{"id":30,"date":"2022-03-25T17:40:16","date_gmt":"2022-03-25T09:40:16","guid":{"rendered":"http:\/\/www.aqwu.net\/wp\/?p=30"},"modified":"2022-04-10T22:01:22","modified_gmt":"2022-04-10T14:01:22","slug":"western-digital-pr4100-nas-%e4%b8%8a%e7%9a%84%e8%bf%9c%e7%a8%8b%e4%bb%a3%e7%a0%81%e6%89%a7%e8%a1%8c-cve-2022-23121","status":"publish","type":"post","link":"https:\/\/www.aqwu.net\/wp\/?p=30","title":{"rendered":"Western Digital PR4100 NAS \u4e0a\u7684\u8fdc\u7a0b\u4ee3\u7801\u6267\u884c (CVE-2022-23121)"},"content":{"rendered":"\n

\u539f\u6587\u94fe\u63a5\uff1ahttps:\/\/research.nccgroup.com\/2022\/03\/24\/remote-code-execution-on-western-digital-pr4100-nas-cve-2022-23121\/<\/a><\/p>\n\n\n\n

\"\"
\u6708\u997c\u6f0f\u6d1e<\/figcaption><\/figure>\n\n\n\n

\u6982\u62ec<\/h1>\n\n\n\n

\u8fd9\u7bc7\u535a\u6587\u63cf\u8ff0\u4e86\u4e00\u4e2a\u672a\u7ecf\u68c0\u67e5\u7684\u8fd4\u56de\u503c\u6f0f\u6d1e\uff0c\u8be5\u6f0f\u6d1e\u7531 NCC \u96c6\u56e2\u5229\u7528\u5f00\u53d1\u5c0f\u7ec4 (EDG) \u7684Alex Plaskett<\/a>\u3001Cedric Halbronn<\/a>\u548cAaron Adams\u4e8e 2021 \u5e74 9 \u6708\u53d1\u73b0\u5e76\u5229\u7528\u3002<\/a>\u6211\u4eec\u5728 2021 \u5e74 11 \u6708\u7684 Pwn2Own 2021 \u7ade\u8d5b\u4e2d\u9488\u5bf9 Western Digital PR4100 \u6210\u529f\u5229\u7528\u4e86\u5b83\u3002Western Digital \u53d1\u5e03\u4e86\u56fa\u4ef6\u66f4\u65b0<\/a>(5.19.117)\uff0c\u5b8c\u5168\u5220\u9664\u4e86\u5bf9\u5f00\u6e90\u7b2c\u4e09\u65b9\u6613\u53d7\u653b\u51fb\u670d\u52a1\u201cDepreciated Netatalk Service\u201d\u7684\u652f\u6301\u3002\u7531\u4e8e\u6b64\u6f0f\u6d1e\u5df2\u5728\u4e0a\u6e38 Netatalk \u4ee3\u7801<\/a>\u4e2d\u5f97\u5230\u89e3\u51b3\uff0c\u56e0\u6b64\u5206\u914d\u4e86 CVE-2022-23121\uff0c\u5e76\u4e0e\u65b0\u7684 Netatalk \u7248\u672c3.1.13<\/a>\u4e00\u8d77\u53d1\u5e03\u4e86 ZDI \u516c\u544a<\/a><\/a>\u5206\u5e03\u5f0f\uff0c\u5b83\u4e0e\u8bb8\u591a\u5176\u4ed6\u6f0f\u6d1e\u4e00\u8d77\u4fee\u590d\u4e86\u6b64\u6f0f\u6d1e\u3002<\/p>\n\n\n\n

\u4ecb\u7ecd<\/h1>\n\n\n\n

\u8be5\u6f0f\u6d1e\u4f4d\u4e8eNetatalk\u9879\u76ee\u4e2d\uff0c\u8be5\u9879\u76ee\u662f<\/a>Apple \u5f52\u6863\u534f\u8bae (AFP)<\/a>\u7684\u5f00\u6e90\u5b9e\u73b0\u3002Netatalk \u4ee3\u7801\u5728\/usr\/sbin\/afpd<\/code>\u670d\u52a1\u548c\/lib64\/libatalk.so<\/code>\u5e93\u4e2d\u5b9e\u73b0\u3002\u8be5afpd<\/code>\u670d\u52a1\u9ed8\u8ba4\u5728Western Digital My Cloud Pro \u7cfb\u5217 PR4100<\/a> NAS \u4e0a\u8fd0\u884c\u3002<\/p>\n\n\n\n

\u8be5\u6f0f\u6d1e\u53ef\u8fdc\u7a0b\u5229\u7528\uff0c\u65e0\u9700\u8eab\u4efd\u9a8c\u8bc1\u3002\u5b83\u5141\u8bb8\u653b\u51fb\u8005\u4ee5nobody<\/code>NAS \u4e0a\u7684\u7528\u6237\u8eab\u4efd\u8fdc\u7a0b\u6267\u884c\u4ee3\u7801\u3002\u6b64\u7528\u6237\u53ef\u4ee5\u8bbf\u95ee\u901a\u5e38\u9700\u8981\u8eab\u4efd\u9a8c\u8bc1\u7684\u79c1\u6709\u5171\u4eab\u3002<\/p>\n\n\n\n

\u6211\u4eec\u5df2\u7ecf\u5206\u6790\u5e76\u5229\u7528\u4e86 5.17.107 \u7248\u672c\u4e0a\u7684\u6f0f\u6d1e\uff0c\u6211\u4eec\u5c06\u5728\u4e0b\u9762\u8be6\u7ec6\u4ecb\u7ecd\uff0c\u4f46\u65e7\u7248\u672c\u4e5f\u53ef\u80fd\u5b58\u5728\u6f0f\u6d1e\u3002<\/p>\n\n\n\n

