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Message-ID: <3322274.jE0xQCEvom@tauon.chronox.de>
Date: Tue, 28 Jul 2020 21:09:10 +0200
From: Stephan Mueller <smueller@...onox.de>
To: Steffen Klassert <steffen.klassert@...unet.com>,
netdev@...r.kernel.org, antony.antony@...unet.com
Cc: Herbert Xu <herbert@...dor.apana.org.au>,
Antony Antony <antony@...nome.org>
Subject: Re: [PATCH ipsec-next] xfrm: add /proc/sys/core/net/xfrm_redact_secret
Am Dienstag, 28. Juli 2020, 17:47:30 CEST schrieb Antony Antony:
Hi Antony,
> when enabled, 1, redact XFRM SA secret in the netlink response to
> xfrm_get_sa() or dump all sa.
>
> e.g
> echo 1 > /proc/sys/net/core/xfrm_redact_secret
> 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
>
> the aead secret is redacted.
>
> /proc/sys/core/net/xfrm_redact_secret is a toggle.
> Once enabled, either at compile or via proc, it can not be disabled.
> Redacting secret is a FIPS 140-2 requirement.
>
> Cc: Stephan Mueller <smueller@...onox.de>
> Signed-off-by: Antony Antony <antony.antony@...unet.com>
> ---
> Documentation/networking/xfrm_sysctl.rst | 7 +++
> include/net/netns/xfrm.h | 1 +
> net/xfrm/Kconfig | 10 ++++
> net/xfrm/xfrm_sysctl.c | 20 +++++++
> net/xfrm/xfrm_user.c | 76 +++++++++++++++++++++---
> 5 files changed, 105 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/networking/xfrm_sysctl.rst
> b/Documentation/networking/xfrm_sysctl.rst index 47b9bbdd0179..26432b0ff3ac
> 100644
> --- a/Documentation/networking/xfrm_sysctl.rst
> +++ b/Documentation/networking/xfrm_sysctl.rst
> @@ -9,3 +9,10 @@ XFRM Syscall
>
> xfrm_acq_expires - INTEGER
> default 30 - hard timeout in seconds for acquire requests
> +
> +xfrm_redact_secret - INTEGER
> + A toggle to redact xfrm SA's secret to userspace.
> + When true the kernel, netlink message will redact SA secret
> + to userspace. This is part of FIPS 140-2 requirement.
> + Once the value is set to true, either at compile or at run time,
> + it can not be set to false.
> diff --git a/include/net/netns/xfrm.h b/include/net/netns/xfrm.h
> index 59f45b1e9dac..0ca9328daad4 100644
> --- a/include/net/netns/xfrm.h
> +++ b/include/net/netns/xfrm.h
> @@ -64,6 +64,7 @@ struct netns_xfrm {
> u32 sysctl_aevent_rseqth;
> int sysctl_larval_drop;
> u32 sysctl_acq_expires;
> + u32 sysctl_redact_secret;
> #ifdef CONFIG_SYSCTL
> struct ctl_table_header *sysctl_hdr;
> #endif
> diff --git a/net/xfrm/Kconfig b/net/xfrm/Kconfig
> index 5b9a5ab48111..270a4e906a15 100644
> --- a/net/xfrm/Kconfig
> +++ b/net/xfrm/Kconfig
> @@ -91,6 +91,16 @@ config XFRM_ESP
> select CRYPTO_SEQIV
> select CRYPTO_SHA256
>
> +config XFRM_REDACT_SECRET
> + bool "Redact xfrm SA secret in netlink message"
> + depends on SYSCTL
> + default n
> + help
> + Enable XFRM SA secret redact in the netlink message.
> + Redacting secret is a FIPS 140-2 requirement.
> + Once enabled at compile, the value can not be set to false on
> + a running system.
