Zero-copy FTP/HTTP Daemon compatible with all POSIX systems
| 1 | /* |
| 2 | * MIT License — Copyright (c) 2026 SeregonWar |
| 3 | * See LICENSE for full text. |
| 4 | */ |
| 5 | |
| 6 | /** |
| 7 | * @file ps5_net_filter.h |
| 8 | * @brief PS5 kernel-level outbound connection filter |
| 9 | * |
| 10 | * PROBLEM AD DRESSED |
| 11 | * ----------------- |
| 12 | * Sony system daemons (ScePatchChecker, PFAuthClient, SceConsoleFeatureFlagChecker, |
| 13 | * SceHidConfigService, SceWorkaroundCtl, RNPS Curl) enter aggressive retry loops |
| 14 | * when DNS blocks their servers. Each failed attempt still generates outgoing |
| 15 | * packets, saturating the bandwidth available to FTP transfers by up to 40%. |
| 16 | * |
| 17 | * ROOT CAUSE |
| 18 | * ---------- |
| 19 | * DNS-level blocking returns NXDOMAIN or timeout, which the daemons treat as a |
| 20 | * *transient* network failure and retry with exponential back-off that saturates |
| 21 | * the wire. The kernel itself never learns that the connection should be rejected. |
| 22 | * |
| 23 | * SOLUTION |
| 24 | * -------- |
| 25 | * Intercept connect(2) at the kernel sysent table level. When a non-zftpd process |
| 26 | * attempts to reach a destination outside the local subnet, return ENETUNREACH |
| 27 | * immediately. The daemon interprets this as a *local* error and either backs off |
| 28 | * aggressively or stops retrying altogether — no packet is ever generated. |
| 29 | * |
| 30 | * |
| 31 | * ARCHITECTURE OVERVIEW |
| 32 | * --------------------- |
| 33 | * |
| 34 | * ┌──────────────────────────────────────────────────────────────┐ |
| 35 | * │ Userland (zftpd) │ |
| 36 | * │ │ |
| 37 | * │ ps5_net_filter_install() │ |
| 38 | * │ │ │ |
| 39 | * │ ├─ [1] Locate sysent[SYS_CONNECT] via firmware table │ |
| 40 | * │ ├─ [2] Save original sy_call pointer │ |
| 41 | * │ ├─ [3] Copy hook_sys_connect() bytes → kernel RWX page │ |
| 42 | * │ └─ [4] kernel_copyin(&hook_addr, &sysent[98].sy_call, 8) │ |
| 43 | * │ │ |
| 44 | * └──────────────────────────────────────────────────────────────┘ |
| 45 | * |
| 46 | * ┌──────────────────────────────────────────────────────────────┐ |
| 47 | * │ Kernel space (PS5 FreeBSD 11) │ |
| 48 | * │ │ |
| 49 | * │ ScePatchChecker calls connect(sock, &sony_addr, len) │ |
| 50 | * │ │ │ |
| 51 | * │ └─► sysent[98].sy_call → hook_sys_connect() │ |
| 52 | * │ │ │ |
| 53 | * │ ├─ td->td_proc->p_pid == zftpd_pid? │ |
| 54 | * │ │ YES → original_connect() (FTP traffic) │ |
| 55 | * │ │ │ |
| 56 | * │ └─ destination in SONY_IP_RANGES? │ |
| 57 | * │ YES → return ENETUNREACH (no packet!) │ |
| 58 | * │ NO → original_connect() │ |
| 59 | * │ │ |
| 60 | * └──────────────────────────────────────────────────────────────┘ |
| 61 | * |
| 62 | * |
| 63 | * USAGE |
| 64 | * ----- |
| 65 | * // After ps5_jailbreak(): |
| 66 | * ps5_net_filter_config_t cfg = PS5_NET_FILTER_CONFIG_DEFAULT; |
| 67 | * int rc = ps5_net_filter_install(&cfg); |
| 68 | * if (rc != 0) { // handle: filter not installed, FTP still works } |
| 69 | * |
| 70 | * // At shutdown: |
| 71 | * ps5_net_filter_uninstall(); |
| 72 | * |
| 73 | * |
| 74 | * SAFETY PROPERTIES |
| 75 | * ----------------- |
| 76 | * - The hook ALWAYS passes through connections from zftpd's own PID. |
