From 8ced425ee630c03beea06c1dfa35190bf8395d07 Mon Sep 17 00:00:00 2001 From: Hannes Frederic Sowa Date: Tue, 5 Apr 2016 17:10:16 +0200 Subject: [PATCH] tun: use socket locks for sk_{attach,detatch}_filter This reverts commit 5a5abb1fa3b05dd ("tun, bpf: fix suspicious RCU usage in tun_{attach, detach}_filter") and replaces it to use lock_sock around sk_{attach,detach}_filter. The checks inside filter.c are updated with lockdep_sock_is_held to check for proper socket locks. It keeps the code cleaner by ensuring that only one lock governs the socket filter instead of two independent locks. Cc: Daniel Borkmann Signed-off-by: Hannes Frederic Sowa Signed-off-by: David S. Miller --- drivers/net/tun.c | 14 +++++++++----- include/linux/filter.h | 4 ---- net/core/filter.c | 35 +++++++++++++---------------------- 3 files changed, 22 insertions(+), 31 deletions(-) diff --git a/drivers/net/tun.c b/drivers/net/tun.c index 9abc36bf77ea..64bc143eddd9 100644 --- a/drivers/net/tun.c +++ b/drivers/net/tun.c @@ -622,8 +622,9 @@ static int tun_attach(struct tun_struct *tun, struct file *file, bool skip_filte /* Re-attach the filter to persist device */ if (!skip_filter && (tun->filter_attached == true)) { - err = __sk_attach_filter(&tun->fprog, tfile->socket.sk, - lockdep_rtnl_is_held()); + lock_sock(tfile->socket.sk); + err = sk_attach_filter(&tun->fprog, tfile->socket.sk); + release_sock(tfile->socket.sk); if (!err) goto out; } @@ -1824,7 +1825,9 @@ static void tun_detach_filter(struct tun_struct *tun, int n) for (i = 0; i < n; i++) { tfile = rtnl_dereference(tun->tfiles[i]); - __sk_detach_filter(tfile->socket.sk, lockdep_rtnl_is_held()); + lock_sock(tfile->socket.sk); + sk_detach_filter(tfile->socket.sk); + release_sock(tfile->socket.sk); } tun->filter_attached = false; @@ -1837,8 +1840,9 @@ static int tun_attach_filter(struct tun_struct *tun) for (i = 0; i < tun->numqueues; i++) { tfile = rtnl_dereference(tun->tfiles[i]); - ret = __sk_attach_filter(&tun->fprog, tfile->socket.sk, - lockdep_rtnl_is_held()); + lock_sock(tfile->socket.sk); + ret = sk_attach_filter(&tun->fprog, tfile->socket.sk); + release_sock(tfile->socket.sk); if (ret) { tun_detach_filter(tun, i); return ret; diff --git a/include/linux/filter.h b/include/linux/filter.h index a51a5361695f..43aa1f8855c7 100644 --- a/include/linux/filter.h +++ b/include/linux/filter.h @@ -465,14 +465,10 @@ int bpf_prog_create_from_user(struct bpf_prog **pfp, struct sock_fprog *fprog, void bpf_prog_destroy(struct bpf_prog *fp); int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk); -int __sk_attach_filter(struct sock_fprog *fprog, struct sock *sk, - bool locked); int sk_attach_bpf(u32 ufd, struct sock *sk); int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk); int sk_reuseport_attach_bpf(u32 ufd, struct sock *sk); int sk_detach_filter(struct sock *sk); -int __sk_detach_filter(struct sock *sk, bool locked); - int sk_get_filter(struct sock *sk, struct sock_filter __user *filter, unsigned int len); diff --git a/net/core/filter.c b/net/core/filter.c index ca7f832b2980..e8486ba601ea 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -1149,8 +1149,7 @@ void bpf_prog_destroy(struct bpf_prog *fp) } EXPORT_SYMBOL_GPL(bpf_prog_destroy); -static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk, - bool locked) +static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk) { struct sk_filter *fp, *old_fp; @@ -1166,8 +1165,10 @@ static int __sk_attach_prog(struct bpf_prog *prog, struct sock *sk, return -ENOMEM; } - old_fp = rcu_dereference_protected(sk->sk_filter, locked); + old_fp = rcu_dereference_protected(sk->sk_filter, + lockdep_sock_is_held(sk)); rcu_assign_pointer(sk->sk_filter, fp); + if (old_fp) sk_filter_uncharge(sk, old_fp); @@ -1246,8 +1247,7 @@ struct bpf_prog *__get_filter(struct sock_fprog *fprog, struct sock *sk) * occurs or there is insufficient memory for the filter a negative * errno code is returned. On success the return is zero. */ -int __sk_attach_filter(struct sock_fprog *fprog, struct sock *sk, - bool locked) +int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) { struct bpf_prog *prog = __get_filter(fprog, sk); int err; @@ -1255,7 +1255,7 @@ int __sk_attach_filter(struct sock_fprog *fprog, struct sock *sk, if (IS_ERR(prog)) return PTR_ERR(prog); - err = __sk_attach_prog(prog, sk, locked); + err = __sk_attach_prog(prog, sk); if (err < 0) { __bpf_prog_release(prog); return err; @@ -1263,12 +1263,7 @@ int __sk_attach_filter(struct sock_fprog *fprog, struct sock *sk, return 0; } -EXPORT_SYMBOL_GPL(__sk_attach_filter); - -int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) -{ - return __sk_attach_filter(fprog, sk, sock_owned_by_user(sk)); -} +EXPORT_SYMBOL_GPL(sk_attach_filter); int sk_reuseport_attach_filter(struct sock_fprog *fprog, struct sock *sk) { @@ -1314,7 +1309,7 @@ int sk_attach_bpf(u32 ufd, struct sock *sk) if (IS_ERR(prog)) return PTR_ERR(prog); - err = __sk_attach_prog(prog, sk, sock_owned_by_user(sk)); + err = __sk_attach_prog(prog, sk); if (err < 0) { bpf_prog_put(prog); return err; @@ -2255,7 +2250,7 @@ static int __init register_sk_filter_ops(void) } late_initcall(register_sk_filter_ops); -int __sk_detach_filter(struct sock *sk, bool locked) +int sk_detach_filter(struct sock *sk) { int ret = -ENOENT; struct sk_filter *filter; @@ -2263,7 +2258,8 @@ int __sk_detach_filter(struct sock *sk, bool locked) if (sock_flag(sk, SOCK_FILTER_LOCKED)) return -EPERM; - filter = rcu_dereference_protected(sk->sk_filter, locked); + filter = rcu_dereference_protected(sk->sk_filter, + lockdep_sock_is_held(sk)); if (filter) { RCU_INIT_POINTER(sk->sk_filter, NULL); sk_filter_uncharge(sk, filter); @@ -2272,12 +2268,7 @@ int __sk_detach_filter(struct sock *sk, bool locked) return ret; } -EXPORT_SYMBOL_GPL(__sk_detach_filter); - -int sk_detach_filter(struct sock *sk) -{ - return __sk_detach_filter(sk, sock_owned_by_user(sk)); -} +EXPORT_SYMBOL_GPL(sk_detach_filter); int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len) @@ -2288,7 +2279,7 @@ int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, lock_sock(sk); filter = rcu_dereference_protected(sk->sk_filter, - sock_owned_by_user(sk)); + lockdep_sock_is_held(sk)); if (!filter) goto out; -- 2.39.5