reqid 1), an IPv4 one to 0.0.0.0/0, a tunnel SA
const std::string vpn = "src 2001:db8::1/128 dst 2001:db8::2/128 \n\tdir out priority 0 \n\ttmpl src 2001:db8::1 dst 2001:db8::2\n\t\tproto esp reqid 1 mode tunnel\n";
const std::string vpn4 = "src 192.0.2.10/32 dst 0.0.0.0/0 \n\tdir out priority 383615 ptype main \n\ttmpl src 192.0.2.10 dst 192.0.2.1\n\t\tproto esp reqid 1 mode tunnel\n";
const std::string tunState = "src 2001:db8::1 dst 2001:db8::2\n\tproto esp spi 0x00000777 reqid 7 mode tunnel\n\treplay-window 32 \n";
// another transport-mode user's reqid 1 + 2 pair on other ports, with its SA between other addresses
const std::string otherOut2 = "src " + ue + "/128 dst 2001:db8::106/128 sport 1 dport 2 \n\tdir out priority 0 \n\ttmpl src " + ue + " dst 2001:db8::106\n\t\tproto esp reqid 2 mode transport\n";
const std::string otherOut1 = "src " + ue + "/128 dst 2001:db8::106/128 sport 3 dport 4 \n\tdir out priority 0 \n\ttmpl src " + ue + " dst 2001:db8::106\n\t\tproto esp reqid 1 mode transport\n";
const std::string otherState = "src 2001:db8::7 dst 2001:db8::106\n\tproto esp spi 0x00000106 reqid 2 mode transport\n\treplay-window 0 \n";
auto dels = OwnXfrmDeleteCommands(State, Policy, ue);
Check(dels.size() == 8, "OwnXfrmDeleteCommands: our four states and four policies -> 8 deletes");
Check(dels.size() == 8 && Join(dels[0]) == "ip xfrm state delete src 2001:db8::105 dst " + ue + " proto esp spi 0x0a84ab2f", "OwnXfrmDeleteCommands: a state by src, dst and SPI, byte-exact");
Check(dels.size() == 8 && Join(dels[4]) == "ip xfrm policy delete src 2001:db8::105/128 dst " + ue + "/128 sport 33421 dport 45062 dir in", "OwnXfrmDeleteCommands: a policy by its selector and direction, byte-exact");
Check(dels.size() == 8 && Join(dels[1]) == "ip xfrm state delete src " + ue + " dst 2001:db8::105 proto esp spi 0x0526f2c1" && Join(dels[2]) == "ip xfrm state delete src 2001:db8::105 dst " + ue + " proto esp spi 0x0071acd4" && Join(dels[3]) == "ip xfrm state delete src " + ue + " dst 2001:db8::105 proto esp spi 0x0526f2c0",
"OwnXfrmDeleteCommands: the other three states byte-exact, in the kernel's order");
Check(dels.size() == 8 && Join(dels[5]) == "ip xfrm policy delete src " + ue + "/128 dst 2001:db8::105/128 sport 45062 dport 33421 dir out" && Join(dels[6]) == "ip xfrm policy delete src 2001:db8::105/128 dst " + ue + "/128 sport 6000 dport 45061 dir in" && Join(dels[7]) == "ip xfrm policy delete src " + ue + "/128 dst 2001:db8::105/128 sport 45061 dport 6000 dir out",
"OwnXfrmDeleteCommands: the other three policies byte-exact, in the kernel's order");
auto besideVpn = OwnXfrmDeleteCommands(std::string(State) + tunState, std::string(Policy) + vpn + vpn4, ue);
Check(besideVpn.size() == 8 && std::ranges::none_of(besideVpn, [](const auto& c) { auto j = Join(c); return j.contains("2001:db8::2") || j.contains("192.0.2.10") || j.contains("0x00000777"); }),
"OwnXfrmDeleteCommands: a VPN's tunnel SA and two tunnel policies beside ours -> ours only, theirs untouched");
Check(OwnXfrmDeleteCommands(otherState, otherOut2 + otherOut1, ue).empty(), "OwnXfrmDeleteCommands: another transport-mode reqid 1 + 2 pair on other ports, with its SA between other addresses -> nothing deleted");
Check(OwnXfrmDeleteCommands(std::string(State) + otherState, std::string(Policy) + otherOut2 + otherOut1, ue).size() == 8, "OwnXfrmDeleteCommands: the same beside our pair -> ours only");
