sys-apps/dbus: do not open /proc/self/oom_score_adj for writing

Bug: https://bugs.gentoo.org/836560
Closes: https://bugs.gentoo.org/839795
Bug: https://bugs.gentoo.org/839807
Closes: https://bugs.gentoo.org/839834
Closes: https://bugs.gentoo.org/839837
Closes: https://bugs.gentoo.org/840119
Closes: https://bugs.gentoo.org/840125
Closes: https://bugs.gentoo.org/840161
Signed-off-by: Mike Gilbert <floppym@gentoo.org>

3 files changed, 121 insertions, 6 deletions

diff --git a/sys-apps/dbus/dbus-1.12.22.ebuild b/sys-apps/dbus/dbus-1.12.22-r1.ebuild
index 0491fc1085d8..6490a2e922d7 100644
--- a/sys-apps/dbus/dbus-1.12.22.ebuild
+++ b/sys-apps/dbus/dbus-1.12.22-r1.ebuild
@@ -64,6 +64,9 @@ PATCHES=(
 	"${FILESDIR}/dbus-daemon-optional.patch" # bug #653136
 
 	"${FILESDIR}/dbus-1.12.22-check-fd.patch"
+
+	# https://bugs.gentoo.org/836560
+	"${FILESDIR}/dbus-1.14.0-oom_score_adj.patch"
 )
 
 pkg_setup() {
@@ -207,9 +210,6 @@ multilib_src_compile() {
 }
 
 src_test() {
-	# https://bugs.gentoo.org/836560
-	addwrite /proc/self
-
 	DBUS_VERBOSE=1 virtx emake -j1 -C "${TBD}" check
 }
 
diff --git a/sys-apps/dbus/dbus-1.14.0.ebuild b/sys-apps/dbus/dbus-1.14.0-r1.ebuild
index 2cddb00c4761..ce9df1f58e2e 100644
--- a/sys-apps/dbus/dbus-1.14.0.ebuild
+++ b/sys-apps/dbus/dbus-1.14.0-r1.ebuild
@@ -68,6 +68,9 @@ PATCHES=(
 
 	"${FILESDIR}/dbus-1.14.0-x-autoconf-fixes.patch"
 	"${FILESDIR}/dbus-1.12.22-check-fd.patch"
+
+	# https://bugs.gentoo.org/836560
+	"${FILESDIR}/dbus-1.14.0-oom_score_adj.patch"
 )
 
