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Blame SOURCES/0514-log-never-log-into-foreign-fd-2-in-PID-1-or-its-pre-.patch

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From 5a7f49bb38bc1d7965d497e775b7cc8053b0c465 Mon Sep 17 00:00:00 2001
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From: Jan Synacek <jsynacek@redhat.com>
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Date: Fri, 18 Aug 2017 10:17:22 +0200
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Subject: [PATCH] log: never log into foreign fd #2 in PID 1 or its
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 pre-execve() children
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(cherry picked from commit 48a601fe5de8aa0d89ba6dadde168769fa7ce992)
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Resolves: #1420505
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---
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 src/core/main.c  | 11 +++++++++--
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 src/shared/log.c |  7 ++++++-
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 src/shared/log.h |  1 +
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 3 files changed, 16 insertions(+), 3 deletions(-)
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diff --git a/src/core/main.c b/src/core/main.c
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index 37e3ea0ced..66393ed6ad 100644
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--- a/src/core/main.c
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+++ b/src/core/main.c
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@@ -1310,10 +1310,17 @@ int main(int argc, char *argv[]) {
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         log_show_color(isatty(STDERR_FILENO) > 0);
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         log_set_upgrade_syslog_to_journal(true);
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-        /* Disable the umask logic */
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-        if (getpid() == 1)
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+        if (getpid() == 1) {
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+                /* Disable the umask logic */
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                 umask(0);
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+                /* Always reopen /dev/console when running as PID 1 or one of its pre-execve() children. This is
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+                 * important so that we never end up logging to any foreign stderr, for example if we have to log in a
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+                 * child process right before execve()'ing the actual binary, at a point in time where socket
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+                 * activation stderr/stdout area already set up. */
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+                log_set_always_reopen_console(true);
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+        }
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+
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         if (getpid() == 1 && detect_container(NULL) <= 0) {
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                 /* Running outside of a container as PID 1 */
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diff --git a/src/shared/log.c b/src/shared/log.c
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index 646a1d6389..3491420308 100644
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--- a/src/shared/log.c
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+++ b/src/shared/log.c
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@@ -52,6 +52,7 @@ static bool show_color = false;
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 static bool show_location = false;
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 static bool upgrade_syslog_to_journal = false;
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+static bool always_reopen_console = false;
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 /* Akin to glibc's __abort_msg; which is private and we hence cannot
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  * use here. */
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@@ -75,7 +76,7 @@ static int log_open_console(void) {
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         if (console_fd >= 0)
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                 return 0;
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-        if (getpid() == 1) {
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+        if (always_reopen_console) {
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                 console_fd = open_terminal("/dev/console", O_WRONLY|O_NOCTTY|O_CLOEXEC);
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                 if (console_fd < 0)
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                         return console_fd;
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@@ -1061,3 +1062,7 @@ void log_received_signal(int level, const struct signalfd_siginfo *si) {
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 void log_set_upgrade_syslog_to_journal(bool b) {
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         upgrade_syslog_to_journal = b;
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 }
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+
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+void log_set_always_reopen_console(bool b) {
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+        always_reopen_console = b;
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+}
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diff --git a/src/shared/log.h b/src/shared/log.h
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index 2889e1e77f..3c9448f1a7 100644
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--- a/src/shared/log.h
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+++ b/src/shared/log.h
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@@ -210,3 +210,4 @@ LogTarget log_target_from_string(const char *s) _pure_;
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 void log_received_signal(int level, const struct signalfd_siginfo *si);
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 void log_set_upgrade_syslog_to_journal(bool b);
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+void log_set_always_reopen_console(bool b);