linux-kernel - [PATCH v5.1 18/19] ipc/shm, mm: Drop do_vma

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>] [day] [month] [year] [list]
Message-ID: <20240816161020.2845-1-spasswolf@web.de>
Date: Fri, 16 Aug 2024 18:10:19 +0200
From: Bert Karwatzki <spasswolf@....de>
To: "Liam R . Howlett" <Liam.Howlett@...cle.com>
Cc: Bert Karwatzki <spasswolf@....de>,
	Suren Baghdasaryan <surenb@...gle.com>,
	Vlastimil Babka <vbabka@...e.cz>,
	Lorenzo Stoakes <lstoakes@...il.com>,
	Matthew Wilcox <willy@...radead.org>,
	sidhartha.kumar@...cle.com,
	"Paul E . McKenney" <paulmck@...nel.org>,
	Jiri Olsa <olsajiri@...il.com>,
	linux-kernel@...r.kernel.org,
	linux-mm@...ck.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Kees Cook <kees@...nel.org>,
	Jeff Xu <jeffxu@...omium.org>,
	"Liam R . Howlett" <Liam.Howlett@...cle.com>
Subject: [PATCH v5.1 18/19] ipc/shm, mm: Drop do_vma_munmap()

The do_vma_munmap() wrapper existed for callers that didn't have a vma
iterator and needed to check the vma mseal status prior to calling the
underlying munmap().  All callers now use a vma iterator and since the
mseal check of can_modify_mm() has been moved to do_vmi_align_munmap()
and the vmas are aligned, this function can just be called instead.

do_vmi_align_munmap() can no longer be static as ipc/shm is using it and
it is exported via the mm.h header.

Signed-off-by: Liam R. Howlett <Liam.Howlett@...cle.com>
---
 include/linux/mm.h |  6 +++---
 ipc/shm.c          |  8 ++++----
 mm/mmap.c          | 31 ++++---------------------------
 3 files changed, 11 insertions(+), 34 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 653287396808..2dccdc7ba09a 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -3292,14 +3292,14 @@ extern unsigned long do_mmap(struct file *file, unsigned long addr,
 extern int do_vmi_munmap(struct vma_iterator *vmi, struct mm_struct *mm,
 			 unsigned long start, size_t len, struct list_head *uf,
 			 bool unlock);
+extern int do_vmi_align_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
+		    struct mm_struct *mm, unsigned long start,
+		    unsigned long end, struct list_head *uf, bool unlock);
 extern int do_munmap(struct mm_struct *, unsigned long, size_t,
 		     struct list_head *uf);
 extern int do_madvise(struct mm_struct *mm, unsigned long start, size_t len_in, int behavior);

 #ifdef CONFIG_MMU
-extern int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
-			 unsigned long start, unsigned long end,
-			 struct list_head *uf, bool unlock);
 extern int __mm_populate(unsigned long addr, unsigned long len,
 			 int ignore_errors);
 static inline void mm_populate(unsigned long addr, unsigned long len)
diff --git a/ipc/shm.c b/ipc/shm.c
index 3e3071252dac..99564c870084 100644
--- a/ipc/shm.c
+++ b/ipc/shm.c
@@ -1778,8 +1778,8 @@ long ksys_shmdt(char __user *shmaddr)
 			 */
 			file = vma->vm_file;
 			size = i_size_read(file_inode(vma->vm_file));
-			do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
-				      NULL, false);
+			do_vmi_align_munmap(&vmi, vma, mm, vma->vm_start,
+					    vma->vm_end, NULL, false);
 			/*
 			 * We discovered the size of the shm segment, so
 			 * break out of here and fall through to the next
@@ -1803,8 +1803,8 @@ long ksys_shmdt(char __user *shmaddr)
 		if ((vma->vm_ops == &shm_vm_ops) &&
 		    ((vma->vm_start - addr)/PAGE_SIZE == vma->vm_pgoff) &&
 		    (vma->vm_file == file)) {
-			do_vma_munmap(&vmi, vma, vma->vm_start, vma->vm_end,
-				      NULL, false);
+			do_vmi_align_munmap(&vmi, vma, mm, vma->vm_start,
+					    vma->vm_end, NULL, false);
 		}

 		vma = vma_next(&vmi);
diff --git a/mm/mmap.c b/mm/mmap.c
index ae74d0674b6d..d2f47cd66650 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -169,11 +169,12 @@ SYSCALL_DEFINE1(brk, unsigned long, brk)
 			goto out; /* mapping intersects with an existing non-brk vma. */
 		/*
 		 * mm->brk must be protected by write mmap_lock.
-		 * do_vma_munmap() will drop the lock on success,  so update it
-		 * before calling do_vma_munmap().
+		 * do_vmi_align_munmap() will drop the lock on success,  so
+		 * update it before calling do_vma_munmap().
 		 */
 		mm->brk = brk;
-		if (do_vma_munmap(&vmi, brkvma, newbrk, oldbrk, &uf, true))
+		if (do_vmi_align_munmap(&vmi, brkvma, mm, newbrk, oldbrk, &uf,
+					/* unlock = */ true))
 			goto out;

 		goto success_unlocked;
@@ -1747,30 +1748,6 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, start, unsigned long, size,
 	return ret;
 }

-/*
- * do_vma_munmap() - Unmap a full or partial vma.
- * @vmi: The vma iterator pointing at the vma
- * @vma: The first vma to be munmapped
- * @start: the start of the address to unmap
- * @end: The end of the address to unmap
- * @uf: The userfaultfd list_head
- * @unlock: Drop the lock on success
- *
- * unmaps a VMA mapping when the vma iterator is already in position.
- * Does not handle alignment.
- *
- * Return: 0 on success drops the lock of so directed, error on failure and will
- * still hold the lock.
- */
-int do_vma_munmap(struct vma_iterator *vmi, struct vm_area_struct *vma,
-		unsigned long start, unsigned long end, struct list_head *uf,
-		bool unlock)
-{
-	struct mm_struct *mm = vma->vm_mm;
-
-	return do_vmi_align_munmap(vmi, vma, mm, start, end, uf, unlock);
-}
-
 /*
  * do_brk_flags() - Increase the brk vma if the flags match.
  * @vmi: The vma iterator
--
2.45.2