diff options
Diffstat (limited to 'src/security.c')
| -rw-r--r-- | src/security.c | 187 |
1 files changed, 93 insertions, 94 deletions
diff --git a/src/security.c b/src/security.c index 9a1faf3..54ab501 100644 --- a/src/security.c +++ b/src/security.c @@ -1,7 +1,7 @@ /** * cerberus – Minimal login program * - * Copyright © 2013, 2014, 2015, 2016, 2020 Mattias Andrée (maandree@kth.se) + * Copyright © 2013, 2014, 2015, 2016, 2020 Mattias Andrée (m@maandree.se) * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by @@ -39,11 +39,12 @@ * * @param str The function that failed. */ -static void fail(const char* str) +static +void fail(const char *str) { - perror(str); - sleep(ERROR_SLEEP); - _exit(1); + perror(str); + sleep(ERROR_SLEEP); + _exit(1); } @@ -52,44 +53,45 @@ static void fail(const char* str) * * @param group The group, -1 for unchanged */ -void secure_tty(gid_t group) +void +secure_tty(gid_t group) { - struct termios tty; - struct termios saved_tty; - char* tty_device; - int fd, i; - - /* Set ownership of this TTY to root:root */ - chown_tty(0, group, 1); - - /* Get TTY name for last part of this functions */ - tty_device = ttyname(STDIN_FILENO); - - /* Kill other processes on this TTY */ - tcgetattr(STDIN_FILENO, &tty); - saved_tty = tty; - tty.c_cflag &= (tcflag_t)~HUPCL; - tcsetattr(0, TCSANOW, &tty); - close(STDIN_FILENO); - close(STDOUT_FILENO); - close(STDERR_FILENO); - signal(SIGHUP, SIG_IGN); - vhangup(); - signal(SIGHUP, SIG_DFL); - - /* Restore terminal and TTY modes */ - fd = open(tty_device, O_RDWR | O_NONBLOCK); - if (fd == -1) - fail("open"); - fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) & ~O_NONBLOCK); - for (i = 0; i < fd; i++) - close(i); - for (i = 0; i < 3; i++) - if (i != fd) - dup2(fd, i); - if (fd > 2) - close(fd); - tcgetattr(STDIN_FILENO, &saved_tty); + struct termios tty; + struct termios saved_tty; + char *tty_device; + int fd, i; + + /* Set ownership of this TTY to root:root */ + chown_tty(0, group, 1); + + /* Get TTY name for last part of this functions */ + tty_device = ttyname(STDIN_FILENO); + + /* Kill other processes on this TTY */ + tcgetattr(STDIN_FILENO, &tty); + saved_tty = tty; + tty.c_cflag &= (tcflag_t)~HUPCL; + tcsetattr(0, TCSANOW, &tty); + close(STDIN_FILENO); + close(STDOUT_FILENO); + close(STDERR_FILENO); + signal(SIGHUP, SIG_IGN); + vhangup(); + signal(SIGHUP, SIG_DFL); + + /* Restore terminal and TTY modes */ + fd = open(tty_device, O_RDWR | O_NONBLOCK); + if (fd == -1) + fail("open"); + fcntl(fd, F_SETFL, fcntl(fd, F_GETFL) & ~O_NONBLOCK); + for (i = 0; i < fd; i++) + close(i); + for (i = 0; i < 3; i++) + if (i != fd) + dup2(fd, i); + if (fd > 2) + close(fd); + tcgetattr(STDIN_FILENO, &saved_tty); } @@ -100,57 +102,54 @@ void secure_tty(gid_t group) * @param group The group, -1 for unchanged * @param with_fail Abort on failure */ -void chown_tty(uid_t owner, gid_t group, char with_fail) +void +chown_tty(uid_t owner, gid_t group, char with_fail) { - #if defined(OWN_VCSA) || defined(OWN_VCS) - struct vt_stat vtstat; - #endif - - /* Set ownership of this TTY */ - if (fchown(STDIN_FILENO, owner, group) && with_fail) - fail("fchown"); - - /* Restrict others from using this TTY */ - if (fchmod(STDIN_FILENO, TTY_PERM) && with_fail) - fail("fchmod"); - - /* Also do the above for /dev/vcs[a][0-9]+ */ - #if defined(OWN_VCSA) || defined(OWN_VCS) - if (ioctl(STDIN_FILENO, VT_GETSTATE, &vtstat) == 0) - { - int n = vtstat.v_active; - char _vcs[VCS_LEN + 6]; - char _vcsa[VCSA_LEN + 6]; - - char* vcs = _vcs; - char* vcsa = _vcsa; - vcs += VCS_LEN + 6; - vcsa += VCSA_LEN + 6; - - if (n) - { - *--vcs = *--vcsa = 0; - while (n) - { - *--vcs = *--vcsa = (char)((n % 10) + '0'); - n /= 10; - } - - vcs -= VCS_LEN; - vcsa -= VCSA_LEN; - strncpy(vcs, VCS, VCS_LEN); - strncpy(vcsa, VCSA, VCSA_LEN); - - #ifdef OWN_VCS - if (chown(vcs, owner, group) && with_fail) fail("chown"); - if (chmod(vcs, TTY_PERM) && with_fail) fail("chmod"); - #endif - #ifdef OWN_VCSA - if (chown(vcsa, owner, group) && with_fail) fail("chown"); - if (chmod(vcsa, TTY_PERM) && with_fail) fail("chmod"); - #endif - } - } - #endif -} +#if defined(OWN_VCSA) || defined(OWN_VCS) + struct vt_stat vtstat; +#endif + + /* Set ownership of this TTY */ + if (fchown(STDIN_FILENO, owner, group) && with_fail) + fail("fchown"); + + /* Restrict others from using this TTY */ + if (fchmod(STDIN_FILENO, TTY_PERM) && with_fail) + fail("fchmod"); + /* Also do the above for /dev/vcs[a][0-9]+ */ +#if defined(OWN_VCSA) || defined(OWN_VCS) + if (!ioctl(STDIN_FILENO, VT_GETSTATE, &vtstat)) { + int n = vtstat.v_active; + char _vcs[VCS_LEN + 6]; + char _vcsa[VCSA_LEN + 6]; + + char *vcs = _vcs; + char *vcsa = _vcsa; + vcs += VCS_LEN + 6; + vcsa += VCSA_LEN + 6; + + if (n) { + *--vcs = *--vcsa = 0; + while (n) { + *--vcs = *--vcsa = (char)((n % 10) + '0'); + n /= 10; + } + + vcs -= VCS_LEN; + vcsa -= VCSA_LEN; + strncpy(vcs, VCS, VCS_LEN); + strncpy(vcsa, VCSA, VCSA_LEN); + +#ifdef OWN_VCS + if (chown(vcs, owner, group) && with_fail) fail("chown"); + if (chmod(vcs, TTY_PERM) && with_fail) fail("chmod"); +#endif +#ifdef OWN_VCSA + if (chown(vcsa, owner, group) && with_fail) fail("chown"); + if (chmod(vcsa, TTY_PERM) && with_fail) fail("chmod"); +#endif + } + } +#endif +} |