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Diffstat (limited to 'kernel/bpf/btf.c')
-rw-r--r--kernel/bpf/btf.c175
1 files changed, 144 insertions, 31 deletions
diff --git a/kernel/bpf/btf.c b/kernel/bpf/btf.c
index 81d9cf75cacd..832b5d7fd892 100644
--- a/kernel/bpf/btf.c
+++ b/kernel/bpf/btf.c
@@ -2651,8 +2651,8 @@ static s32 btf_func_check_meta(struct btf_verifier_env *env,
return -EINVAL;
}
- if (btf_type_vlen(t)) {
- btf_verifier_log_type(env, t, "vlen != 0");
+ if (btf_type_vlen(t) > BTF_FUNC_GLOBAL) {
+ btf_verifier_log_type(env, t, "Invalid func linkage");
return -EINVAL;
}
@@ -3506,7 +3506,8 @@ static u8 bpf_ctx_convert_map[] = {
static const struct btf_member *
btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
- const struct btf_type *t, enum bpf_prog_type prog_type)
+ const struct btf_type *t, enum bpf_prog_type prog_type,
+ int arg)
{
const struct btf_type *conv_struct;
const struct btf_type *ctx_struct;
@@ -3527,12 +3528,13 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
* is not supported yet.
* BPF_PROG_TYPE_RAW_TRACEPOINT is fine.
*/
- bpf_log(log, "BPF program ctx type is not a struct\n");
+ if (log->level & BPF_LOG_LEVEL)
+ bpf_log(log, "arg#%d type is not a struct\n", arg);
return NULL;
}
tname = btf_name_by_offset(btf, t->name_off);
if (!tname) {
- bpf_log(log, "BPF program ctx struct doesn't have a name\n");
+ bpf_log(log, "arg#%d struct doesn't have a name\n", arg);
return NULL;
}
/* prog_type is valid bpf program type. No need for bounds check. */
@@ -3565,11 +3567,12 @@ btf_get_prog_ctx_type(struct bpf_verifier_log *log, struct btf *btf,
static int btf_translate_to_vmlinux(struct bpf_verifier_log *log,
struct btf *btf,
const struct btf_type *t,
- enum bpf_prog_type prog_type)
+ enum bpf_prog_type prog_type,
+ int arg)
{
const struct btf_member *prog_ctx_type, *kern_ctx_type;
- prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type);
+ prog_ctx_type = btf_get_prog_ctx_type(log, btf, t, prog_type, arg);
if (!prog_ctx_type)
return -ENOENT;
kern_ctx_type = prog_ctx_type + 1;
@@ -3731,7 +3734,7 @@ bool btf_ctx_access(int off, int size, enum bpf_access_type type,
info->reg_type = PTR_TO_BTF_ID;
if (tgt_prog) {
- ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type);
+ ret = btf_translate_to_vmlinux(log, btf, t, tgt_prog->type, arg);
if (ret > 0) {
info->btf_id = ret;
return true;
@@ -4112,11 +4115,16 @@ int btf_distill_func_proto(struct bpf_verifier_log *log,
return 0;
}
-int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
+/* Compare BTF of a function with given bpf_reg_state.
+ * Returns:
+ * EFAULT - there is a verifier bug. Abort verification.
+ * EINVAL - there is a type mismatch or BTF is not available.
+ * 0 - BTF matches with what bpf_reg_state expects.
+ * Only PTR_TO_CTX and SCALAR_VALUE states are recognized.
+ */
+int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog,
+ struct bpf_reg_state *reg)
{
- struct bpf_verifier_state *st = env->cur_state;
- struct bpf_func_state *func = st->frame[st->curframe];
- struct bpf_reg_state *reg = func->regs;
struct bpf_verifier_log *log = &env->log;
struct bpf_prog *prog = env->prog;
struct btf *btf = prog->aux->btf;
@@ -4126,27 +4134,30 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
const char *tname;
if (!prog->aux->func_info)
- return 0;
+ return -EINVAL;
btf_id = prog->aux->func_info[subprog].type_id;
if (!btf_id)
- return 0;
+ return -EFAULT;
if (prog->aux->func_info_aux[subprog].unreliable)
- return 0;
+ return -EINVAL;
t = btf_type_by_id(btf, btf_id);
if (!t || !btf_type_is_func(t)) {
- bpf_log(log, "BTF of subprog %d doesn't point to KIND_FUNC\n",
+ /* These checks were already done by the verifier while loading
+ * struct bpf_func_info
+ */
+ bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
subprog);
- return -EINVAL;
+ return -EFAULT;
}
tname = btf_name_by_offset(btf, t->name_off);
t = btf_type_by_id(btf, t->type);
if (!t || !btf_type_is_func_proto(t)) {
- bpf_log(log, "Invalid type of func %s\n", tname);
- return -EINVAL;
+ bpf_log(log, "Invalid BTF of func %s\n", tname);
+ return -EFAULT;
}
args = (const struct btf_param *)(t + 1);
nargs = btf_type_vlen(t);
@@ -4172,25 +4183,127 @@ int btf_check_func_arg_match(struct bpf_verifier_env *env, int subprog)
bpf_log(log, "R%d is not a pointer\n", i + 1);
goto out;
}
- /* If program is passing PTR_TO_CTX into subprogram
- * check that BTF type matches.
+ /* If function expects ctx type in BTF check that caller
+ * is passing PTR_TO_CTX.
