[PATCH net-next 1/3] netlink: convert to getsockopt_iter
From: Breno Leitao <leitao@debian.org>
Date: 2026-05-01 15:53:15
Also in:
linux-kselftest, lkml, virtualization
Subsystem:
networking [general], the rest · Maintainers:
"David S. Miller", Eric Dumazet, Jakub Kicinski, Paolo Abeni, Linus Torvalds
Convert AF_NETLINK's getsockopt implementation to use the new getsockopt_iter callback with sockopt_t. Key changes: - Replace (char __user *optval, int __user *optlen) with sockopt_t *opt - Use opt->optlen for buffer length (input) and returned size (output) - Use copy_to_iter() instead of put_user()/copy_to_user() - For NETLINK_LIST_MEMBERSHIPS: walk the groups bitmap and emit each u32 sequentially via copy_to_iter(), then set opt->optlen to the total size required (ALIGN(BITS_TO_BYTES(ngroups), sizeof(u32))). The wrapper writes opt->optlen back to userspace even on partial failure, preserving the existing API that lets userspace discover the needed allocation size. Signed-off-by: Breno Leitao <leitao@debian.org> --- net/netlink/af_netlink.c | 21 +++++++++++---------- 1 file changed, 11 insertions(+), 10 deletions(-)
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 2aeb0680807d6..db3be485b4804 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c@@ -39,6 +39,7 @@ #include <linux/fs.h> #include <linux/slab.h> #include <linux/uaccess.h> +#include <linux/uio.h> #include <linux/skbuff.h> #include <linux/netdevice.h> #include <linux/rtnetlink.h>
@@ -1716,18 +1717,18 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname, } static int netlink_getsockopt(struct socket *sock, int level, int optname, - char __user *optval, int __user *optlen) + sockopt_t *opt) { struct sock *sk = sock->sk; struct netlink_sock *nlk = nlk_sk(sk); unsigned int flag; int len, val; + u32 group; if (level != SOL_NETLINK) return -ENOPROTOOPT; - if (get_user(len, optlen)) - return -EFAULT; + len = opt->optlen; if (len < 0) return -EINVAL;
@@ -1751,14 +1752,14 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname, idx = pos / sizeof(unsigned long); shift = (pos % sizeof(unsigned long)) * 8; - if (put_user((u32)(nlk->groups[idx] >> shift), - (u32 __user *)(optval + pos))) { + group = (u32)(nlk->groups[idx] >> shift); + if (copy_to_iter(&group, sizeof(u32), + &opt->iter_out) != sizeof(u32)) { err = -EFAULT; break; } } - if (put_user(ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)), optlen)) - err = -EFAULT; + opt->optlen = ALIGN(BITS_TO_BYTES(nlk->ngroups), sizeof(u32)); netlink_unlock_table(); return err; }
@@ -1784,8 +1785,8 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname, len = sizeof(int); val = test_bit(flag, &nlk->flags); - if (put_user(len, optlen) || - copy_to_user(optval, &val, len)) + opt->optlen = len; + if (copy_to_iter(&val, len, &opt->iter_out) != len) return -EFAULT; return 0;
@@ -2813,7 +2814,7 @@ static const struct proto_ops netlink_ops = { .listen = sock_no_listen, .shutdown = sock_no_shutdown, .setsockopt = netlink_setsockopt, - .getsockopt = netlink_getsockopt, + .getsockopt_iter = netlink_getsockopt, .sendmsg = netlink_sendmsg, .recvmsg = netlink_recvmsg, .mmap = sock_no_mmap,
--
2.52.0