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sctp: Add peeloff-flags socket option

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Based on a request raised on the sctp devel list, there is a need to
augment the sctp_peeloff operation while specifying the O_CLOEXEC and
O_NONBLOCK flags (simmilar to the socket syscall).  Since modifying the
SCTP_SOCKOPT_PEELOFF socket option would break user space ABI for existing
programs, this patch creates a new socket option
SCTP_SOCKOPT_PEELOFF_FLAGS, which accepts a third flags parameter to
allow atomic assignment of the socket descriptor flags.

Tested successfully by myself and the requestor

Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
CC: Vlad Yasevich <vyasevich@gmail.com>
CC: "David S. Miller" <davem@davemloft.net>
CC: Andreas Steinmetz <ast@domdv.de>
CC: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Neil Horman 2017-06-30 13:32:57 -04:00 committed by David S. Miller
parent 15324b25d5
commit 2cb5c8e378
2 changed files with 84 additions and 21 deletions
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6
include/uapi/linux/sctp.h
View File

@ -121,6 +121,7 @@ typedef __s32 sctp_assoc_t;
#define SCTP_RESET_STREAMS 119
#define SCTP_RESET_ASSOC 120
#define SCTP_ADD_STREAMS 121
#define SCTP_SOCKOPT_PEELOFF_FLAGS 122
/* PR-SCTP policies */
#define SCTP_PR_SCTP_NONE 0x0000
@ -978,6 +979,11 @@ typedef struct {
int sd;
} sctp_peeloff_arg_t;
typedef struct {
sctp_peeloff_arg_t p_arg;
unsigned flags;
} sctp_peeloff_flags_arg_t;
/*
* Peer Address Thresholds socket option
*/

99
net/sctp/socket.c
View File

@ -4933,11 +4933,47 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp)
}
EXPORT_SYMBOL(sctp_do_peeloff);
static int sctp_getsockopt_peeloff_common(struct sock *sk, sctp_peeloff_arg_t *peeloff,
struct file **newfile, unsigned flags)
{
struct socket *newsock;
int retval;
retval = sctp_do_peeloff(sk, peeloff->associd, &newsock);
if (retval < 0)
goto out;
/* Map the socket to an unused fd that can be returned to the user. */
retval = get_unused_fd_flags(flags & SOCK_CLOEXEC);
if (retval < 0) {
sock_release(newsock);
goto out;
}
*newfile = sock_alloc_file(newsock, 0, NULL);
if (IS_ERR(*newfile)) {
put_unused_fd(retval);
sock_release(newsock);
retval = PTR_ERR(*newfile);
*newfile = NULL;
return retval;
}
pr_debug("%s: sk:%p, newsk:%p, sd:%d\n", __func__, sk, newsock->sk,
retval);
peeloff->sd = retval;
if (flags & SOCK_NONBLOCK)
(*newfile)->f_flags |= O_NONBLOCK;
out:
return retval;
}
static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval, int __user *optlen)
{
sctp_peeloff_arg_t peeloff;
struct socket *newsock;
struct file *newfile;
struct file *newfile = NULL;
int retval = 0;
if (len < sizeof(sctp_peeloff_arg_t))
@ -4946,34 +4982,52 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval
if (copy_from_user(&peeloff, optval, len))
return -EFAULT;
retval = sctp_do_peeloff(sk, peeloff.associd, &newsock);
retval = sctp_getsockopt_peeloff_common(sk, &peeloff, &newfile, 0);
if (retval < 0)
goto out;
/* Map the socket to an unused fd that can be returned to the user. */
retval = get_unused_fd_flags(0);
if (retval < 0) {
sock_release(newsock);
goto out;
}
newfile = sock_alloc_file(newsock, 0, NULL);
if (IS_ERR(newfile)) {
put_unused_fd(retval);
sock_release(newsock);
return PTR_ERR(newfile);
}
pr_debug("%s: sk:%p, newsk:%p, sd:%d\n", __func__, sk, newsock->sk,
retval);
/* Return the fd mapped to the new socket. */
if (put_user(len, optlen)) {
fput(newfile);
put_unused_fd(retval);
return -EFAULT;
}
peeloff.sd = retval;
if (copy_to_user(optval, &peeloff, len)) {
fput(newfile);
put_unused_fd(retval);
return -EFAULT;
}
fd_install(retval, newfile);
out:
return retval;
}
static int sctp_getsockopt_peeloff_flags(struct sock *sk, int len,
char __user *optval, int __user *optlen)
{
sctp_peeloff_flags_arg_t peeloff;
struct file *newfile = NULL;
int retval = 0;
if (len < sizeof(sctp_peeloff_flags_arg_t))
return -EINVAL;
len = sizeof(sctp_peeloff_flags_arg_t);
if (copy_from_user(&peeloff, optval, len))
return -EFAULT;
retval = sctp_getsockopt_peeloff_common(sk, &peeloff.p_arg,
&newfile, peeloff.flags);
if (retval < 0)
goto out;
/* Return the fd mapped to the new socket. */
if (put_user(len, optlen)) {
fput(newfile);
put_unused_fd(retval);
return -EFAULT;
}
if (copy_to_user(optval, &peeloff, len)) {
fput(newfile);
put_unused_fd(retval);
@ -6759,6 +6813,9 @@ static int sctp_getsockopt(struct sock *sk, int level, int optname,
case SCTP_SOCKOPT_PEELOFF:
retval = sctp_getsockopt_peeloff(sk, len, optval, optlen);
break;
case SCTP_SOCKOPT_PEELOFF_FLAGS:
retval = sctp_getsockopt_peeloff_flags(sk, len, optval, optlen);
break;
case SCTP_PEER_ADDR_PARAMS:
retval = sctp_getsockopt_peer_addr_params(sk, len, optval,
optlen);