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[86.156.84.164]) by smtp.googlemail.com with ESMTPSA id u6-20020a5d6ac6000000b002f2789d1bcfsm4546827wrw.21.2023.04.14.16.27.44 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Fri, 14 Apr 2023 16:27:45 -0700 (PDT) From: Lorenzo Stoakes To: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Andrew Morton Cc: Matthew Wilcox , David Hildenbrand , Lorenzo Stoakes Subject: [PATCH 4/7] mm/gup: introduce the FOLL_SAME_FILE GUP flag Date: Sat, 15 Apr 2023 00:27:40 +0100 Message-Id: <7ed66bd5243f7535030e0fa6a8a94b76dc5033f1.1681508038.git.lstoakes@gmail.com> X-Mailer: git-send-email 2.40.0 In-Reply-To: References: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" This flag causes GUP to assert that all VMAs within the input range possess the same vma->vm_file. If not, the operation fails. This is part of a patch series which eliminates the vmas parameter from the GUP API, implementing the one remaining assertion within the entire kernel that requires access to the VMAs associated with a GUP range. Signed-off-by: Lorenzo Stoakes --- include/linux/mm_types.h | 2 ++ mm/gup.c | 16 ++++++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h index 3fc9e680f174..84d1aec9dbab 100644 --- a/include/linux/mm_types.h +++ b/include/linux/mm_types.h @@ -1185,6 +1185,8 @@ enum { FOLL_PCI_P2PDMA =3D 1 << 10, /* allow interrupts from generic signals */ FOLL_INTERRUPTIBLE =3D 1 << 11, + /* assert that the range spans VMAs with the same vma->vm_file */ + FOLL_SAME_FILE =3D 1 << 12, =20 /* See also internal only FOLL flags in mm/internal.h */ }; diff --git a/mm/gup.c b/mm/gup.c index 9440aa54c741..3954ce499a4a 100644 --- a/mm/gup.c +++ b/mm/gup.c @@ -959,7 +959,8 @@ static int faultin_page(struct vm_area_struct *vma, return 0; } =20 -static int check_vma_flags(struct vm_area_struct *vma, unsigned long gup_f= lags) +static int check_vma_flags(struct vm_area_struct *vma, struct file *file, + unsigned long gup_flags) { vm_flags_t vm_flags =3D vma->vm_flags; int write =3D (gup_flags & FOLL_WRITE); @@ -968,7 +969,7 @@ static int check_vma_flags(struct vm_area_struct *vma, = unsigned long gup_flags) if (vm_flags & (VM_IO | VM_PFNMAP)) return -EFAULT; =20 - if (gup_flags & FOLL_ANON && !vma_is_anonymous(vma)) + if ((gup_flags & FOLL_ANON) && !vma_is_anonymous(vma)) return -EFAULT; =20 if ((gup_flags & FOLL_LONGTERM) && vma_is_fsdax(vma)) @@ -977,6 +978,9 @@ static int check_vma_flags(struct vm_area_struct *vma, = unsigned long gup_flags) if (vma_is_secretmem(vma)) return -EFAULT; =20 + if ((gup_flags & FOLL_SAME_FILE) && vma->vm_file !=3D file) + return -EFAULT; + if (write) { if (!(vm_flags & VM_WRITE)) { if (!(gup_flags & FOLL_FORCE)) @@ -1081,6 +1085,7 @@ static long __get_user_pages(struct mm_struct *mm, long ret =3D 0, i =3D 0; struct vm_area_struct *vma =3D NULL; struct follow_page_context ctx =3D { NULL }; + struct file *file =3D NULL; =20 if (!nr_pages) return 0; @@ -1111,10 +1116,13 @@ static long __get_user_pages(struct mm_struct *mm, ret =3D -EFAULT; goto out; } - ret =3D check_vma_flags(vma, gup_flags); + ret =3D check_vma_flags(vma, i =3D=3D 0 ? vma->vm_file : file, + gup_flags); if (ret) goto out; =20 + file =3D vma->vm_file; + if (is_vm_hugetlb_page(vma)) { i =3D follow_hugetlb_page(mm, vma, pages, vmas, &start, &nr_pages, i, @@ -1595,7 +1603,7 @@ long faultin_vma_page_range(struct vm_area_struct *vm= a, unsigned long start, * We want to report -EINVAL instead of -EFAULT for any permission * problems or incompatible mappings. */ - if (check_vma_flags(vma, gup_flags)) + if (check_vma_flags(vma, vma->vm_file, gup_flags)) return -EINVAL; =20 ret =3D __get_user_pages(mm, start, nr_pages, gup_flags, --=20 2.40.0