From 0962590e553331db2cc0aef2dc35c57f6300dbbe Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 1 Nov 2018 00:05:52 +0100 Subject: bpf: fix partial copy of map_ptr when dst is scalar ALU operations on pointers such as scalar_reg += map_value_ptr are handled in adjust_ptr_min_max_vals(). Problem is however that map_ptr and range in the register state share a union, so transferring state through dst_reg->range = ptr_reg->range is just buggy as any new map_ptr in the dst_reg is then truncated (or null) for subsequent checks. Fix this by adding a raw member and use it for copying state over to dst_reg. Fixes: f1174f77b50c ("bpf/verifier: rework value tracking") Signed-off-by: Daniel Borkmann Cc: Edward Cree Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 171a2c88e77d..774fa40a32ae 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -3046,7 +3046,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, dst_reg->umax_value = umax_ptr; dst_reg->var_off = ptr_reg->var_off; dst_reg->off = ptr_reg->off + smin_val; - dst_reg->range = ptr_reg->range; + dst_reg->raw = ptr_reg->raw; break; } /* A new variable offset is created. Note that off_reg->off @@ -3076,10 +3076,11 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, } dst_reg->var_off = tnum_add(ptr_reg->var_off, off_reg->var_off); dst_reg->off = ptr_reg->off; + dst_reg->raw = ptr_reg->raw; if (reg_is_pkt_pointer(ptr_reg)) { dst_reg->id = ++env->id_gen; /* something was added to pkt_ptr, set range to zero */ - dst_reg->range = 0; + dst_reg->raw = 0; } break; case BPF_SUB: @@ -3108,7 +3109,7 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, dst_reg->var_off = ptr_reg->var_off; dst_reg->id = ptr_reg->id; dst_reg->off = ptr_reg->off - smin_val; - dst_reg->range = ptr_reg->range; + dst_reg->raw = ptr_reg->raw; break; } /* A new variable offset is created. If the subtrahend is known @@ -3134,11 +3135,12 @@ static int adjust_ptr_min_max_vals(struct bpf_verifier_env *env, } dst_reg->var_off = tnum_sub(ptr_reg->var_off, off_reg->var_off); dst_reg->off = ptr_reg->off; + dst_reg->raw = ptr_reg->raw; if (reg_is_pkt_pointer(ptr_reg)) { dst_reg->id = ++env->id_gen; /* something was added to pkt_ptr, set range to zero */ if (smin_val < 0) - dst_reg->range = 0; + dst_reg->raw = 0; } break; case BPF_AND: -- cgit v1.2.1 From 4d31f30148cea6e97e42616231eed55295117fe7 Mon Sep 17 00:00:00 2001 From: Daniel Borkmann Date: Thu, 1 Nov 2018 00:05:53 +0100 Subject: bpf: don't set id on after map lookup with ptr_to_map_val return In the verifier there is no such semantics where registers with PTR_TO_MAP_VALUE type have an id assigned to them. This is only used in PTR_TO_MAP_VALUE_OR_NULL and later on nullified once the test against NULL has been pattern matched and type transformed into PTR_TO_MAP_VALUE. Fixes: 3e6a4b3e0289 ("bpf/verifier: introduce BPF_PTR_TO_MAP_VALUE") Signed-off-by: Daniel Borkmann Cc: Roman Gushchin Acked-by: Alexei Starovoitov Signed-off-by: Alexei Starovoitov --- kernel/bpf/verifier.c | 11 ++++++----- 1 file changed, 6 insertions(+), 5 deletions(-) (limited to 'kernel') diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index 774fa40a32ae..1971ca325fb4 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -2852,10 +2852,6 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn regs[BPF_REG_0].type = NOT_INIT; } else if (fn->ret_type == RET_PTR_TO_MAP_VALUE_OR_NULL || fn->ret_type == RET_PTR_TO_MAP_VALUE) { - if (fn->ret_type == RET_PTR_TO_MAP_VALUE) - regs[BPF_REG_0].type = PTR_TO_MAP_VALUE; - else - regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; /* There is no offset yet applied, variable or fixed */ mark_reg_known_zero(env, regs, BPF_REG_0); /* remember map_ptr, so that check_map_access() @@ -2868,7 +2864,12 @@ static int check_helper_call(struct bpf_verifier_env *env, int func_id, int insn return -EINVAL; } regs[BPF_REG_0].map_ptr = meta.map_ptr; - regs[BPF_REG_0].id = ++env->id_gen; + if (fn->ret_type == RET_PTR_TO_MAP_VALUE) { + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE; + } else { + regs[BPF_REG_0].type = PTR_TO_MAP_VALUE_OR_NULL; + regs[BPF_REG_0].id = ++env->id_gen; + } } else if (fn->ret_type == RET_PTR_TO_SOCKET_OR_NULL) { int id = acquire_reference_state(env, insn_idx); if (id < 0) -- cgit v1.2.1