\u6ce8\u610f\uff1a\u897f\u90e8\u6570\u636e My Cloud Pro \u7cfb\u5217 PR4100 NAS \u57fa\u4e8e x86_64 \u67b6\u6784\u3002<\/p>\n\n\n\n

\u6211\u4eec\u5c06\u6211\u4eec\u7684\u6f0f\u6d1e\u5229\u7528\u547d\u540d\u4e3a\u201cMooncake\u201d\u3002\u8fd9\u662f\u56e0\u4e3a\u6211\u4eec\u5728 2021 \u5e74 9 \u6708 21 \u65e5\u5b8c\u6210\u4e86\u7f16\u5199\u6211\u4eec\u7684\u6f0f\u6d1e\u5229\u7528\u7a0b\u5e8f\uff0c\u8fd9\u6070\u597d\u662f 2021 \u5e74\u4e2d\u79cb\u8282\u53c8\u540d\u6708\u997c\u8282<\/a>\u7684\u65e5\u5b50\u3002<\/p>\n\n\n\n

\u6f0f\u6d1e\u8be6\u60c5<\/h1>\n\n\n\n

\u80cc\u666f<\/h2>\n\n\n\n

DSI \/ AFP \u534f\u8bae<\/h3>\n\n\n\n

Apple \u5f52\u6863\u534f\u8bae (AFP)<\/a>\u662f\u4f17\u6240\u5468\u77e5\u7684\u670d\u52a1\u5668\u6d88\u606f\u5757 (SMB)<\/a>\u534f\u8bae\u7684\u66ff\u4ee3\u65b9\u6848\uff0c\u7528\u4e8e\u901a\u8fc7\u7f51\u7edc\u5171\u4eab\u6587\u4ef6\u3002\u53ef\u4ee5\u5728\u6b64\u5904<\/a>\u627e\u5230 AFP \u89c4\u8303\u3002<\/p>\n\n\n\n

AFP \u901a\u8fc7\u6570\u636e\u6d41\u63a5\u53e3 (DSI)<\/a>\u534f\u8bae\u4f20\u8f93\uff0c\u8be5\u534f\u8bae\u672c\u8eab\u901a\u8fc7 TCP\/IP \u5728 TCP \u7aef\u53e3 548 \u4e0a\u4f20\u8f93\u3002<\/p>\n\n\n\n

\u7136\u800c\uff0cSMB \u4f3c\u4e4e\u8d62\u5f97\u4e86\u6587\u4ef6\u5171\u4eab\u7f51\u7edc\u534f\u8bae\u4e4b\u6218\uff0c\u800c AFP \u9c9c\u4e3a\u4eba\u77e5\uff0c\u5373\u4f7f\u4ecd\u7136\u652f\u6301 NAS \u7b49\u8bbe\u5907\u3002AFP \u534f\u8bae\u5728 OS X 10.9 \u4e2d\u88ab\u5f03\u7528\uff0cAFP \u670d\u52a1\u5668\u5728 OS X 11 \u4e2d\u88ab\u79fb\u9664\u3002<\/p>\n\n\n\n

\u7f51\u804a<\/h3>\n\n\n\n

Netatalk\u9879\u76ee\u662f\u7528\u4e8e<\/a>UNIX \u5e73\u53f0\u7684 AFP\/DSI \u5b9e\u73b0\uff0c\u4e8e 2000 \u5e74\u79fb\u81f3 SourceForge\u3002\u5176\u6700\u521d\u76ee\u7684\u662f\u5141\u8bb8\u7c7b UNIX \u64cd\u4f5c\u7cfb\u7edf\u4f5c\u4e3a\u8bb8\u591a Macintosh\/OS X \u5ba2\u6237\u7aef\u7684 AFP \u670d\u52a1\u5668\u3002<\/p>\n\n\n\n

\u5982\u524d\u6240\u8ff0\uff0c\u6cd5\u65b0\u793e\u7684\u5174\u8da3\u8d8a\u6765\u8d8a\u5c11\u3002\u8fd9\u4e5f\u53cd\u6620\u5728 Netatalk \u9879\u76ee\u4e2d\u3002\u6700\u65b0\u7684 Netatalk\u7a33\u5b9a\u7248\u672c<\/a>(3.1.12) \u4e8e 2018 \u5e74 12 \u6708\u53d1\u5e03\uff0c\u8fd9\u4f7f\u5176\u6210\u4e3a\u4e00\u4e2a\u76f8\u5f53\u5f03\u7528\u4e14\u4e0d\u53d7\u652f\u6301\u7684\u9879\u76ee\u3002<\/p>\n\n\n\n

Netatalk \u9879\u76ee\u5bb9\u6613\u53d7\u5230CVE-2018-1160<\/a>dsi_opensession()<\/code>\u6f0f\u6d1e\u7684\u653b\u51fb\uff0c\u8be5\u6f0f\u6d1e\u662fNetatalk < 3.1.12 \u4e2dDSIOpensession \u547d\u4ee4 ( ) \u4e2d\u7684\u8d8a\u754c\u5199\u5165\u3002\u7531\u4e8e\u6ca1\u6709 ASLR\uff0c\u8fd9\u5728Seagate NAS<\/a>\u4e0a\u88ab\u6210\u529f\u5229\u7528\uff0c\u540e\u6765\u5728\u5e26\u6709 ASLR \u7684\u73af\u5883\u4e2d\u4f5c\u4e3aHitcon 2019 CTF \u6311\u6218<\/a>\u7684\u4e00\u90e8\u5206\u3002<\/p>\n\n\n\n

AppleDouble \u6587\u4ef6\u683c\u5f0f<\/h3>\n\n\n\n

AppleSingle \u548c AppleDouble<\/a>\u6587\u4ef6\u683c\u5f0f\u65e8\u5728\u5b58\u50a8\u5e38\u89c4\u6587\u4ef6\u7684\u5143\u6570\u636e\uff0c\u5e76\u5141\u8bb8\u5728\u4e0d\u540c\u6587\u4ef6\u7cfb\u7edf\u4e4b\u95f4\u5171\u4eab\u8be5\u4fe1\u606f\uff0c\u800c\u4e0d\u5fc5\u62c5\u5fc3\u4e92\u64cd\u4f5c\u6027\u3002<\/p>\n\n\n\n

