{"id":477,"date":"2016-09-15T12:51:49","date_gmt":"2016-09-15T04:51:49","guid":{"rendered":"http:\/\/www.5x44.cn\/?p=477"},"modified":"2016-12-01T15:27:19","modified_gmt":"2016-12-01T07:27:19","slug":"%e7%bb%88%e7%ab%af%e7%99%bb%e9%99%86","status":"publish","type":"post","link":"https:\/\/www.5x44.cn\/?p=477","title":{"rendered":"\u7ec8\u7aef\u767b\u9646"},"content":{"rendered":"<h2>BSD\u7ec8\u7aef\u767b\u9646<\/h2>\n<p>\u5728\u8fc7\u53bb\u768430\u5e74\u4e2d\u8fd9\u4e2a\u8fc7\u7a0b\u4e5f\u6ca1\u6709\u592a\u591a\u7684\u6539\u53d8\u3002\u7cfb\u7edf\u7ba1\u7406\u5458\u521b\u5efa\u4e00\u4e2a\u6587\u4ef6\uff0c\u901a\u5e38\u5e38\u662f<span style=\"color: #993300;\">\/etc\/ttys<\/span>\uff0c\u5b83\u662f\u6bcf\u4e2a\u7ec8\u7aef\u8bbe\u5907\u4e00\u884c\u3002\u6bcf\u884c\u90fd\u6307\u5b9a\u4e86\u8bbe\u5907\u540d\u548c\u4f20\u9012\u7ed9<span style=\"color: #993300;\">getty<\/span>\u7a0b\u5e8f\u7684\u53c2\u6570\u3002\u5176\u4e2d\u4e00\u4e2a\u53c2\u6570\u662f\u6ce2\u7279\u7387\uff0c\u4f8b\u5982\uff1a\u5f53\u4e00\u4e2a\u7cfb\u7edf\u88ab\u5f15\u5bfc\uff0c\u5185\u6838\u5efa\u7acb\u8fdb\u7a0bID1\u2014\u2014<span style=\"color: #993300;\">init<\/span>\u8fdb\u7a0b\uff0c\u8fd9\u4e2a\u8fdb\u7a0b\u53ef\u4ee5\u8ba9\u7cfb\u7edf\u542f\u52a8\u5230\u591a\u7528\u6237\u3002<span style=\"color: #993300;\">init<\/span>\u8fdb\u7a0b\u8bfb\u53d6<span style=\"color: #993300;\">\/etc\/ttys<span style=\"color: #000000;\">\uff0c\u5e76\u4e3a<\/span><\/span>\u6bcf\u4e2a\u5141\u8bb8\u767b\u9646\u7684\u7ec8\u7aef\u8bbe\u5907<span style=\"color: #993300;\">fork<\/span>\u4e00\u4e2a\u5b50\u8fdb\u7a0b\uff0c\u8be5\u5b50\u8fdb\u7a0b\u4f7f\u7528<span style=\"color: #993300;\">exec<\/span>\u8c03\u7528<span style=\"color: #993300;\">getty<\/span>\u51fd\u6570\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-482\" src=\"http:\/\/blog.5x44.cn\/wp-content\/uploads\/2016\/09\/figure-9.1.jpg\" alt=\"figure 9.1\" width=\"571\" height=\"315\" srcset=\"https:\/\/www.5x44.cn\/wp-content\/uploads\/2016\/09\/figure-9.1.jpg 571w, https:\/\/www.5x44.cn\/wp-content\/uploads\/2016\/09\/figure-9.1-300x165.jpg 300w\" sizes=\"auto, (max-width: 571px) 100vw, 571px\" \/><\/p>\n<p>\u5982\u4e0a\u56fe\u6240\u793a\uff0c\u6240\u6709\u7684\u8fdb\u7a0b\u7684\u5b9e\u9645\u7528\u6237ID\u548c\u6709\u6548\u7528\u6237ID\u90fd\u662f0\uff08\u4e5f\u5c31\u662f\u8bf4\u5b83\u4eec\u90fd\u62e5\u6709\u8d85\u7ea7\u7528\u6237\u7684\u6743\u9650\uff09\u3002<span style=\"color: #993300;\">init<\/span>\u8fdb\u7a0b<span style=\"color: #993300;\">exec<\/span>\u8c03\u7528<span style=\"color: #993300;\">getty<\/span>\u7a0b\u5e8f\u65f6\uff0c\u4f7f\u7528\u7a7a\u7684\u73af\u5883\u53d8\u91cf\u3002<\/p>\n<p><span style=\"color: #993300;\">getty<\/span>\u51fd\u6570\u4e3a\u7ec8\u7aef\u8bbe\u5907\u8c03\u7528<span style=\"color: #993300;\">open<\/span>\u51fd\u6570\u3002\u7ec8\u7aef\u4ee5\u8bfb\u3001\u5199\u7684\u65b9\u5f0f\u6253\u5f00\u3002\u5982\u679c\u8bbe\u5907\u662fmodem\uff0c<span style=\"color: #993300;\">open<\/span>\u51fd\u6570\u53ef\u4ee5\u5ef6\u8fdf\u8bbe\u5907\u9a71\u52a8\u76f4\u5230\u62e8\u53f7\u6216\u88ab\u54cd\u5e94\u3002\u8bbe\u5907\u4e00\u7ecf\u6253\u5f00\uff0c\u6587\u4ef6\u63cf\u8ff0\u7b260\u30011\u30012\u5c31\u4f1a\u88ab\u8bbe\u7f6e\u5230\u8bbe\u5907\u4e0a\u3002\u4e4b\u540egetty\u4f1a\u6709\u4e00\u4e9b\u8f93\u51fa\uff08\u5982\uff1alogin:\uff0c\u7b49\u5f85\u6211\u4eec\u8f93\u5165\u7528\u6237\u540d\uff09\u3002\u5982\u679c\u8bbe\u5907\u652f\u6301\u591a\u79cd\u901f\u5ea6\uff0c<span style=\"color: #993300;\">getty<\/span>\u80fd\u53d1\u73b0\u7279\u6b8a\u5b57\u7b26\uff0c\u8fd9\u4e9b\u7279\u6b8a\u5b57\u7b26\u53ef\u4ee5\u6539\u53d8\u7ec8\u7aef\u901f\u5ea6\uff08\u6ce2\u7279\u7387\uff09\u3002\u5bf9\u4e8e<span style=\"color: #993300;\">getty<\/span>\u7a0b\u5e8f\u548c\u6570\u636e\u6587\u4ef6\uff08<span style=\"color: #993300;\">gettytab<\/span>\uff09\u53ef\u4ee5\u67e5\u770b\u7cfb\u7edf\u624b\u518c\uff0c\u5b83\u4eec\u51b3\u5b9a\u4e86\u5177\u4f53\u7684\u52a8\u4f5c\u3002<\/p>\n<p>\u5f53\u6211\u4eec\u8f93\u5165\u5b8c\u7528\u6237\u540d\u540e<span style=\"color: #993300;\">getty<\/span>\u7684\u5de5\u4f5c\u5c31\u5b8c\u6210\u4e86\uff0c\u4e4b\u540e\u5b83\u4f1a\u8c03\u7528<span style=\"color: #993300;\">login<\/span>\u7a0b\u5e8f\uff0c\u7c7b\u4f3c\uff1a<\/p>\n<p><span style=\"color: #993300;\">execle(&#8220;\/bin\/login&#8221;, &#8220;login&#8221;, &#8220;-p&#8221;, username, (char *)0, envp);<\/span><\/p>\n<p>\uff08\u5728gettytab\u6587\u4ef6\u4e2d\u6709\u9009\u9879\uff0c\u53ef\u4ee5\u8ba9\u5b83\u8c03\u7528\u5176\u5b83\u7a0b\u5e8f\uff0c\u4f46\u9ed8\u8ba4\u662f<span style=\"color: #993300;\">login<\/span>\u7a0b\u5e8f\u3002\uff09<span style=\"color: #993300;\">init<\/span>\u7a0b\u5e8f\u5e26\u4e00\u4e2a\u7a7a\u73af\u5883\u53d8\u91cf\u8c03\u7528<span style=\"color: #993300;\">getty<\/span>\uff1b<span style=\"color: #993300;\">getty<\/span>\u4e3a<span style=\"color: #993300;\">login<\/span>\u5efa\u7acb\u4e00\u4e2a\u73af\u5883\u53d8\u91cf\uff08<span style=\"color: #993300;\">envp<\/span>\u53c2\u6570\uff09\uff0c\u5305\u542b\u7ec8\u7aef\u540d\uff08\u4e00\u4e9b\u7c7b\u4f3c<span style=\"color: #993300;\">TERM=foo<\/span>\uff0c\u8fd9\u91cc\u7684\u7ec8\u7aef\u7c7b\u578b<span style=\"color: #993300;\">foo<\/span>\u662f\u6765\u81ea<span style=\"color: #993300;\">gettytab<\/span>\u6587\u4ef6\uff09\u548c\u4efb\u4f55\u5728<span style=\"color: #993300;\">gettytab<\/span>\u4e2d\u6307\u5b9a\u7684\u73af\u5883\u5b57\u7b26\u4e32\u3002login\u4e2d\u7684-p\u6807\u8bb0\u662f\u7528\u6765\u544a\u8bc9\u7a0b\u5e8f\u4fdd\u6301\u4f20\u9012\u8fc7\u6765\u73af\u5883\u53d8\u91cf\u5e76\u5411\u5176\u589e\u52a0\u5176\u5b83\u53d8\u91cf\uff0c\u800c\u4e0d\u662f\u66ff\u4ee3\u5b83\u3002<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-487\" src=\"http:\/\/blog.5x44.cn\/wp-content\/uploads\/2016\/09\/figure9.2.png\" alt=\"figure9.2\" width=\"534\" height=\"347\" srcset=\"https:\/\/www.5x44.cn\/wp-content\/uploads\/2016\/09\/figure9.2.png 534w, https:\/\/www.5x44.cn\/wp-content\/uploads\/2016\/09\/figure9.2-300x195.png 300w\" sizes=\"auto, (max-width: 534px) 100vw, 534px\" \/><\/p>\n<p>\u4e0a\u56fe\u663e\u793a\u4e86\u6240\u6709\u7684\u8fc7\u7a0b\uff0c\u56e0\u4e3a<span style=\"color: #993300;\">init<\/span>\u8fdb\u7a0b\u662f\u8d85\u7ea7\u7528\u6237\u6743\u9650\uff0c\u6240\u4ee5\u4e0a\u56fe\u6240\u793a\u662f\u6709\u8d85\u7ea7\u7528\u6237\u6743\u9650\u7684\u3002\u4e0b\u9762\u4e09\u4e2a\u8fdb\u7a0b\u540c\u6837\u662f\u6709\u8d85\u7ea7\u7528\u6237\u6743\u9650\u7684\uff0c\u56e0\u4e3a<span style=\"color: #993300;\">exec<\/span>\u4e0d\u4f1a\u6539\u53d8\u8fdb\u7a0bID\u3002\u6240\u4ee5\uff0c\u9664\u4e86\u6700\u521d\u7684<span style=\"color: #993300;\">init<\/span>\u8fdb\u7a0b\u5916\u6240\u6709\u5176\u5b83\u8fdb\u7a0b\u7684\u7236\u8fdb\u7a0bID\u90fd\u662f1\u3002<\/p>\n<p><span style=\"color: #993300;\">login<\/span>\u7a0b\u5e8f\u505a\u4e86\u5f88\u591a\u7684\u4e8b\u60c5\u3002\u56e0\u4e3a\u5b83\u6709\u6211\u4eec\u7684\u7528\u6237\u540d\uff0c\u5b83\u80fd\u8c03\u7528<span style=\"color: #993300;\">getpwnam<\/span>\u83b7\u5f97\u5bc6\u7801\u6587\u4ef6\u7684\u6761\u76ee\u3002\u4e4b\u540e<span style=\"color: #993300;\">login<\/span>\u8c03\u7528<span style=\"color: #993300;\">getpass<\/span>\u663e\u793a\u63d0\u793aPASSWORD:\u5e76\u8bfb\u53d6\u5bc6\u7801\u3002\u5b83\u8c03\u7528<span style=\"color: #993300;\">crypt<\/span>\u53bb\u52a0\u5bc6\u521a\u8f93\u5165\u7684\u5bc6\u7801\u5e76\u548cshadow\u5bc6\u7801\u6587\u4ef6\u4e2d\u7684<span style=\"color: #993300;\">pw_passwd<\/span>\u5b57\u6bb5\u505a\u6bd4\u8f83\u3002\u5982\u679c\u7531\u4e8e\u5bc6\u7801\u65e0\u6548\u800c\u5931\u8d25<span style=\"color: #993300;\">login<\/span>\u8c03\u7528\u53c2\u6570\u4e3a1\u7684<span style=\"color: #993300;\">exit<\/span>\u51fd\u6570\u3002\u5f53\u7ec8\u7aef\u7684\u7236\u8fdb\u7a0b\u5f97\u77e5\u8fd9\u4e2a\u60c5\u51b5\u540e\u4f1a\u518d\u6b21<span style=\"color: #993300;\">fork<\/span>\u53e6\u4e00\u4e2a<span style=\"color: #993300;\">exec<\/span>\u7684<span style=\"color: #993300;\">getty<\/span>\uff0c\u91cd\u65b0\u5f00\u59cb\u8fd9\u4e2a\u7ec8\u7aef\u3002<\/p>\n<p>\u73b0\u5728\u4e3b\u6d41UNIX\u7cfb\u7edf\u90fd\u5728\u4f7f\u7528PAM\u3002\u5728\u8bbf\u95ee\u76f8\u5e94\u7684\u670d\u52a1\u65f6\uff0cPAM\u5141\u8bb8\u7ba1\u7406\u5458\u914d\u7f6e\u4e0d\u540c\u7684\u6388\u6743\u65b9\u5f0f\u3002<\/p>\n<p>\u5982\u679c\u767b\u5f55\u6210\u529f\uff0c<span style=\"color: #993300;\">login<\/span>\u4f1a\uff1a<\/p>\n<ul>\n<li>\u6539\u53d8\u6211\u4eec\u7684home\u76ee\u5f55\uff08<span style=\"color: #993300;\">chdir<\/span>\uff09<\/li>\n<li>\u6539\u53d8\u6211\u4eec\u7684\u7ec8\u7aef\u8bbe\u5907\u6240\u5c5e\uff08<span style=\"color: #993300;\">chown<\/span>\uff09\uff0c\u8fd9\u65f6\u767b\u5f55\u7528\u6237\u62e5\u6709\u5b83\u3002<\/li>\n<li>\u6539\u53d8\u7ec8\u7aef\u8bbe\u5907\u7684\u8bbf\u95ee\u6743\u9650\uff0c\u8ba9\u6211\u4eec\u53ef\u4ee5\u5bf9\u5176\u8fdb\u884c\u8bfb\u5199\u3002<\/li>\n<li>\u901a\u8fc7\u8c03\u7528<span style=\"color: #993300;\">setgid<\/span>\u548c<span style=\"color: #993300;\">initgroups<\/span>\u8bbe\u7f6e\u6211\u4eec\u7684\u7ec4ID<\/li>\n<li>\u4f7f\u7528\u6240\u6709login\u83b7\u5f97\u7684\u4fe1\u606f\u521d\u59cb\u5316\u73af\u5883\u53d8\u91cf\uff0chome\u76ee\u5f55\uff08<span style=\"color: #993300;\">HOME<\/span>\uff09\uff0cshell\uff08<span style=\"color: #993300;\">SHELL<\/span>\uff09\uff0c\u7528\u6237\u540d\uff08<span style=\"color: #993300;\">USER<\/span>\u548c<span style=\"color: #993300;\">LOGNAME<\/span>\uff09\u548c\u9ed8\u8ba4\u76ee\u5f55\uff08<span style=\"color: #993300;\">PATH<\/span>\uff09<\/li>\n<li>\u6539\u53d8\u7528\u6237ID\uff08<span style=\"color: #993300;\">setuid<\/span>\uff09\u5e76\u8c03\u7528\u6211\u4eec\u7684\u767b\u5f55shell\uff0c\u5982\uff1a<br \/>\n<span style=\"color: #993300;\">execl(&#8220;\/bin\/sh&#8221;, &#8220;-sh&#8221;, (char *)0);<\/span><br \/>\n\u51cf\u53f7\u505a\u4e3aargv[0]\u7684\u7b2c\u4e00\u5b57\u7b26\uff0c\u662f\u7528\u6765\u6807\u8bb0\u8c03\u7528\u7684shell\u662f\u505a\u4e3a\u767b\u5f55shell\u4f7f\u7528\u3002shell\u53ef\u4ee5\u6839\u636e\u8fd9\u4e2a\u5b57\u7b26\u6539\u53d8\u5b83\u7684\u542f\u52a8\u8fc7\u7a0b\u3002<\/li>\n<\/ul>\n<p>login\u5b9e\u9645\u505a\u7684\u8981\u6bd4\u8fd9\u4e2a\u63cf\u8ff0\u8fd8\u8981\u591a\u3002<\/p>\n<p>\u4e3a\u7ec8\u7aef\u767b\u5f55\u8bbe\u7f6e\u6240\u6709\u4e8b\u60c5\u7684\u8fc7\u7a0b\u5982\u4e0b\uff1a<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"aligncenter size-full wp-image-489\" src=\"http:\/\/blog.5x44.cn\/wp-content\/uploads\/2016\/09\/figure9.3.png\" alt=\"figure9.3\" width=\"717\" height=\"394\" srcset=\"https:\/\/www.5x44.cn\/wp-content\/uploads\/2016\/09\/figure9.3.png 717w, https:\/\/www.5x44.cn\/wp-content\/uploads\/2016\/09\/figure9.3-300x165.png 300w\" sizes=\"auto, (max-width: 