Check(OwnXfrmDeleteCommands("", "", ue).empty(), "OwnXfrmDeleteCommands: nothing -> nothing");
Check(OwnXfrmDeleteCommands(State, "", ue).size() == 4, "OwnXfrmDeleteCommands: policy-less states of imsd's on the UE's address are deleted (a setup whose policy add failed leaves them)");
Check(OwnXfrmDeleteCommands(otherState, "", ue).empty(), "OwnXfrmDeleteCommands: a policy-less state between other addresses is left");
// the fingerprint selects, not a pair: a lone transport-mode reqid-1 policy carrying the protected port between other addresses goes, with the reqid-1 state between them (the §12 residual)
const std::string loneOther = "src 2001:db8::7/128 dst 2001:db8::106/128 sport 45061 dport 4 \n\tdir out priority 0 \n\ttmpl src 2001:db8::7 dst 2001:db8::106\n\t\tproto esp reqid 1 mode transport\n";
const std::string loneOtherState = "src 2001:db8::7 dst 2001:db8::106\n\tproto esp spi 0x00000107 reqid 1 mode transport\n\treplay-window 0 \n";
Check(OwnXfrmDeleteCommands(loneOtherState, loneOther, ue).size() == 2, "OwnXfrmDeleteCommands: a lone policy carrying the fingerprint between other addresses, and the reqid-1 state in its direction, are deleted (the fingerprint selects, not a pair)");
// a reqid-1/2 transport-mode state on the UE's address goes whoever made it: the other user's SA between the UE address and its peer, its policies on other ports staying (the §12 residual)
const std::string otherOnUe = "src " + ue + " dst 2001:db8::106\n\tproto esp spi 0x00000108 reqid 1 mode transport\n\treplay-window 0 \n";
auto onUe = OwnXfrmDeleteCommands(otherOnUe, otherOut2 + otherOut1, ue);
Check(onUe.size() == 1 && Join(onUe[0]) == "ip xfrm state delete src " + ue + " dst 2001:db8::106 proto esp spi 0x00000108", "OwnXfrmDeleteCommands: another transport-mode user's reqid-1 state on the UE's address is deleted whoever made it; its policies on other ports stay (the §12 residual)");
Check(OwnXfrmDeleteCommands("src " + ue + " dst 2001:db8::106\n\tproto ah spi 0x00000109 reqid 1 mode transport\n\treplay-window 0 \n", otherOut2 + otherOut1, ue).empty(), "OwnXfrmDeleteCommands: an AH reqid-1 transport state on the UE's address is not selected (the delete names proto esp)");
// the selector as `ip xfrm policy` prints it: a fingerprinted policy with a protocol (and a dev) keeps them in its delete, a missing port is no empty token
const std::string protoOther = "src 2001:db8::7/128 dst 2001:db8::106/128 proto udp sport 45061 dport 4 \n\tdir out priority 0 \n\ttmpl src 2001:db8::7 dst 2001:db8::106\n\t\tproto esp reqid 1 mode transport\n";
auto protoDels = OwnXfrmDeleteCommands("", protoOther, ue);
Check(protoDels.size() == 1 && Join(protoDels[0]) == "ip xfrm policy delete src 2001:db8::7/128 dst 2001:db8::106/128 proto udp sport 45061 dport 4 dir out", "OwnXfrmDeleteCommands: a fingerprinted policy with a protocol in its selector is deleted by that selector (proto kept; the tmpl's 'proto esp' is not the selector's)");
const std::string portlessOther = "src 2001:db8::7/128 dst 2001:db8::106/128 sport 45061 dev qmapmux0.0 \n\tdir out priority 0 \n\ttmpl src 2001:db8::7 dst 2001:db8::106\n\t\tproto esp reqid 1 mode transport\n";
auto portlessDels = OwnXfrmDeleteCommands("", portlessOther, ue);