\u4e3b\u8981\u601d\u60f3\u662f\u57fa\u4e8e\u4efb\u4f55\u6587\u4ef6\u7cfb\u7edf\u90fd\u5141\u8bb8\u5c06\u6587\u4ef6\u5b58\u50a8\u4e3a\u4e00\u7cfb\u5217\u5b57\u8282\u7684\u4e8b\u5b9e\u3002\u56e0\u6b64\uff0c\u5982\u679c\u53e6\u4e00\u7aef\u7684\u6587\u4ef6\u7cfb\u7edf\u652f\u6301\u5b83\u4eec\uff0c\u5219\u53ef\u4ee5\u5c06\u5e38\u89c4\u6587\u4ef6\u7684\u5143\u6570\u636e\uff08\u53c8\u540d\u5c5e\u6027\uff09\u4fdd\u5b58\u5230\u5e38\u89c4\u6587\u4ef6\u4e2d\u7684\u9644\u52a0\u6587\u4ef6\u4e2d\uff0c\u5e76\u5c06\u8fd9\u4e9b\u5c5e\u6027\u53cd\u6620\u56de\u53e6\u4e00\u7aef\uff08\u6216\u81f3\u5c11\u5176\u4e2d\u4e00\u4e9b\uff09\u3002\u5426\u5219\uff0c\u53ef\u4ee5\u4e22\u5f03\u9644\u52a0\u5c5e\u6027\u3002<\/p>\n\n\n\n

AppleSingle \u548c AppleDouble \u89c4\u8303\u53ef\u5728 \u6b64\u5904<\/a>\u627e\u5230\u3002AppleDouble \u6587\u4ef6\u683c\u5f0f\u4e5f\u5728samba \u6e90\u4ee3\u7801<\/a>\u4e2d\u7528\u8fd9\u5f20\u56fe\u89e3\u91ca\uff1a<\/p>\n\n\n\n

\/*\n   \"._\" AppleDouble Header File Layout:\n         MAGIC          0x00051607\n         VERSION        0x00020000\n         FILLER         0\n         COUNT          2\n     .-- AD ENTRY[0]    Finder Info Entry (must be first)\n  .--+-- AD ENTRY[1]    Resource Fork Entry (must be last)\n  |  |   \/\/\/\/\/\/\/\/\/\/\/\/\/\n  |  '-> FINDER INFO    Fixed Size Data (32 Bytes)\n  |      ~~~~~~~~~~~~~  2 Bytes Padding\n  |      EXT ATTR HDR   Fixed Size Data (36 Bytes)\n  |      \/\/\/\/\/\/\/\/\/\/\/\/\/\n  |      ATTR ENTRY[0] --.\n  |      ATTR ENTRY[1] --+--.\n  |      ATTR ENTRY[2] --+--+--.\n  |         ...          |  |  |\n  |      ATTR ENTRY[N] --+--+--+--.\n  |      ATTR DATA 0   <-'  |  |  |\n  |      \/\/\/\/\/\/\/\/\/\/\/\/       |  |  |\n  |      ATTR DATA 1   <----'  |  |\n  |      \/\/\/\/\/\/\/\/\/\/\/\/\/         |  |\n  |      ATTR DATA 2   <-------'  |\n  |      \/\/\/\/\/\/\/\/\/\/\/\/\/            |\n  |         ...                   |\n  |      ATTR DATA N   <----------'\n  |      \/\/\/\/\/\/\/\/\/\/\/\/\/\n  |         ...          Attribute Free Space\n  |\n  '----> RESOURCE FORK\n            ...          Variable Sized Data\n            ...\n*\/<\/code><\/pre>\n\n\n\n
afpd<\/code>\u4e8c\u8fdb\u5236\u6587\u4ef6\u548c\u5e93libatalk.so<\/code>\u6ca1\u6709\u7b26\u53f7\u3002\u4f46\u662f\uff0cWestern Digital \u53d1\u5e03\u4e86\u4ed6\u4eec\u4f7f\u7528\u7684\u57fa\u4e8e Netatalk \u5f00\u6e90\u7684\u5b9e\u73b0\uff0c\u4ee5\u53ca\u7531\u4e8eGNU \u901a\u7528\u516c\u5171\u8bb8\u53ef\u8bc1 (GPL)\u800c\u5728<\/a>\u6b64\u5904<\/a>\u5b9e\u73b0\u7684\u8865\u4e01\u3002\u897f\u90e8\u6570\u636e\u53d1\u5e03\u7684\u6700\u65b0\u6e90\u4ee3\u7801\u5b58\u6863\u662f 5.16.105 \u7248\u672c\uff0c\u4e0e\u5206\u6790\u7684\u6700\u65b0\u7248\u672c (5.17.107) \u4e0d\u5339\u914d\u3002\u4f46\u662f\uff0c\u6211\u4eec\u5df2\u7ecf\u786e\u8ba4\u4e86\u8fd9\u4e00\u70b9\uff0c\u5e76\u4e14\u8fc4\u4eca\u4e3a\u6b62\u4ece\u672a\u5728\u6240\u6709 OS 5 \u7248\u672c\u4e2d\u8fdb\u884c\u8fc7\u4fee\u6539\u3002\u56e0\u6b64\uff0c\u4e0b\u9762\u663e\u793a\u7684\u4ee3\u7801\u901a\u5e38\u662f\u6307 Netatalk \u6e90\u4ee3\u7801\u3002<\/a>afpd<\/code>netatalk.so<\/code><\/p>\n\n\n\n
\u6ce8\u610f\uff1aWestern Digital PR4100 \u4f7f\u7528\u6700\u65b0\u7684 3.1.12 netatalk \u6e90\u4ee3\u7801\u4f5c\u4e3a\u57fa\u7840\u3002<\/p>\n\n\n\n
\u8ba9\u6211\u4eec\u5206\u6790\u4e00\u4e0b netatalk \u4ee3\u7801\u5728\u5904\u7406\u4ee5 AppleDouble \u6587\u4ef6\u683c\u5f0f\u5b58\u50a8\u7684\u6253\u5f00\u5206\u53c9\u6587\u4ef6\u65f6\u5982\u4f55\u63a5\u53d7\u5ba2\u6237\u7aef\u8fde\u63a5\u3001\u89e3\u6790 AFP \u8bf7\u6c42\u4ee5\u5230\u8fbe\u6613\u53d7\u653b\u51fb\u7684\u4ee3\u7801\u3002<\/p>\n\n\n\n
\u5165\u53e3\u70b9\u51fd\u6570\u521d\u59cb\u5316\u5185\u5b58\u4e2d\u7684main()<\/code>\u5927\u91cf\u5bf9\u8c61\uff0c\u52a0\u8f7d AFP \u914d\u7f6e\uff0c\u5e76\u5f00\u59cb\u76d1\u542c AFP \u7aef\u53e3 (TCP 548)\u3002<\/p>\n\n\n\n

