diff --git a/src/log.c b/src/log.c index 1ec3447..bcd6e52 100644 --- a/src/log.c +++ b/src/log.c @@ -100,10 +100,23 @@ int log_start(struct passwd *ent_pw, int errfd) /* If we're running as root and going to change uid later, change the ownership here so that the file is always owned by the dnsmasq user. Then logrotate can just copy the owner. - Failure of the chown call is OK, (for instance when started as non-root) */ - if (log_to_file && !log_stderr && ent_pw && ent_pw->pw_uid != 0 && - fchown(log_fd, ent_pw->pw_uid, -1) != 0) - ret = errno; + Failure of the chown call is OK, (for instance when started as non-root). + + If we've created a file with group-id root, we also make + the file group-writable. This gives processes in the root group + write access to the file and avoids the problem that on some systems, + once the file is owned by the dnsmasq user, it can't be written + whilst dnsmasq is running as root during startup. + */ + if (log_to_file && !log_stderr && ent_pw && ent_pw->pw_uid != 0) + { + struct stat ls; + if (getgid() == 0 && fstat(log_fd, &ls) == 0 && ls.st_gid == 0 && + (ls.st_mode & S_IWGRP) == 0) + (void)fchmod(log_fd, S_IRUSR|S_IWUSR|S_IRGRP|S_IWGRP); + if (fchown(log_fd, ent_pw->pw_uid, -1) != 0) + ret = errno; + } return ret; } @@ -118,7 +131,7 @@ int log_reopen(char *log_file) /* NOTE: umask is set to 022 by the time this gets called */ if (log_file) - log_fd = open(log_file, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR|S_IRGRP); + log_fd = open(log_file, O_WRONLY|O_CREAT|O_APPEND, S_IRUSR|S_IWUSR|S_IRGRP); else { #if defined(HAVE_SOLARIS_NETWORK) || defined(__ANDROID__)