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Date: Tue, 17 Jun 2014 16:05:08 -0400 From: Neil Horman <nhorman@...driver.com> To: linux-kernel@...r.kernel.org Cc: Zhang Rui <rui.zhang@...el.com>, Jacob Pan <jacob.jun.pan@...ux.intel.com>, Neil Horman <nhorman@...driver.com> Subject: [PATCH 1/2] 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 <nhorman@...driver.com> CC: Zhang Rui <rui.zhang@...el.com> CC: Jacob Pan <jacob.jun.pan@...ux.intel.com> --- tools/thermal/tmon/tmon.c | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) 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 */ -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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