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Subject[TOMOYO #5 18/18] LSM expansion for TOMOYO Linux.
LSM hooks for sending signal:
* task_kill_unlocked is added in sys_kill
* task_tkill_unlocked is added in sys_tkill
* task_tgkill_unlocked is added in sys_tgkill
LSM hooks for network accept and recv:
* socket_post_accept is modified to return int.
* post_recv_datagram is added in skb_recv_datagram.

You can try TOMOYO Linux without this patch, but in that case, you
can't use access control functionality for restricting signal
transmission and incoming network data.

Signed-off-by: Kentaro Takeda <takedakn@nttdata.co.jp>
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
include/linux/security.h | 74 +++++++++++++++++++++++++++++++++++++++++++----
kernel/signal.c | 17 ++++++++++
net/core/datagram.c | 22 +++++++++++++
net/socket.c | 7 +++-
security/dummy.c | 32 ++++++++++++++++++--
security/security.c | 25 ++++++++++++++-
6 files changed, 165 insertions(+), 12 deletions(-)
--- linux-2.6-mm.orig/include/linux/security.h 2007-11-14 15:14:10.000000000 +0900
+++ linux-2.6-mm/include/linux/security.h 2007-11-14 15:15:44.000000000 +0900
@@ -657,6 +657,25 @@ struct request_sock;
* @sig contains the signal value.
* @secid contains the sid of the process where the signal originated
* Return 0 if permission is granted.
+ * @task_kill_unlocked:
+ * Check permission before sending signal @sig to the process of @pid
+ * with sys_kill.
+ * @pid contains the pid of target process.
+ * @sig contains the signal value.
+ * Return 0 if permission is granted.
+ * @task_tkill_unlocked:
+ * Check permission before sending signal @sig to the process of @pid
+ * with sys_tkill.
+ * @pid contains the pid of target process.
+ * @sig contains the signal value.
+ * Return 0 if permission is granted.
+ * @task_tgkill_unlocked:
+ * Check permission before sending signal @sig to the process of @pid
+ * with sys_tgkill.
+ * @tgid contains the thread group id.
+ * @pid contains the pid of target process.
+ * @sig contains the signal value.
+ * Return 0 if permission is granted.
* @task_wait:
* Check permission before allowing a process to reap a child process @p
* and collect its status information.
@@ -778,8 +797,12 @@ struct request_sock;
* @socket_post_accept:
* This hook allows a security module to copy security
* information into the newly created socket's inode.
+ * This hook also allows a security module to filter connections
+ * from unwanted peers.
+ * The connection will be aborted if this hook returns nonzero.
* @sock contains the listening socket structure.
* @newsock contains the newly created server socket for connection.
+ * Return 0 if permission is granted.
* @socket_sendmsg:
* Check permission before transmitting a message to another socket.
* @sock contains the socket structure.
@@ -793,6 +816,12 @@ struct request_sock;
* @size contains the size of message structure.
* @flags contains the operational flags.
* Return 0 if permission is granted.
+ * @post_recv_datagram:
+ * Check permission after receiving a datagram.
+ * @sk contains the socket.
+ * @skb contains the socket buffer (may be NULL).
+ * @flags contains the operational flags.
+ * Return 0 if permission is granted.
* @socket_getsockname:
* Check permission before the local address (name) of the socket object
* @sock is retrieved.
@@ -1319,6 +1348,9 @@ struct security_operations {
int (*task_movememory) (struct task_struct * p);
int (*task_kill) (struct task_struct * p,
struct siginfo * info, int sig, u32 secid);
+ int (*task_kill_unlocked) (int pid, int sig);
+ int (*task_tkill_unlocked) (int pid, int sig);
+ int (*task_tgkill_unlocked) (int tgid, int pid, int sig);
int (*task_wait) (struct task_struct * p);
int (*task_prctl) (int option, unsigned long arg2,
unsigned long arg3, unsigned long arg4,
@@ -1384,12 +1416,16 @@ 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);
+#define TMY_LSM_EXPANSION
+ int (*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,
struct msghdr * msg, int size, int flags);
+ int (*post_recv_datagram) (struct sock *sk,
+ struct sk_buff *skb,
+ unsigned int flags);
int (*socket_getsockname) (struct socket * sock);
int (*socket_getpeername) (struct socket * sock);
int (*socket_getsockopt) (struct socket * sock, int level, int optname);
@@ -1567,6 +1603,9 @@ int security_task_getscheduler(struct ta
int security_task_movememory(struct task_struct *p);
int security_task_kill(struct task_struct *p, struct siginfo *info,
int sig, u32 secid);
+int security_task_kill_unlocked(int pid, int sig);
+int security_task_tkill_unlocked(int pid, int sig);
+int security_task_tgkill_unlocked(int tgid, int pid, int sig);
int security_task_wait(struct task_struct *p);
int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5);
@@ -2112,6 +2151,21 @@ static inline int security_task_kill (st
return cap_task_kill(p, info, sig, secid);
}

