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authorJiri Slaby <jslaby@suse.cz>2018-01-12 13:23:05 +0100
committerJiri Slaby <jslaby@suse.cz>2018-01-12 14:55:28 +0100
commit2123ca2d10a748c354fd4aa2916d04611c718b0b (patch)
tree3857d32f91629e72202b5829d0854201ac8dae54
parent24be077d25ba9b388e3c8635e0920046855543c0 (diff)
bpf: refactor fixup_bpf_calls() (bsc#1068032 CVE-2017-5753).
-rw-r--r--kernel/bpf/verifier.c72
1 files changed, 33 insertions, 39 deletions
diff --git a/kernel/bpf/verifier.c b/kernel/bpf/verifier.c
index 198737d36754..47bb3eee950c 100644
--- a/kernel/bpf/verifier.c
+++ b/kernel/bpf/verifier.c
@@ -2158,57 +2158,51 @@ 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 ...
+/* fixup insn->imm field of bpf_call instructions
*
* this function is called after eBPF program passed verification
*/
-static void fixup_bpf_calls(struct bpf_prog *prog)
+static int fixup_bpf_calls(struct verifier_env *env)
{
+ struct bpf_prog *prog = env->prog;
+ struct bpf_insn *insn = prog->insnsi;
const struct bpf_func_proto *fn;
+ const int insn_cnt = prog->len;
int i;
- for (i = 0; i < prog->len; i++) {
- struct bpf_insn *insn = &prog->insnsi[i];
+ for (i = 0; i < insn_cnt; i++, insn++) {
+ if (insn->code != (BPF_JMP | BPF_CALL))
+ continue;
- 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
+ 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 the interpeter for every normal
+ * call and to prevent accidental JITing by JIT compiler
+ * that doesn't support bpf_tail_call yet
*/
- 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;
- }
+ 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;
+ 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
+ */
+ if (!fn->func) {
+ verbose("kernel subsystem misconfigured func %d\n",
+ insn->imm);
+ return -EFAULT;
}
+ insn->imm = fn->func - __bpf_call_base;
}
-}
+ return 0;
+}
static void free_states(struct verifier_env *env)
{
@@ -2309,7 +2303,7 @@ skip_full_check:
ret = convert_ctx_accesses(env);
if (ret == 0)
- fixup_bpf_calls(env->prog);
+ ret = fixup_bpf_calls(env);
if (log_level && log_len >= log_size - 1) {
BUG_ON(log_len >= log_size);