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[PATCHv4,bpf-next,3/5] bpf: Don't refcount LISTEN sockets in sk_assign()

Message ID 20200328185509.20892-4-joe@wand.net.nz
State Changes Requested
Delegated to: BPF Maintainers
Headers show
Series Add bpf_sk_assign eBPF helper | expand

Commit Message

Joe Stringer March 28, 2020, 6:55 p.m. UTC 
Avoid taking a reference on listen sockets by checking the socket type
in the sk_assign and in the corresponding skb_steal_sock() code in the
the transport layer, and by ensuring that the prefetch free (sock_pfree)
function uses the same logic to check whether the socket is refcounted.

Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Joe Stringer <joe@wand.net.nz>
Acked-by: Martin KaFai Lau <kafai@fb.com>
---
v4: Directly use sock_gen_put() from sock_pfree()
v3: No changes
v2: Initial version
---
 include/net/sock.h | 25 +++++++++++++++++--------
 net/core/filter.c  |  6 +++---
 net/core/sock.c    |  3 ++-
 3 files changed, 22 insertions(+), 12 deletions(-)

Comments

kernel test robot March 29, 2020, 9:12 p.m. UTC | #1 
Hi Joe,

Thank you for the patch! Yet something to improve:

[auto build test ERROR on bpf-next/master]
[cannot apply to bpf/master net/master net-next/master linus/master ipvs/master v5.6-rc7 next-20200327]
[if your patch is applied to the wrong git tree, please drop us a note to help
improve the system. BTW, we also suggest to use '--base' option to specify the
base tree in git format-patch, please see https://stackoverflow.com/a/37406982]

url:    https://github.com/0day-ci/linux/commits/Joe-Stringer/Add-bpf_sk_assign-eBPF-helper/20200329-025903
base:   https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next.git master
config: arm-spear3xx_defconfig (attached as .config)
compiler: arm-linux-gnueabi-gcc (GCC) 9.3.0
reproduce:
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        GCC_VERSION=9.3.0 make.cross ARCH=arm 

If you fix the issue, kindly add following tag
Reported-by: kbuild test robot <lkp@intel.com>

All errors (new ones prefixed by >>):

   arm-linux-gnueabi-ld: net/core/sock.o: in function `sock_pfree':
   sock.c:(.text+0x8bc): undefined reference to `sock_gen_put'
>> arm-linux-gnueabi-ld: sock.c:(.text+0x8d0): undefined reference to `sock_gen_put'

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
diff mbox series

Patch

diff --git a/include/net/sock.h b/include/net/sock.h
index 1ca2e808cb8e..3ec1865f173e 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -2533,6 +2533,21 @@  skb_sk_is_prefetched(struct sk_buff *skb)
 	return skb->destructor == sock_pfree;
 }
 
+/* This helper checks if a socket is a full socket,
+ * ie _not_ a timewait or request socket.
+ */
+static inline bool sk_fullsock(const struct sock *sk)
+{
+	return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
+}
+
+static inline bool
+sk_is_refcounted(struct sock *sk)
+{
+	/* Only full sockets have sk->sk_flags. */
+	return !sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE);
+}
+
 /**
  * skb_steal_sock
  * @skb to steal the socket from
@@ -2545,6 +2560,8 @@  skb_steal_sock(struct sk_buff *skb, bool *refcounted)
 		struct sock *sk = skb->sk;
 
 		*refcounted = true;
+		if (skb_sk_is_prefetched(skb))
+			*refcounted = sk_is_refcounted(sk);
 		skb->destructor = NULL;
 		skb->sk = NULL;
 		return sk;
@@ -2553,14 +2570,6 @@  skb_steal_sock(struct sk_buff *skb, bool *refcounted)
 	return NULL;
 }
 
-/* This helper checks if a socket is a full socket,
- * ie _not_ a timewait or request socket.
- */
-static inline bool sk_fullsock(const struct sock *sk)
-{
-	return (1 << sk->sk_state) & ~(TCPF_TIME_WAIT | TCPF_NEW_SYN_RECV);
-}
-
 /* Checks if this SKB belongs to an HW offloaded socket
  * and whether any SW fallbacks are required based on dev.
  * Check decrypted mark in case skb_orphan() cleared socket.
diff --git a/net/core/filter.c b/net/core/filter.c
index ac5c1633f8d2..7628b947dbc3 100644
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -5401,8 +5401,7 @@  static const struct bpf_func_proto bpf_sk_lookup_udp_proto = {
 
 BPF_CALL_1(bpf_sk_release, struct sock *, sk)
 {
-	/* Only full sockets have sk->sk_flags. */
-	if (!sk_fullsock(sk) || !sock_flag(sk, SOCK_RCU_FREE))
+	if (sk_is_refcounted(sk))
 		sock_gen_put(sk);
 	return 0;
 }
@@ -5928,7 +5927,8 @@  BPF_CALL_3(bpf_sk_assign, struct sk_buff *, skb, struct sock *, sk, u64, flags)
 		return -ENETUNREACH;
 	if (unlikely(sk->sk_reuseport))
 		return -ESOCKTNOSUPPORT;
-	if (unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
+	if (sk_is_refcounted(sk) &&
+	    unlikely(!refcount_inc_not_zero(&sk->sk_refcnt)))
 		return -ENOENT;
 
 	skb_orphan(skb);
diff --git a/net/core/sock.c b/net/core/sock.c
index a95ac2ec7beb..c33b6afdb774 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -2076,7 +2076,8 @@  EXPORT_SYMBOL(sock_efree);
  */
 void sock_pfree(struct sk_buff *skb)
 {
-	sock_gen_put(skb->sk);
+	if (sk_is_refcounted(skb->sk))
+		sock_gen_put(skb->sk);
 }
 EXPORT_SYMBOL(sock_pfree);