releases/4.19.31/bpf-lpm-fix-lookup-bug-in-map_delete_elem.patch

   1 From b767f332f8defabc623af4217793f028897be730 Mon Sep 17 00:00:00 2001
   2 From: Alban Crequy <alban@kinvolk.io>
   3 Date: Fri, 22 Feb 2019 14:19:08 +0100
   4 Subject: bpf, lpm: fix lookup bug in map_delete_elem
   5
   6 [ Upstream commit 7c0cdf0b3940f63d9777c3fcf250a2f83859ca54 ]
   7
   8 trie_delete_elem() was deleting an entry even though it was not matching
   9 if the prefixlen was correct. This patch adds a check on matchlen.
  10
  11 Reproducer:
  12
  13 $ sudo bpftool map create /sys/fs/bpf/mylpm type lpm_trie key 8 value 1 entries 128 name mylpm flags 1
  14 $ sudo bpftool map update pinned /sys/fs/bpf/mylpm key hex 10 00 00 00 aa bb cc dd value hex 01
  15 $ sudo bpftool map dump pinned /sys/fs/bpf/mylpm
  16 key: 10 00 00 00 aa bb cc dd  value: 01
  17 Found 1 element
  18 $ sudo bpftool map delete pinned /sys/fs/bpf/mylpm key hex 10 00 00 00 ff ff ff ff
  19 $ echo $?
  20 0
  21 $ sudo bpftool map dump pinned /sys/fs/bpf/mylpm
  22 Found 0 elements
  23
  24 A similar reproducer is added in the selftests.
  25
  26 Without the patch:
  27
  28 $ sudo ./tools/testing/selftests/bpf/test_lpm_map
  29 test_lpm_map: test_lpm_map.c:485: test_lpm_delete: Assertion `bpf_map_delete_elem(map_fd, key) == -1 && errno == ENOENT' failed.
  30 Aborted
  31
  32 With the patch: test_lpm_map runs without errors.
  33
  34 Fixes: e454cf595853 ("bpf: Implement map_delete_elem for BPF_MAP_TYPE_LPM_TRIE")
  35 Cc: Craig Gallek <kraig@google.com>
  36 Signed-off-by: Alban Crequy <alban@kinvolk.io>
  37 Acked-by: Craig Gallek <kraig@google.com>
  38 Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
  39 Signed-off-by: Sasha Levin <sashal@kernel.org>
  40 ---
  41  kernel/bpf/lpm_trie.c                      |  1 +
  42  tools/testing/selftests/bpf/test_lpm_map.c | 10 ++++++++++
  43  2 files changed, 11 insertions(+)
  44
  45 diff --git a/kernel/bpf/lpm_trie.c b/kernel/bpf/lpm_trie.c
  46 index 9058317ba9de..4f3138e6ecb2 100644
  47 --- a/kernel/bpf/lpm_trie.c
  48 +++ b/kernel/bpf/lpm_trie.c
  49 @@ -432,6 +432,7 @@ static int trie_delete_elem(struct bpf_map *map, void *_key)
  50         }
  51
  52         if (!node || node->prefixlen != key->prefixlen ||
  53 +           node->prefixlen != matchlen ||
  54             (node->flags & LPM_TREE_NODE_FLAG_IM)) {
  55                 ret = -ENOENT;
  56                 goto out;
  57 diff --git a/tools/testing/selftests/bpf/test_lpm_map.c b/tools/testing/selftests/bpf/test_lpm_map.c
  58 index 147e34cfceb7..02d7c871862a 100644
  59 --- a/tools/testing/selftests/bpf/test_lpm_map.c
  60 +++ b/tools/testing/selftests/bpf/test_lpm_map.c
  61 @@ -474,6 +474,16 @@ static void test_lpm_delete(void)
  62         assert(bpf_map_lookup_elem(map_fd, key, &value) == -1 &&
  63                 errno == ENOENT);
  64
  65 +       key->prefixlen = 30; // unused prefix so far
  66 +       inet_pton(AF_INET, "192.255.0.0", key->data);
  67 +       assert(bpf_map_delete_elem(map_fd, key) == -1 &&
  68 +               errno == ENOENT);
  69 +
  70 +       key->prefixlen = 16; // same prefix as the root node
  71 +       inet_pton(AF_INET, "192.255.0.0", key->data);
  72 +       assert(bpf_map_delete_elem(map_fd, key) == -1 &&
  73 +               errno == ENOENT);
  74 +
  75         /* assert initial lookup */
  76         key->prefixlen = 32;
  77         inet_pton(AF_INET, "192.168.0.1", key->data);
  78 --
  79 2.19.1
  80