From 109f6e39fa07c48f580125f531f46cb7c245b528 Mon Sep 17 00:00:00 2001 From: "Eric W. Biederman" Date: Sun, 13 Jun 2010 03:30:14 +0000 Subject: [PATCH] af_unix: Allow SO_PEERCRED to work across namespaces. Use struct pid and struct cred to store the peer credentials on struct sock. This gives enough information to convert the peer credential information to a value relative to whatever namespace the socket is in at the time. This removes nasty surprises when using SO_PEERCRED on socket connetions where the processes on either side are in different pid and user namespaces. Signed-off-by: Eric W. Biederman Acked-by: Daniel Lezcano Acked-by: Pavel Emelyanov Signed-off-by: David S. Miller --- include/net/sock.h | 3 ++- net/core/sock.c | 18 ++++++++++++------ net/unix/af_unix.c | 37 ++++++++++++++++++++++++++++--------- 3 files changed, 42 insertions(+), 16 deletions(-) diff --git a/include/net/sock.h b/include/net/sock.h index f8acf38f092f..4f26f2f83be9 100644 --- a/include/net/sock.h +++ b/include/net/sock.h @@ -295,7 +295,8 @@ struct sock { unsigned short sk_ack_backlog; unsigned short sk_max_ack_backlog; __u32 sk_priority; - struct ucred sk_peercred; + struct pid *sk_peer_pid; + const struct cred *sk_peer_cred; long sk_rcvtimeo; long sk_sndtimeo; struct sk_filter *sk_filter; diff --git a/net/core/sock.c b/net/core/sock.c index db8335ad7559..0229d5566a46 100644 --- a/net/core/sock.c +++ b/net/core/sock.c @@ -915,11 +915,15 @@ int sock_getsockopt(struct socket *sock, int level, int optname, break; case SO_PEERCRED: - if (len > sizeof(sk->sk_peercred)) - len = sizeof(sk->sk_peercred); - if (copy_to_user(optval, &sk->sk_peercred, len)) + { + struct ucred peercred; + if (len > sizeof(peercred)) + len = sizeof(peercred); + cred_to_ucred(sk->sk_peer_pid, sk->sk_peer_cred, &peercred); + if (copy_to_user(optval, &peercred, len)) return -EFAULT; goto lenout; + } case SO_PEERNAME: { @@ -1133,6 +1137,9 @@ static void __sk_free(struct sock *sk) printk(KERN_DEBUG "%s: optmem leakage (%d bytes) detected.\n", __func__, atomic_read(&sk->sk_omem_alloc)); + if (sk->sk_peer_cred) + put_cred(sk->sk_peer_cred); + put_pid(sk->sk_peer_pid); put_net(sock_net(sk)); sk_prot_free(sk->sk_prot_creator, sk); } @@ -1968,9 +1975,8 @@ void sock_init_data(struct socket *sock, struct sock *sk) sk->sk_sndmsg_page = NULL; sk->sk_sndmsg_off = 0; - sk->sk_peercred.pid = 0; - sk->sk_peercred.uid = -1; - sk->sk_peercred.gid = -1; + sk->sk_peer_pid = NULL; + sk->sk_peer_cred = NULL; sk->sk_write_pending = 0; sk->sk_rcvlowat = 1; sk->sk_rcvtimeo = MAX_SCHEDULE_TIMEOUT; diff --git a/net/unix/af_unix.c b/net/unix/af_unix.c index fef2cc5e9d2b..e1f1349fae86 100644 --- a/net/unix/af_unix.c +++ b/net/unix/af_unix.c @@ -450,11 +450,31 @@ static int unix_release_sock(struct sock *sk, int embrion) return 0; } +static void init_peercred(struct sock *sk) +{ + put_pid(sk->sk_peer_pid); + if (sk->sk_peer_cred) + put_cred(sk->sk_peer_cred); + sk->sk_peer_pid = get_pid(task_tgid(current)); + sk->sk_peer_cred = get_current_cred(); +} + +static void copy_peercred(struct sock *sk, struct sock *peersk) +{ + put_pid(sk->sk_peer_pid); + if (sk->sk_peer_cred) + put_cred(sk->sk_peer_cred); + sk->sk_peer_pid = get_pid(peersk->sk_peer_pid); + sk->sk_peer_cred = get_cred(peersk->sk_peer_cred); +} + static int unix_listen(struct socket *sock, int backlog) { int err; struct sock *sk = sock->sk; struct unix_sock *u = unix_sk(sk); + struct pid *old_pid = NULL; + const struct cred *old_cred = NULL; err = -EOPNOTSUPP; if (sock->type != SOCK_STREAM && sock->type != SOCK_SEQPACKET) @@ -470,12 +490,14 @@ static int unix_listen(struct socket *sock, int backlog) sk->sk_max_ack_backlog = backlog; sk->sk_state = TCP_LISTEN; /* set credentials so connect can copy them */ - sk->sk_peercred.pid = task_tgid_vnr(current); - current_euid_egid(&sk->sk_peercred.uid, &sk->sk_peercred.gid); + init_peercred(sk); err = 0; out_unlock: unix_state_unlock(sk); + put_pid(old_pid); + if (old_cred) + put_cred(old_cred); out: return err; } @@ -1140,8 +1162,7 @@ restart: unix_peer(newsk) = sk; newsk->sk_state = TCP_ESTABLISHED; newsk->sk_type = sk->sk_type; - newsk->sk_peercred.pid = task_tgid_vnr(current); - current_euid_egid(&newsk->sk_peercred.uid, &newsk->sk_peercred.gid); + init_peercred(newsk); newu = unix_sk(newsk); newsk->sk_wq = &newu->peer_wq; otheru = unix_sk(other); @@ -1157,7 +1178,7 @@ restart: } /* Set credentials */ - sk->sk_peercred = other->sk_peercred; + copy_peercred(sk, other); sock->state = SS_CONNECTED; sk->sk_state = TCP_ESTABLISHED; @@ -1199,10 +1220,8 @@ static int unix_socketpair(struct socket *socka, struct socket *sockb) sock_hold(skb); unix_peer(ska) = skb; unix_peer(skb) = ska; - ska->sk_peercred.pid = skb->sk_peercred.pid = task_tgid_vnr(current); - current_euid_egid(&skb->sk_peercred.uid, &skb->sk_peercred.gid); - ska->sk_peercred.uid = skb->sk_peercred.uid; - ska->sk_peercred.gid = skb->sk_peercred.gid; + init_peercred(ska); + init_peercred(skb); if (ska->sk_type != SOCK_DGRAM) { ska->sk_state = TCP_ESTABLISHED; -- 2.20.1