+static inline int security_task_kill_unlocked(int pid, int sig)
+{
+ return 0;
+}
+
+static inline int security_task_tkill_unlocked(int pid, int sig)
+{
+ return 0;
+}
+
+static inline int security_task_tgkill_unlocked(int tgid, int pid, int sig)
+{
+ return 0;
+}
+
static inline int security_task_wait (struct task_struct *p)
{
return 0;
@@ -2294,10 +2348,12 @@ int security_socket_bind(struct socket *
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_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);
+int security_post_recv_datagram(struct sock *sk, struct sk_buff *skb,
+ unsigned int flags);
int security_socket_getsockname(struct socket *sock);
int security_socket_getpeername(struct socket *sock);
int security_socket_getsockopt(struct socket *sock, int level, int optname);
@@ -2373,9 +2429,10 @@ static inline int security_socket_accept
return 0;
}

-static inline void security_socket_post_accept(struct socket * sock,
- struct socket * newsock)
+static inline int security_socket_post_accept(struct socket *sock,
+ struct socket *newsock)
{
+ return 0;
}

static inline int security_socket_sendmsg(struct socket * sock,
@@ -2391,6 +2448,13 @@ static inline int security_socket_recvms
return 0;
}

+static inline int security_post_recv_datagram(struct sock *sk,
+ struct sk_buff *skb,
+ unsigned int flags)
+{
+ return 0;
+}
+
static inline int security_socket_getsockname(struct socket * sock)
{
return 0;
--- linux-2.6-mm.orig/kernel/signal.c 2007-11-14 15:14:17.000000000 +0900
+++ linux-2.6-mm/kernel/signal.c 2007-11-14 15:15:44.000000000 +0900
@@ -2218,6 +2218,11 @@ asmlinkage long
sys_kill(int pid, int sig)
{
struct siginfo info;
+ int ret;
+
+ ret = security_task_kill_unlocked(pid, sig);
+ if (ret)
+ return ret;

info.si_signo = sig;
info.si_errno = 0;
@@ -2273,10 +2278,16 @@ static int do_tkill(int tgid, int pid, i
*/
asmlinkage long sys_tgkill(int tgid, int pid, int sig)
{
+ int ret;
+
/* This is only valid for single tasks */
if (pid <= 0 || tgid <= 0)
return -EINVAL;

+ ret = security_task_tgkill_unlocked(tgid, pid, sig);
+ if (ret)
+ return ret;
+
return do_tkill(tgid, pid, sig);
}

@@ -2286,10 +2297,16 @@ asmlinkage long sys_tgkill(int tgid, int
asmlinkage long
sys_tkill(int pid, int sig)
{
+ int ret;
+
/* This is only valid for single tasks */
if (pid <= 0)
return -EINVAL;

+ ret = security_task_tkill_unlocked(pid, sig);
+ if (ret)
+ return ret;
+
return do_tkill(0, pid, sig);
}

--- linux-2.6-mm.orig/net/socket.c 2007-11-14 15:12:08.000000000 +0900
+++ linux-2.6-mm/net/socket.c 2007-11-14 15:15:44.000000000 +0900
@@ -1442,13 +1442,16 @@ asmlinkage long sys_accept(int fd, struc
goto out_fd;
}

+ /* Filter connections from unwanted peers like TCP Wrapper. */
+ err = security_socket_post_accept(sock, newsock);
+ if (err)
+ goto out_fd;
+
/* File flags are not inherited via accept() unlike another OSes. */

fd_install(newfd, newfile);
err = newfd;

- security_socket_post_accept(sock, newsock);
-
out_put:
fput_light(sock->file, fput_needed);
out:
--- linux-2.6-mm.orig/security/dummy.c 2007-11-14 15:14:10.000000000 +0900
+++ linux-2.6-mm/security/dummy.c 2007-11-14 15:15:44.000000000 +0900
@@ -576,6 +576,21 @@ static int dummy_task_kill (struct task_
return 0;
}

+static int dummy_task_kill_unlocked(int pid, int sig)
+{
+ return 0;
+}
+
+static int dummy_task_tkill_unlocked(int pid, int sig)
+{
+ return 0;
+}
+
+static int dummy_task_tgkill_unlocked(int tgid, int pid, int sig)
+{
+ return 0;
+}
+
static int dummy_task_prctl (int option, unsigned long arg2, unsigned long arg3,
unsigned long arg4, unsigned long arg5)
{
@@ -753,10 +768,10 @@ static int dummy_socket_accept (struct s
return 0;
}

