{"id":107119,"date":"2023-03-06T12:48:15","date_gmt":"2023-03-06T10:48:15","guid":{"rendered":"https:\/\/prohoster.info\/?p=107119"},"modified":"2023-03-06T16:13:41","modified_gmt":"2023-03-06T14:13:41","slug":"dlya-izbavleniya-glibc-ot-problemy-2038-goda-predlozheno-prekratit-ispolzovanie-utmp","status":"publish","type":"post","link":"https:\/\/prohoster.info\/ro\/blog\/news\/dlya-izbavleniya-glibc-ot-problemy-2038-goda-predlozheno-prekratit-ispolzovanie-utmp","title":{"rendered":"Pentru a elimina problema din Glibc \u00een 2038, se propune renun\u021barea la utilizarea utmp","gt_translate_keys":[{"key":"rendered","format":"text"}]},"content":{"rendered":"

Thorsten Kukuk, liderul echipei de dezvoltare a tehnologiilor viitoare la SUSE (Future Technology Team, care dezvolt\u0103 openSUSE MicroOS \u0219i SLE Micro), care a condus anterior timp de 10 ani proiectul SUSE LINUX Enterprise Server, a propus eliminarea fi\u0219ierului \/var\/run\/utmp din distribu\u021bii pentru a rezolva complet problema anului 2038 \u00een Glibc. Toate aplica\u021biile care folosesc utmp, wtmp \u0219i lastlog sunt sugerate s\u0103 fie migrate la ob\u021binerea listei utilizatorilor prin systemd-logind. <\/p>\n

Pe 19 ianuarie 2038, va avea loc o dep\u0103\u0219ire a contorilor de timp epoch seta\u021bi de tipul 32-bit time_t. \u00cen biblioteca Glibc, \u00een ciuda implement\u0103rii tipului 64-bit time_t, pentru a men\u021bine compatibilitatea cu aplica\u021biile de 32-bit, \u00een anumite cazuri, pe platformele de 64-bit, se continu\u0103 utilizarea tipului 32-bit time_t. Un astfel de caz este fi\u0219ierul \/var\/run\/utmp, care stocheaz\u0103 date despre utilizatorii care sunt \u00een prezent conecta\u021bi la sistem. C\u00e2mpul de timp \u00een utmp este setat folosind o valoare time_t de 32 de bi\u021bi. <\/p>\n

Pur \u0219i simplu \u00eenlocuirea c\u00e2mpului de timp \u00een utmp de la tipul de 32 de bi\u021bi la cel de 64 de bi\u021bi nu va fi posibil\u0103, deoarece aceasta va conduce la modificarea ABI Glibc (se va schimba tipul \u00een func\u021bii precum login(), getutid() \u0219i utmpname()) \u0219i va duce la incompatibilit\u0103\u021bi cu aplica\u021biile care folosesc utmp, inclusiv w, who, uptime, login, su, sudo, useradd, systemd, sysvinit, tcsh, managerii de display xterm, emacs, openssh, qemu, samba, rsyslog \u0219i altele. Din cauza abunden\u021bei de capcane posibile \u0219i a complexit\u0103\u021bii, ideea de a schimba tipul time_t \u00een utmp a fost respins\u0103 de dezvoltatorii Glibc. Din acelea\u0219i motive, a fost abandonat\u0103 \u0219i op\u021biunea de a utiliza spa\u021biul liber existent \u00een structura utmp pentru a ad\u0103uga un c\u00e2mp suplimentar de 64 de bi\u021bi pentru timp. <\/p>\n

\u00cen plus, modificarea dimensiunii tipului \u00een utmp nu rezolv\u0103 alte probleme existente de care ne-am dori s\u0103 sc\u0103p\u0103m. De exemplu, pentru a scrie \u00een utmp sunt necesare privilegii speciale, ceea ce necesit\u0103 acordarea de privilegii suplimentare proceselor. O alt\u0103 problem\u0103 este legat\u0103 de arhitectura utmp, care permite utilizatorilor locali s\u0103 efectueze atacuri DoS, afect\u00e2nd func\u021bionarea serviciului utmp prin manipularea bloc\u0103rilor de fi\u0219iere, astfel \u00eenc\u00e2t nu poate fi garantat c\u0103 con\u021binutul utmp reflect\u0103 starea real\u0103 a sistemului. S-a propus utilizarea unui proces de fundal suplimentar pentru a gestiona accesul la utmp, dar pentru astfel de sarcini exist\u0103 deja procesul systemd-logind \u0219i lansarea unui alt proces specializat nu este ra\u021bional\u0103 (aplica\u021biile vor trebui s\u0103 transmit\u0103 date simultan la doi procesatori). <\/p>\n

Chiar \u0219i \u00een cazul rezolv\u0103rii problemei cu atacurile DoS, con\u021binutul utmp r\u0103m\u00e2ne doar informativ, f\u0103r\u0103 a garanta o reflec\u021bie a realit\u0103\u021bii. De exemplu, diferite emulatori \u0219i multiplexoare de terminale \u00ee\u0219i reflect\u0103 starea diferit \u2014 lansarea a cinci terminale GNOME va duce la o reflectare \u00een utmp a unui utilizator, \u00een timp ce lansarea a cinci terminale konsole sau xterm \u00een KDE va conduce la \u0219ase. Comportamentul lui screen \u0219i tmux difer\u0103 de asemenea; \u00een primul caz, fiecare sesiune este considerat\u0103 ca un utilizator distinct, \u00een timp ce \u00een al doilea, este reflectat doar un singur utilizator pentru toate sesiunile. <\/p>\n

