summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
authorLorenzo Colitti <lorenzo@google.com>2016-11-04 02:23:41 +0900
committerDavid S. Miller <davem@davemloft.net>2016-11-04 14:45:22 -0400
commit86741ec25462e4c8cdce6df2f41ead05568c7d5e (patch)
treef6eb304465cbe0fc8309fe6593de0ab996756fda
parent0d53072aa42b3cdc340a0d483febd14f2d68da52 (diff)
net: core: Add a UID field to struct sock.
Protocol sockets (struct sock) don't have UIDs, but most of the time, they map 1:1 to userspace sockets (struct socket) which do. Various operations such as the iptables xt_owner match need access to the "UID of a socket", and do so by following the backpointer to the struct socket. This involves taking sk_callback_lock and doesn't work when there is no socket because userspace has already called close(). Simplify this by adding a sk_uid field to struct sock whose value matches the UID of the corresponding struct socket. The semantics are as follows: 1. Whenever sk_socket is non-null: sk_uid is the same as the UID in sk_socket, i.e., matches the return value of sock_i_uid. Specifically, the UID is set when userspace calls socket(), fchown(), or accept(). 2. When sk_socket is NULL, sk_uid is defined as follows: - For a socket that no longer has a sk_socket because userspace has called close(): the previous UID. - For a cloned socket (e.g., an incoming connection that is established but on which userspace has not yet called accept): the UID of the socket it was cloned from. - For a socket that has never had an sk_socket: UID 0 inside the user namespace corresponding to the network namespace the socket belongs to. Kernel sockets created by sock_create_kern are a special case of #1 and sk_uid is the user that created them. For kernel sockets created at network namespace creation time, such as the per-processor ICMP and TCP sockets, this is the user that created the network namespace. Signed-off-by: Lorenzo Colitti <lorenzo@google.com> Signed-off-by: David S. Miller <davem@davemloft.net>
-rw-r--r--include/net/sock.h7
-rw-r--r--net/core/sock.c5
-rw-r--r--net/socket.c14
3 files changed, 25 insertions, 1 deletions
diff --git a/include/net/sock.h b/include/net/sock.h
index 93331a1492db..cf617ee16723 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -419,6 +419,7 @@ struct sock {
u32 sk_max_ack_backlog;
__u32 sk_priority;
__u32 sk_mark;
+ kuid_t sk_uid;
struct pid *sk_peer_pid;
const struct cred *sk_peer_cred;
long sk_rcvtimeo;
@@ -1664,6 +1665,7 @@ static inline void sock_graft(struct sock *sk, struct socket *parent)
sk->sk_wq = parent->wq;
parent->sk = sk;
sk_set_socket(sk, parent);
+ sk->sk_uid = SOCK_INODE(parent)->i_uid;
security_sock_graft(sk, parent);
write_unlock_bh(&sk->sk_callback_lock);
}
@@ -1671,6 +1673,11 @@ static inline void sock_graft(struct sock *sk, struct socket *parent)
kuid_t sock_i_uid(struct sock *sk);
unsigned long sock_i_ino(struct sock *sk);
+static inline kuid_t sock_net_uid(const struct net *net, const struct sock *sk)
+{
+ return sk ? sk->sk_uid : make_kuid(net->user_ns, 0);
+}
+
static inline u32 net_tx_rndhash(void)
{
u32 v = prandom_u32();
diff --git a/net/core/sock.c b/net/core/sock.c
index d8e4532e89e7..40dbc13453f9 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2460,8 +2460,11 @@ void sock_init_data(struct socket *sock, struct sock *sk)
sk->sk_type = sock->type;
sk->sk_wq = sock->wq;
sock->sk = sk;
- } else
+ sk->sk_uid = SOCK_INODE(sock)->i_uid;
+ } else {
sk->sk_wq = NULL;
+ sk->sk_uid = make_kuid(sock_net(sk)->user_ns, 0);
+ }
rwlock_init(&sk->sk_callback_lock);
lockdep_set_class_and_name(&sk->sk_callback_lock,
diff --git a/net/socket.c b/net/socket.c
index 970a7ea3fc4a..4ce33c35e606 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -518,8 +518,22 @@ static ssize_t sockfs_listxattr(struct dentry *dentry, char *buffer,
return used;
}
+int sockfs_setattr(struct dentry *dentry, struct iattr *iattr)
+{
+ int err = simple_setattr(dentry, iattr);
+
+ if (!err) {
+ struct socket *sock = SOCKET_I(d_inode(dentry));
+
+ sock->sk->sk_uid = iattr->ia_uid;
+ }
+
+ return err;
+}
+
static const struct inode_operations sockfs_inode_ops = {
.listxattr = sockfs_listxattr,
+ .setattr = sockfs_setattr,
};
/**