> +
> config XFRM_IPCOMP
> tristate
> select XFRM_ALGO
> diff --git a/net/xfrm/xfrm_sysctl.c b/net/xfrm/xfrm_sysctl.c
> index 0c6c5ef65f9d..a41aa325a478 100644
> --- a/net/xfrm/xfrm_sysctl.c
> +++ b/net/xfrm/xfrm_sysctl.c
> @@ -4,15 +4,25 @@
> #include <net/net_namespace.h>
> #include <net/xfrm.h>
>
> +#ifdef CONFIG_SYSCTL
> +#ifdef CONFIG_XFRM_REDACT_SECRET
> +#define XFRM_REDACT_SECRET 1
> +#else
> +#define XFRM_REDACT_SECRET 0
> +#endif
> +#endif
> +
> static void __net_init __xfrm_sysctl_init(struct net *net)
> {
> net->xfrm.sysctl_aevent_etime = XFRM_AE_ETIME;
> net->xfrm.sysctl_aevent_rseqth = XFRM_AE_SEQT_SIZE;
> net->xfrm.sysctl_larval_drop = 1;
> net->xfrm.sysctl_acq_expires = 30;
> + net->xfrm.sysctl_redact_secret = XFRM_REDACT_SECRET;
> }
>
> #ifdef CONFIG_SYSCTL
> +
> static struct ctl_table xfrm_table[] = {
> {
> .procname = "xfrm_aevent_etime",
> @@ -38,6 +48,15 @@ static struct ctl_table xfrm_table[] = {
> .mode = 0644,
> .proc_handler = proc_dointvec
> },
> + {
> + .procname = "xfrm_redact_secret",
> + .maxlen = sizeof(u32),
> + .mode = 0644,
> + /* only handle a transition from "0" to "1" */
> + .proc_handler = proc_dointvec_minmax,
> + .extra1 = SYSCTL_ONE,
> + .extra2 = SYSCTL_ONE,
> + },
> {}
> };
>
> @@ -54,6 +73,7 @@ int __net_init xfrm_sysctl_init(struct net *net)
> table[1].data = &net->xfrm.sysctl_aevent_rseqth;
> table[2].data = &net->xfrm.sysctl_larval_drop;
> table[3].data = &net->xfrm.sysctl_acq_expires;
> + table[4].data = &net->xfrm.sysctl_redact_secret;
>
> /* Don't export sysctls to unprivileged users */
> if (net->user_ns != &init_user_ns)
> diff --git a/net/xfrm/xfrm_user.c b/net/xfrm/xfrm_user.c
> index e6cfaa680ef3..a3e89dddea9d 100644
> --- a/net/xfrm/xfrm_user.c
> +++ b/net/xfrm/xfrm_user.c
> @@ -848,21 +848,78 @@ static int copy_user_offload(struct xfrm_state_offload
> *xso, struct sk_buff *skb return 0;
> }
>
> -static int copy_to_user_auth(struct xfrm_algo_auth *auth, struct sk_buff
> *skb) +static int copy_to_user_auth(u32 redact_secret, struct
> xfrm_algo_auth *auth, + struct sk_buff *skb)
> {
> struct xfrm_algo *algo;
> + struct xfrm_algo_auth *ap;
> struct nlattr *nla;
>
> 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)
You test for auth->alg_key_len above. Shouldn't there such a check here too?
> + 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(u32 redact_secret,
> + 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;
> +
> + if (!nla)
> + return -EMSGSIZE;
> +
> + ap = nla_data(nla);
> + memcpy(ap, aead, sizeof(*aead));
> +
> + if (redact_secret)
And here?
> + 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(u32 redact_secret, struct xfrm_algo *ealg,
> + struct sk_buff *skb)
> +{
> + struct xfrm_algo *ap;
> + 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)
Here, too?
> + 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;
> }
>
> @@ -884,6 +941,7 @@ static int copy_to_user_state_extra(struct xfrm_state
> *x, struct sk_buff *skb)
> {
> int ret = 0;
> + struct net *net = xs_net(x);
>
> copy_to_user_state(x, p);
>
> @@ -906,20 +964,20 @@ 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(net->xfrm.sysctl_redact_secret,
> + 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);
> + ret = copy_to_user_auth(net->xfrm.sysctl_redact_secret,
> + x->aalg, skb);
> 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(net->xfrm.sysctl_redact_secret,
> + x->ealg, skb);
> if (ret)
> goto out;
> }
Ciao
Stephan
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