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Subject[PATCH 17/21] userns: Convert xt_LOG to print socket kuids and kgids as uids and gids
From: "Eric W. Biederman" <ebiederm@xmission.com>

xt_LOG always writes messages via sb_add via printk. Therefore when
xt_LOG logs the uid and gid of a socket a packet came from the
values should be converted to be in the initial user namespace.

Thus making xt_LOG as user namespace safe as possible.

Cc: Pablo Neira Ayuso <pablo@netfilter.org>
Cc: Patrick McHardy <kaber@trash.net>
Acked-by: Serge Hallyn <serge.hallyn@canonical.com>
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
---
init/Kconfig | 1 -
net/netfilter/xt_LOG.c | 16 ++++++++++------
2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index b44c3a3..c8911eb 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -945,7 +945,6 @@ config UIDGID_CONVERTED
depends on NET_9P = n
depends on NETFILTER_XT_MATCH_OWNER = n
depends on NETFILTER_XT_MATCH_RECENT = n
- depends on NETFILTER_XT_TARGET_LOG = n
depends on AF_RXRPC = n
depends on NET_KEY = n
depends on DNS_RESOLVER = n
diff --git a/net/netfilter/xt_LOG.c b/net/netfilter/xt_LOG.c
index ff5f75f..02a2bf4 100644
--- a/net/netfilter/xt_LOG.c
+++ b/net/netfilter/xt_LOG.c
@@ -363,10 +363,12 @@ static void dump_ipv4_packet(struct sbuff *m,
/* Max length: 15 "UID=4294967295 " */
if ((logflags & XT_LOG_UID) && !iphoff && skb->sk) {
read_lock_bh(&skb->sk->sk_callback_lock);
- if (skb->sk->sk_socket && skb->sk->sk_socket->file)
+ if (skb->sk->sk_socket && skb->sk->sk_socket->file) {
+ const struct cred *cred = skb->sk->sk_socket->file->f_cred;
sb_add(m, "UID=%u GID=%u ",
- skb->sk->sk_socket->file->f_cred->fsuid,
- skb->sk->sk_socket->file->f_cred->fsgid);
+ from_kuid_munged(&init_user_ns, cred->fsuid),
+ from_kgid_munged(&init_user_ns, cred->fsgid));
+ }
read_unlock_bh(&skb->sk->sk_callback_lock);
}

@@ -719,10 +721,12 @@ static void dump_ipv6_packet(struct sbuff *m,
/* Max length: 15 "UID=4294967295 " */
if ((logflags & XT_LOG_UID) && recurse && skb->sk) {
read_lock_bh(&skb->sk->sk_callback_lock);
- if (skb->sk->sk_socket && skb->sk->sk_socket->file)
+ if (skb->sk->sk_socket && skb->sk->sk_socket->file) {
+ const struct cred *cred = skb->sk->sk_socket->file->f_cred;
sb_add(m, "UID=%u GID=%u ",
- skb->sk->sk_socket->file->f_cred->fsuid,
- skb->sk->sk_socket->file->f_cred->fsgid);
+ from_kuid_munged(&init_user_ns, cred->fsuid),
+ from_kgid_munged(&init_user_ns, cred->fsgid));
+ }
read_unlock_bh(&skb->sk->sk_callback_lock);
}

--
1.7.5.4


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