diff options
author | Lorenzo Colitti <lorenzo@google.com> | 2016-11-04 02:23:41 +0900 |
---|---|---|
committer | David S. Miller <davem@davemloft.net> | 2016-11-04 14:45:22 -0400 |
commit | 86741ec25462e4c8cdce6df2f41ead05568c7d5e (patch) | |
tree | f6eb304465cbe0fc8309fe6593de0ab996756fda | |
parent | 0d53072aa42b3cdc340a0d483febd14f2d68da52 (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.h | 7 | ||||
-rw-r--r-- | net/core/sock.c | 5 | ||||
-rw-r--r-- | net/socket.c | 14 |
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, }; /** |