From: Steffen Klassert <steffen.klassert@secunet.com>
To: David Miller <davem@davemloft.net>, Jakub Kicinski <kuba@kernel.org>
Cc: Herbert Xu <herbert@gondor.apana.org.au>,
Steffen Klassert <steffen.klassert@secunet.com>,
<netdev@vger.kernel.org>
Subject: [PATCH] xfrm: redact SA secret with lockdown confidentiality
Date: Sat, 12 Dec 2020 09:57:37 +0100 [thread overview]
Message-ID: <20201212085737.2101294-2-steffen.klassert@secunet.com> (raw)
In-Reply-To: <20201212085737.2101294-1-steffen.klassert@secunet.com>
From: Antony Antony <antony.antony@secunet.com>
redact XFRM SA secret in the netlink response to xfrm_get_sa()
or dumpall sa.
Enable lockdown, confidentiality mode, at boot or at run time.
e.g. when enabled:
cat /sys/kernel/security/lockdown
none integrity [confidentiality]
ip xfrm state
src 172.16.1.200 dst 172.16.1.100
proto esp spi 0x00000002 reqid 2 mode tunnel
replay-window 0
aead rfc4106(gcm(aes)) 0x0000000000000000000000000000000000000000 96
note: the aead secret is redacted.
Redacting secret is also a FIPS 140-2 requirement.
v1->v2
- add size checks before memset calls
v2->v3
- replace spaces with tabs for consistency
v3->v4
- use kernel lockdown instead of a /proc setting
v4->v5
- remove kconfig option
Reviewed-by: Stephan Mueller <smueller@chronox.de>
Signed-off-by: Antony Antony <antony.antony@secunet.com>
Signed-off-by: Steffen Klassert <steffen.klassert@secunet.com>
---
include/linux/security.h | 1 +
net/xfrm/xfrm_user.c | 74 ++++++++++++++++++++++++++++++++++++----
security/security.c | 1 +
3 files changed, 69 insertions(+), 7 deletions(-)
diff --git a/include/linux/security.h b/include/linux/security.h
index bc2725491560..1112a79a7dba 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -127,6 +127,7 @@ enum lockdown_reason {
LOCKDOWN_PERF,
LOCKDOWN_TRACEFS,
LOCKDOWN_XMON_RW,
+ LOCKDOWN_XFRM_SECRET,
LOCKDOWN_CONFIDENTIALITY_MAX,
};
diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
index d0c32a8fcc4a..0727ac853b55 100644
--- a/net/xfrm/xfrm_user.c
+++ b/net/xfrm/xfrm_user.c
@@ -848,21 +848,84 @@ static int copy_user_offload(struct xfrm_state_offload *xso, struct sk_buff *skb
return 0;
}
+static bool xfrm_redact(void)
+{
+ return IS_ENABLED(CONFIG_SECURITY) &&
+ security_locked_down(LOCKDOWN_XFRM_SECRET);
+}
+
static int copy_to_user_auth(struct xfrm_algo_auth *auth, struct sk_buff *skb)
{
struct xfrm_algo *algo;
+ struct xfrm_algo_auth *ap;
struct nlattr *nla;
+ bool redact_secret = xfrm_redact();
nla = nla_reserve(skb, XFRMA_ALG_AUTH,
sizeof(*algo) + (auth->alg_key_len + 7) / 8);
if (!nla)
return -EMSGSIZE;
-
algo = nla_data(nla);
strncpy(algo->alg_name, auth->alg_name, sizeof(algo->alg_name));
- memcpy(algo->alg_key, auth->alg_key, (auth->alg_key_len + 7) / 8);
+
+ if (redact_secret && auth->alg_key_len)
+ memset(algo->alg_key, 0, (auth->alg_key_len + 7) / 8);
+ else
+ memcpy(algo->alg_key, auth->alg_key,
+ (auth->alg_key_len + 7) / 8);
algo->alg_key_len = auth->alg_key_len;
+ nla = nla_reserve(skb, XFRMA_ALG_AUTH_TRUNC, xfrm_alg_auth_len(auth));
+ if (!nla)
+ return -EMSGSIZE;
+ ap = nla_data(nla);
