linux-kernel - [PATCH 7/7] uprobes: _register() should always do register_for_each

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]

Date:	Fri, 23 Nov 2012 21:28:17 +0100
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...e.hu>, Peter Zijlstra <peterz@...radead.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Ananth N Mavinakayanahalli <ananth@...ibm.com>,
	Anton Arapov <anton@...hat.com>, linux-kernel@...r.kernel.org
Subject: [PATCH 7/7] uprobes: _register() should always do
	register_for_each_vma(true)

To support the filtering uprobe_register() should do
register_for_each_vma(true) every time the new consumer comes,
we need to install the previously nacked breakpoints.

Note:
	- uprobes_mutex[] should die, what is actually protects is
	  alloc_uprobe().

	- UPROBE_RUN_HANDLER should die too, obviously it can't work
	  unless uprobe has a single consumer. The consumer should
	  serialize with _register/_unregister itself. Or this flag
	  should live in uprobe_consumer->state.

	- Perhaps we can do some optimizations later. For example, if
	  filter_chain() never returns false uprobe can record this
	  fact and avoid the unnecessary register_for_each_vma().

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |   31 +++++++++++++------------------
 1 files changed, 13 insertions(+), 18 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index 7c98671..c80507d 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -482,16 +482,12 @@ static void handler_chain(struct uprobe *uprobe, struct pt_regs *regs)
 	up_read(&uprobe->consumer_rwsem);
 }
 
-/* Returns the previous consumer */
-static struct uprobe_consumer *
-consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
+static void consumer_add(struct uprobe *uprobe, struct uprobe_consumer *uc)
 {
 	down_write(&uprobe->consumer_rwsem);
 	uc->next = uprobe->consumers;
 	uprobe->consumers = uc;
 	up_write(&uprobe->consumer_rwsem);
-
-	return uc->next;
 }
 
 /*
@@ -820,9 +816,15 @@ static int register_for_each_vma(struct uprobe *uprobe, bool is_register)
 	return err;
 }
 
-static int __uprobe_register(struct uprobe *uprobe)
+static int __uprobe_register(struct uprobe *uprobe, struct uprobe_consumer *uc)
 {
-	return register_for_each_vma(uprobe, true);
+	int err;
+
+	consumer_add(uprobe, uc);
+	err = register_for_each_vma(uprobe, true);
+	if (!err) /* TODO: pointless unless the first consumer */
+		set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
+	return err;
 }
 
 static void __uprobe_unregister(struct uprobe *uprobe, struct uprobe_consumer *uc)
@@ -867,21 +869,14 @@ int uprobe_register(struct inode *inode, loff_t offset, struct uprobe_consumer *
 	if (offset > i_size_read(inode))
 		return -EINVAL;
 
-	ret = 0;
+	ret = -ENOMEM;
 	mutex_lock(uprobes_hash(inode));
 	uprobe = alloc_uprobe(inode, offset);
-
-	if (!uprobe) {
-		ret = -ENOMEM;
-	} else if (!consumer_add(uprobe, uc)) {
-		ret = __uprobe_register(uprobe);
-		if (ret) {
+	if (uprobe) {
+		ret = __uprobe_register(uprobe, uc);
+		if (ret)
 			__uprobe_unregister(uprobe, uc);
-		} else {
-			set_bit(UPROBE_RUN_HANDLER, &uprobe->flags);
-		}
 	}
-
 	mutex_unlock(uprobes_hash(inode));
 	if (uprobe)
 		put_uprobe(uprobe);
-- 
1.5.5.1

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/