717px) 100vw, 717px\" \/><\/p>\n<p>\u73b0\u5728\u6211\u4eec\u767b\u5f55\u7684shell\u4f1a\u8bfb\u53d6\u5b83\u7684\u542f\u52a8\u6587\u4ef6\uff08<span style=\"color: #993300;\">.profile<\/span>\u662fBourne shell\u548cKorn shell\u7684\u542f\u52a8\u6587\u4ef6\uff1b<span style=\"color: #993300;\">.bash_profile<\/span>,<span style=\"color: #993300;\"> .bash_login<\/span>, <span style=\"color: #993300;\">.profile<\/span>\u662fGNU Bourne-again shell\u7684\u542f\u52a8\u6587\u4ef6\uff1b<span style=\"color: #993300;\">.cshrc<\/span>\u548c<span style=\"color: #993300;\">.login<\/span>\u662fC shell\u7684\u542f\u52a8\u6587\u4ef6\uff09\u8fd9\u4e9b\u542f\u52a8\u6587\u4ef6\u901a\u5e38\u4f1a\u6539\u53d8\u4e00\u4e9b\u73af\u5883\u53d8\u91cf\u5e76\u6dfb\u52a0\u5f88\u591a\u73af\u5883\u53d8\u91cf\u3002\u4f8b\u5982\u5f88\u591a\u7528\u6237\u4f1a\u8bbe\u7f6e\u4ed6\u4eec\u7684<span style=\"color: #993300;\">PATH<\/span>\u548c\u5b9e\u9645\u7ec8\u7aef\u7c7b\u578b\uff08<span style=\"color: #993300;\">TERM<\/span>\uff09\u7684\u63d0\u793a\u7b26\u3002\u5f53\u542f\u52a8\u6587\u4ef6\u7ed3\u675f\u540e\uff0c\u6211\u4eec\u4f1a\u770b\u5230shell\u7684\u63d0\u793a\u7b26\u5e76\u4e14\u53ef\u4ee5\u8f93\u5165\u547d\u4ee4\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>BSD\u7ec8\u7aef\u767b\u9646 \u5728\u8fc7\u53bb\u768430\u5e74\u4e2d\u8fd9\u4e2a\u8fc7\u7a0b\u4e5f\u6ca1\u6709\u592a\u591a\u7684\u6539\u53d8\u3002\u7cfb\u7edf\u7ba1\u7406\u5458\u521b\u5efa\u4e00\u4e2a\u6587\u4ef6\uff0c\u901a\u5e38\u5e38\u662f\/etc\/ttys\uff0c\u5b83\u662f\u6bcf\u4e2a\u7ec8\u7aef\u8bbe\u5907\u4e00\u884c\u3002\u6bcf\u884c\u90fd\u6307\u5b9a\u4e86\u8bbe\u5907\u540d\u548c\u4f20\u9012\u7ed9g&#8230;<\/p>\n<p class=\"read-more\"><a class=\"btn btn-default\" href=\"https:\/\/www.5x44.cn\/?p=477\"> Read More<span class=\"screen-reader-text\">  Read More<\/span><\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[18],"tags":[],"class_list":["post-477","post","type-post","status-publish","format-standard","hentry","category-apue"],"_links":{"self":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/477","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=477"}],"version-history":[{"count":16,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/477\/revisions"}],"predecessor-version":[{"id":496,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=\/wp\/v2\/posts\/477\/revisions\/496"}],"wp:attachment":[{"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=477"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=477"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.5x44.cn\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=477"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}