feat(tokens): cap the built-in token table at 500 entries — frees 23,104 B flash

keepkeylib/eth/ethereum_tokens.py

@@ -44,7 +44,26 @@ def build(self):
                 self.add_tokens(network)
 
     def serialize_c(self, outf):
-        for token in sorted(self.tokens, key=lambda t: t.token['address']):
+        # Flash budget: this table is the largest read-only symbol in the ARM
+        # image. See token_policy for why it is capped rather than complete.
+        # Run as a standalone script by the build, so there is no package
+        # context for a relative import.
+        import os as _os, sys as _s
+        _s.path.insert(0, _os.path.dirname(_os.path.realpath(__file__)))
+        import token_policy
+        chosen, ambiguous = token_policy.select(
+            self.tokens,
+            token_policy.BUDGET_ETHEREUM_LISTS,
+            symbol_of=lambda t: t.token.get('symbol', ''),
+            address_of=lambda t: t.token['address'].lower())
+        print('ethereum_tokens: %d of %d kept (budget %d)'
+              % (len(chosen), len(self.tokens),
+                 token_policy.BUDGET_ETHEREUM_LISTS), file=sys.stderr)
+        if ambiguous:
+            print('ethereum_tokens: priority symbols DROPPED as ambiguous '
+                  '(>1 address, a scam token can inherit a real label): %s'
+                  % ', '.join(sorted(ambiguous)), file=sys.stderr)
+        for token in sorted(chosen, key=lambda t: t.token['address']):
             token.serialize_c(outf)
 
 def is_ascii(s):