\/\/netatalk-3.1.12\/etc\/afpd\/main.c\nint main(int ac, char **av)\n{\n    ...\n    \/* wait for an appleshare connection. parent remains in the loop\n     * while the children get handled by afp_over_{asp,dsi}.  this is\n     * currently vulnerable to a denial-of-service attack if a\n     * connection is made without an actual login attempt being made\n     * afterwards. establishing timeouts for logins is a possible\n     * solution. *\/\n    while (1) {\n        ...\n        for (int i = 0; i < asev->used; i++) {\n            if (asev->fdset[i].revents & (POLLIN | POLLERR | POLLHUP | POLLNVAL)) {\n                switch (asev->data[i].fdtype) {\n\n                case LISTEN_FD:\n                    if ((child = dsi_start(&obj, (DSI *)(asev->data[i].private), server_children))) {\n                        ...\n                    }\n                    break;\n    ...\n```\n<\/pre>\n\n\n\n
\u8be5dsi_start()<\/code>\u51fd\u6570\u57fa\u672c\u4e0a\u8c03\u7528\u4e86 2 \u4e2a\u51fd\u6570\uff1adsi_getsession()<\/code>\u548cafp_over_dsi()<\/code>.<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/etc\/afpd\/main.c\nstatic afp_child_t *dsi_start(AFPObj *obj, DSI *dsi, server_child_t *server_children)\n{\n    afp_child_t *child = NULL;\n\n    if (dsi_getsession(dsi, server_children, obj->options.tickleval, &child) != 0) {\n        LOG(log_error, logtype_afpd, \"dsi_start: session error: %s\", strerror(errno));\n        return NULL;\n    }\n\n    \/* we've forked. *\/\n    if (child == NULL) {\n        configfree(obj, dsi);\n        afp_over_dsi(obj); \/* start a session *\/\n        exit (0);\n    }\n\n    return child;\n}\n<\/pre>\n\n\n\n
\u5bf9\u51fd\u6570\u6307\u9488\u7684dsi_getsession()<\/code>\u8c03\u7528\u662f\uff1adsi->proto_opendsi_tcp_open()<\/code><\/p>\n\n\n\n
\/\/netatalk-3.1.12\/libatalk\/dsi\/dsi_getsess.c\n\/*!\n * Start a DSI session, fork an afpd process\n *\n * @param childp    (w) after fork: parent return pointer to child, child returns NULL\n * @returns             0 on sucess, any other value denotes failure\n *\/\nint dsi_getsession(DSI *dsi, server_child_t *serv_children, int tickleval, afp_child_t **childp)\n{\n  ...\n  switch (pid = dsi->proto_open(dsi)) { \/* in libatalk\/dsi\/dsi_tcp.c *\/\n<\/pre>\n\n\n\n
\u8be5dsi_tcp_open()<\/code>\u51fd\u6570\u63a5\u53d7\u5ba2\u6237\u7aef\u8fde\u63a5\uff0c\u521b\u5efa\u4e00\u4e2a\u5b50\u8fdb\u7a0bfork()<\/code>\u5e76\u5f00\u59cb\u521d\u59cb\u5316\u4e0e\u5ba2\u6237\u7aef\u7684 DSI \u4f1a\u8bdd\u3002<\/p>\n\n\n\n
Teaser\uff1a\u8fd9\u5bf9\u5265\u524a\u5f88\u6709\u7528\u3002<\/p>\n\n\n\n
\/* accept the socket and do a little sanity checking *\/\nstatic pid_t dsi_tcp_open(DSI *dsi)\n{\n    pid_t pid;\n    SOCKLEN_T len;\n\n    len = sizeof(dsi->client);\n    dsi->socket = accept(dsi->serversock, (struct sockaddr *) &dsi->client, &len);\n    ...\n   if (0 == (pid = fork()) ) { \/* child *\/\n        ...\n    }\n\n    \/* send back our pid *\/\n    return pid;\n}<\/pre>\n\n\n\n
\u56de\u5230dsi_getsession()<\/code>\u7236afpd<\/code>\u96c6\uff0c\u800c\u5904\u7406\u5ba2\u6237\u7aef\u8fde\u63a5\u96c6*childp != NULL<\/code>\u7684\u5206\u53c9\u5b50\u96c6afpd*childp == NULL<\/code><\/p>\n\n\n\n
\/\/netatalk-3.1.12\/libatalk\/dsi\/dsi_getsess.c\n\/*!\n * Start a DSI session, fork an afpd process\n *\n * @param childp    (w) after fork: parent return pointer to child, child returns NULL\n * @returns             0 on sucess, any other value denotes failure\n *\/\nint dsi_getsession(DSI *dsi, server_child_t *serv_children, int tickleval, afp_child_t **childp)\n{\n  ...