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authorJiri Slaby <jslaby@suse.cz>2018-01-12 13:23:05 +0100
committerJiri Slaby <jslaby@suse.cz>2018-01-12 16:49:36 +0100
commitb93121874b8f3d4fc1f37e503dcdabc850d263f6 (patch)
tree9df28577442e1901b426907fae0366e6fd38bd2f
parent5d6372171e5db9af477d38ee873d64b578a9416d (diff)
bpf: move fixup_bpf_calls() function (bsc#1068032
CVE-2017-5753). suse-commit: 4ed9f50d5d5660dba6e83a2eea1c6da56818b08e
-rw-r--r--kernel/bpf/syscall.c54
-rw-r--r--kernel/bpf/verifier.c55
2 files changed, 55 insertions, 54 deletions
diff --git a/kernel/bpf/syscall.c b/kernel/bpf/syscall.c
index 4e32cc94edd9..424accd20c2d 100644
--- a/kernel/bpf/syscall.c
+++ b/kernel/bpf/syscall.c
@@ -447,57 +447,6 @@ void bpf_register_prog_type(struct bpf_prog_type_list *tl)
list_add(&tl->list_node, &bpf_prog_types);
}
-/* fixup insn->imm field of bpf_call instructions:
- * if (insn->imm == BPF_FUNC_map_lookup_elem)
- * insn->imm = bpf_map_lookup_elem - __bpf_call_base;
- * else if (insn->imm == BPF_FUNC_map_update_elem)
- * insn->imm = bpf_map_update_elem - __bpf_call_base;
- * else ...
- *
- * this function is called after eBPF program passed verification
- */
-static void fixup_bpf_calls(struct bpf_prog *prog)
-{
- const struct bpf_func_proto *fn;
- int i;
-
- for (i = 0; i < prog->len; i++) {
- struct bpf_insn *insn = &prog->insnsi[i];
-
- if (insn->code == (BPF_JMP | BPF_CALL)) {
- /* we reach here when program has bpf_call instructions
- * and it passed bpf_check(), means that
- * ops->get_func_proto must have been supplied, check it
- */
- BUG_ON(!prog->aux->ops->get_func_proto);
-
- if (insn->imm == BPF_FUNC_get_route_realm)
- prog->dst_needed = 1;
- if (insn->imm == BPF_FUNC_get_prandom_u32)
- bpf_user_rnd_init_once();
- if (insn->imm == BPF_FUNC_tail_call) {
- /* mark bpf_tail_call as different opcode
- * to avoid conditional branch in
- * interpeter for every normal call
- * and to prevent accidental JITing by
- * JIT compiler that doesn't support
- * bpf_tail_call yet
- */
- insn->imm = 0;
- insn->code |= BPF_X;
- continue;
- }
-
- fn = prog->aux->ops->get_func_proto(insn->imm);
- /* all functions that have prototype and verifier allowed
- * programs to call them, must be real in-kernel functions
- */
- BUG_ON(!fn->func);
- insn->imm = fn->func - __bpf_call_base;
- }
- }
-}
-
/* drop refcnt on maps used by eBPF program and free auxilary data */
static void free_used_maps(struct bpf_prog_aux *aux)
{
@@ -680,9 +629,6 @@ static int bpf_prog_load(union bpf_attr *attr)
if (err < 0)
goto free_used_maps;
- /* fixup BPF_CALL->imm field */
- fixup_bpf_calls(prog);
-
/* eBPF program is ready to be JITed */
err = bpf_prog_select_runtime(prog);
if (err < 0)
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 769d2ec44802..198737d36754 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2158,6 +2158,58 @@ static int convert_ctx_accesses(struct verifier_env *env)
return 0;
}
+/* fixup insn->imm field of bpf_call instructions:
+ * if (insn->imm == BPF_FUNC_map_lookup_elem)
+ * insn->imm = bpf_map_lookup_elem - __bpf_call_base;
+ * else if (insn->imm == BPF_FUNC_map_update_elem)
+ * insn->imm = bpf_map_update_elem - __bpf_call_base;
+ * else ...
+ *
+ * this function is called after eBPF program passed verification
+ */
+static void fixup_bpf_calls(struct bpf_prog *prog)
+{
+ const struct bpf_func_proto *fn;
+ int i;
+
+ for (i = 0; i < prog->len; i++) {
+ struct bpf_insn *insn = &prog->insnsi[i];
+
+ if (insn->code == (BPF_JMP | BPF_CALL)) {
+ /* we reach here when program has bpf_call instructions
+ * and it passed bpf_check(), means that
+ * ops->get_func_proto must have been supplied, check it
+ */
+ BUG_ON(!prog->aux->ops->get_func_proto);
+
+ if (insn->imm == BPF_FUNC_get_route_realm)
+ prog->dst_needed = 1;
+ if (insn->imm == BPF_FUNC_get_prandom_u32)
+ bpf_user_rnd_init_once();
+ if (insn->imm == BPF_FUNC_tail_call) {
+ /* mark bpf_tail_call as different opcode
+ * to avoid conditional branch in
+ * interpeter for every normal call
+ * and to prevent accidental JITing by
+ * JIT compiler that doesn't support
+ * bpf_tail_call yet
+ */
+ insn->imm = 0;
+ insn->code |= BPF_X;
+ continue;
+ }
+
+ fn = prog->aux->ops->get_func_proto(insn->imm);
+ /* all functions that have prototype and verifier allowed
+ * programs to call them, must be real in-kernel functions
+ */
+ BUG_ON(!fn->func);
+ insn->imm = fn->func - __bpf_call_base;
+ }
+ }
+}
+
+
static void free_states(struct verifier_env *env)
{
struct verifier_state_list *sl, *sln;
@@ -2256,6 +2308,9 @@ skip_full_check:
/* program is valid, convert *(u32*)(ctx + off) accesses */
ret = convert_ctx_accesses(env);
+ if (ret == 0)
+ fixup_bpf_calls(env->prog);
+
if (log_level && log_len >= log_size - 1) {
BUG_ON(log_len >= log_size);
/* verifier log exceeded user supplied buffer */