-static void dummy_socket_post_accept (struct socket *sock,
- struct socket *newsock)
+static int dummy_socket_post_accept(struct socket *sock,
+ struct socket *newsock)
{
- return;
+ return 0;
}

static int dummy_socket_sendmsg (struct socket *sock, struct msghdr *msg,
@@ -771,6 +786,13 @@ static int dummy_socket_recvmsg (struct
return 0;
}

+static int dummy_post_recv_datagram(struct sock *sk,
+ struct sk_buff *skb,
+ unsigned int flags)
+{
+ return 0;
+}
+
static int dummy_socket_getsockname (struct socket *sock)
{
return 0;
@@ -1062,6 +1084,9 @@ void security_fixup_ops (struct security
set_to_dummy_if_null(ops, task_movememory);
set_to_dummy_if_null(ops, task_wait);
set_to_dummy_if_null(ops, task_kill);
+ set_to_dummy_if_null(ops, task_kill_unlocked);
+ set_to_dummy_if_null(ops, task_tkill_unlocked);
+ set_to_dummy_if_null(ops, task_tgkill_unlocked);
set_to_dummy_if_null(ops, task_prctl);
set_to_dummy_if_null(ops, task_reparent_to_init);
set_to_dummy_if_null(ops, task_to_inode);
@@ -1104,6 +1129,7 @@ void security_fixup_ops (struct security
set_to_dummy_if_null(ops, socket_post_accept);
set_to_dummy_if_null(ops, socket_sendmsg);
set_to_dummy_if_null(ops, socket_recvmsg);
+ set_to_dummy_if_null(ops, post_recv_datagram);
set_to_dummy_if_null(ops, socket_getsockname);
set_to_dummy_if_null(ops, socket_getpeername);
set_to_dummy_if_null(ops, socket_setsockopt);
--- linux-2.6-mm.orig/net/core/datagram.c 2007-10-10 05:31:38.000000000 +0900
+++ linux-2.6-mm/net/core/datagram.c 2007-11-14 15:15:44.000000000 +0900
@@ -55,6 +55,7 @@
#include <net/checksum.h>
#include <net/sock.h>
#include <net/tcp_states.h>
+#include <linux/security.h>

/*
* Is a socket 'connection oriented' ?
@@ -178,6 +179,27 @@ struct sk_buff *skb_recv_datagram(struct
} else
skb = skb_dequeue(&sk->sk_receive_queue);

+ error = security_post_recv_datagram(sk, skb, flags);
+ if (error) {
+ unsigned long cpu_flags;
+
+ if (!(flags & MSG_PEEK))
+ goto no_peek;
+
+ spin_lock_irqsave(&sk->sk_receive_queue.lock,
+ cpu_flags);
+ if (skb == skb_peek(&sk->sk_receive_queue)) {
+ __skb_unlink(skb,
+ &sk->sk_receive_queue);
+ atomic_dec(&skb->users);
+ }
+ spin_unlock_irqrestore(&sk->sk_receive_queue.lock,
+ cpu_flags);
+no_peek:
+ skb_free_datagram(sk, skb);
+ goto no_packet;
+ }
+
if (skb)
return skb;

--- linux-2.6-mm.orig/security/security.c 2007-11-14 15:14:10.000000000 +0900
+++ linux-2.6-mm/security/security.c 2007-11-14 15:54:12.000000000 +0900
@@ -662,6 +662,21 @@ int security_task_kill(struct task_struc
return security_ops->task_kill(p, info, sig, secid);
}

+int security_task_kill_unlocked(int pid, int sig)
+{
+ return security_ops->task_kill_unlocked(pid, sig);
+}
+
+int security_task_tkill_unlocked(int pid, int sig)
+{
+ return security_ops->task_tkill_unlocked(pid, sig);
+}
+
+int security_task_tgkill_unlocked(int tgid, int pid, int sig)
+{
+ return security_ops->task_tgkill_unlocked(tgid, pid, sig);
+}
+
int security_task_wait(struct task_struct *p)
{
return security_ops->task_wait(p);
@@ -869,9 +884,9 @@ int security_socket_accept(struct socket
return security_ops->socket_accept(sock, newsock);
}

-void security_socket_post_accept(struct socket *sock, struct socket *newsock)
+int security_socket_post_accept(struct socket *sock, struct socket *newsock)
{
- security_ops->socket_post_accept(sock, newsock);
+ return security_ops->socket_post_accept(sock, newsock);
}

int security_socket_sendmsg(struct socket *sock, struct msghdr *msg, int size)
@@ -885,6 +900,12 @@ int security_socket_recvmsg(struct socke
return security_ops->socket_recvmsg(sock, msg, size, flags);
}

+int security_post_recv_datagram(struct sock *sk, struct sk_buff *skb,
+ unsigned int flags)
+{
+ return security_ops->post_recv_datagram(sk, skb, flags);
+}
+
int security_socket_getsockname(struct socket *sock)
{
return security_ops->socket_getsockname(sock);
--
-
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