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authorDavid Miller <davem@davemloft.net>2018-11-30 21:08:14 -0800
committerAlexei Starovoitov <ast@kernel.org>2018-11-30 21:38:48 -0800
commite9ee9efc0d176512cdce9d27ff8549d7ffa2bfcd (patch)
tree94b32bfcaa32c3538810330370ed7cd4b07e15e4 /kernel/bpf/verifier.c
parent88945f460603ad8909b556c67a9229bb23188d41 (diff)
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bpf: Add BPF_F_ANY_ALIGNMENT.
Often we want to write tests cases that check things like bad context offset accesses. And one way to do this is to use an odd offset on, for example, a 32-bit load. This unfortunately triggers the alignment checks first on platforms that do not set CONFIG_EFFICIENT_UNALIGNED_ACCESS. So the test case see the alignment failure rather than what it was testing for. It is often not completely possible to respect the original intention of the test, or even test the same exact thing, while solving the alignment issue. Another option could have been to check the alignment after the context and other validations are performed by the verifier, but that is a non-trivial change to the verifier. Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel/bpf/verifier.c')
-rw-r--r--kernel/bpf/verifier.c2
1 files changed, 2 insertions, 0 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 9584438fa2cc..71988337ac14 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -6505,6 +6505,8 @@ int bpf_check(struct bpf_prog **prog, union bpf_attr *attr,
env->strict_alignment = !!(attr->prog_flags & BPF_F_STRICT_ALIGNMENT);
if (!IS_ENABLED(CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS))
env->strict_alignment = true;
+ if (attr->prog_flags & BPF_F_ANY_ALIGNMENT)
+ env->strict_alignment = false;
ret = replace_map_fd_with_map_ptr(env);
if (ret < 0)