*/
- if (reg[i + 1].type == PTR_TO_CTX &&
- !btf_get_prog_ctx_type(log, btf, t, prog->type))
- goto out;
- /* All other pointers are ok */
- continue;
+ if (btf_get_prog_ctx_type(log, btf, t, prog->type, i)) {
+ if (reg[i + 1].type != PTR_TO_CTX) {
+ bpf_log(log,
+ "arg#%d expected pointer to ctx, but got %s\n",
+ i, btf_kind_str[BTF_INFO_KIND(t->info)]);
+ goto out;
+ }
+ if (check_ctx_reg(env, &reg[i + 1], i + 1))
+ goto out;
+ continue;
+ }
}
- bpf_log(log, "Unrecognized argument type %s\n",
- btf_kind_str[BTF_INFO_KIND(t->info)]);
+ bpf_log(log, "Unrecognized arg#%d type %s\n",
+ i, btf_kind_str[BTF_INFO_KIND(t->info)]);
goto out;
}
return 0;
out:
- /* LLVM optimizations can remove arguments from static functions. */
- bpf_log(log,
- "Type info disagrees with actual arguments due to compiler optimizations\n");
+ /* Compiler optimizations can remove arguments from static functions
+ * or mismatched type can be passed into a global function.
+ * In such cases mark the function as unreliable from BTF point of view.
+ */
prog->aux->func_info_aux[subprog].unreliable = true;
+ return -EINVAL;
+}
+
+/* Convert BTF of a function into bpf_reg_state if possible
+ * Returns:
+ * EFAULT - there is a verifier bug. Abort verification.
+ * EINVAL - cannot convert BTF.
+ * 0 - Successfully converted BTF into bpf_reg_state
+ * (either PTR_TO_CTX or SCALAR_VALUE).
+ */
+int btf_prepare_func_args(struct bpf_verifier_env *env, int subprog,
+ struct bpf_reg_state *reg)
+{
+ struct bpf_verifier_log *log = &env->log;
+ struct bpf_prog *prog = env->prog;
+ struct btf *btf = prog->aux->btf;
+ const struct btf_param *args;
+ const struct btf_type *t;
+ u32 i, nargs, btf_id;
+ const char *tname;
+
+ if (!prog->aux->func_info ||
+ prog->aux->func_info_aux[subprog].linkage != BTF_FUNC_GLOBAL) {
+ bpf_log(log, "Verifier bug\n");
+ return -EFAULT;
+ }
+
+ btf_id = prog->aux->func_info[subprog].type_id;
+ if (!btf_id) {
+ bpf_log(log, "Global functions need valid BTF\n");
+ return -EFAULT;
+ }
+
+ t = btf_type_by_id(btf, btf_id);
+ if (!t || !btf_type_is_func(t)) {
+ /* These checks were already done by the verifier while loading
+ * struct bpf_func_info
+ */
+ bpf_log(log, "BTF of func#%d doesn't point to KIND_FUNC\n",
+ subprog);
+ return -EFAULT;
+ }
+ tname = btf_name_by_offset(btf, t->name_off);
+
+ if (log->level & BPF_LOG_LEVEL)
+ bpf_log(log, "Validating %s() func#%d...\n",
+ tname, subprog);
+
+ if (prog->aux->func_info_aux[subprog].unreliable) {
+ bpf_log(log, "Verifier bug in function %s()\n", tname);
+ return -EFAULT;
+ }
+
+ t = btf_type_by_id(btf, t->type);
+ if (!t || !btf_type_is_func_proto(t)) {
+ bpf_log(log, "Invalid type of function %s()\n", tname);
+ return -EFAULT;
+ }
+ args = (const struct btf_param *)(t + 1);
+ nargs = btf_type_vlen(t);
+ if (nargs > 5) {
+ bpf_log(log, "Global function %s() with %d > 5 args. Buggy compiler.\n",
+ tname, nargs);
+ return -EINVAL;
+ }
+ /* check that function returns int */
+ t = btf_type_by_id(btf, t->type);
+ while (btf_type_is_modifier(t))
+ t = btf_type_by_id(btf, t->type);
+ if (!btf_type_is_int(t) && !btf_type_is_enum(t)) {
+ bpf_log(log,
+ "Global function %s() doesn't return scalar. Only those are supported.\n",
+ tname);
+ return -EINVAL;
+ }
+ /* Convert BTF function arguments into verifier types.
+ * Only PTR_TO_CTX and SCALAR are supported atm.
+ */
+ for (i = 0; i < nargs; i++) {
+ t = btf_type_by_id(btf, args[i].type);
+ while (btf_type_is_modifier(t))
+ t = btf_type_by_id(btf, t->type);
+ if (btf_type_is_int(t) || btf_type_is_enum(t)) {
+ reg[i + 1].type = SCALAR_VALUE;
+ continue;
+ }
+ if (btf_type_is_ptr(t) &&
+ btf_get_prog_ctx_type(log, btf, t, prog->type, i)) {
+ reg[i + 1].type = PTR_TO_CTX;
+ continue;
+ }
+ bpf_log(log, "Arg#%d type %s in %s() is not supported yet.\n",
+ i, btf_kind_str[BTF_INFO_KIND(t->info)], tname);
+ return -EINVAL;
+ }
return 0;
}
Copyright © 1996 – 2023 Jason A. Donenfeld. All Rights Reverse Engineered.