| 77 | * - The hook ALWAYS passes through connections to RFC-1918 addresses |
| 78 | * (10.0.0.0/8, 172.16.0.0/12, 192.168.0.0/16) and loopback. |
| 79 | * - The blocklist is a fixed compile-time array; no dynamic allocation |
| 80 | * occurs in kernel context. |
| 81 | * - If the sysent offset table does not contain an entry for the running |
| 82 | * firmware version, install() returns an error and the kernel is NOT |
| 83 | * modified. |
| 84 | * - uninstall() is idempotent. |
| 85 | * |
| 86 | * |
| 87 | * FIRMWARE SUPPORT |
| 88 | * ---------------- |
| 89 | * Supported firmware versions (sysent offsets validated): |
| 90 | * 4.03, 7.00, 7.61, 8.20, 8.60, 9.00, 9.40, 9.60, 10.00, 10.01, 10.50 |
| 91 | * |
| 92 | * Unsupported firmware: install() returns PS5_NET_FILTER_ERR_FW_UNSUPPORTED. |
| 93 | * |
| 94 | * |
| 95 | * THREAD SAFETY |
| 96 | * ------------- |
| 97 | * - install() and uninstall() must be called from the main thread only. |
| 98 | * - Must be called after ps5_jailbreak() and before ftp_server_start(). |
| 99 | * - The installed kernel hook itself is fully re-entrant (no mutable globals |
| 100 | * in the kernel-context code path). |
| 101 | * |
| 102 | * |
| 103 | * @note This module is compiled ONLY when PLATFORM_PS5 is defined. |
| 104 | * On all other platforms the header provides no-op stubs. |
| 105 | * |
| 106 | * @warning Modifies kernel sysent table. Always call uninstall() before |
| 107 | * the payload exits, otherwise the kernel will jump to freed memory. |
| 108 | */ |
| 109 | |
| 110 | #ifndef PS5_NET_FILTER_H |
| 111 | #define PS5_NET_FILTER_H |
| 112 | |
| 113 | /*===========================================================================* |
| 114 | * COMPILE GUARD — PS5 only |
| 115 | *===========================================================================*/ |
| 116 | |
| 117 | #ifdef PLATFORM_PS5 |
| 118 | |
| 119 | #include <stdint.h> |
| 120 | #include <stdatomic.h> |
| 121 | #include <netinet/in.h> |
| 122 | |
| 123 | #ifdef __cplusplus |
| 124 | extern "C" { |
| 125 | #endif |
| 126 | |
| 127 | /*===========================================================================* |
| 128 | * CONSTANTS |
| 129 | *===========================================================================*/ |
| 130 | |
| 131 | /** |
| 132 | * Maximum number of IP subnet rules in the block list. |
| 133 | * |
| 134 | * RATIONALE: Fixed compile-time limit prevents any dynamic allocation |
| 135 | * in the kernel-context hot path. 32 entries covers all known Sony |
| 136 | * CDN and PSN IP ranges with room to spare. |
| 137 | */ |
| 138 | #define PS5_NET_FILTER_MAX_RULES 32U |
| 139 | |
| 140 | /** Maximum length of a daemon name string (including NUL). */ |
| 141 | #define PS5_NET_FILTER_MAX_NAME 24U |
| 142 | |
| 143 | /*===========================================================================* |
| 144 | * ERROR CODES |
| 145 | *===========================================================================*/ |
| 146 | |
| 147 | typedef enum { |
| 148 | PS5_NET_FILTER_OK = 0, /**< Success */ |
| 149 | PS5_NET_FILTER_ERR_INVALID_PARAM = -1, /**< NULL pointer or bad argument */ |
| 150 | PS5_NET_FILTER_ERR_FW_UNSUPPORTED = -2, /**< Firmware version not in table */ |
| 151 | PS5_NET_FILTER_ERR_ALREADY_ACTIVE = -3, /**< install() called twice */ |
