Michael Kerrisk wrote:
>> On Fri, Oct 31, 2008 at 4:56 PM, Daniel Lezcano <dlezcano@xxxxxxxxxx> wrote:
>>> This patch adds the socketat syscall which allows to specify in
>>> which network namespace we want to create a socket. The network
>>> namespace destination is referred by a socket fd previously opened
>>> in the destination network namespace.
>
> Daniel,
>
> Is there any documentation for this system call, and/or test programs?
Not yet.
This small patch is a proposition to Andreas and Vivien to have a single
process being able to manage several network namespaces.
When a process unshares the network, it creates a socket which is used
as a socket control (it belongs to the network namespace). Each time a
network namespace is created, a socket control is created.
When the process has to create a socket for a specific network
namespace, it can use the socket control to specify it. This is the
purpose of the socketat syscall.
One example for a program in userspace:
int main(int argc, char *argv[])
{
const int maxunshare = 128;
int scs[maxunshare];
int i, fd;
for (i = 0; i < maxunshare; i++) {
scs[i] = socket(PF_INET, SOCK_DGRAM, 0);
unshare(CLONE_NEWNET);
}
....
/* I want to create a socket inside the network namespace #10 */
fd = socketat(scs[10], PF_INET, SOCKET_STREAM, 0);
....
bind, listen, etc ...
}
>>> Signed-off-by: Daniel Lezcano <dlezcano@xxxxxxxxxx>
>>> ---
>>> arch/x86/include/asm/unistd_32.h | 1
>>> arch/x86/include/asm/unistd_64.h | 3 +-
>>> arch/x86/kernel/syscall_table_32.S | 1
>>> include/linux/syscalls.h | 1
>>> kernel/sys_ni.c | 1
>>> net/socket.c | 45 +++++++++++++++++++++++++++++++++++++
>>> 6 files changed, 51 insertions(+), 1 deletion(-)
>>>
>>> Index: net-next-2.6/arch/x86/include/asm/unistd_32.h
>>> ===================================================================
>>> --- net-next-2.6.orig/arch/x86/include/asm/unistd_32.h
>>> +++ net-next-2.6/arch/x86/include/asm/unistd_32.h
>>> @@ -338,6 +338,7 @@
>>> #define __NR_dup3 330
>>> #define __NR_pipe2 331
>>> #define __NR_inotify_init1 332
>>> +#define __NR_socketat 333
>>>
>>> #ifdef __KERNEL__
>>>
>>> Index: net-next-2.6/arch/x86/include/asm/unistd_64.h
>>> ===================================================================
>>> --- net-next-2.6.orig/arch/x86/include/asm/unistd_64.h
>>> +++ net-next-2.6/arch/x86/include/asm/unistd_64.h
>>> @@ -653,7 +653,8 @@ __SYSCALL(__NR_dup3, sys_dup3)
>>> __SYSCALL(__NR_pipe2, sys_pipe2)
>>> #define __NR_inotify_init1 294
>>> __SYSCALL(__NR_inotify_init1, sys_inotify_init1)
>>> -
>>> +#define __NR_socketat 295
>>> +__SYSCALL(__NR_socketat, sys_socketat)
>>>
>>> #ifndef __NO_STUBS
>>> #define __ARCH_WANT_OLD_READDIR
>>> Index: net-next-2.6/arch/x86/kernel/syscall_table_32.S
>>> ===================================================================
>>> --- net-next-2.6.orig/arch/x86/kernel/syscall_table_32.S
>>> +++ net-next-2.6/arch/x86/kernel/syscall_table_32.S
>>> @@ -332,3 +332,4 @@ ENTRY(sys_call_table)
>>> .long sys_dup3 /* 330 */
>>> .long sys_pipe2
>>> .long sys_inotify_init1
>>> + .long sys_socketat
>>> Index: net-next-2.6/net/socket.c
>>> ===================================================================
