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[PATCH 4.12 06/52] bpf: fix map value attribute for hash of maps

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4.12-stable review patch.  If anyone has any objections, please let me know.

------------------

From: Daniel Borkmann <daniel@iogearbox.net>


[ Upstream commit 33ba43ed0afc13a29b1314e3e45a9938d310ba13 ]

Currently, iproute2's BPF ELF loader works fine with array of maps
when retrieving the fd from a pinned node and doing a selfcheck
against the provided map attributes from the object file, but we
fail to do the same for hash of maps and thus refuse to get the
map from pinned node.

Reason is that when allocating hash of maps, fd_htab_map_alloc() will
set the value size to sizeof(void *), and any user space map creation
requests are forced to set 4 bytes as value size. Thus, selfcheck
will complain about exposed 8 bytes on 64 bit archs vs. 4 bytes from
object file as value size. Contract is that fdinfo or BPF_MAP_GET_FD_BY_ID
returns the value size used to create the map.

Fix it by handling it the same way as we do for array of maps, which
means that we leave value size at 4 bytes and in the allocation phase
round up value size to 8 bytes. alloc_htab_elem() needs an adjustment
in order to copy rounded up 8 bytes due to bpf_fd_htab_map_update_elem()
calling into htab_map_update_elem() with the pointer of the map
pointer as value. Unlike array of maps where we just xchg(), we're
using the generic htab_map_update_elem() callback also used from helper
calls, which published the key/value already on return, so we need
to ensure to memcpy() the right size.

Fixes: bcc6b1b7ebf8 ("bpf: Add hash of maps support")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
 kernel/bpf/hashtab.c |   30 +++++++++++++++++-------------
 1 file changed, 17 insertions(+), 13 deletions(-)

--- a/kernel/bpf/hashtab.c
+++ b/kernel/bpf/hashtab.c
@@ -652,12 +652,27 @@ static void pcpu_copy_value(struct bpf_h
 	}
 }
 
+static bool fd_htab_map_needs_adjust(const struct bpf_htab *htab)
+{
+	return htab->map.map_type == BPF_MAP_TYPE_HASH_OF_MAPS &&
+	       BITS_PER_LONG == 64;
+}
+
+static u32 htab_size_value(const struct bpf_htab *htab, bool percpu)
+{
+	u32 size = htab->map.value_size;
+
+	if (percpu || fd_htab_map_needs_adjust(htab))
+		size = round_up(size, 8);
+	return size;
+}
+
 static struct htab_elem *alloc_htab_elem(struct bpf_htab *htab, void *key,
 					 void *value, u32 key_size, u32 hash,
 					 bool percpu, bool onallcpus,
 					 struct htab_elem *old_elem)
 {
-	u32 size = htab->map.value_size;
+	u32 size = htab_size_value(htab, percpu);
 	bool prealloc = htab_is_prealloc(htab);
 	struct htab_elem *l_new, **pl_new;
 	void __percpu *pptr;
@@ -696,9 +711,6 @@ static struct htab_elem *alloc_htab_elem
 
 	memcpy(l_new->key, key, key_size);
 	if (percpu) {
-		/* round up value_size to 8 bytes */
-		size = round_up(size, 8);
-
 		if (prealloc) {
 			pptr = htab_elem_get_ptr(l_new, key_size);
 		} else {
@@ -1209,17 +1221,9 @@ const struct bpf_map_ops htab_lru_percpu
 
 static struct bpf_map *fd_htab_map_alloc(union bpf_attr *attr)
 {
-	struct bpf_map *map;
-
 	if (attr->value_size != sizeof(u32))
 		return ERR_PTR(-EINVAL);
-
-	/* pointer is stored internally */
-	attr->value_size = sizeof(void *);
-	map = htab_map_alloc(attr);
-	attr->value_size = sizeof(u32);
-
-	return map;
+	return htab_map_alloc(attr);
 }
 
 static void fd_htab_map_free(struct bpf_map *map)

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[PATCH 4.12 00/52] 4.12.14-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:20 +0200
  [PATCH 4.12 25/52] net/mlx5: Fix arm SRQ command for ISSI version 0 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:20 +0200
  [PATCH 4.12 45/52] f2fs: check hot_data for roll-forward recovery Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.12 49/52] fuse: allow server to run in different pid_ns Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.12 52/52] md/raid5: release/flush io in raid5_do_work() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:40 +0200
  [PATCH 4.12 06/52] bpf: fix map value attribute for hash of maps Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 39/52] vhost_net: correctly check tx avail during rx busy polling Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 20/52] packet: Dont write vnet header beyond end of buffer Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 31/52] net/mlx5e: Fix CQ moderation mode not set properly Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 21/52] kcm: do not attach PF_KCM sockets to avoid deadlock Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 17/52] cxgb4: Fix stack out-of-bounds read due to wrong size to t4_record_mbox() Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 38/52] gianfar: Fix Tx flow control deactivation Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 12/52] net: bcmgenet: Be drop monitor friendly Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 23/52] net/mlx5e: Check for qos capability in dcbnl_initialize Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 48/52] x86/switch_to/64: Rewrite FS/GS switching yet again to fix AMD CPUs Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 41/52] ipv6: fix memory leak with multiple tables during netns destruction Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 29/52] net/mlx5: E-Switch, Unload the representors in the correct order Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 33/52] net: fec: Allow reception of frames bigger than 1522 bytes Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 16/52] net: mvpp2: fix the mac address used when using PPv2.2 Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 09/52] qlge: avoid memcpy buffer overflow Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 13/52] net: systemport: Free DMA coherent descriptors on errors Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 40/52] ip6_gre: update mtu properly in ip6gre_err Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 43/52] sctp: fix missing wake ups in some situations Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 27/52] net/mlx5e: Dont override user RSS upon set channels Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 19/52] ipv6: do not set sk_destruct in IPV6_ADDRFORM sockopt Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 37/52] Revert "net: fix percpu memory leaks" Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 15/52] udp6: set rx_dst_cookie on rx_dst updates Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 26/52] net/mlx5e: Fix dangling page pointer on DMA mapping error Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 28/52] net/mlx5e: Properly resolve TC offloaded ipv6 vxlan tunnel source address Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 46/52] x86/fsgsbase/64: Fully initialize FS and GS state in start_thread_common Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 11:50 +0200
  [PATCH 4.12 02/52] ipv6: add rcu grace period before freeing fib6_node Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 12:00 +0200
  [PATCH 4.12 03/52] ipv6: fix sparse warning on rt6i_node Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 12:00 +0200
  [PATCH 4.12 10/52] tipc: Fix tipc_sk_reinit handling of -EAGAIN Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-18 12:00 +0200
  Re: [PATCH 4.12 00/52] 4.12.14-stable review Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2017-09-18 16:30 +0200
    Re: [PATCH 4.12 00/52] 4.12.14-stable review Greg Kroah-Hartman <gregkh@linuxfoundation.org> - 2017-09-19 08:40 +0200
      Re: [PATCH 4.12 00/52] 4.12.14-stable review Sudip Mukherjee <sudipm.mukherjee@gmail.com> - 2017-09-20 14:20 +0200
  Re: [PATCH 4.12 00/52] 4.12.14-stable review Guenter Roeck <linux@roeck-us.net> - 2017-09-18 21:30 +0200
  Re: [PATCH 4.12 00/52] 4.12.14-stable review Shuah Khan <shuahkh@osg.samsung.com> - 2017-09-18 22:20 +0200

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