From 951fda3d8c644597a1d5cdae14cab31567e754a1 Mon Sep 17 00:00:00 2001 From: Neil Horman Date: Tue, 17 Jun 2014 16:05:08 -0400 Subject: tmon: Check log file for common secuirty issues The tmon logging system blindly opens its log file on a static path, making it very easy for someone to redirect that log information to inappropriate places or overwrite other users data. Do some easy checking to make sure we're not logging to a symlink or a file owned by another user. Signed-off-by: Neil Horman Acked-by: Jacob Pan Signed-off-by: Zhang Rui --- tools/thermal/tmon/tmon.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) (limited to 'tools/thermal/tmon') diff --git a/tools/thermal/tmon/tmon.c b/tools/thermal/tmon/tmon.c index b30f531..059e0be 100644 --- a/tools/thermal/tmon/tmon.c +++ b/tools/thermal/tmon/tmon.c @@ -142,6 +142,7 @@ static void start_syslog(void) static void prepare_logging(void) { int i; + struct stat logstat; if (!logging) return; @@ -152,6 +153,29 @@ static void prepare_logging(void) return; } + if (lstat(TMON_LOG_FILE, &logstat) < 0) { + syslog(LOG_ERR, "Unable to stat log file %s\n", TMON_LOG_FILE); + fclose(tmon_log); + tmon_log = NULL; + return; + } + + /* The log file must be a regular file owned by us */ + if (S_ISLNK(logstat.st_mode)) { + syslog(LOG_ERR, "Log file is a symlink. Will not log\n"); + fclose(tmon_log); + tmon_log = NULL; + return; + } + + if (logstat.st_uid != getuid()) { + syslog(LOG_ERR, "We don't own the log file. Not logging\n"); + fclose(tmon_log); + tmon_log = NULL; + return; + } + + fprintf(tmon_log, "#----------- THERMAL SYSTEM CONFIG -------------\n"); for (i = 0; i < ptdata.nr_tz_sensor; i++) { char binding_str[33]; /* size of long + 1 */ -- cgit v1.1