diff options
| -rw-r--r-- | loginutils/login.c | 80 |
1 files changed, 44 insertions, 36 deletions
diff --git a/loginutils/login.c b/loginutils/login.c index 861382f12..70e3b1333 100644 --- a/loginutils/login.c +++ b/loginutils/login.c @@ -52,7 +52,7 @@ static char* short_tty; * command line flags. */ -static void read_or_build_utent(struct utmp *utptr, int picky) +static void read_or_build_utent(struct utmp *utptr, int run_by_root) { struct utmp *ut; pid_t pid = getpid(); @@ -60,30 +60,33 @@ static void read_or_build_utent(struct utmp *utptr, int picky) setutent(); /* First, try to find a valid utmp entry for this process. */ - while ((ut = getutent())) - if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] && - (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS)) - break; + /* If there is one, just use it. */ + while ((ut = getutent()) != NULL) + if (ut->ut_pid == pid && ut->ut_line[0] && ut->ut_id[0] + && (ut->ut_type == LOGIN_PROCESS || ut->ut_type == USER_PROCESS) + ) { + *utptr = *ut; /* struct copy */ + if (run_by_root) /* why only for root? */ + memset(utptr->ut_host, 0, sizeof(utptr->ut_host)); + return; + } - /* If there is one, just use it, otherwise create a new one. */ - if (ut) { - *utptr = *ut; - } else { - if (picky) - bb_error_msg_and_die("no utmp entry found"); - - memset(utptr, 0, sizeof(*utptr)); - utptr->ut_type = LOGIN_PROCESS; - utptr->ut_pid = pid; - strncpy(utptr->ut_line, short_tty, sizeof(utptr->ut_line)); - /* This one is only 4 chars wide. Try to fit something - * remotely meaningful by skipping "tty"... */ - strncpy(utptr->ut_id, short_tty + 3, sizeof(utptr->ut_id)); - strncpy(utptr->ut_user, "LOGIN", sizeof(utptr->ut_user)); - utptr->ut_tv.tv_sec = time(NULL); - } - if (!picky) /* root login */ - memset(utptr->ut_host, 0, sizeof(utptr->ut_host)); +// Why? Do we require non-root to exec login from another +// former login process (e.g. login shell)? Some login's have +// login shells as children, so it won't work... +// if (!run_by_root) +// bb_error_msg_and_die("no utmp entry found"); + + /* Otherwise create a new one. */ + memset(utptr, 0, sizeof(*utptr)); + utptr->ut_type = LOGIN_PROCESS; + utptr->ut_pid = pid; + strncpy(utptr->ut_line, short_tty, sizeof(utptr->ut_line)); + /* This one is only 4 chars wide. Try to fit something + * remotely meaningful by skipping "tty"... */ + strncpy(utptr->ut_id, short_tty + 3, sizeof(utptr->ut_id)); + strncpy(utptr->ut_user, "LOGIN", sizeof(utptr->ut_user)); + utptr->ut_tv.tv_sec = time(NULL); } /* @@ -109,7 +112,7 @@ static void write_utent(struct utmp *utptr, const char *username) #endif } #else /* !ENABLE_FEATURE_UTMP */ -#define read_or_build_utent(utptr, picky) ((void)0) +#define read_or_build_utent(utptr, run_by_root) ((void)0) #define write_utent(utptr, username) ((void)0) #endif /* !ENABLE_FEATURE_UTMP */ @@ -225,7 +228,7 @@ int login_main(int argc UNUSED_PARAM, char **argv) char *fromhost; char username[USERNAME_SIZE]; const char *tmp; - int amroot; + int run_by_root; unsigned opt; int count = 0; struct passwd *pw; @@ -248,8 +251,9 @@ int login_main(int argc UNUSED_PARAM, char **argv) signal(SIGALRM, alarm_handler); alarm(TIMEOUT); - /* More of suid paranoia if called by non-root */ - amroot = !sanitize_env_if_suid(); /* Clear dangerous stuff, set PATH */ + /* More of suid paranoia if called by non-root: */ + /* Clear dangerous stuff, set PATH */ + run_by_root = !sanitize_env_if_suid(); /* Mandatory paranoia for suid applet: * ensure that fd# 0,1,2 are opened (at least to /dev/null) @@ -259,7 +263,7 @@ int login_main(int argc UNUSED_PARAM, char **argv) opt = getopt32(argv, "f:h:p", &opt_user, &opt_host); if (opt & LOGIN_OPT_f) { - if (!amroot) + if (!run_by_root) bb_error_msg_and_die("-f is for root only"); safe_strncpy(username, opt_user, sizeof(username)); } @@ -278,7 +282,7 @@ int login_main(int argc UNUSED_PARAM, char **argv) short_tty = full_tty + 5; } - read_or_build_utent(&utent, !amroot); + read_or_build_utent(&utent, run_by_root); if (opt & LOGIN_OPT_h) { USE_FEATURE_UTMP( @@ -396,10 +400,12 @@ int login_main(int argc UNUSED_PARAM, char **argv) return EXIT_FAILURE; } username[0] = '\0'; - } + } /* while (1) */ alarm(0); - if (!amroot) + /* We can ignore /etc/nologin if we are logging in as root, + * it doesn't matter whether we are run by root or not */ + if (pw->pw_uid != 0) die_if_nologin(); write_utent(&utent, username); @@ -433,7 +439,7 @@ int login_main(int argc UNUSED_PARAM, char **argv) fchmod(0, 0600); /* We trust environment only if we run by root */ - if (ENABLE_LOGIN_SCRIPTS && amroot) { + if (ENABLE_LOGIN_SCRIPTS && run_by_root) { char *t_argv[2]; t_argv[0] = getenv("LOGIN_PRE_SUID_SCRIPT"); @@ -479,14 +485,16 @@ int login_main(int argc UNUSED_PARAM, char **argv) // bb_setpgrp(); // If this stuff is really needed, add it and explain why! - /* set signals to defaults */ - signal(SIGALRM, SIG_DFL); + /* Set signals to defaults */ + /*signal(SIGALRM, SIG_DFL); - not needed, we already set it + * to non-SIG_IGN, and on exec such signals are reset to SIG_DFL */ + /* Is this correct? This way user can ctrl-c out of /etc/profile, * potentially creating security breach (tested with bash 3.0). * But without this, bash 3.0 will not enable ctrl-c either. * Maybe bash is buggy? * Need to find out what standards say about /bin/login - - * should it leave SIGINT etc enabled or disabled? */ + * should we leave SIGINT etc enabled or disabled? */ signal(SIGINT, SIG_DFL); /* Exec login shell with no additional parameters */ |