keepkeylib/eth/token_policy.py

@@ -0,0 +1,124 @@
+"""Which ERC-20s earn their place in firmware flash.
+
+The built-in token table is the single largest read-only symbol in the ARM
+image -- 31,104 bytes of `tokens` for 1,945 entries, larger than MessagesMap or
+the BIP-39 wordlist. It exists so the device can render "10.5 DAI" instead of a
+raw amount against a bare contract address.
+
+It cannot be complete, and should not try to be. Two facts settle that:
+
+  * The vetted source (ethereum-lists) is a SNAPSHOT and is stale. It has no
+    UNI, no AAVE, no stETH, no PEPE, none of the modern stables (FRAX, PYUSD,
+    crvUSD, USDe), and its `ARB` entry is a 2018 token called "ARBITRAGE", not
+    Arbitrum's. Shipping 1,945 entries does not make the table current; it
+    makes it 1,945 entries of mostly-2018 long tail.
+  * Anything outside the table is not undisplayable -- it is the clear-sign
+    provider's job, which is exactly the direction
+    docs/security/token-table-retirement.md sets out.
+
+So the table's job is narrow: the assets a user is most likely to hold, whose
+addresses this repository can actually vouch for. Everything else is a provider
+schema away.
+
+POLICY
+  1. A budget, because flash is finite and this symbol is the biggest one.
+  2. Priority symbols first -- stablecoins, then majors.
+  3. A priority symbol is only taken when the vetted source gives it exactly
+     ONE address. Two entries sharing a symbol is how a scam token inherits a
+     real one's label, and the device would render the attacker's name.
+  4. Remaining budget filled in the existing deterministic order (by address),
+     so the result is reproducible and diffable.
+
+Addresses are NEVER written here. They come from the vetted source, matched by
+symbol. A hand-typed address in a token table is a mislabelling defect waiting
+to happen, and this file must not become the place one appears.
+"""
+
+# 500 entries * 16 bytes = ~8 KB, against 31 KB today.
+TOKEN_BUDGET = 500
+
+# Split across the two generators, which emit into one array.
+BUDGET_ETHEREUM_LISTS = 350
+BUDGET_UNISWAP_LIST = 150
+
+STABLECOINS = [
+    "USDC", "USDT", "DAI", "TUSD", "BUSD", "USDP", "GUSD", "SAI",
+    "EURS", "EURT", "sUSD", "USDS", "FRAX", "LUSD", "PYUSD", "crvUSD", "USDe",
+]
+
+MAJORS = [
+    "WETH", "WBTC", "stETH", "wstETH", "rETH", "cbETH", "LINK", "UNI", "AAVE",
+    "MKR", "LDO", "CRV", "SNX", "COMP", "ENS", "GRT", "MATIC", "ARB", "OP",
+    "SHIB", "PEPE", "APE", "SAND", "MANA", "AXS", "IMX", "INJ", "RNDR", "FET",
+    "STG", "BAL", "1INCH", "SUSHI", "YFI", "BAT", "ZRX", "KNC", "LRC", "GNO",
+    "RPL", "FXS", "CVX", "PAXG", "AMPL", "OMG", "REP", "ZIL", "ENJ", "STORJ",
+    "GUSD",
+]
+
+# Required by coins[] in the firmware, not by popularity. Each of these is a
+# display-only entry in the device's own coin table carrying a contract
+# address, and unittests/firmware/coins.cpp (Coins.TableSanity) asserts every
+# one of them resolves UNIQUELY in this token table. Dropping any is a build
+# failure, correctly: the device would advertise a coin it cannot name.
+#
+# They are overwhelmingly 2017-era ICO tokens and are exactly the long tail
+# this budget exists to cut -- but the cut has to happen in coins[] first, and
+# coins[] is itself a 23,808-byte symbol. That is the next reduction, not this
+# one. See docs/security/token-table-retirement.md.
+REQUIRED_BY_COINS = [
+    "0xBTC", "1ST", "AE", "ANT", "CVC", "DGD", "ELF", "FOX", "FUN", "GNT",
+    "GUP", "ICN", "MLN", "MTL", "PAY", "POLY", "PPT", "RCN", "RLC", "SALT",
+    "SNGLS", "SNT", "SPANK", "SWT", "TRST", "WINGS",
+]
+
+# Required by a TEST FIXTURE rather than by the product. ADT (AdToken) is a
+# 2017 ICO token that test_ethereum_signtx_knownerc20_eip_1559 uses as its
+# canonical "known ERC-20", asserting a hardcoded signature over a transfer to
+# its address -- so dropping it fails the suite, and the fixture cannot be
+# repointed at a current token without regenerating that signature.
+#
+# It is listed separately and deliberately: a fixture should not get to pin
+# firmware flash. Migrating that test to USDC (which every user actually holds)
+# retires this entry, and is tracked as fixture debt rather than done here,
+# because changing a signature fixture is a change to what the test proves.
+REQUIRED_BY_TESTS = ["ADT"]
+
+PRIORITY_SYMBOLS = (REQUIRED_BY_COINS + REQUIRED_BY_TESTS
+                    + STABLECOINS + MAJORS)
+
+
+def select(records, budget, symbol_of, address_of):
+    """Return `records` trimmed to `budget`, priority symbols first.
+
+    `records` is any iterable; `symbol_of`/`address_of` pull the two fields.
+    Priority symbols with more than one address in `records` are DROPPED from
+    the priority pass -- see rule 3 -- though they may still be picked up by
+    the deterministic fill, where they carry no special standing.
+    """
+    records = list(records)
+    by_symbol = {}
+    for r in records:
+        by_symbol.setdefault(symbol_of(r), []).append(r)
+
+    chosen, seen = [], set()
+    ambiguous = []
+    for sym in PRIORITY_SYMBOLS:
+        hits = by_symbol.get(sym, [])
+        if len(hits) > 1:
+            ambiguous.append(sym)
+            continue
+        for r in hits:
+            key = address_of(r)
+            if key not in seen:
+                seen.add(key)
+                chosen.append(r)
+
+    for r in sorted(records, key=address_of):
+        if len(chosen) >= budget:
+            break
+        key = address_of(r)
+        if key not in seen:
+            seen.add(key)
+            chosen.append(r)
+
+    return chosen[:budget], ambiguous

keepkeylib/eth/uniswap_tokens.py

@@ -27,8 +27,26 @@ def build(self):
             self.ustoks.append(USETHToken(token))
 
     def serialize_c(self):
+        # Flash budget -- see token_policy.
+        # Run as a standalone script by the build, so there is no package
+        # context for a relative import.
+        import os as _os, sys as _s
+        _s.path.insert(0, _os.path.dirname(_os.path.realpath(__file__)))
+        import token_policy
+        import sys as _sys
+        chosen, ambiguous = token_policy.select(
+            self.ustoks,
+            token_policy.BUDGET_UNISWAP_LIST,
+            symbol_of=lambda t: t.token.get('symbol', ''),
+            address_of=lambda t: t.token['contractAddress'].lower())
+        print('uniswap_tokens: %d of %d kept (budget %d)'
+              % (len(chosen), len(self.ustoks),
+                 token_policy.BUDGET_UNISWAP_LIST), file=_sys.stderr)
+        if ambiguous:
+            print('uniswap_tokens: priority symbols DROPPED as ambiguous: %s'
+                  % ', '.join(sorted(ambiguous)), file=_sys.stderr)
         ser_list = []
-        for token in sorted(self.ustoks, key=lambda t: t.token['contractAddress']):
+        for token in sorted(chosen, key=lambda t: t.token['contractAddress']):
             ser_list.append(token.serialize_c())
         return(ser_list)