 pkg_setup() {
@@ -207,9 +210,6 @@ multilib_src_compile() {
 }
 
 src_test() {
-	# https://bugs.gentoo.org/836560
-	addwrite /proc
-
 	# DBUS_TEST_MALLOC_FAILURES=0 to avoid huge test logs
 	# https://gitlab.freedesktop.org/dbus/dbus/-/blob/master/CONTRIBUTING.md#L231
 	DBUS_TEST_MALLOC_FAILURES=0 DBUS_VERBOSE=1 virtx emake -j1 -C "${TBD}" check
diff --git a/sys-apps/dbus/files/dbus-1.14.0-oom_score_adj.patch b/sys-apps/dbus/files/dbus-1.14.0-oom_score_adj.patch
new file mode 100644
index 000000000000..094529708088
--- /dev/null
+++ b/sys-apps/dbus/files/dbus-1.14.0-oom_score_adj.patch
@@ -0,0 +1,115 @@
+From 499cdfde1b3f5d812912e89b1a1a0d7a4fb83306 Mon Sep 17 00:00:00 2001
+From: Simon McVittie <smcv@collabora.com>
+Date: Fri, 1 Apr 2022 18:58:34 +0100
+Subject: [PATCH 1/2] activation-helper: Never crash if unable to write
+ oom_score_adj
+
+_dbus_warn() normally only logs a warning, but can be made fatal by
+environment variables. In particular, we do that during unit testing,
+which can result in a build-time test failure if dbus is built in a
+sandbox environment that prevents write access.
+
+_dbus_log() does only the logging part of _dbus_warn(), which seems
+more appropriate here.
+
+Signed-off-by: Simon McVittie <smcv@collabora.com>
+---
+ bus/activation-helper.c | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/bus/activation-helper.c b/bus/activation-helper.c
+index 8a4fd732..df0472ce 100644
+--- a/bus/activation-helper.c
++++ b/bus/activation-helper.c
+@@ -348,7 +348,7 @@ exec_for_correct_user (char *exec, char *user, DBusError *error)
+   /* Resetting the OOM score adjustment is best-effort, so we don't
+    * treat a failure to do so as fatal. */
+   if (!_dbus_reset_oom_score_adj (&error_str))
+-    _dbus_warn ("%s: %s", error_str, strerror (errno));
++    _dbus_log (DBUS_SYSTEM_LOG_WARNING, "%s: %s", error_str, strerror (errno));
+ 
+   if (!switch_user (user, error))
+     return FALSE;
+-- 
+GitLab
+
+
+From 5c8e5b7140c4f1f88684c7a83ce9587fff2def0c Mon Sep 17 00:00:00 2001
+From: Simon McVittie <smcv@collabora.com>
+Date: Fri, 1 Apr 2022 18:56:26 +0100
+Subject: [PATCH 2/2] sysdeps: Only open oom_score_adj read/write if we need to
+ write it
+
+If we're running in a sandbox, we might not have write access to
+oom_score_adj. In the common case where we don't have any special
+protection from the OOM-killer, we can detect that with only read
+access, and skip the part where we open it for writing.
+
+(We would also not have write access to oom_score_adj if we're running
+with elevated Linux capabilities while not root, but that should never
+actually happen for dbus-daemon-launch-helper, which is setuid root
+for production use or has no capabilities during unit-testing.)
+
+Signed-off-by: Simon McVittie <smcv@collabora.com>
+---
+ dbus/dbus-sysdeps-util-unix.c | 26 +++++++++++++++++++++++---
+ 1 file changed, 23 insertions(+), 3 deletions(-)
+
+diff --git a/dbus/dbus-sysdeps-util-unix.c b/dbus/dbus-sysdeps-util-unix.c
+index 8f079cbf..ca130cff 100644
+--- a/dbus/dbus-sysdeps-util-unix.c
++++ b/dbus/dbus-sysdeps-util-unix.c
+@@ -1627,12 +1627,12 @@ _dbus_reset_oom_score_adj (const char **error_str_p)
+   const char *error_str = NULL;
+ 
+ #ifdef O_CLOEXEC
+-  fd = open ("/proc/self/oom_score_adj", O_RDWR | O_CLOEXEC);
++  fd = open ("/proc/self/oom_score_adj", O_RDONLY | O_CLOEXEC);
+ #endif
+ 
+   if (fd < 0)
+     {
+-      fd = open ("/proc/self/oom_score_adj", O_RDWR);
++      fd = open ("/proc/self/oom_score_adj", O_RDONLY);
+       if (fd >= 0)
+         _dbus_fd_set_close_on_exec (fd);
+     }
+@@ -1680,6 +1680,26 @@ _dbus_reset_oom_score_adj (const char **error_str_p)
+           goto out;
+         }
+ 
++      close (fd);
++#ifdef O_CLOEXEC
++      fd = open ("/proc/self/oom_score_adj", O_WRONLY | O_CLOEXEC);
++
++      if (fd < 0)
++#endif
++        {
++          fd = open ("/proc/self/oom_score_adj", O_WRONLY);
++          if (fd >= 0)
++            _dbus_fd_set_close_on_exec (fd);
++        }
++
++      if (fd < 0)
++        {
++          ret = FALSE;
++          error_str = "open(/proc/self/oom_score_adj) for writing";
++          saved_errno = errno;
++          goto out;
++        }
++
+       if (pwrite (fd, "0", sizeof (char), 0) < 0)
+         {
+           ret = FALSE;
+@@ -1700,7 +1720,7 @@ _dbus_reset_oom_score_adj (const char **error_str_p)
+   else
+     {
+       ret = FALSE;
+-      error_str = "open(/proc/self/oom_score_adj)";
++      error_str = "open(/proc/self/oom_score_adj) for reading";
+       saved_errno = errno;
+       goto out;
+     }
+-- 
+GitLab
+