linux-kernel - [PATCH 2/3] uprobes: use vm_special

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: <20150709214449.GA15018@redhat.com>
Date:	Thu, 9 Jul 2015 23:44:49 +0200
From:	Oleg Nesterov <oleg@...hat.com>
To:	Ingo Molnar <mingo@...nel.org>,
	Srikar Dronamraju <srikar@...ux.vnet.ibm.com>
Cc:	Andy Lutomirski <luto@...capital.net>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] uprobes: use vm_special_mapping to name the xol vma

Change xol_add_vma() to use _install_special_mapping(), this way
we can name the vma installed by uprobes. Currently it looks like
private anonymous mapping, this is confusing and complicates the
debugging. With this change /proc/$pid/maps reports "[uprobes]".

Signed-off-by: Oleg Nesterov <oleg@...hat.com>
---
 kernel/events/uprobes.c |   30 ++++++++++++++++++++----------
 1 files changed, 20 insertions(+), 10 deletions(-)

diff --git a/kernel/events/uprobes.c b/kernel/events/uprobes.c
index bd35bee..6a9c5e0 100644
--- a/kernel/events/uprobes.c
+++ b/kernel/events/uprobes.c
@@ -96,17 +96,18 @@ struct uprobe {
  * allocated.
  */
 struct xol_area {
-	wait_queue_head_t 	wq;		/* if all slots are busy */
-	atomic_t 		slot_count;	/* number of in-use slots */
-	unsigned long 		*bitmap;	/* 0 = free slot */
-	struct page 		*pages[2];
+	wait_queue_head_t 		wq;		/* if all slots are busy */
+	atomic_t 			slot_count;	/* number of in-use slots */
+	unsigned long 			*bitmap;	/* 0 = free slot */
 
+	struct vm_special_mapping	xol_mapping;
+	struct page 			*pages[2];
 	/*
 	 * We keep the vma's vm_start rather than a pointer to the vma
 	 * itself.  The probed process or a naughty kernel module could make
 	 * the vma go away, and we must handle that reasonably gracefully.
 	 */
-	unsigned long 		vaddr;		/* Page(s) of instruction slots */
+	unsigned long 			vaddr;		/* Page(s) of instruction slots */
 };
 
 /*
@@ -1125,11 +1126,14 @@ void uprobe_munmap(struct vm_area_struct *vma, unsigned long start, unsigned lon
 /* Slot allocation for XOL */
 static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
 {
-	int ret = -EALREADY;
+	struct vm_area_struct *vma;
+	int ret;
 
 	down_write(&mm->mmap_sem);
-	if (mm->uprobes_state.xol_area)
+	if (mm->uprobes_state.xol_area) {
+		ret = -EALREADY;
 		goto fail;
+	}
 
 	if (!area->vaddr) {
 		/* Try to map as high as possible, this is only a hint. */
@@ -1141,11 +1145,15 @@ static int xol_add_vma(struct mm_struct *mm, struct xol_area *area)
 		}
 	}
 
-	ret = install_special_mapping(mm, area->vaddr, PAGE_SIZE,
-				VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO, area->pages);
-	if (ret)
+	vma = _install_special_mapping(mm, area->vaddr, PAGE_SIZE,
+				VM_EXEC|VM_MAYEXEC|VM_DONTCOPY|VM_IO,
+				&area->xol_mapping);
+	if (IS_ERR(vma)) {
+		ret = PTR_ERR(vma);
 		goto fail;
+	}
 
+	ret = 0;
 	smp_wmb();	/* pairs with get_xol_area() */
 	mm->uprobes_state.xol_area = area;
  fail:
@@ -1168,6 +1176,8 @@ static struct xol_area *__create_xol_area(unsigned long vaddr)
 	if (!area->bitmap)
 		goto free_area;
 
+	area->xol_mapping.name = "[uprobes]";
+	area->xol_mapping.pages = area->pages;
 	area->pages[0] = alloc_page(GFP_HIGHUSER);
 	if (!area->pages[0])
 		goto free_bitmap;
-- 
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/