| 152 | PS5_NET_FILTER_ERR_NOT_INSTALLED = -4, /**< uninstall() without install() */ |
| 153 | PS5_NET_FILTER_ERR_KMAP_FAILED = -5, /**< Could not map kernel executable page */ |
| 154 | PS5_NET_FILTER_ERR_KWRITE_FAILED = -6, /**< kernel_copyin() failed */ |
| 155 | PS5_NET_FILTER_ERR_FW_DETECT = -7, /**< Could not read firmware version */ |
| 156 | PS5_NET_FILTER_ERR_SYSENT_INVALID = -8, /**< Sysent sanity check failed */ |
| 157 | PS5_NET_FILTER_ERR_EXTERNAL_HOOK = -9, /**< Another payload already hooked sysent */ |
| 158 | } ps5_net_filter_err_t; |
| 159 | |
| 160 | /*===========================================================================* |
| 161 | * IP SUBNET RULE |
| 162 | *===========================================================================*/ |
| 163 | |
| 164 | /** |
| 165 | * An IPv4 subnet to block (network byte order). |
| 166 | * |
| 167 | * A connection is blocked when: |
| 168 | * (dest_addr & mask) == (network & mask) |
| 169 | */ |
| 170 | typedef struct { |
| 171 | uint32_t network; /**< Network address (network byte order) */ |
| 172 | uint32_t mask; /**< Subnet mask (network byte order) */ |
| 173 | } ps5_net_filter_rule_t; |
| 174 | |
| 175 | /*===========================================================================* |
| 176 | * STATISTICS |
| 177 | *===========================================================================*/ |
| 178 | |
| 179 | /** |
| 180 | * Runtime statistics collected by the kernel hook. |
| 181 | * |
| 182 | * @note All fields updated with atomic increments; safe to read at any time. |
| 183 | */ |
| 184 | typedef struct { |
| 185 | uint64_t blocked_total; /**< Total connections blocked */ |
| 186 | uint64_t allowed_self; /**< Connections allowed: zftpd's own PID */ |
| 187 | uint64_t allowed_local; /**< Connections allowed: RFC-1918 / loopback */ |
| 188 | uint64_t allowed_other; /**< Connections allowed: not in block list */ |
| 189 | uint64_t hook_calls_total; /**< Total hook invocations */ |
| 190 | } ps5_net_filter_stats_t; |
| 191 | |
| 192 | /*===========================================================================* |
| 193 | * CONFIGURATION |
| 194 | *===========================================================================*/ |
| 195 | |
| 196 | /** |
| 197 | * Filter configuration passed to ps5_net_filter_install(). |
| 198 | * |
| 199 | * DESIGN: The caller builds the rule table in userland before install(). |
| 200 | * The table is copied into the kernel-accessible hook page alongside the |
| 201 | * hook code itself, avoiding any userland pointer dereferences in kernel |
| 202 | * context. |
| 203 | */ |
| 204 | typedef struct { |
| 205 | /** |
| 206 | * Array of IP subnets to block. |
| 207 | * |
| 208 | * If rule_count == 0, the default Sony IP table is used automatically. |
| 209 | * To disable all blocking (test/debug), set rule_count = 0 and |
| 210 | * use_default_rules = false — install() will still succeed but the |
| 211 | * hook will be a passthrough. |
| 212 | */ |
| 213 | ps5_net_filter_rule_t rules[PS5_NET_FILTER_MAX_RULES]; |
| 214 | |
| 215 | /** Number of valid entries in rules[]. Range [0, PS5_NET_FILTER_MAX_RULES]. */ |
| 216 | uint32_t rule_count; |
| 217 | |
| 218 | /** |
| 219 | * If true and rule_count == 0, fill rules[] with the built-in Sony |