+ memcpy(ap, auth, sizeof(struct xfrm_algo_auth));
+ if (redact_secret && auth->alg_key_len)
+ memset(ap->alg_key, 0, (auth->alg_key_len + 7) / 8);
+ else
+ memcpy(ap->alg_key, auth->alg_key,
+ (auth->alg_key_len + 7) / 8);
+ return 0;
+}
+
+static int copy_to_user_aead(struct xfrm_algo_aead *aead, struct sk_buff *skb)
+{
+ struct nlattr *nla = nla_reserve(skb, XFRMA_ALG_AEAD, aead_len(aead));
+ struct xfrm_algo_aead *ap;
+ bool redact_secret = xfrm_redact();
+
+ if (!nla)
+ return -EMSGSIZE;
+
+ ap = nla_data(nla);
+ memcpy(ap, aead, sizeof(*aead));
+
+ if (redact_secret && aead->alg_key_len)
+ memset(ap->alg_key, 0, (aead->alg_key_len + 7) / 8);
+ else
+ memcpy(ap->alg_key, aead->alg_key,
+ (aead->alg_key_len + 7) / 8);
+ return 0;
+}
+
+static int copy_to_user_ealg(struct xfrm_algo *ealg, struct sk_buff *skb)
+{
+ struct xfrm_algo *ap;
+ bool redact_secret = xfrm_redact();
+ struct nlattr *nla = nla_reserve(skb, XFRMA_ALG_CRYPT,
+ xfrm_alg_len(ealg));
+ if (!nla)
+ return -EMSGSIZE;
+
+ ap = nla_data(nla);
+ memcpy(ap, ealg, sizeof(*ealg));
+
+ if (redact_secret && ealg->alg_key_len)
+ memset(ap->alg_key, 0, (ealg->alg_key_len + 7) / 8);
+ else
+ memcpy(ap->alg_key, ealg->alg_key,
+ (ealg->alg_key_len + 7) / 8);
+
return 0;
}
@@ -906,20 +969,17 @@ static int copy_to_user_state_extra(struct xfrm_state *x,
goto out;
}
if (x->aead) {
- ret = nla_put(skb, XFRMA_ALG_AEAD, aead_len(x->aead), x->aead);
+ ret = copy_to_user_aead(x->aead, skb);
if (ret)
goto out;
}
if (x->aalg) {
ret = copy_to_user_auth(x->aalg, skb);
- if (!ret)
- ret = nla_put(skb, XFRMA_ALG_AUTH_TRUNC,
- xfrm_alg_auth_len(x->aalg), x->aalg);
if (ret)
goto out;
}
if (x->ealg) {
- ret = nla_put(skb, XFRMA_ALG_CRYPT, xfrm_alg_len(x->ealg), x->ealg);
+ ret = copy_to_user_ealg(x->ealg, skb);
if (ret)
goto out;
}
diff --git a/security/security.c b/security/security.c
index a28045dc9e7f..abff77c1c8a7 100644
--- a/security/security.c
+++ b/security/security.c
@@ -65,6 +65,7 @@ const char *const lockdown_reasons[LOCKDOWN_CONFIDENTIALITY_MAX+1] = {
[LOCKDOWN_PERF] = "unsafe use of perf",
[LOCKDOWN_TRACEFS] = "use of tracefs",
[LOCKDOWN_XMON_RW] = "xmon read and write access",
+ [LOCKDOWN_XFRM_SECRET] = "xfrm SA secret",
[LOCKDOWN_CONFIDENTIALITY_MAX] = "confidentiality",
};
--
2.25.1
next prev parent reply other threads:[~2020-12-12 10:14 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-12-12 8:57 pull request (net-next): ipsec-next 2020-12-12 Steffen Klassert
2020-12-12 8:57 ` Steffen Klassert [this message]
2020-12-12 21:40 ` [PATCH] xfrm: redact SA secret with lockdown confidentiality patchwork-bot+netdevbpf
2020-12-12 21:40 ` pull request (net-next): ipsec-next 2020-12-12 patchwork-bot+netdevbpf
-- strict thread matches above, loose matches on Subject: below --
2020-07-28 15:47 [PATCH ipsec-next] xfrm: add /proc/sys/core/net/xfrm_redact_secret Antony Antony
2020-10-16 13:36 ` [PATCH] xfrm: redact SA secret with lockdown confidentiality Antony Antony
2020-10-31 10:49 ` Steffen Klassert
2020-11-17 16:46 ` Antony Antony
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