linux-kernel - [PATCH] proc/sysctl: make protected

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-Id: <20200709235115.56954-1-jpitti@cisco.com>
Date:   Thu,  9 Jul 2020 16:51:15 -0700
From:   Julius Hemanth Pitti <jpitti@...co.com>
To:     keescook@...omium.org, yzaikin@...gle.com, mcgrof@...nel.org
Cc:     linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        akpm@...ux-foundation.org, mingo@...e.hu, viro@...iv.linux.org.uk,
        xe-linux-external@...co.com,
        Julius Hemanth Pitti <jpitti@...co.com>
Subject: [PATCH] proc/sysctl: make protected_* world readable

protected_* files have 600 permissions which prevents
non-superuser from reading them.

Container like "AWS greengrass" refuse to launch unless
protected_hardlinks and protected_symlinks are set. When
containers like these run with "userns-remap" or "--user"
mapping container's root to non-superuser on host, they
fail to run due to denied read access to these files.

As these protections are hardly a secret, and do not
possess any security risk, making them world readable.

Though above greengrass usecase needs read access to
only protected_hardlinks and protected_symlinks files,
setting all other protected_* files to 644 to keep
consistency.

Fixes: 800179c9b8a1 ("fs: add link restrictions")
Signed-off-by: Julius Hemanth Pitti <jpitti@...co.com>
---
 kernel/sysctl.c |    8 ++++----
 1 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index db1ce7a..aeca2fd 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -3223,7 +3223,7 @@ int proc_do_static_key(struct ctl_table *table, int write,
 		.procname	= "protected_symlinks",
 		.data		= &sysctl_protected_symlinks,
 		.maxlen		= sizeof(int),
-		.mode		= 0600,
+		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
@@ -3232,7 +3232,7 @@ int proc_do_static_key(struct ctl_table *table, int write,
 		.procname	= "protected_hardlinks",
 		.data		= &sysctl_protected_hardlinks,
 		.maxlen		= sizeof(int),
-		.mode		= 0600,
+		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= SYSCTL_ONE,
@@ -3241,7 +3241,7 @@ int proc_do_static_key(struct ctl_table *table, int write,
 		.procname	= "protected_fifos",
 		.data		= &sysctl_protected_fifos,
 		.maxlen		= sizeof(int),
-		.mode		= 0600,
+		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
@@ -3250,7 +3250,7 @@ int proc_do_static_key(struct ctl_table *table, int write,
 		.procname	= "protected_regular",
 		.data		= &sysctl_protected_regular,
 		.maxlen		= sizeof(int),
-		.mode		= 0600,
+		.mode		= 0644,
 		.proc_handler	= proc_dointvec_minmax,
 		.extra1		= SYSCTL_ZERO,
 		.extra2		= &two,
-- 
1.7.1