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-rw-r--r--kernel/bpf/core.c145
1 files changed, 104 insertions, 41 deletions
diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
index d315b393abdd..6ef6746a7871 100644
--- a/kernel/bpf/core.c
+++ b/kernel/bpf/core.c
@@ -218,47 +218,84 @@ int bpf_prog_calc_tag(struct bpf_prog *fp)
return 0;
}
-static void bpf_adj_branches(struct bpf_prog *prog, u32 pos, u32 delta)
+static int bpf_adj_delta_to_imm(struct bpf_insn *insn, u32 pos, u32 delta,
+ u32 curr, const bool probe_pass)
{
+ const s64 imm_min = S32_MIN, imm_max = S32_MAX;
+ s64 imm = insn->imm;
+
+ if (curr < pos && curr + imm + 1 > pos)
+ imm += delta;
+ else if (curr > pos + delta && curr + imm + 1 <= pos + delta)
+ imm -= delta;
+ if (imm < imm_min || imm > imm_max)
+ return -ERANGE;
+ if (!probe_pass)
+ insn->imm = imm;
+ return 0;
+}
+
+static int bpf_adj_delta_to_off(struct bpf_insn *insn, u32 pos, u32 delta,
+ u32 curr, const bool probe_pass)
+{
+ const s32 off_min = S16_MIN, off_max = S16_MAX;
+ s32 off = insn->off;
+
+ if (curr < pos && curr + off + 1 > pos)
+ off += delta;
+ else if (curr > pos + delta && curr + off + 1 <= pos + delta)
+ off -= delta;
+ if (off < off_min || off > off_max)
+ return -ERANGE;
+ if (!probe_pass)
+ insn->off = off;
+ return 0;
+}
+
+static int bpf_adj_branches(struct bpf_prog *prog, u32 pos, u32 delta,
+ const bool probe_pass)
+{
+ u32 i, insn_cnt = prog->len + (probe_pass ? delta : 0);
struct bpf_insn *insn = prog->insnsi;
- u32 i, insn_cnt = prog->len;
- bool pseudo_call;
- u8 code;
- int off;
+ int ret = 0;
for (i = 0; i < insn_cnt; i++, insn++) {
+ u8 code;
+
+ /* In the probing pass we still operate on the original,
+ * unpatched image in order to check overflows before we
+ * do any other adjustments. Therefore skip the patchlet.
+ */
+ if (probe_pass && i == pos) {
+ i += delta + 1;
+ insn++;
+ }
code = insn->code;
- if (BPF_CLASS(code) != BPF_JMP)
- continue;
- if (BPF_OP(code) == BPF_EXIT)
+ if (BPF_CLASS(code) != BPF_JMP ||
+ BPF_OP(code) == BPF_EXIT)
continue;
+ /* Adjust offset of jmps if we cross patch boundaries. */
if (BPF_OP(code) == BPF_CALL) {
- if (insn->src_reg == BPF_PSEUDO_CALL)
- pseudo_call = true;
- else
+ if (insn->src_reg != BPF_PSEUDO_CALL)
continue;
+ ret = bpf_adj_delta_to_imm(insn, pos, delta, i,
+ probe_pass);
} else {
- pseudo_call = false;
+ ret = bpf_adj_delta_to_off(insn, pos, delta, i,
+ probe_pass);
}
- off = pseudo_call ? insn->imm : insn->off;
-
- /* Adjust offset of jmps if we cross boundaries. */
- if (i < pos && i + off + 1 > pos)
- off += delta;
- else if (i > pos + delta && i + off + 1 <= pos + delta)
- off -= delta;
-
- if (pseudo_call)
- insn->imm = off;
- else
- insn->off = off;
+ if (ret)
+ break;
}
+
+ return ret;
}
struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
const struct bpf_insn *patch, u32 len)
{
u32 insn_adj_cnt, insn_rest, insn_delta = len - 1;
+ const u32 cnt_max = S16_MAX;
struct bpf_prog *prog_adj;
/* Since our patchlet doesn't expand the image, we're done. */
@@ -269,6 +306,15 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
insn_adj_cnt = prog->len + insn_delta;
+ /* Reject anything that would potentially let the insn->off
+ * target overflow when we have excessive program expansions.