\n  switch (pid = dsi->proto_open(dsi)) { \/* in libatalk\/dsi\/dsi_tcp.c *\/\n  case -1:\n    \/* if we fail, just return. it might work later *\/\n    LOG(log_error, logtype_dsi, \"dsi_getsess: %s\", strerror(errno));\n    return -1;\n\n  case 0: \/* child. mostly handled below. *\/\n    break;\n\n  default: \/* parent *\/\n    \/* using SIGKILL is hokey, but the child might not have\n     * re-established its signal handler for SIGTERM yet. *\/\n    close(ipc_fds[1]);\n    if ((child = server_child_add(serv_children, pid, ipc_fds[0])) ==  NULL) {\n      LOG(log_error, logtype_dsi, \"dsi_getsess: %s\", strerror(errno));\n      close(ipc_fds[0]);\n      dsi->header.dsi_flags = DSIFL_REPLY;\n      dsi->header.dsi_data.dsi_code = htonl(DSIERR_SERVBUSY);\n      dsi_send(dsi);\n      dsi->header.dsi_data.dsi_code = DSIERR_OK;\n      kill(pid, SIGKILL);\n    }\n    dsi->proto_close(dsi);\n    *childp = child;\n    return 0;\n  }\n  ...\n  switch (dsi->header.dsi_command) {\n  ...\n  case DSIFUNC_OPEN: \/* setup session *\/\n    \/* set up the tickle timer *\/\n    dsi->timer.it_interval.tv_sec = dsi->timer.it_value.tv_sec = tickleval;\n    dsi->timer.it_interval.tv_usec = dsi->timer.it_value.tv_usec = 0;\n    dsi_opensession(dsi);\n    *childp = NULL;\n    return 0;\n\n  default: \/* just close *\/\n    LOG(log_info, logtype_dsi, \"DSIUnknown %d\", dsi->header.dsi_command);\n    dsi->proto_close(dsi);\n    exit(EXITERR_CLNT);\n  }\n}<\/pre>\n\n\n\n
\u6211\u4eec\u73b0\u5728\u56de\u5230dsi_start()<\/code>.\u00a0\u5bf9\u4e8e\u7236\u7ea7\uff0c\u6ca1\u6709\u4efb\u4f55\u53cd\u5e94\uff0cmain()<\/code>\u6c38\u8fdc\u5faa\u73af\u7ee7\u7eed\u7b49\u5f85\u5176\u4ed6\u5ba2\u6237\u7aef\u8fde\u63a5\u3002\u5bf9\u4e8e\u5904\u7406\u8fde\u63a5\u7684\u5b69\u5b50\uff0cafp_over_dsi()<\/code>\u88ab\u8c03\u7528\u3002\u8be5\u51fd\u6570\u8bfb\u53d6 AFP \u6570\u636e\u5305\uff08\u5373 DSI \u6709\u6548\u8d1f\u8f7d\uff09\uff0c\u786e\u5b9a AFP \u547d\u4ee4\u5e76\u8c03\u7528afp_switch[]<\/code>\u5168\u5c40\u6570\u7ec4\u5185\u7684\u51fd\u6570\u6307\u9488\u6765\u5904\u7406\u8be5 AFP \u547d\u4ee4\u3002<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/etc\/afpd\/afp_dsi.c\n\/* -------------------------------------------\n afp over dsi. this never returns.\n*\/\nvoid afp_over_dsi(AFPObj *obj)\n{\n    ...\n    \/* get stuck here until the end *\/\n    while (1) {\n        ...\n        \/* Blocking read on the network socket *\/\n        cmd = dsi_stream_receive(dsi);\n        ...\n        switch(cmd) {\n        ...\n        case DSIFUNC_CMD:\n            ...\n                \/* send off an afp command. in a couple cases, we take advantage\n                 * of the fact that we're a stream-based protocol. *\/\n                if (afp_switch[function]) {\n                    dsi->datalen = DSI_DATASIZ;\n                    dsi->flags |= DSI_RUNNING;\n\n                    LOG(log_debug, logtype_afpd, \"<== Start AFP command: %s\", AfpNum2name(function));\n\n                    AFP_AFPFUNC_START(function, (char *)AfpNum2name(function));\n                    err = (*afp_switch[function])(obj,\n                                                  (char *)dsi->commands, dsi->cmdlen,\n                                                  (char *)&dsi->data, &dsi->datalen);<\/pre>\n\n\n\n
afp_switch[]<\/code>\u5168\u5c40\u6570\u7ec4\u521d\u59cb\u5316\u4e3a\u521d\u59cb\u503c\uff0c\u8be5\u503cpreauth_switch<\/code>\u4ec5\u5305\u542b\u51e0\u4e2a\u53ef\u7528\u7684\u9884\u8eab\u4efd\u9a8c\u8bc1\u5904\u7406\u7a0b\u5e8f\u3002postauth_switch<\/code>\u4e00\u65e6\u5ba2\u6237\u7aef\u901a\u8fc7\u8eab\u4efd\u9a8c\u8bc1\uff0c\u6211\u4eec\u53ef\u4ee5\u731c\u6d4b\u5b83\u88ab\u8bbe\u7f6e\u4e3a\u8be5\u503c\u3002\u8fd9\u53ef\u4ee5\u8bbf\u95ee\u8bb8\u591a\u5176\u4ed6 AFP \u529f\u80fd\u3002<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/etc\/afpd\/switch.c\n\/*\n * Routines marked \"NULL\" are not AFP functions.\n * Routines marked \"afp_null\" are AFP functions\n * which are not yet implemented. A fine line...\n *\/\nstatic AFPCmd preauth_switch[] = {\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, NULL,\t\t\t\t\t\/*   0 -   7 *\/\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, NULL,\t\t\t\t\t\/*   8 -  15 *\/\n    NULL, NULL, afp_login, afp_logincont,\n    afp_logout, NULL, NULL, NULL,\t\t\t\t\/*  16 -  23 *\/\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, NULL,\t\t\t\t\t\/*  24 -  31 *\/\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, NULL,\t\t\t\t\t\/*  32 -  39 *\/\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, NULL,\t\t\t\t\t\/*  40 -  47 *\/\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, NULL,\t\t\t\t\t\/*  48 -  55 *\/\n    NULL, NULL, NULL, NULL,\n    NULL, NULL, NULL, afp_login_ext,\t\t\t\t\/*  56 -  63 *\/\n    ...