sys-apps/rng-tools: open entropy src with O_NOCTTY flag #556456

This revision patches the source file 'rngd_entsource.c', adding 'O_NOCTTY'
flag to the open() call that opens the entropy source for rngd.

Gentoo-Bug: https://bugs.gentoo.org/556456

Package-Manager: portage-2.2.20.1

diff --git a/sys-apps/rng-tools/files/rng-tools-5-fix-noctty.patch b/sys-apps/rng-tools/files/rng-tools-5-fix-noctty.patch
new file mode 100644 (file)
index 0000000..a48b235
--- /dev/null
+++ b/sys-apps/rng-tools/files/rng-tools-5-fix-noctty.patch
@@ -0,0 +1,45 @@
+From: Gokturk Yuksek <gokturk@binghamton.edu>
+Subject: [PATCH] Fix rngd to open the entropy source with 'O_NOCTTY' flag
+
+When start-stop-daemon starts a rngd instance configured to use a tty
+device as its entropy source, the application crashes due to not being
+able to read from the entropy device. This is caused by
+start-stop-daemon calling setsid() before executing rngd, which
+disassociates the controlling terminal. When rngd attempts to open a
+hardware entropy source that's a tty device, per POSIX rules, the
+device becomes the controlling terminal for the process. Then rngd
+calls daemon(), which internally calls setsid(), and consequently
+disassociates the controlling terminal for the child. Meanwhile the
+parent rngd process exits. This results in tty device hanging up. By
+looking at the strace logs attached to the bug, it can be observed
+that although the parent rngd process is able to read() from the
+entropy source successfully, further attempts to read() by the child
+rngd process return 0. This complies with the POSIX, which states that
+read() calls on a hung up terminal shall return 0.
+
+Note that when rngd is started without start-stop-daemon, this problem
+does not happen because at the time of opening the entropy source rngd
+already has a controlling terminal.
+
+Prevent the entropy source from becoming the controlling terminal by
+passing 'O_NOCTTY' flag to open() when opening an entropy source. This
+flag prevents a tty device from becoming the controlling terminal for
+a process without a controlling terminal at the time of open().
+
+Thanks to John Bowler <jbowler@acm.org> for debugging the problem and
+pinpointing the issue as well as confirming the fix.
+
+Gentoo-Bug-URL: https://bugs.gentoo.org/556456
+Reported-By: John Bowler <jbowler@acm.org>
+
+--- rngd_entsource.c
++++ rngd_entsource.c
+@@ -175,7 +175,7 @@
+  */
+ int init_entropy_source(struct rng *ent_src)
+ {
+-      ent_src->rng_fd = open(ent_src->rng_name, O_RDONLY);
++      ent_src->rng_fd = open(ent_src->rng_name, O_RDONLY | O_NOCTTY);
+       if (ent_src->rng_fd == -1) {
+               return 1;
+       }

diff --git a/sys-apps/rng-tools/rng-tools-5-r2.ebuild b/sys-apps/rng-tools/rng-tools-5-r2.ebuild
index 61e60b00cd633f332966e2a1d506ca134fa5c10d..a104f8b5eb28570552009a221a17fea82bbef0a8 100644 (file)
--- a/sys-apps/rng-tools/rng-tools-5-r2.ebuild
+++ b/sys-apps/rng-tools/rng-tools-5-r2.ebuild
@@ -26,6 +26,7 @@ src_prepare() {
        epatch "${FILESDIR}"/${P}-fix-textrels-on-PIC-x86.patch #469962
        epatch "${FILESDIR}"/${P}-man-fill-watermark.patch #555094
        epatch "${FILESDIR}"/${P}-man-rng-device.patch #555106
+       epatch "${FILESDIR}"/${P}-fix-noctty.patch #556456
        eautoreconf
 
        sed -i '/^AR /d' Makefile.in || die