diff options
Diffstat (limited to 'src/who.c')
-rw-r--r-- | src/who.c | 22 |
1 files changed, 21 insertions, 1 deletions
@@ -37,6 +37,10 @@ #include "hard-locale.h" #include "quote.h" +#ifdef TTY_GROUP_NAME +# include <grp.h> +#endif + /* The official name of this program (e.g., no `g' prefix). */ #define PROGRAM_NAME "who" @@ -308,6 +312,22 @@ print_line (int userlen, const char *user, const char state, free (x_exitstr); } +/* Return true if a terminal device given as PSTAT allows other users + to send messages to; false otherwise */ +static bool +is_tty_writable (struct stat const *pstat) +{ +#ifdef TTY_GROUP_NAME + /* Ensure the group of the TTY device matches TTY_GROUP_NAME, more info at + https://bugzilla.redhat.com/454261 */ + struct group *ttygr = getgrnam (TTY_GROUP_NAME); + if (!ttygr || (pstat->st_gid != ttygr->gr_gid)) + return false; +#endif + + return pstat->st_mode & S_IWGRP; +} + /* Send properly parsed USER_PROCESS info to print_line. The most recent boot time is BOOTTIME. */ static void @@ -346,7 +366,7 @@ print_user (const STRUCT_UTMP *utmp_ent, time_t boottime) if (stat (line, &stats) == 0) { - mesg = (stats.st_mode & S_IWGRP) ? '+' : '-'; + mesg = is_tty_writable (&stats) ? '+' : '-'; last_change = stats.st_atime; } else |