From 04ac0fa0d1b557a15aa51fd1dad004236b28c470 Mon Sep 17 00:00:00 2001 From: Lorenzo Colitti Date: Fri, 4 Nov 2016 02:23:41 +0900 Subject: 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. Bug: 16355602 Change-Id: Idbc3e9a0cec91c4c6e01916b967b6237645ebe59 Signed-off-by: Lorenzo Colitti Signed-off-by: David S. Miller --- net/socket.c | 14 ++++++++++++++ 1 file changed, 14 insertions(+) (limited to 'net/socket.c') diff --git a/net/socket.c b/net/socket.c index 0090225eeb1e..66d984ac2991 100644 --- a/net/socket.c +++ b/net/socket.c @@ -520,9 +520,23 @@ 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 = { .getxattr = sockfs_getxattr, .listxattr = sockfs_listxattr, + .setattr = sockfs_setattr, }; /** -- cgit v1.2.3 From ab53926305170c84f6531562a99490188af79485 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Fri, 30 Dec 2016 17:42:32 -0600 Subject: net: socket: don't set sk_uid to garbage value in ->setattr() ->setattr() was recently implemented for socket files to sync the socket inode's uid to the new 'sk_uid' member of struct sock. It does this by copying over the ia_uid member of struct iattr. However, ia_uid is actually only valid when ATTR_UID is set in ia_valid, indicating that the uid is being changed, e.g. by chown. Other metadata operations such as chmod or utimes leave ia_uid uninitialized. Therefore, sk_uid could be set to a "garbage" value from the stack. Fix this by only copying the uid over when ATTR_UID is set. [cherry-pick of net e1a3a60a2ebe991605acb14cd58e39c0545e174e] Bug: 16355602 Change-Id: I20e53848e54282b72a388ce12bfa88da5e3e9efe Fixes: 86741ec25462 ("net: core: Add a UID field to struct sock.") Signed-off-by: Eric Biggers Tested-by: Lorenzo Colitti Acked-by: Lorenzo Colitti Signed-off-by: David S. Miller --- net/socket.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'net/socket.c') diff --git a/net/socket.c b/net/socket.c index 66d984ac2991..1f69e48b1501 100644 --- a/net/socket.c +++ b/net/socket.c @@ -524,7 +524,7 @@ int sockfs_setattr(struct dentry *dentry, struct iattr *iattr) { int err = simple_setattr(dentry, iattr); - if (!err) { + if (!err && (iattr->ia_valid & ATTR_UID)) { struct socket *sock = SOCKET_I(d_inode(dentry)); sock->sk->sk_uid = iattr->ia_uid; -- cgit v1.2.3