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| author | Chema Gonzalez <chema@google.com> | 2014-05-30 10:15:12 -0700 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2014-06-02 16:32:43 -0700 |
| commit | e9d9450497f77ee40c7d895bf1b5b134b9347d5f (patch) | |
| tree | 5b56ae0ed1e7cc3b4ff1aaf4f41d141c026af380 | |
| parent | f7b4e71c9d6154969270d8bbd49e78ca86d455cd (diff) | |
| download | linux-e9d9450497f77ee40c7d895bf1b5b134b9347d5f.tar.gz linux-e9d9450497f77ee40c7d895bf1b5b134b9347d5f.tar.bz2 linux-e9d9450497f77ee40c7d895bf1b5b134b9347d5f.zip | |
net: filter: fix length calculation in BPF testsuite
The current probe_filter_length() (the function that calculates the
length of a test BPF filter) behavior is to declare the end of the
filter as soon as it finds {0, *, *, 0}. This is actually a valid
insn ("ld #0"), so any filter with includes "BPF_STMT(BPF_LD | BPF_IMM, 0)"
fails (its length is cut short).
We are changing probe_filter_length() so as to start from the end, and
declare the end of the filter as the first instruction which is not
{0, *, *, 0}. This solution produces a simpler patch than the
alternative of using an explicit end-of-filter mark. It is technically
incorrect if your filter ends up with "ld #0", but that should not
happen anyway.
We also add a new test (LD_IMM_0) that includes ld #0 (does not work
without this patch).
Signed-off-by: Chema Gonzalez <chema@google.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
| -rw-r--r-- | lib/test_bpf.c | 21 |
1 files changed, 16 insertions, 5 deletions
diff --git a/lib/test_bpf.c b/lib/test_bpf.c index f8d2b2a13131..ea60ad8d5242 100644 --- a/lib/test_bpf.c +++ b/lib/test_bpf.c @@ -158,6 +158,18 @@ static struct bpf_test tests[] = { { { 0, 0x800000ff }, { 1, 0x800000ff } }, }, { + "LD_IMM_0", + .u.insns = { + BPF_STMT(BPF_LD | BPF_IMM, 0), /* ld #0 */ + BPF_JUMP(BPF_JMP | BPF_JEQ | BPF_K, 0, 1, 0), + BPF_STMT(BPF_RET | BPF_K, 0), + BPF_STMT(BPF_RET | BPF_K, 1), + }, + CLASSIC, + { }, + { { 1, 1 } }, + }, + { "LD_IND", .u.insns = { BPF_STMT(BPF_LDX | BPF_LEN, 0), @@ -1734,12 +1746,11 @@ static int probe_filter_length(struct sock_filter *fp) { int len = 0; - while (fp->code != 0 || fp->k != 0) { - fp++; - len++; - } + for (len = MAX_INSNS - 1; len > 0; --len) + if (fp[len].code != 0 || fp[len].k != 0) + break; - return len; + return len + 1; } static struct sk_filter *generate_filter(int which, int *err) |