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| author | Andrii Nakryiko <andrii@kernel.org> | 2022-12-23 06:49:16 +0100 |
|---|---|---|
| committer | Alexei Starovoitov <ast@kernel.org> | 2022-12-28 02:37:07 +0100 |
| commit | a73bf9f2d969cbb04d5ca778f2a224060cda1027 (patch) | |
| tree | 0ca09c6ab86d829b8b6a991419473dad92a45416 /kernel | |
| parent | bpf: teach refsafe() to take into account ID remapping (diff) | |
| download | linux-a73bf9f2d969cbb04d5ca778f2a224060cda1027.tar.xz linux-a73bf9f2d969cbb04d5ca778f2a224060cda1027.zip | |
bpf: reorganize struct bpf_reg_state fields
Move id and ref_obj_id fields after scalar data section (var_off and
ranges). This is necessary to simplify next patch which will change
regsafe()'s logic to be safer, as it makes the contents that has to be
an exact match (type-specific parts, off, type, and var_off+ranges)
a single sequential block of memory, while id and ref_obj_id should
always be remapped and thus can't be memcp()'ed.
There are few places that assume that var_off is after id/ref_obj_id to
clear out id/ref_obj_id with the single memset(0). These are changed to
explicitly zero-out id/ref_obj_id fields. Other places are adjusted to
preserve exact byte-by-byte comparison behavior.
No functional changes.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/r/20221223054921.958283-3-andrii@kernel.org
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/bpf/verifier.c | 17 |
1 files changed, 8 insertions, 9 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c index ab8337f6a576..e419e6024251 100644 --- a/kernel/bpf/verifier.c +++ b/kernel/bpf/verifier.c @@ -1402,9 +1402,11 @@ static void ___mark_reg_known(struct bpf_reg_state *reg, u64 imm) */ static void __mark_reg_known(struct bpf_reg_state *reg, u64 imm) { - /* Clear id, off, and union(map_ptr, range) */ + /* Clear off and union(map_ptr, range) */ memset(((u8 *)reg) + sizeof(reg->type), 0, offsetof(struct bpf_reg_state, var_off) - sizeof(reg->type)); + reg->id = 0; + reg->ref_obj_id = 0; ___mark_reg_known(reg, imm); } @@ -1750,11 +1752,13 @@ static void __mark_reg_unknown(const struct bpf_verifier_env *env, struct bpf_reg_state *reg) { /* - * Clear type, id, off, and union(map_ptr, range) and + * Clear type, off, and union(map_ptr, range) and * padding between 'type' and union */ memset(reg, 0, offsetof(struct bpf_reg_state, var_off)); reg->type = SCALAR_VALUE; + reg->id = 0; + reg->ref_obj_id = 0; reg->var_off = tnum_unknown; reg->frameno = 0; reg->precise = !env->bpf_capable; @@ -13104,7 +13108,7 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, if (type_may_be_null(rold->type)) { if (!type_may_be_null(rcur->type)) return false; - if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, id))) + if (memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off))) return false; /* Check our ids match any regs they're supposed to */ return check_ids(rold->id, rcur->id, idmap); @@ -13112,13 +13116,8 @@ static bool regsafe(struct bpf_verifier_env *env, struct bpf_reg_state *rold, /* If the new min/max/var_off satisfy the old ones and * everything else matches, we are OK. - * 'id' is not compared, since it's only used for maps with - * bpf_spin_lock inside map element and in such cases if - * the rest of the prog is valid for one map element then - * it's valid for all map elements regardless of the key - * used in bpf_map_lookup() */ - return memcmp(rold, rcur, offsetof(struct bpf_reg_state, id)) == 0 && + return memcmp(rold, rcur, offsetof(struct bpf_reg_state, var_off)) == 0 && range_within(rold, rcur) && tnum_in(rold->var_off, rcur->var_off) && check_ids(rold->id, rcur->id, idmap); |