From 629a61339823cd65351c7aeb294b3337db06dccb Mon Sep 17 00:00:00 2001
From: Nick Mathewson <nickm@torproject.org>
Date: Sun, 15 Nov 2009 18:59:59 +0000
Subject: [PATCH] When running set[ug]id, don't check the environment.

Idea from OpenBSD, but made a bit more generic to handle uncivilized lands
that do not define issetugid.

svn:r1530
---
 ChangeLog       |  3 ++-
 configure.in    |  2 +-
 event.c         |  4 ++--
 evutil.c        | 28 ++++++++++++++++++++++++++++
 util-internal.h |  2 ++
 5 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/ChangeLog b/ChangeLog
index d369e524..4798c608 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -44,7 +44,8 @@ Changes in 2.0.3-alpha:
  o Make EV_PERSIST timeouts more accurate: schedule the next event based on the scheduled time of the previous event, not based on the current time.
  o Allow http.c to handle cases where getaddrinfo returns an IPv6 address.  Patch from Ryan Phillips.
  o Fix a problem with excessive memory allocation when using multiple event priorities.
- o Default to using arc4random for DNS transaction IDs on systems that have it.
+ o Default to using arc4random for DNS transaction IDs on systems that have it; from OpenBSD.
+ o Never check the environment when we're running setuid or setgid; from OpenBSD.
 
 
 Changes in 2.0.2-alpha:
diff --git a/configure.in b/configure.in
index 9e45bbf8..6f826f43 100644
--- a/configure.in
+++ b/configure.in
@@ -176,7 +176,7 @@ AC_C_INLINE
 AC_HEADER_TIME
 
 dnl Checks for library functions.
-AC_CHECK_FUNCS(gettimeofday vasprintf fcntl clock_gettime strtok_r strsep getaddrinfo getnameinfo strlcpy inet_ntop inet_pton signal sigaction strtoll inet_aton pipe eventfd sendfile mmap splice arc4random)
+AC_CHECK_FUNCS(gettimeofday vasprintf fcntl clock_gettime strtok_r strsep getaddrinfo getnameinfo strlcpy inet_ntop inet_pton signal sigaction strtoll inet_aton pipe eventfd sendfile mmap splice arc4random issetugid geteuid getegid)
 
 AC_CHECK_SIZEOF(long)
 
diff --git a/event.c b/event.c
index ec91f8e9..bbd6b73c 100644
--- a/event.c
+++ b/event.c
@@ -242,7 +242,7 @@ event_is_method_disabled(const char *name)
 	evutil_snprintf(environment, sizeof(environment), "EVENT_NO%s", name);
 	for (i = 8; environment[i] != '\0'; ++i)
 		environment[i] = toupper(environment[i]);
-	return (getenv(environment) != NULL);
+	return (evutil_getenv(environment) != NULL);
 }
 
 int
@@ -334,7 +334,7 @@ event_base_new_with_config(struct event_config *cfg)
 		return NULL;
 	}
 
-	if (getenv("EVENT_SHOW_METHOD"))
+	if (evutil_getenv("EVENT_SHOW_METHOD"))
 		event_msgx("libevent using: %s", base->evsel->name);
 
 	/* allocate a single active event queue */
diff --git a/evutil.c b/evutil.c
index 5a57c288..072b22b4 100644
--- a/evutil.c
+++ b/evutil.c
@@ -952,3 +952,31 @@ int evutil_ascii_strncasecmp(const char *s1, const char *s2, size_t n)
 	}
 	return 0;
 }
+
+static int
+evutil_issetugid(void)
+{
+#ifdef _EVENT_HAVE_ISSETUGID
+	return issetugid();
+#else
+
+#ifdef _EVENT_HAVE_GETEUID
+	if (getuid() != geteuid())
+		return 1;
+#endif
+#ifdef _EVENT_HAVE_GETEGID
+	if (getgid() != getegid())
+		return 1;
+#endif
+	return 0;
+#endif
+}
+
+const char *
+evutil_getenv(const char *varname)
+{
+	if (evutil_issetugid())
+		return NULL;
+
+	return getenv(varname);
+}
diff --git a/util-internal.h b/util-internal.h
index 3c243d63..6f524d3a 100644
--- a/util-internal.h
+++ b/util-internal.h
@@ -144,6 +144,8 @@ int evutil_socket_finished_connecting(evutil_socket_t fd);
 int evutil_resolve(int family, const char *hostname, struct sockaddr *sa,
     ev_socklen_t *socklen, int port);
 
+const char *evutil_getenv(const char *name);
+
 /* Evaluates to the same boolean value as 'p', and hints to the compiler that
  * we expect this value to be false. */
 #ifdef __GNUC__X
-- 
2.40.0