Check(portlessDels.size() == 1 && Join(portlessDels[0]) == "ip xfrm policy delete src 2001:db8::7/128 dst 2001:db8::106/128 sport 45061 dev qmapmux0.0 dir out", "OwnXfrmDeleteCommands: a selector without a dport and with a dev -> no empty token, the dev kept");
// the SA reader's ports come from our pair, never from a foreign transport policy that happens to carry ports
auto saBeside = ParseExistingSa(State, std::string(Policy) + otherOut2, "2001:db8::105", ue);
Check(saBeside && saBeside->portPc == 33421 && saBeside->portPs == 6000, "ParseExistingSa: a foreign transport policy's ports beside ours are not taken");
}
// ---- fresh setup command sequence
{
SaParams p;
@ -111,23 +159,21 @@ int main() {
p.spiUc = 100; p.spiUs = 200; p.spiPc = 300; p.spiPs = 400;
p.portUc = 45061; p.portUs = 45062; p.portPs = 6000; p.portPc = 33421;
auto cmds = BuildSetupCommands(p);
Check(cmds.size() == 10, "flush x2 + 4 states + 4 policies");
Check(Join(cmds[0]) == "ip xfrm state flush", "state flush first");
Check(Join(cmds[1]) == "ip xfrm policy flush", "policy flush second");
Check(cmds.size() == 8, "4 states + 4 policies, no flush (OwnXfrmDeleteCommands takes imsd's previous entries out)");
// reqid1 outbound state: src LOCAL dst P spi=spiPs, IK auth, CK enc
Check(Join(cmds[2]) ==
Check(Join(cmds[0]) ==
"ip xfrm state add src 2001:db8::db43 dst 2001:db8::105 "
"proto esp spi 400 mode transport reqid 1 "
"auth-trunc hmac(sha1) 0xabababababababababababababababab 96 "
"enc cbc(aes) 0xcdcdcdcdcdcdcdcdcdcdcdcdcdcdcdcd",
"state add reqid1 outbound byte-exact");
// first out policy: sport PORT_UC dport PORT_PS reqid 1
Check(Join(cmds[6]) == "ip xfrm policy add src 2001:db8::db43/128 dst 2001:db8::105/128 " "sport 45061 dport 6000 dir out tmpl src 2001:db8::db43 " "dst 2001:db8::105 proto esp reqid 1 mode transport", "policy add out reqid1 byte-exact");
Check(Join(cmds[4]) == "ip xfrm policy add src 2001:db8::db43/128 dst 2001:db8::105/128 " "sport 45061 dport 6000 dir out tmpl src 2001:db8::db43 " "dst 2001:db8::105 proto esp reqid 1 mode transport", "policy add out reqid1 byte-exact");
// v4 uses /32
SaParams p4 = p;
p4.local = "10.0.0.2"; p4.pcscf = "10.0.0.1";
auto c4 = BuildSetupCommands(p4);
Check(c4[6][5] == "10.0.0.2/32", "v4 prefix length /32");
Check(c4[4][5] == "10.0.0.2/32", "v4 prefix length /32");
}
// null cipher -> cipher_null + empty key arg
{
@ -137,7 +183,7 @@ int main() {
p.ck = {};
p.ealg = "null";
auto cmds = BuildSetupCommands(p);
auto& st = cmds[2];
auto& st = cmds[0];
Check(st[st.size() - 3] == "enc" && st[st.size() - 2] == "cipher_null" && st[st.size() - 1].empty(), "null cipher: cipher_null + empty key");
}
@ -149,7 +195,7 @@ int main() {
p.ck = {};
p.alg = "hmac-md5-96"; p.ealg = "null";
auto cmds = BuildSetupCommands(p);
Check(cmds[2][17] == "hmac(md5)" && cmds[2][18] == "0x01010101010101010101010101010101" && cmds[2][19] == "96", "md5: auth-trunc hmac(md5) IK 96");
Check(cmds[0][17] == "hmac(md5)" && cmds[0][18] == "0x01010101010101010101010101010101" && cmds[0][19] == "96", "md5: auth-trunc hmac(md5) IK 96");
Check(KernelAuth("hmac-sha-1-96") == "hmac(sha1)" && KernelAuth("hmac-md5-96") == "hmac(md5)" && !KernelAuth("hmac-sha-256-128"), "KernelAuth names");
Check(KnownEalg("null") && KnownEalg("aes-cbc") && KnownEalg("des-ede3-cbc") && !KnownEalg("aes-gcm") && !KnownEalg("") && !KnownEalg("3des"), "KnownEalg set (canonical names only)");
}