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SubjectRe: [RFC v2 00/10] snet: Security for NETwork syscalls
Date
Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> writes:

> Regarding [RFC v2 02/10] Revert "lsm: Remove the socket_post_accept() hook"
> @@ -1538,6 +1538,8 @@ SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr,
> fd_install(newfd, newfile);
> err = newfd;
>
> + security_socket_post_accept(sock, newsock);
> +
> out_put:
> fput_light(sock->file, fput_needed);
> out:
>
> Please move security_socket_post_accept() to before fd_install().
> Otherwise, other threads which share fd tables can use
> security-informations-not-yet-updated accept()ed sockets.

Tetsuo, what about this patch ?

From 6bbae933058e5f0857e9d7c1a720f9d09080474e Mon Sep 17 00:00:00 2001
From: Samir Bellabes <sam@synack.fr>
Date: Fri, 1 Jan 2010 03:24:52 +0100
Subject: [PATCH] lsm: add security_post_accept() hook

snet need to reintroduce this hook, as it was designed to be: a hook for
updating security informations on objects.

This patch is the result of :
Revert "lsm: Remove the socket_post_accept() hook"
the revert of 8651d5c0b1f874c5b8307ae2b858bc40f9f02482.

and the comment of Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp> :

> Please move security_socket_post_accept() to before fd_install().
> Otherwise, other threads which share fd tables can use
> security-informations-not-yet-updated accept()ed sockets.

Signed-off-by: Samir Bellabes <sam@synack.fr>
---
include/linux/security.h | 13 +++++++++++++
net/socket.c | 2 ++
security/capability.c | 5 +++++
security/security.c | 5 +++++
4 files changed, 25 insertions(+), 0 deletions(-)

diff --git a/include/linux/security.h b/include/linux/security.h
index 74e564b..d8ad624 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -938,6 +938,11 @@ static inline void security_free_mnt_opts(struct security_mnt_opts *opts)
* @sock contains the listening socket structure.
* @newsock contains the newly created server socket for connection.
* Return 0 if permission is granted.
+ * @socket_post_accept:
+ * This hook allows a security module to copy security
+ * information into the newly created socket's inode.
+ * @sock contains the listening socket structure.
+ * @newsock contains the newly created server socket for connection.
* @socket_sendmsg:
* Check permission before transmitting a message to another socket.
* @sock contains the socket structure.
@@ -1674,6 +1679,8 @@ struct security_operations {
struct sockaddr *address, int addrlen);
int (*socket_listen) (struct socket *sock, int backlog);
int (*socket_accept) (struct socket *sock, struct socket *newsock);
+ void (*socket_post_accept) (struct socket *sock,
+ struct socket *newsock);
int (*socket_sendmsg) (struct socket *sock,
struct msghdr *msg, int size);
int (*socket_recvmsg) (struct socket *sock,
@@ -2696,6 +2703,7 @@ int security_socket_bind(struct socket *sock, struct sockaddr *address, int addr
int security_socket_connect(struct socket *sock, struct sockaddr *address, int addrlen);
int security_socket_listen(struct socket *sock, int backlog);
int security_socket_accept(struct socket *sock, struct socket *newsock);
+void security_socket_post_accept(struct socket *sock, struct socket *newsock);
int security_socket_sendmsg(struct socket *sock, struct msghdr *msg, int size);
int security_socket_recvmsg(struct socket *sock, struct msghdr *msg,
int size, int flags);
@@ -2778,6 +2786,11 @@ static inline int security_socket_accept(struct socket *sock,
return 0;
}

+static inline void security_socket_post_accept(struct socket *sock,
+ struct socket *newsock)
+{
+}
+
static inline int security_socket_sendmsg(struct socket *sock,
struct msghdr *msg, int size)
{
diff --git a/net/socket.c b/net/socket.c
index b4eb361..384e23d 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -1533,6 +1533,8 @@ SYSCALL_DEFINE4(accept4, int, fd, struct sockaddr __user *, upeer_sockaddr,
goto out_fd;
}

+ security_socket_post_accept(sock, newsock);
+
/* File flags are not inherited via accept() unlike another OSes. */

fd_install(newfd, newfile);
diff --git a/security/capability.c b/security/capability.c
index a9810dc..61eae40 100644
--- a/security/capability.c
+++ b/security/capability.c
@@ -641,6 +641,10 @@ static int cap_socket_accept(struct socket *sock, struct socket *newsock)
return 0;
}

+static void cap_socket_post_accept(struct socket *sock, struct socket *newsock)
+{
+}
+
static int cap_socket_sendmsg(struct socket *sock, struct msghdr *msg, int size)
{
return 0;
@@ -1081,6 +1085,7 @@ void security_fixup_ops(struct security_operations *ops)
set_to_cap_if_null(ops, socket_connect);
set_to_cap_if_null(ops, socket_listen);
set_to_cap_if_null(ops, socket_accept);
+ set_to_cap_if_null(ops, socket_post_accept);
set_to_cap_if_null(ops, socket_sendmsg);
set_to_cap_if_null(ops, socket_recvmsg);
set_to_cap_if_null(ops, socket_getsockname);
diff --git a/security/security.c b/security/security.c
index 288c3a8..673979f 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1082,6 +1082,11 @@ int security_socket_accept(struct socket *sock, struct socket *newsock)
return security_ops->socket_accept(sock, newsock);
}

+void security_socket_post_accept(struct socket *sock, struct socket *newsock)
+{
+ security_ops->socket_post_accept(sock, newsock);
+}
+
int security_socket_sendmsg(struct socket *sock, struct msghdr *msg, int size)
{
return security_ops->socket_sendmsg(sock, msg, size);
--
1.6.2.5


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