kernel-hardening.lists.openwall.com archive mirror
 help / color / mirror / Atom feed
From: John Wood <john.wood@gmx.com>
To: Kees Cook <keescook@chromium.org>, Jann Horn <jannh@google.com>,
	Randy Dunlap <rdunlap@infradead.org>,
	Jonathan Corbet <corbet@lwn.net>,
	James Morris <jmorris@namei.org>, Shuah Khan <shuah@kernel.org>
Cc: John Wood <john.wood@gmx.com>,
	"Serge E. Hallyn" <serge@hallyn.com>,
	Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
	linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org,
	linux-security-module@vger.kernel.org,
	linux-kselftest@vger.kernel.org,
	kernel-hardening@lists.openwall.com
Subject: [PATCH v5 1/8] security: Add LSM hook at the point where a task gets a fatal signal
Date: Sat, 27 Feb 2021 16:30:06 +0100	[thread overview]
Message-ID: <20210227153013.6747-2-john.wood@gmx.com> (raw)
In-Reply-To: <20210227153013.6747-1-john.wood@gmx.com>

Add a security hook that allows a LSM to be notified when a task gets a
fatal signal. This patch is a previous step on the way to compute the
task crash period by the "brute" LSM (linux security module to detect
and mitigate fork brute force attack against vulnerable userspace
processes).

Signed-off-by: John Wood <john.wood@gmx.com>
---
 include/linux/lsm_hook_defs.h | 1 +
 include/linux/lsm_hooks.h     | 4 ++++
 include/linux/security.h      | 4 ++++
 kernel/signal.c               | 1 +
 security/security.c           | 5 +++++
 5 files changed, 15 insertions(+)

diff --git a/include/linux/lsm_hook_defs.h b/include/linux/lsm_hook_defs.h
index 477a597db013..0208df0955fa 100644
--- a/include/linux/lsm_hook_defs.h
+++ b/include/linux/lsm_hook_defs.h
@@ -220,6 +220,7 @@ LSM_HOOK(int, -ENOSYS, task_prctl, int option, unsigned long arg2,
 	 unsigned long arg3, unsigned long arg4, unsigned long arg5)
 LSM_HOOK(void, LSM_RET_VOID, task_to_inode, struct task_struct *p,
 	 struct inode *inode)
+LSM_HOOK(void, LSM_RET_VOID, task_fatal_signal, const kernel_siginfo_t *siginfo)
 LSM_HOOK(int, 0, ipc_permission, struct kern_ipc_perm *ipcp, short flag)
 LSM_HOOK(void, LSM_RET_VOID, ipc_getsecid, struct kern_ipc_perm *ipcp,
 	 u32 *secid)
diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
index fb7f3193753d..beedaa6ee745 100644
--- a/include/linux/lsm_hooks.h
+++ b/include/linux/lsm_hooks.h
@@ -784,6 +784,10 @@
  *	security attributes, e.g. for /proc/pid inodes.
  *	@p contains the task_struct for the task.
  *	@inode contains the inode structure for the inode.
+ * @task_fatal_signal:
+ *	This hook allows security modules to be notified when a task gets a
+ *	fatal signal.
+ *	@siginfo contains the signal information.
  *
  * Security hooks for Netlink messaging.
  *
diff --git a/include/linux/security.h b/include/linux/security.h
index 8aeebd6646dc..e4025a13630f 100644
--- a/include/linux/security.h
+++ b/include/linux/security.h
@@ -430,6 +430,7 @@ int security_task_kill(struct task_struct *p, struct kernel_siginfo *info,
 int security_task_prctl(int option, unsigned long arg2, unsigned long arg3,
 			unsigned long arg4, unsigned long arg5);
 void security_task_to_inode(struct task_struct *p, struct inode *inode);
+void security_task_fatal_signal(const kernel_siginfo_t *siginfo);
 int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag);
 void security_ipc_getsecid(struct kern_ipc_perm *ipcp, u32 *secid);
 int security_msg_msg_alloc(struct msg_msg *msg);
@@ -1165,6 +1166,9 @@ static inline int security_task_prctl(int option, unsigned long arg2,
 static inline void security_task_to_inode(struct task_struct *p, struct inode *inode)
 { }