\n};\n\nAFPCmd *afp_switch = preauth_switch;\n\nAFPCmd postauth_switch[] = {\n    NULL, afp_bytelock, afp_closevol, afp_closedir,\n    afp_closefork, afp_copyfile, afp_createdir, afp_createfile,\t\/*   0 -   7 *\/\n    afp_delete, afp_enumerate, afp_flush, afp_flushfork,\n    afp_null, afp_null, afp_getforkparams, afp_getsrvrinfo,\t\/*   8 -  15 *\/\n    afp_getsrvrparms, afp_getvolparams, afp_login, afp_logincont,\n    afp_logout, afp_mapid, afp_mapname, afp_moveandrename,\t\/*  16 -  23 *\/\n    afp_openvol, afp_opendir, afp_openfork, afp_read,\n    afp_rename, afp_setdirparams, afp_setfilparams, afp_setforkparams,\n    \/*  24 -  31 *\/\n    afp_setvolparams, afp_write, afp_getfildirparams, afp_setfildirparams,\n    afp_changepw, afp_getuserinfo, afp_getsrvrmesg, afp_createid, \/*  32 -  39 *\/\n    afp_deleteid, afp_resolveid, afp_exchangefiles, afp_catsearch,\n    afp_null, afp_null, afp_null, afp_null,\t\t\t\/*  40 -  47 *\/\n    afp_opendt, afp_closedt, afp_null, afp_geticon,\n    afp_geticoninfo, afp_addappl, afp_rmvappl, afp_getappl,\t\/*  48 -  55 *\/\n    afp_addcomment, afp_rmvcomment, afp_getcomment, NULL,\n    ...\n};<\/pre>\n\n\n\n
\u6709\u8da3\u7684\u662f\uff0c\u897f\u90e8\u6570\u636e PR4100Public<\/code>\u9ed8\u8ba4\u5177\u6709 AFP \u5171\u4eab\uff0c\u65e0\u9700\u7528\u6237\u8eab\u4efd\u9a8c\u8bc1\u5373\u53ef\u4f7f\u7528\u3002\u8fd9\u610f\u5473\u7740\u53ea\u8981\u6211\u4eec\u4ee5Public<\/code>\u5171\u4eab\u4e3a\u76ee\u6807\uff0c\u6211\u4eec\u5c31\u53ef\u4ee5\u8bbf\u95ee\u6240\u6709\u8fd9\u4e9b\u8eab\u4efd\u9a8c\u8bc1\u540e\u5904\u7406\u7a0b\u5e8f\u3002\u8fd8\u503c\u5f97\u4e00\u63d0\u7684\u662f\uff0c\u76f8\u540c\u7684Public<\/code>\u5171\u4eab\u53ef\u901a\u8fc7\u670d\u52a1\u5668\u6d88\u606f\u5757 (SMB) \u534f\u8bae\u63d0\u4f9b\u7ed9\u6765\u5bbe\u7528\u6237\uff0c\u65e0\u9700\u4efb\u4f55\u5bc6\u7801\u3002\u8fd9\u610f\u5473\u7740\u6211\u4eec\u53ef\u4ee5\u901a\u8fc7 AFP \u6216 SMB \u8bfb\u53d6\/\u521b\u5efa\/\u4fee\u6539\u4efb\u4f55\u6587\u4ef6\uff0c\u53ea\u8981\u5b83\u4eec\u5b58\u50a8\u5728Public<\/code>\u5171\u4eab\u4e2d\u3002<\/p>\n\n\n\n
\u6211\u4eec\u611f\u5174\u8da3\u7684AFP\u547d\u4ee4\u662f\u201cFPOpenFork\u201d\uff0c\u7531afp_openfork()<\/code>handler\u5904\u7406\u3002\u5982\u524d\u6240\u8ff0\uff0cfork \u6587\u4ef6\u662f\u4e00\u79cd\u7279\u6b8a\u7c7b\u578b\u7684\u6587\u4ef6\uff0c\u7528\u4e8e\u5b58\u50a8\u4e0e\u5e38\u89c4\u6587\u4ef6\u5173\u8054\u7684\u5143\u6570\u636e\u3002fork \u6587\u4ef6\u4ee5 AppleDouble \u6587\u4ef6\u683c\u5f0f\u5b58\u50a8\u3002afp_openfork()<\/code>\u5904\u7406\u7a0b\u5e8f\u627e\u5230\u8981\u6253\u5f00\u548c\u8c03\u7528\u7684\u5377\u548c\u5206\u53c9\u6587\u4ef6\u8def\u5f84\uff08ad_open()<\/code>\u201cad\u201d\u4ee3\u8868 AppleDouble\uff09\u3002<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/etc\/afpd\/fork.c\n\/* ----------------------- *\/\nint afp_openfork(AFPObj *obj _U_, char *ibuf, size_t ibuflen _U_, char *rbuf, size_t *rbuflen)\n{\n    ...\n    struct adouble  *adsame = NULL;\n    ...\n    if ((opened = of_findname(vol, s_path))) {\n        adsame = opened->of_ad;\n    }\n    ...\n    if ((ofork = of_alloc(vol, curdir, path, &ofrefnum, eid, adsame, st)) == NULL)\n        return AFPERR_NFILE;\n    ...\n    \/* First ad_open(), opens data or ressource fork *\/\n    if (ad_open(ofork->of_ad, upath, adflags, 0666) < 0) {<\/pre>\n\n\n\n
\u8be5ad_open()<\/code>\u51fd\u6570\u975e\u5e38\u901a\u7528\uff0c\u56e0\u4e3a\u5b83\u53ef\u4ee5\u6253\u5f00\u4e0d\u540c\u7684\u5206\u53c9\u6587\u4ef6\uff1a\u6570\u636e\u5206\u53c9\u6587\u4ef6\u3001\u5143\u6570\u636e\u5206\u53c9\u6587\u4ef6\u6216\u8d44\u6e90\u5206\u53c9\u6587\u4ef6\u3002\u7531\u4e8e\u6211\u4eec\u5728\u8fd9\u91cc\u5904\u7406\u8d44\u6e90\u5206\u53c9\uff0c\u6211\u4eec\u6700\u7ec8\u8c03\u7528ad_open_rf()<\/code>\uff08\u201crf\u201d\u4ee3\u8868\u8d44\u6e90\u5206\u53c9\uff09\u3002<\/p>\n\n\n\n
