From 4288ea006c73e37c2a4f60dfaef20dd167b8df31 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Fri, 28 Sep 2018 14:33:21 +0100 Subject: bpf: harden flags check in cgroup_storage_update_elem() cgroup_storage_update_elem() shouldn't accept any flags argument values except BPF_ANY and BPF_EXIST to guarantee the backward compatibility, had a new flag value been added. Fixes: de9cbbaadba5 ("bpf: introduce cgroup storage maps") Signed-off-by: Roman Gushchin Reported-by: Daniel Borkmann Cc: Alexei Starovoitov Signed-off-by: Daniel Borkmann --- kernel/bpf/local_storage.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c index 22ad967d1e5f..94126cbffc88 100644 --- a/kernel/bpf/local_storage.c +++ b/kernel/bpf/local_storage.c @@ -129,7 +129,7 @@ static int cgroup_storage_update_elem(struct bpf_map *map, void *_key, struct bpf_cgroup_storage *storage; struct bpf_storage_buffer *new; - if (flags & BPF_NOEXIST) + if (flags != BPF_ANY && flags != BPF_EXIST) return -EINVAL; storage = cgroup_storage_lookup((struct bpf_cgroup_storage_map *)map, -- cgit v1.2.3-59-g8ed1b From b0584ea66d73919cbf5878a3420a837f06ab8396 Mon Sep 17 00:00:00 2001 From: Roman Gushchin Date: Tue, 2 Oct 2018 02:41:53 +0000 Subject: bpf: don't accept cgroup local storage with zero value size Explicitly forbid creating cgroup local storage maps with zero value size, as it makes no sense and might even cause a panic. Reported-by: syzbot+18628320d3b14a5c459c@syzkaller.appspotmail.com Signed-off-by: Roman Gushchin Cc: Alexei Starovoitov Cc: Daniel Borkmann Signed-off-by: Daniel Borkmann --- kernel/bpf/local_storage.c | 3 +++ 1 file changed, 3 insertions(+) (limited to 'kernel') diff --git a/kernel/bpf/local_storage.c b/kernel/bpf/local_storage.c index 94126cbffc88..830d7f095748 100644 --- a/kernel/bpf/local_storage.c +++ b/kernel/bpf/local_storage.c @@ -195,6 +195,9 @@ static struct bpf_map *cgroup_storage_map_alloc(union bpf_attr *attr) if (attr->key_size != sizeof(struct bpf_cgroup_storage_key)) return ERR_PTR(-EINVAL); + if (attr->value_size == 0) + return ERR_PTR(-EINVAL); + if (attr->value_size > PAGE_SIZE) return ERR_PTR(-E2BIG); -- cgit v1.2.3-59-g8ed1b From b799207e1e1816b09e7a5920fbb2d5fcf6edd681 Mon Sep 17 00:00:00 2001 From: Jann Horn Date: Fri, 5 Oct 2018 18:17:59 +0200 Subject: bpf: 32-bit RSH verification must truncate input before the ALU op When I wrote commit 468f6eafa6c4 ("bpf: fix 32-bit ALU op verification"), I assumed that, in order to emulate 64-bit arithmetic with 32-bit logic, it is sufficient to just truncate the output to 32 bits; and so I just moved the register size coercion that used to be at the start of the function to the end of the function. That assumption is true for almost every op, but not for 32-bit right shifts, because those can propagate information towards the least significant bit. Fix it by always truncating inputs for 32-bit ops to 32 bits. Also get rid of the coerce_reg_to_size() after the ALU op, since that has no effect. Fixes: 468f6eafa6c4 ("bpf: fix 32-bit ALU op verification") Acked-by: Daniel Borkmann Signed-off-by: Jann Horn Signed-off-by: Daniel Borkmann --- kernel/bpf/verifier.c | 10 +++++++++- 1 file changed, 9 insertions(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index bb07e74b34a2..465952a8e465 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2896,6 +2896,15 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, u64 umin_val, umax_val; u64 insn_bitness = (BPF_CLASS(insn->code) == BPF_ALU64) ? 64 : 32; + if (insn_bitness == 32) { + /* Relevant for 32-bit RSH: Information can propagate towards + * LSB, so it isn't sufficient to only truncate the output to + * 32 bits. + */ + coerce_reg_to_size(dst_reg, 4); + coerce_reg_to_size(&src_reg, 4); + } + smin_val = src_reg.smin_value; smax_val = src_reg.smax_value; umin_val = src_reg.umin_value; @@ -3131,7 +3140,6 @@ static int adjust_scalar_min_max_vals(struct bpf_verifier_env *env, if (BPF_CLASS(insn->code) != BPF_ALU64) { /* 32-bit ALU ops are (32,32)->32 */ coerce_reg_to_size(dst_reg, 4); - coerce_reg_to_size(&src_reg, 4); } __reg_deduce_bounds(dst_reg); -- cgit v1.2.3-59-g8ed1b