+static inline void security_task_fatal_signal(const kernel_siginfo_t *siginfo)
+{ }
+
 static inline int security_ipc_permission(struct kern_ipc_perm *ipcp,
 					  short flag)
 {
diff --git a/kernel/signal.c b/kernel/signal.c
index 5ad8566534e7..893c07a77c76 100644
--- a/kernel/signal.c
+++ b/kernel/signal.c
@@ -2750,6 +2750,7 @@ bool get_signal(struct ksignal *ksig)
 		/*
 		 * Anything else is fatal, maybe with a core dump.
 		 */
+		security_task_fatal_signal(&ksig->info);
 		current->flags |= PF_SIGNALED;

 		if (sig_kernel_coredump(signr)) {
diff --git a/security/security.c b/security/security.c
index 5ac96b16f8fa..d9cf653a4e70 100644
--- a/security/security.c
+++ b/security/security.c
@@ -1840,6 +1840,11 @@ void security_task_to_inode(struct task_struct *p, struct inode *inode)
 	call_void_hook(task_to_inode, p, inode);
 }

+void security_task_fatal_signal(const kernel_siginfo_t *siginfo)
+{
+	call_void_hook(task_fatal_signal, siginfo);
+}
+
 int security_ipc_permission(struct kern_ipc_perm *ipcp, short flag)
 {
 	return call_int_hook(ipc_permission, 0, ipcp, flag);
--
2.25.1


  reply	other threads:[~2021-02-27 15:52 UTC|newest]

Thread overview: 27+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-02-27 15:30 [PATCH v5 0/8] Fork brute force attack mitigation John Wood
2021-02-27 15:30 ` John Wood [this message]
2021-02-27 15:30 ` [PATCH v5 2/8] security/brute: Define a LSM and manage statistical data John Wood
2021-03-02  5:49   ` [security/brute] cfe92ab6a3: WARNING:inconsistent_lock_state kernel test robot
2021-03-02 18:39     ` John Wood
2021-02-27 15:30 ` [PATCH v5 3/8] securtiy/brute: Detect a brute force attack John Wood
2021-02-27 15:30 ` [PATCH v5 4/8] security/brute: Fine tuning the attack detection John Wood
2021-02-27 15:30 ` [PATCH v5 5/8] security/brute: Mitigate a brute force attack John Wood
2021-03-11 20:32   ` peter enderborg
2021-03-12 16:19     ` John Wood
2021-02-27 15:30 ` [PATCH v5 6/8] selftests/brute: Add tests for the Brute LSM John Wood
2021-02-27 15:30 ` [PATCH v5 7/8] Documentation: Add documentation " John Wood
2021-02-28 18:56   ` Andi Kleen
2021-03-02 18:31     ` John Wood
2021-03-07 15:19       ` Andi Kleen
2021-03-07 16:45         ` John Wood
2021-03-07 17:25           ` Andi Kleen
2021-03-07 18:05             ` John Wood
2021-03-07 22:49               ` Andi Kleen
2021-03-09 18:40                 ` John Wood
2021-03-11 18:22                   ` John Wood
2021-03-11 20:08                     ` Andi Kleen
2021-03-12 17:47                       ` John Wood
2021-03-11 20:05                   ` Andi Kleen
2021-03-12 17:54                     ` John Wood
2021-02-27 15:30 ` [PATCH v5 8/8] MAINTAINERS: Add a new entry " John Wood
2021-02-27 18:44 ` [PATCH v5 0/8] Fork brute force attack mitigation John Wood

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20210227153013.6747-2-john.wood@gmx.com \
    --to=john.wood@gmx.com \
    --cc=corbet@lwn.net \
    --cc=gregkh@linuxfoundation.org \
    --cc=jannh@google.com \
    --cc=jmorris@namei.org \
    --cc=keescook@chromium.org \
    --cc=kernel-hardening@lists.openwall.com \
    --cc=linux-doc@vger.kernel.org \
    --cc=linux-kernel@vger.kernel.org \
    --cc=linux-kselftest@vger.kernel.org \
    --cc=linux-security-module@vger.kernel.org \
    --cc=rdunlap@infradead.org \
    --cc=serge@hallyn.com \
    --cc=shuah@kernel.org \
    --subject='Re: [PATCH v5 1/8] security: Add LSM hook at the point where a task gets a fatal signal' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).