| 220 | * CDN/PSN table before installing. Default: true. |
| 221 | */ |
| 222 | uint8_t use_default_rules; |
| 223 | |
| 224 | /** |
| 225 | * Also hook sendto(2) in addition to connect(2). |
| 226 | * |
| 227 | * Sony's Curl-based daemons (RNPS) use sendto() on UDP sockets for |
| 228 | * some telemetry paths. Enabling this intercepts those as well. |
| 229 | * |
| 230 | * Default: true. |
| 231 | */ |
| 232 | uint8_t hook_sendto; |
| 233 | |
| 234 | /** Reserved for future use. Must be zero-initialised. */ |
| 235 | uint8_t _reserved[2]; |
| 236 | |
| 237 | } ps5_net_filter_config_t; |
| 238 | |
| 239 | /** |
| 240 | * Default configuration initialiser. |
| 241 | * |
| 242 | * Usage: |
| 243 | * ps5_net_filter_config_t cfg = PS5_NET_FILTER_CONFIG_DEFAULT; |
| 244 | * ps5_net_filter_install(&cfg); |
| 245 | */ |
| 246 | #define PS5_NET_FILTER_CONFIG_DEFAULT \ |
| 247 | { .rules = {{0, 0}}, .rule_count = 0U, .use_default_rules = 1, .hook_sendto = 1, ._reserved = {0, 0} } |
| 248 | |
| 249 | /*===========================================================================* |
| 250 | * PUBLIC API |
| 251 | *===========================================================================*/ |
| 252 | |
| 253 | /** |
| 254 | * @brief Install the outbound connection filter into the PS5 kernel. |
| 255 | * |
| 256 | * Steps performed: |
| 257 | * 1. Detect running firmware version. |
| 258 | * 2. Look up sysent[SYS_CONNECT] offset for that firmware. |
| 259 | * 3. Populate cfg->rules[] with default Sony IP table if requested. |
| 260 | * 4. Allocate a kernel-executable page and copy the hook code + rule |
| 261 | * table into it. |
| 262 | * 5. Atomically replace sysent[98].sy_call (and optionally sysent[133]) |
| 263 | * with the address of the installed hook. |
| 264 | * 6. Save our own PID so the hook can fast-path our FTP traffic. |
| 265 | * |
| 266 | * @param[in] cfg Filter configuration. May be NULL to use all defaults. |
| 267 | * |
| 268 | * @return PS5_NET_FILTER_OK on success, negative error code on failure. |
| 269 | * |
| 270 | * @retval PS5_NET_FILTER_OK Hook installed successfully. |
| 271 | * @retval PS5_NET_FILTER_ERR_FW_UNSUPPORTED Firmware not in support table. |
| 272 | * @retval PS5_NET_FILTER_ERR_ALREADY_ACTIVE Called twice without uninstall. |
| 273 | * @retval PS5_NET_FILTER_ERR_KMAP_FAILED Kernel page allocation failed. |
| 274 | * @retval PS5_NET_FILTER_ERR_KWRITE_FAILED kernel_copyin() failed. |
| 275 | * |
| 276 | * @pre ps5_jailbreak() has been called successfully (kernel r/w access). |
| 277 | * @pre Must be called from the main thread. |
| 278 | * @post On success, sysent[98].sy_call points to the installed hook. |
| 279 | * |
| 280 | * @note Thread-safety: NOT thread-safe. Call from main thread only. |
| 281 | * @note The install is reversible: always call ps5_net_filter_uninstall() |
| 282 | * before the payload exits. |
| 283 | * @note Failure is non-fatal: FTP server can start and operate normally; |
| 284 | * bandwidth saturation will continue to occur. |
| 285 | */ |
| 286 | int ps5_net_filter_install(const ps5_net_filter_config_t *cfg); |
| 287 | |
| 288 | /** |
| 289 | * @brief Uninstall the connection filter and restore the original kernel state. |
| 290 | * |
| 291 | * Restores the original sysent[98].sy_call (and sysent[133] if hooked). |