\u6ce8\u610f\uff1aad_open()<\/code>\u5728libatalk\/<\/code>\u6587\u4ef6\u5939\u4e2d\uff0c\u800c\u4e0d\u662fetc\/afpd<\/code>\u524d\u9762\u8ba8\u8bba\u7684\u4ee3\u7801\u3002\u56e0\u6b64\uff0c\u6211\u4eec\u4ece\u73b0\u5728\u5f00\u59cb\u5206\u6790\u7684\u4ee3\u7801\u5728libatalk.so<\/code>.<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/libatalk\/adouble\/ad_open.c\n\/*!\n * Open data-, metadata(header)- or ressource fork\n *\n * ad_open(struct adouble *ad, const char *path, int adflags, int flags)\n * ad_open(struct adouble *ad, const char *path, int adflags, int flags, mode_t mode)\n *\n * You must call ad_init() before ad_open, usually you'll just call it like this: \\n\n * @code\n *      struct adoube ad;\n *      ad_init(&ad, vol->v_adouble, vol->v_ad_options);\n * @endcode\n *\n * Open a files data fork, metadata fork or ressource fork.\n *\n * @param ad        (rw) pointer to struct adouble\n * @param path      (r)  Path to file or directory\n * @param adflags   (r)  Flags specifying which fork to open, can be or'd:\n *                         ADFLAGS_DF:        open data fork\n *                         ADFLAGS_RF:        open ressource fork\n *                         ADFLAGS_HF:        open header (metadata) file\n *                         ADFLAGS_NOHF:      it's not an error if header file couldn't be opened\n *                         ADFLAGS_NORF:      it's not an error if reso fork couldn't be opened\n *                         ADFLAGS_DIR:       if path is a directory you MUST or ADFLAGS_DIR to adflags\n *\n *                       Access mode for the forks:\n *                         ADFLAGS_RDONLY:    open read only\n *                         ADFLAGS_RDWR:      open read write\n *\n *                       Creation flags:\n *                         ADFLAGS_CREATE:    create if not existing\n *                         ADFLAGS_TRUNC:     truncate\n *\n *                       Special flags:\n *                         ADFLAGS_CHECK_OF:  check for open forks from us and other afpd's\n *                         ADFLAGS_SETSHRMD:  this adouble struct will be used to set sharemode locks.\n *                                            This basically results in the files being opened RW instead of RDONLY.\n * @param mode      (r)  mode used with O_CREATE\n *\n * The open mode flags (rw vs ro) have to take into account all the following requirements:\n * - we remember open fds for files because me must avoid a single close releasing fcntl locks for other\n *   fds of the same file\n *\n * BUGS:\n *\n * * on Solaris (HAVE_EAFD) ADFLAGS_RF doesn't work without\n *   ADFLAGS_HF, because it checks whether ad_meta_fileno() is already\n *   openend. As a workaround pass ADFLAGS_SETSHRMD.\n *\n * @returns 0 on success, any other value indicates an error\n *\/\nint ad_open(struct adouble *ad, const char *path, int adflags, ...)\n{\n    ...\n    if (adflags & ADFLAGS_RF) {\n        if (ad_open_rf(path, adflags, mode, ad) != 0) {\n            EC_FAIL;\n        }\n    }<\/pre>\n\n\n\n
ad_open_rf()<\/code>\u7136\u540e\u8c03\u7528ad_open_rf_ea()<\/code>\uff1a<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/libatalk\/adouble\/ad_open.c\n\/*!\n * Open ressource fork\n *\/\nstatic int ad_open_rf(const char *path, int adflags, int mode, struct adouble *ad)\n{\n    int ret = 0;\n\n    switch (ad->ad_vers) {\n    case AD_VERSION2:\n        ret = ad_open_rf_v2(path, adflags, mode, ad);\n        break;\n    case AD_VERSION_EA:\n        ret = ad_open_rf_ea(path, adflags, mode, ad);\n        break;\n    default:\n        ret = -1;\n        break;\n    }\n\n    return ret;\n}<\/pre>\n\n\n\n