\u00cen concluzie, ca cea mai simpl\u0103 solu\u021bie, se propune trecerea tuturor aplica\u021biilor la utilizarea deja existentului serviciu alternativ systemd-logind \u0219i, dup\u0103 ce nu vor mai exista programe relevante care acceseaz\u0103 utmp, s\u0103 se opreasc\u0103 \u00eenregistrarea \u00een utmp. Pentru a \u00eenlocui wtmp, se propune preg\u0103tirea interfe\u021belor de programare pentru \u00eenregistrarea \u0219i citirea informa\u021biilor despre utilizatori prin intermediul systemd-journald. Func\u021biile necesare pentru a oferi datele de \u00eenlocuire utmp prin libsystemd folosind API-ul sd-login.h sau prin DBUS sunt deja incluse \u00een baza de cod a urm\u0103toarei versiuni systemd 254.
\n
Sursa: opennet.ro<\/a> <\/p>","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"excerpt":{"rendered":"

\u0422\u043e\u0440\u0441\u0442\u0435\u043d \u041a\u0443\u043a\u0443\u043a (Thorsten Kukuk), \u043b\u0438\u0434\u0435\u0440 \u0433\u0440\u0443\u043f\u043f\u044b \u043f\u043e \u0440\u0430\u0437\u0432\u0438\u0442\u0438\u044e \u0442\u0435\u0445\u043d\u043e\u043b\u043e\u0433\u0438\u0439 \u0431\u0443\u0434\u0443\u0449\u0435\u0433\u043e \u0432 \u043a\u043e\u043c\u043f\u0430\u043d\u0438\u0438 SUSE (Future Technology Team, \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u0435\u0442 openSUSE MicroOS \u0438 SLE Micro), \u0440\u0430\u043d\u0435\u0435 10 \u043b\u0435\u0442 \u0440\u0443\u043a\u043e\u0432\u043e\u0434\u0438\u0432\u0448\u0438\u0439 \u043f\u0440\u043e\u0435\u043a\u0442\u043e\u043c SUSE LINUX Enterprise Server, \u043f\u0440\u0435\u0434\u043b\u043e\u0436\u0438\u043b \u0438\u0437\u0431\u0430\u0432\u0438\u0442\u044c\u0441\u044f \u043e\u0442 \u0444\u0430\u0439\u043b\u0430 \/var\/run\/utmp \u0432 \u0434\u0438\u0441\u0442\u0440\u0438\u0431\u0443\u0442\u0438\u0432\u0430\u0445 \u0434\u043b\u044f \u043f\u043e\u043b\u043d\u043e\u0433\u043e \u0440\u0435\u0448\u0435\u043d\u0438\u044f \u043f\u0440\u043e\u0431\u043b\u0435\u043c\u044b 2038 \u0433\u043e\u0434\u0430 \u0432 Glibc. \u0412\u0441\u0435 \u043f\u0440\u0438\u043b\u043e\u0436\u0435\u043d\u0438\u044f, \u0438\u0441\u043f\u043e\u043b\u044c\u0437\u0443\u044e\u0449\u0438\u0435 utmp, wtmp \u0438 lastlog, \u043f\u0440\u0435\u0434\u043b\u0430\u0433\u0430\u0435\u0442\u0441\u044f \u043f\u0435\u0440\u0435\u0432\u0435\u0441\u0442\u0438 […]<\/p>\n","protected":false,"gt_translate_keys":[{"key":"rendered","format":"html"}]},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[702],"tags":[],"class_list":["post-107119","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"aioseo_head":"\n\t\t\n\t\n\t\n\t\n\t\n\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\t\t\n\n","aioseo_head_json":{"title":"\ud83e\udd47Pentru a elimina problema anului 2038 din Glibc, s-a propus \u00eencetarea utiliz\u0103rii utmp | ProHoster","description":"Thorsten Kukuk, liderul grupului de dezvoltare a tehnologiilor viitoare \u00een cadrul companiei SUSE (Future Technology Team, dezvolt\u0103 openSUSE MicroOS \u0219i SLE Micro), care a condus anterior proiectul SUSE LINUX Enterprise timp de 10 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\u0438\u0441\u043f\u043e\u043b\u044c\u0437\u043e\u0432\u0430\u043d\u0438\u0435 utmp | ProHoster","og:description":"\u0422\u043e\u0440\u0441\u0442\u0435\u043d \u041a\u0443\u043a\u0443\u043a (Thorsten Kukuk), \u043b\u0438\u0434\u0435\u0440 \u0433\u0440\u0443\u043f\u043f\u044b \u043f\u043e \u0440\u0430\u0437\u0432\u0438\u0442\u0438\u044e \u0442\u0435\u0445\u043d\u043e\u043b\u043e\u0433\u0438\u0439 \u0431\u0443\u0434\u0443\u0449\u0435\u0433\u043e \u0432 \u043a\u043e\u043c\u043f\u0430\u043d\u0438\u0438 SUSE (Future Technology Team, \u0440\u0430\u0437\u0432\u0438\u0432\u0430\u0435\u0442 openSUSE MicroOS \u0438 SLE Micro), \u0440\u0430\u043d\u0435\u0435 10 \u043b\u0435\u0442 \u0440\u0443\u043a\u043e\u0432\u043e\u0434\u0438\u0432\u0448\u0438\u0439 \u043f\u0440\u043e\u0435\u043a\u0442\u043e\u043c SUSE LINUX 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