From 2cb5c8e378d10a57aa1c9eaee36bea46c27dd2b9 Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Fri, 30 Jun 2017 13:32:57 -0400 Subject: [PATCH] sctp: Add peeloff-flags socket option 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 CC: Vlad Yasevich CC: "David S. Miller" CC: Andreas Steinmetz CC: Marcelo Ricardo Leitner Acked-by: Marcelo Ricardo Leitner Signed-off-by: David S. Miller --- include/uapi/linux/sctp.h | 6 ++++ net/sctp/socket.c | 87 +++++++++++++++++++++++++++++++++++++++-------- 2 files changed, 78 insertions(+), 15 deletions(-) diff --git a/include/uapi/linux/sctp.h b/include/uapi/linux/sctp.h index ced9d8b..6217ff8 100644 --- a/include/uapi/linux/sctp.h +++ b/include/uapi/linux/sctp.h @@ -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 */ diff --git a/net/sctp/socket.c b/net/sctp/socket.c index 0af103f..1db478e 100644 --- a/net/sctp/socket.c +++ b/net/sctp/socket.c @@ -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)) @@ -4946,26 +4982,44 @@ 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; + /* Return the fd mapped to the new socket. */ + if (put_user(len, optlen)) { + fput(newfile); + put_unused_fd(retval); + return -EFAULT; } - newfile = sock_alloc_file(newsock, 0, NULL); - if (IS_ERR(newfile)) { + if (copy_to_user(optval, &peeloff, len)) { + fput(newfile); put_unused_fd(retval); - sock_release(newsock); - return PTR_ERR(newfile); + return -EFAULT; } + fd_install(retval, newfile); +out: + return retval; +} - pr_debug("%s: sk:%p, newsk:%p, sd:%d\n", __func__, sk, newsock->sk, - 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)) { @@ -4973,7 +5027,7 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval put_unused_fd(retval); return -EFAULT; } - peeloff.sd = retval; + 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); -- 2.7.4