[PATCH] sctp: Add peeloff-flags socket option
From: Neil Horman <nhorman@tuxdriver.com>
Date: 2017-06-29 18:14:11
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: Alexander Viro <viro@zeniv.linux.org.uk> CC: Vlad Yasevich <redacted> CC: "David S. Miller" <davem@davemloft.net> CC: Andreas Steinmetz <redacted> CC: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com> --- fs/file.c | 1 + include/uapi/linux/sctp.h | 6 ++++ net/sctp/socket.c | 92 ++++++++++++++++++++++++++++++++++++++--------- 3 files changed, 83 insertions(+), 16 deletions(-)
diff --git a/fs/file.c b/fs/file.c
index 1c2972e..a4521da 100644
--- a/fs/file.c
+++ b/fs/file.c@@ -807,6 +807,7 @@ void set_close_on_exec(unsigned int fd, int flag) __clear_close_on_exec(fd, fdt); spin_unlock(&files->file_lock); } +EXPORT_SYMBOL(set_close_on_exec); bool get_close_on_exec(unsigned int fd) {
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 7b6e20e..7341053 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c@@ -4933,20 +4933,12 @@ int sctp_do_peeloff(struct sock *sk, sctp_assoc_t id, struct socket **sockp) } EXPORT_SYMBOL(sctp_do_peeloff); -static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval, int __user *optlen) +static int sctp_getsockopt_peeloff_common(struct sock *sk, sctp_peeloff_arg_t *peeloff, struct file **newfile, unsigned flags) { - sctp_peeloff_arg_t peeloff; struct socket *newsock; - struct file *newfile; int retval = 0; - if (len < sizeof(sctp_peeloff_arg_t)) - return -EINVAL; - len = sizeof(sctp_peeloff_arg_t); - if (copy_from_user(&peeloff, optval, len)) - return -EFAULT; - - retval = sctp_do_peeloff(sk, peeloff.associd, &newsock); + retval = sctp_do_peeloff(sk, peeloff->associd, &newsock); if (retval < 0) goto out;
@@ -4957,25 +4949,90 @@ static int sctp_getsockopt_peeloff(struct sock *sk, int len, char __user *optval goto out; } - newfile = sock_alloc_file(newsock, 0, NULL); - if (IS_ERR(newfile)) { + *newfile = sock_alloc_file(newsock, 0, NULL); + if (IS_ERR(*newfile)) { put_unused_fd(retval); sock_release(newsock); - return PTR_ERR(newfile); + 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; + + set_close_on_exec(peeloff->sd, !!(flags & SOCK_CLOEXEC)); + + 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 file *newfile = NULL; + int retval = 0; + + if (len < sizeof(sctp_peeloff_arg_t)) + return -EINVAL; + len = sizeof(sctp_peeloff_arg_t); + if (copy_from_user(&peeloff, optval, len)) + return -EFAULT; + + retval = sctp_getsockopt_peeloff_common(sk, &peeloff, &newfile, 0); + if (retval < 0) + goto out; /* Return the fd mapped to the new socket. */ if (put_user(len, optlen)) { - fput(newfile); + if (newfile) + fput(newfile); put_unused_fd(retval); return -EFAULT; } - peeloff.sd = retval; + if (copy_to_user(optval, &peeloff, len)) { - fput(newfile); + if (newfile) + 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)) { + if (newfile) + fput(newfile); + put_unused_fd(retval); + return -EFAULT; + } + + if (copy_to_user(optval, &peeloff, len)) { + if (newfile) + fput(newfile); put_unused_fd(retval); return -EFAULT; }
@@ -6758,6 +6815,9 @@ 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);
--
2.9.4