\u8be5ad_open_rf_ea()<\/code>\u51fd\u6570\u6253\u5f00\u8d44\u6e90\u5206\u53c9\u6587\u4ef6\u3002\u5047\u8bbe\u6587\u4ef6\u5df2\u7ecf\u5b58\u5728\uff0c\u5b83\u6700\u7ec8\u8c03\u7528ad_header_read_osx()<\/code>\u6765\u8bfb\u53d6\u5b9e\u9645\u5185\u5bb9\uff0c\u5b83\u662f AppleDouble \u683c\u5f0f\u7684\uff1a<\/p>\n\n\n\n
static int ad_open_rf_ea(const char *path, int adflags, int mode, struct adouble *ad)\n{\n    ...\n\n#ifdef HAVE_EAFD\n    ...\n#else\n    EC_NULL_LOG( rfpath = ad->ad_ops->ad_path(path, adflags) );\n    if ((ad_reso_fileno(ad) = open(rfpath, oflags)) == -1) {\n        ...\n    }\n#endif\n    opened = 1;\n    ad->ad_rfp->adf_refcount = 1;\n    ad->ad_rfp->adf_flags = oflags;\n    ad->ad_reso_refcount++;\n\n#ifndef HAVE_EAFD\n    EC_ZERO_LOG( fstat(ad_reso_fileno(ad), &st) );\n    if (ad->ad_rfp->adf_flags & O_CREAT) {\n        \/* This is a new adouble header file, create it *\/\n        LOG(log_debug, logtype_ad, \"ad_open_rf(\\\"%s\\\"): created adouble rfork, initializing: \\\"%s\\\"\",\n            path, rfpath);\n        EC_NEG1_LOG( new_ad_header(ad, path, NULL, adflags) );\n        LOG(log_debug, logtype_ad, \"ad_open_rf(\\\"%s\\\"): created adouble rfork, flushing: \\\"%s\\\"\",\n            path, rfpath);\n        ad_flush(ad);\n    } else {\n        \/* Read the adouble header *\/\n        LOG(log_debug, logtype_ad, \"ad_open_rf(\\\"%s\\\"): reading adouble rfork: \\\"%s\\\"\",\n            path, rfpath);\n        EC_NEG1_LOG( ad_header_read_osx(rfpath, ad, &st) );\n    }\n#endif<\/pre>\n\n\n\n
\u6211\u4eec\u7ec8\u4e8e\u8fbe\u5230\u4e86\u6211\u4eec\u7684\u6613\u53d7\u653b\u51fb\u7684\u529f\u80fd\uff1aad_header_read_osx()<\/code>.<\/p>\n\n\n\n
\u4e86\u89e3\u6f0f\u6d1e<\/h2>\n\n\n\n
\u8bfb\u53d6\u8d44\u6e90\u5206\u652f\u7684ad_header_read_osx()<\/code>\u5185\u5bb9\uff0c\u5373\u4ee5 AppleDouble \u6587\u4ef6\u683c\u5f0f\u89e3\u91ca\u5b83\u3002Netatalk \u5c06 AppleDouble \u6587\u4ef6\u683c\u5f0f\u7684\u5143\u7d20\u5b58\u50a8\u5728\u5176\u81ea\u5df1\u7684adouble<\/code>\u7ed3\u6784\u4e2d\uff0c\u6211\u4eec\u5c06\u5f88\u5feb\u8be6\u7ec6\u8bf4\u660e\u3002ad_header_read_osx()<\/code>\u9996\u5148\u8bfb\u53d6 AppleDouble \u6807\u5934\u4ee5\u786e\u5b9a\u6709\u591a\u5c11\u6761\u76ee\u3002<\/p>\n\n\n\n
\/\/netatalk-3.1.12\/libatalk\/adouble\/ad_open.c\n\/* Read an ._ file, only uses the resofork, finderinfo is taken from EA *\/\nstatic int ad_header_read_osx(const char *path, struct adouble *ad, const struct stat *hst)\n{\n    ...\n    struct adouble      adosx;\n    ...\n    LOG(log_debug, logtype_ad, \"ad_header_read_osx: %s\", path ? fullpathname(path) : \"\");\n    ad_init_old(&adosx, AD_VERSION_EA, ad->ad_options);\n    buf = &adosx.ad_data[0];\n    memset(buf, 0, sizeof(adosx.ad_data));\n    adosx.ad_rfp->adf_fd = ad_reso_fileno(ad);\n\n    \/* read the header *\/\n    EC_NEG1( header_len = adf_pread(ad->ad_rfp, buf, AD_DATASZ_OSX, 0) );\n    ...\n    memcpy(&adosx.ad_magic, buf, sizeof(adosx.ad_magic));\n    memcpy(&adosx.ad_version, buf + ADEDOFF_VERSION, sizeof(adosx.ad_version));\n    adosx.ad_magic = ntohl(adosx.ad_magic);\n    adosx.ad_version = ntohl(adosx.ad_version);\n    ...\n    memcpy(&nentries, buf + ADEDOFF_NENTRIES, sizeof( nentries ));\n    nentries = ntohs(nentries);\n    len = nentries * AD_ENTRY_LEN;<\/pre>\n\n\n\n
\u7136\u540e\u6211\u4eec\u770b\u5230\u5b83\u8c03\u7528parse_entries()<\/code>\u6765\u89e3\u6790\u4e0d\u540c\u7684 AppleDouble \u6761\u76ee\u3002\u4e0b\u9762\u6709\u8da3\u7684\u662f\uff0c\u5982\u679cparse_entries()<\/code>\u5931\u8d25\uff0c\u5b83\u4f1a\u8bb0\u5f55\u4e00\u4e2a\u9519\u8bef\u4f46\u4e0d\u4f1a\u9000\u51fa\u3002<\/p>\n\n\n\n
    nentries = len \/ AD_ENTRY_LEN; \nif (parse_entries( & adosx, buf, nentries) != 0 ) {         LOG(log_warning, logtype_ad, \"ad_header_read(%s): malformed AppleDouble\" ,             path ? fullpathname(path) : \"\" );     }     \n\n \n<\/pre>\n\n\n\n
\u5982\u679c\u6211\u4eec\u4ed4\u7ec6\u89c2\u5bdfparse_entries()<\/code>\uff0c\u6211\u4eec\u4f1a\u53d1\u73b0\u5982\u679c\u53d1\u751f\u4ee5\u4e0b\u60c5\u51b5\u4e4b\u4e00\uff0c\u5b83\u4f1a\u8bbe\u7f6e\u9519\u8bef\uff1a<\/p>\n\n\n\n