linux-kernel - [PATCH 3/6] kmod: provide wrappers for kmod

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

Message-Id: <20170519032444.18416-4-mcgrof@kernel.org>
Date:   Thu, 18 May 2017 20:24:41 -0700
From:   "Luis R. Rodriguez" <mcgrof@...nel.org>
To:     shuah@...nel.org, jeyu@...hat.com, rusty@...tcorp.com.au,
        ebiederm@...ssion.com, dmitry.torokhov@...il.com, acme@...hat.com,
        corbet@....net
Cc:     martin.wilck@...e.com, mmarek@...e.com, pmladek@...e.com,
        hare@...e.com, rwright@....com, jeffm@...e.com, DSterba@...e.com,
        fdmanana@...e.com, neilb@...e.com, linux@...ck-us.net,
        rgoldwyn@...e.com, subashab@...eaurora.org, xypron.glpk@....de,
        keescook@...omium.org, atomlin@...hat.com, mbenes@...e.cz,
        paulmck@...ux.vnet.ibm.com, dan.j.williams@...el.com,
        jpoimboe@...hat.com, davem@...emloft.net, mingo@...hat.com,
        akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
        gregkh@...uxfoundation.org, linux-kselftest@...r.kernel.org,
        linux-doc@...r.kernel.org, linux-kernel@...r.kernel.org,
        "Luis R. Rodriguez" <mcgrof@...nel.org>
Subject: [PATCH 3/6] kmod: provide wrappers for kmod_concurrent inc/dec

kmod_concurrent is used as an atomic counter for enabling
the allowed limit of modprobe calls, provide wrappers for it
to enable this to be expanded on more easily. This will be done
later.

Signed-off-by: Luis R. Rodriguez <mcgrof@...nel.org>
---
 kernel/kmod.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/kernel/kmod.c b/kernel/kmod.c
index 6fe6848787b2..7635915dc91c 100644
--- a/kernel/kmod.c
+++ b/kernel/kmod.c
@@ -59,6 +59,7 @@ static DEFINE_SPINLOCK(umh_sysctl_lock);
 static DECLARE_RWSEM(umhelper_sem);
 
 #ifdef CONFIG_MODULES
+static atomic_t kmod_concurrent = ATOMIC_INIT(0);
 
 /*
 	modprobe_path is set via /proc/sys.
@@ -110,6 +111,20 @@ static int call_modprobe(char *module_name, int wait)
 	return -ENOMEM;
 }
 
+static int kmod_umh_threads_get(void)
+{
+	atomic_inc(&kmod_concurrent);
+	if (atomic_read(&kmod_concurrent) <= max_modprobes)
+		return 0;
+	atomic_dec(&kmod_concurrent);
+	return -ENOMEM;
+}
+
+static void kmod_umh_threads_put(void)
+{
+	atomic_dec(&kmod_concurrent);
+}
+
 /**
  * __request_module - try to load a kernel module
  * @wait: wait (or not) for the operation to complete
@@ -131,7 +146,6 @@ int __request_module(bool wait, const char *fmt, ...)
 	va_list args;
 	char module_name[MODULE_NAME_LEN];
 	int ret;
-	static atomic_t kmod_concurrent = ATOMIC_INIT(0);
 	static int kmod_loop_msg;
 
 	/*
@@ -155,8 +169,8 @@ int __request_module(bool wait, const char *fmt, ...)
 	if (ret)
 		return ret;
 
-	atomic_inc(&kmod_concurrent);
-	if (atomic_read(&kmod_concurrent) > max_modprobes) {
+	ret = kmod_umh_threads_get();
+	if (ret) {
 		/* We may be blaming an innocent here, but unlikely */
 		if (kmod_loop_msg < 5) {
 			printk(KERN_ERR
@@ -164,15 +178,14 @@ int __request_module(bool wait, const char *fmt, ...)
 			       module_name);
 			kmod_loop_msg++;
 		}
-		atomic_dec(&kmod_concurrent);
-		return -ENOMEM;
+		return ret;
 	}
 
 	trace_module_request(module_name, wait, _RET_IP_);
 
 	ret = call_modprobe(module_name, wait ? UMH_WAIT_PROC : UMH_WAIT_EXEC);
 
-	atomic_dec(&kmod_concurrent);
+	kmod_umh_threads_put();
 	return ret;
 }
 EXPORT_SYMBOL(__request_module);
-- 
2.11.0