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MaxBodySize logged r.URL.Path untruncated at WARN, and routes.go registers it ahead of RequireAuth, so an unauthenticated POST /source/<8 KB>/edit with an oversize declared Content-Length wrote attacker-chosen text of attacker-chosen length into the operator's log, for the cost of a request with no body. The 2,560-byte per-line budget #146 established did not reach it: that budget lives in the access-log field capping and this is a separate slog call. The capping mechanism moves out of internal/middleware into internal/logfield so there is one budget and one implementation rather than a second ad-hoc truncation. Truncate and EncodedBytes are unchanged; the access log now spends logfield.MaxBytes where it spent maxLogFieldBytes. The sweep the issue asked for found five more call sites of the same shape, all reachable unauthenticated, all now capped: the CSRF 403 (also registered ahead of RequireAuth), the rate limiters' 429 (the per-entrypoint receiver limiter is unauthenticated), RequireAuth's own DEBUG line, the unknown-entrypoint DEBUG line on the receiver, and the failed-login DEBUG lines. DEBUG being off by default is not a bound: an operator turning it on to diagnose a flood must not thereby hand the flood an unbounded write. Every other slog call in the tree was read and judged; the PR body lists all of them, including the ones left alone and why. MaxBodySize stays ahead of RequireAuth. An oversize body should be refused before the request buys a cookie decrypt and a session load, and rejecting first is what keeps an unauthenticated flood from choosing how much session work the process does. The ordering and what it costs are now written at the registration, on maxFormBodySize. MaxAccessLogLineBytes is restated as the ceiling on every slog line carrying a client-supplied value, not just the access log's: each of these lines carries strictly fewer client-supplied fields than the access log does, so none can be wider. That is asserted per line under both handlers rather than argued. Two writers are called out as NOT covered, so the figure is not read as more than it is: the log delivery target, which exists to emit the whole event and is deliberate, and GORM's default logger, which prints the interpolated SQL to stdout on a record-not-found and is unbounded on the receiver and login lookups. That second one is a real defect this audit turned up and is filed separately as #178, not fixed here. Tests drive 8 KB of client-chosen text at all six sites, through both handlers internal/logger can install and through each character they escape — including a bare C0 control, which costs six bytes on the line against the one it cost to send and is the case a raw-byte budget breaks on first. Each holds the encoded line to the ceiling, holds the whole flood's output to what that ceiling allows, and asserts the markers at the far end of the input are absent, so a value that merely happened to be short cannot pass. internal/logfield gains a test that measures the per-rune charge against what the handlers really emit over roughly 3,000 code points on each, so an undercharged rune fails a test instead of quietly falsifying the ceiling. Verified by mutation: reverting the MaxBodySize cap alone fails 12 subtests with a 16,583-byte line against the 2,560 ceiling; reverting the other five fails 70; budgeting raw bytes instead of encoded ones fails 23 across three packages.
7.7 KiB
7.7 KiB