>>> --- net-next-2.6.orig/net/socket.c
>>> +++ net-next-2.6/net/socket.c
>>> @@ -1253,6 +1253,51 @@ out_release:
>>> return retval;
>>> }
>>>
>>> +asmlinkage long sys_socketat(int fd, int family, int type, int protocol)
>>> +{
>>> + int retval, fput_needed;
>>> + struct socket *sock;
>>> + struct socket *sockat;
>>> + struct net *net;
>>> + int flags;
>>> +
>>> + /* Check the SOCK_* constants for consistency. */
>>> + BUILD_BUG_ON(SOCK_CLOEXEC != O_CLOEXEC);
>>> + BUILD_BUG_ON((SOCK_MAX | SOCK_TYPE_MASK) != SOCK_TYPE_MASK);
>>> + BUILD_BUG_ON(SOCK_CLOEXEC & SOCK_TYPE_MASK);
>>> + BUILD_BUG_ON(SOCK_NONBLOCK & SOCK_TYPE_MASK);
>>> +
>>> + flags = type & ~SOCK_TYPE_MASK;
>>> + if (flags & ~(SOCK_CLOEXEC | SOCK_NONBLOCK))
>>> + return -EINVAL;
>>> + type &= SOCK_TYPE_MASK;
>>> +
>>> + if (SOCK_NONBLOCK != O_NONBLOCK && (flags & SOCK_NONBLOCK))
>>> + flags = (flags & ~SOCK_NONBLOCK) | O_NONBLOCK;
>>> +
>>> + sock = sockfd_lookup_light(fd, &retval, &fput_needed);
>>> + if (!sock)
>>> + goto out;
>>> +
>>> + net = sock_net(sock->sk);
>>> +
>>> + retval = __sock_create(net, family, type, protocol, &sockat, 0);
>>> + if (retval)
>>> + goto out_fput;
>>> +
>>> + retval = sock_map_fd(sock, flags & (O_CLOEXEC | O_NONBLOCK));
>>> + if (retval < 0)
>>> + goto out_release;
>>> +out_fput:
>>> + fput_light(sock->file, fput_needed);
>>> +out:
>>> + return retval;
>>> +
>>> +out_release:
>>> + sock_release(sockat);
>>> + goto out;
>>> +}
>>> +
>>> /*
>>> * Create a pair of connected sockets.
>>> */
>>> Index: net-next-2.6/include/linux/syscalls.h
>>> ===================================================================
>>> --- net-next-2.6.orig/include/linux/syscalls.h
>>> +++ net-next-2.6/include/linux/syscalls.h
>>> @@ -423,6 +423,7 @@ asmlinkage long sys_recvfrom(int, void _
>>> struct sockaddr __user *, int __user *);
>>> asmlinkage long sys_recvmsg(int fd, struct msghdr __user *msg, unsigned flags);
>>> asmlinkage long sys_socket(int, int, int);
>>> +asmlinkage long sys_socketat(int, int, int, int);
>>> asmlinkage long sys_socketpair(int, int, int, int __user *);
>>> asmlinkage long sys_socketcall(int call, unsigned long __user *args);
>>> asmlinkage long sys_listen(int, int);
>>> Index: net-next-2.6/kernel/sys_ni.c
>>> ===================================================================
>>> --- net-next-2.6.orig/kernel/sys_ni.c
>>> +++ net-next-2.6/kernel/sys_ni.c
>>> @@ -40,6 +40,7 @@ cond_syscall(sys_send);
>>> cond_syscall(sys_recvfrom);
>>> cond_syscall(sys_recv);
>>> cond_syscall(sys_socket);
>>> +cond_syscall(sys_socketat);
>>> cond_syscall(sys_setsockopt);
>>> cond_syscall(compat_sys_setsockopt);
>>> cond_syscall(sys_getsockopt);
>>>
>>> --
>>> _______________________________________________
>>> Containers mailing list
>>> Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx
>>> https://lists.linux-foundation.org/mailman/listinfo/containers
>>>
>>
>>
>> --
>> Michael Kerrisk Linux man-pages maintainer;
>> http://www.kernel.org/doc/man-pages/ Found a documentation bug?
>> http://www.kernel.org/doc/man-pages/reporting_bugs.html
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>>
>
>
>
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