| 292 | * Frees the kernel-executable page. |
| 293 | * |
| 294 | * @return PS5_NET_FILTER_OK on success, negative error code on failure. |
| 295 | * |
| 296 | * @retval PS5_NET_FILTER_OK Hook removed, kernel restored. |
| 297 | * @retval PS5_NET_FILTER_ERR_NOT_INSTALLED install() was never called. |
| 298 | * @retval PS5_NET_FILTER_ERR_KWRITE_FAILED kernel_copyin() failed. |
| 299 | * |
| 300 | * @note Idempotent: safe to call even if install() failed. |
| 301 | * @note Thread-safety: NOT thread-safe. Call from main thread only. |
| 302 | * @note WCET: Two kernel_copyin() calls + one munmap(). Bounded. |
| 303 | */ |
| 304 | int ps5_net_filter_uninstall(void); |
| 305 | |
| 306 | /** |
| 307 | * @brief Check whether the filter is currently installed. |
| 308 | * |
| 309 | * @return 1 if installed and active, 0 otherwise. |
| 310 | * |
| 311 | * @note Thread-safety: Safe (atomic load). |
| 312 | */ |
| 313 | int ps5_net_filter_is_active(void); |
| 314 | |
| 315 | /** |
| 316 | * @brief Read runtime statistics from the filter. |
| 317 | * |
| 318 | * @param[out] out Destination buffer for statistics snapshot. |
| 319 | * |
| 320 | * @return PS5_NET_FILTER_OK on success, PS5_NET_FILTER_ERR_INVALID_PARAM |
| 321 | * if out is NULL. |
| 322 | * |
| 323 | * @pre out != NULL |
| 324 | * @note Thread-safety: Safe (atomic reads, snapshot may be slightly stale). |
| 325 | */ |
| 326 | int ps5_net_filter_get_stats(ps5_net_filter_stats_t *out); |
| 327 | |
| 328 | /** |
| 329 | * @brief Retrieve a human-readable description of an error code. |
| 330 | * |
| 331 | * @param[in] err Error code returned by any ps5_net_filter_* function. |
| 332 | * |
| 333 | * @return Static string describing the error. Never returns NULL. |
| 334 | * |
| 335 | * @note Thread-safety: Safe (read-only static data). |
| 336 | */ |
| 337 | const char *ps5_net_filter_strerror(int err); |
| 338 | |
| 339 | #ifdef __cplusplus |
| 340 | } |
| 341 | #endif |
| 342 | |
| 343 | /*===========================================================================* |
| 344 | * STUB IMPLEMENTATIONS — non-PS5 platforms |
| 345 | *===========================================================================*/ |
| 346 | |
| 347 | #else /* !PLATFORM_PS5 */ |
| 348 | |
| 349 | /* |
| 350 | * Provide no-op stubs so callers can compile on POSIX without ifdefs. |
| 351 | * The compiler will inline and eliminate these entirely at -O2. |
| 352 | */ |
| 353 | typedef struct { int _dummy; } ps5_net_filter_config_t; |
| 354 | typedef struct { int _dummy; } ps5_net_filter_stats_t; |
| 355 | |
| 356 | #define PS5_NET_FILTER_CONFIG_DEFAULT { 0 } |
| 357 | #define PS5_NET_FILTER_OK 0 |
| 358 | |
| 359 | static inline int ps5_net_filter_install(const ps5_net_filter_config_t *cfg) |
| 360 | { (void)cfg; return 0; } |
| 361 | static inline int ps5_net_filter_uninstall(void) { return 0; } |
| 362 | static inline int ps5_net_filter_is_active(void) { return 0; } |
| 363 | static inline int ps5_net_filter_get_stats(ps5_net_filter_stats_t *s) |
| 364 | { (void)s; return 0; } |
| 365 | static inline const char *ps5_net_filter_strerror(int e) |
| 366 | { (void)e; return "not supported on this platform"; } |
| 367 | |
| 368 | #endif /* PLATFORM_PS5 */ |
| 369 | |
| 370 | #endif /* PS5_NET_FILTER_H */ |
| 371 |