+ * We need to probe here before we do any reallocation where
+ * we afterwards may not fail anymore.
+ */
+ if (insn_adj_cnt > cnt_max &&
+ bpf_adj_branches(prog, off, insn_delta, true))
+ return NULL;
+
/* Several new instructions need to be inserted. Make room
* for them. Likely, there's no need for a new allocation as
* last page could have large enough tailroom.
@@ -294,7 +340,11 @@ struct bpf_prog *bpf_patch_insn_single(struct bpf_prog *prog, u32 off,
sizeof(*patch) * insn_rest);
memcpy(prog_adj->insnsi + off, patch, sizeof(*patch) * len);
- bpf_adj_branches(prog_adj, off, insn_delta);
+ /* We are guaranteed to not fail at this point, otherwise
+ * the ship has sailed to reverse to the original state. An
+ * overflow cannot happen at this point.
+ */
+ BUG_ON(bpf_adj_branches(prog_adj, off, insn_delta, false));
return prog_adj;
}
@@ -1572,13 +1622,32 @@ int bpf_prog_array_length(struct bpf_prog_array __rcu *progs)
return cnt;
}
+static bool bpf_prog_array_copy_core(struct bpf_prog **prog,
+ u32 *prog_ids,
+ u32 request_cnt)
+{
+ int i = 0;
+
+ for (; *prog; prog++) {
+ if (*prog == &dummy_bpf_prog.prog)
+ continue;
+ prog_ids[i] = (*prog)->aux->id;
+ if (++i == request_cnt) {
+ prog++;
+ break;
+ }
+ }
+
+ return !!(*prog);
+}
+
int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
__u32 __user *prog_ids, u32 cnt)
{
struct bpf_prog **prog;
unsigned long err = 0;
- u32 i = 0, *ids;
bool nospc;
+ u32 *ids;
/* users of this function are doing:
* cnt = bpf_prog_array_length();
@@ -1595,16 +1664,7 @@ int bpf_prog_array_copy_to_user(struct bpf_prog_array __rcu *progs,
return -ENOMEM;
rcu_read_lock();
prog = rcu_dereference(progs)->progs;
- for (; *prog; prog++) {
- if (*prog == &dummy_bpf_prog.prog)
- continue;
- ids[i] = (*prog)->aux->id;
- if (++i == cnt) {
- prog++;
- break;
- }
- }
- nospc = !!(*prog);
+ nospc = bpf_prog_array_copy_core(prog, ids, cnt);
rcu_read_unlock();
err = copy_to_user(prog_ids, ids, cnt * sizeof(u32));
kfree(ids);
@@ -1683,22 +1743,25 @@ int bpf_prog_array_copy(struct bpf_prog_array __rcu *old_array,
}
int bpf_prog_array_copy_info(struct bpf_prog_array __rcu *array,
- __u32 __user *prog_ids, u32 request_cnt,
- __u32 __user *prog_cnt)
+ u32 *prog_ids, u32 request_cnt,
+ u32 *prog_cnt)
{
+ struct bpf_prog **prog;
u32 cnt = 0;
if (array)
cnt = bpf_prog_array_length(array);
- if (copy_to_user(prog_cnt, &cnt, sizeof(cnt)))
- return -EFAULT;
+ *prog_cnt = cnt;
/* return early if user requested only program count or nothing to copy */
if (!request_cnt || !cnt)
return 0;
- return bpf_prog_array_copy_to_user(array, prog_ids, request_cnt);
+ /* this function is called under trace/bpf_trace.c: bpf_event_mutex */
+ prog = rcu_dereference_check(array, 1)->progs;
+ return bpf_prog_array_copy_core(prog, prog_ids, request_cnt) ? -ENOSPC
+ : 0;
}
static void bpf_prog_free_deferred(struct work_struct *work)
generated by cgit (git 2.34.1) at 2024-05-17 22:05:53 +0000