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Manjarres" To: lorenzo.stoakes@oracle.com, gregkh@linuxfoundation.org, Muchun Song , Oscar Salvador , David Hildenbrand , Alexander Viro , Christian Brauner , Jan Kara , Andrew Morton , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Ingo Molnar , Peter Zijlstra , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Steven Rostedt , Ben Segall , Mel Gorman , Valentin Schneider , "Matthew Wilcox (Oracle)" , Jann Horn , Pedro Falcato , Hugh Dickins , Baolin Wang Cc: aliceryhl@google.com, stable@vger.kernel.org, "Isaac J. Manjarres" , kernel-team@android.com, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Lorenzo Stoakes , Andy Lutomirski , Mike Kravetz Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" From: Lorenzo Stoakes [ Upstream commit 28464bbb2ddc199433383994bcb9600c8034afa1 ] The seal_check_future_write() function is called by shmem_mmap() or hugetlbfs_file_mmap() to disallow any future writable mappings of an memfd sealed this way. The F_SEAL_WRITE flag is not checked here, as that is handled via the mapping->i_mmap_writable mechanism and so any attempt at a mapping would fail before this could be run. However we intend to change this, meaning this check can be performed for F_SEAL_WRITE mappings also. The logic here is equally applicable to both flags, so update this function to accommodate both and rename it accordingly. Link: https://lkml.kernel.org/r/913628168ce6cce77df7d13a63970bae06a526e0.16= 97116581.git.lstoakes@gmail.com Signed-off-by: Lorenzo Stoakes Reviewed-by: Jan Kara Cc: Alexander Viro Cc: Andy Lutomirski Cc: Christian Brauner Cc: Hugh Dickins Cc: Matthew Wilcox (Oracle) Cc: Mike Kravetz Cc: Muchun Song Signed-off-by: Andrew Morton Cc: stable@vger.kernel.org Signed-off-by: Isaac J. Manjarres --- fs/hugetlbfs/inode.c | 2 +- include/linux/mm.h | 15 ++++++++------- mm/shmem.c | 2 +- 3 files changed, 10 insertions(+), 9 deletions(-) diff --git a/fs/hugetlbfs/inode.c b/fs/hugetlbfs/inode.c index 47b292f9b4f8..c18a47a86e8b 100644 --- a/fs/hugetlbfs/inode.c +++ b/fs/hugetlbfs/inode.c @@ -152,7 +152,7 @@ static int hugetlbfs_file_mmap(struct file *file, struc= t vm_area_struct *vma) vma->vm_flags |=3D VM_HUGETLB | VM_DONTEXPAND; vma->vm_ops =3D &hugetlb_vm_ops; =20 - ret =3D seal_check_future_write(info->seals, vma); + ret =3D seal_check_write(info->seals, vma); if (ret) return ret; =20 diff --git a/include/linux/mm.h b/include/linux/mm.h index 47d56c96447a..57cba6e4fdcd 100644 --- a/include/linux/mm.h +++ b/include/linux/mm.h @@ -2946,25 +2946,26 @@ static inline int pages_identical(struct page *page= 1, struct page *page2) } =20 /** - * seal_check_future_write - Check for F_SEAL_FUTURE_WRITE flag and handle= it + * seal_check_write - Check for F_SEAL_WRITE or F_SEAL_FUTURE_WRITE flags = and + * handle them. * @seals: the seals to check * @vma: the vma to operate on * - * Check whether F_SEAL_FUTURE_WRITE is set; if so, do proper check/handli= ng on - * the vma flags. Return 0 if check pass, or <0 for errors. + * Check whether F_SEAL_WRITE or F_SEAL_FUTURE_WRITE are set; if so, do pr= oper + * check/handling on the vma flags. Return 0 if check pass, or <0 for err= ors. */ -static inline int seal_check_future_write(int seals, struct vm_area_struct= *vma) +static inline int seal_check_write(int seals, struct vm_area_struct *vma) { - if (seals & F_SEAL_FUTURE_WRITE) { + if (seals & (F_SEAL_WRITE | F_SEAL_FUTURE_WRITE)) { /* * New PROT_WRITE and MAP_SHARED mmaps are not allowed when - * "future write" seal active. + * write seals are active. */ if ((vma->vm_flags & VM_SHARED) && (vma->vm_flags & VM_WRITE)) return -EPERM; =20 /* - * Since an F_SEAL_FUTURE_WRITE sealed memfd can be mapped as + * Since an F_SEAL_[FUTURE_]WRITE sealed memfd can be mapped as * MAP_SHARED and read-only, take care to not allow mprotect to * revert protections on such mappings. Do this only for shared * mappings. For private mappings, don't need to mask diff --git a/mm/shmem.c b/mm/shmem.c index 264229680ad7..8475d56f5977 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -2215,7 +2215,7 @@ static int shmem_mmap(struct file *file, struct vm_ar= ea_struct *vma) struct shmem_inode_info *info =3D SHMEM_I(file_inode(file)); int ret; =20 - ret =3D seal_check_future_write(info->seals, vma); + ret =3D seal_check_write(info->seals, vma); if (ret) return ret; =20 --=20 2.50.1.552.g942d659e1b-goog