diff options
| author | Lorenzo Stoakes <lorenzo.stoakes@oracle.com> | 2024-12-06 21:28:46 +0000 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2025-01-13 22:40:51 -0800 |
| commit | fa00b8ef1803fe133b4897c25227aa0d298dd093 (patch) | |
| tree | ecd954177179d272726be18d12aef7614561e88a /mm/mmap.c | |
| parent | 24bd843b1d1017ffc479246c7fc17537eb180763 (diff) | |
mm: perform all memfd seal checks in a single place
We no longer actually need to perform these checks in the f_op->mmap()
hook any longer.
We already moved the operation which clears VM_MAYWRITE on a read-only
mapping of a write-sealed memfd in order to work around the restrictions
imposed by commit 5de195060b2e ("mm: resolve faulty mmap_region() error
path behaviour").
There is no reason for us not to simply go ahead and additionally check to
see if any pre-existing seals are in place here rather than defer this to
the f_op->mmap() hook.
By doing this we remove more logic from shmem_mmap() which doesn't belong
there, as well as doing the same for hugetlbfs_file_mmap(). We also
remove dubious shared logic in mm.h which simply does not belong there
either.
It makes sense to do these checks at the earliest opportunity, we know
these are shmem (or hugetlbfs) mappings whose relevant VMA flags will not
change from the invoking do_mmap() so there is simply no need to wait.
This also means the implementation of further memfd seal flags can be done
within mm/memfd.c and also have the opportunity to modify VMA flags as
necessary early in the mapping logic.
[lorenzo.stoakes@oracle.com: fix typos in !memfd inline stub]
Link: https://lkml.kernel.org/r/7dee6c5d-480b-4c24-b98e-6fa47dbd8a23@lucifer.local
Link: https://lkml.kernel.org/r/20241206212846.210835-1-lorenzo.stoakes@oracle.com
Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com>
Tested-by: Isaac J. Manjarres <isaacmanjarres@google.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Jann Horn <jannh@google.com>
Cc: Kalesh Singh <kaleshsingh@google.com>
Cc: Liam R. Howlett <Liam.Howlett@Oracle.com>
Cc: Muchun Song <muchun.song@linux.dev>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Jeff Xu <jeffxu@chromium.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/mmap.c')
| -rw-r--r-- | mm/mmap.c | 12 |
1 files changed, 9 insertions, 3 deletions
diff --git a/mm/mmap.c b/mm/mmap.c index b373486bd1c6..df9154b15ef9 100644 --- a/mm/mmap.c +++ b/mm/mmap.c @@ -368,8 +368,8 @@ unsigned long do_mmap(struct file *file, unsigned long addr, if (file) { struct inode *inode = file_inode(file); - unsigned int seals = memfd_file_seals(file); unsigned long flags_mask; + int err; if (!file_mmap_ok(file, inode, pgoff, len)) return -EOVERFLOW; @@ -409,8 +409,6 @@ unsigned long do_mmap(struct file *file, unsigned long addr, vm_flags |= VM_SHARED | VM_MAYSHARE; if (!(file->f_mode & FMODE_WRITE)) vm_flags &= ~(VM_MAYWRITE | VM_SHARED); - else if (is_readonly_sealed(seals, vm_flags)) - vm_flags &= ~VM_MAYWRITE; fallthrough; case MAP_PRIVATE: if (!(file->f_mode & FMODE_READ)) @@ -430,6 +428,14 @@ unsigned long do_mmap(struct file *file, unsigned long addr, default: return -EINVAL; } + + /* + * Check to see if we are violating any seals and update VMA + * flags if necessary to avoid future seal violations. + */ + err = memfd_check_seals_mmap(file, &vm_flags); + if (err) + return (unsigned long)err; } else { switch (flags & MAP_TYPE) { case MAP_SHARED: |