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Shutemov" , Lorenzo Stoakes Cc: Paul Moore , ebpqwerty472123@gmail.com, kirill.shutemov@linux.intel.com, zohar@linux.ibm.com, dmitry.kasatkin@gmail.com, eric.snowberg@oracle.com, jmorris@namei.org, serge@hallyn.com, linux-integrity@vger.kernel.org, linux-security-module@vger.kernel.org, linux-kernel@vger.kernel.org, bpf@vger.kernel.org, Roberto Sassu , linux-mm@kvack.org, akpm@linux-foundation.org, vbabka@suse.cz, linux-fsdevel@vger.kernel.org, Liam Howlett , Jann Horn Date: Fri, 18 Oct 2024 15:29:05 +0200 In-Reply-To: References: <20241008165732.2603647-1-roberto.sassu@huaweicloud.com> <7358f12d852964d9209492e337d33b8880234b74.camel@huaweicloud.com> <593282dbc9f48673c8f3b8e0f28e100f34141115.camel@huaweicloud.com> <15bb94a306d3432de55c0a12f29e7ed2b5fa3ba1.camel@huaweicloud.com> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.44.4-0ubuntu2 MIME-Version: 1.0 X-CM-TRANSID:LxC2BwDHWDClYhJnwGEYAw--.52096S2 X-Coremail-Antispam: 1UD129KBjvJXoWxuF13JFWrJw1fuF43Jw4Utwb_yoW5Crykpr yrJa4qgFWYqFyxXrn2q3Z0gFn0yayUKFy7urWrXry8AwnrtFnxCr4rGFy5urs8Ar1kAFyF vF4UCFZakFW7JFJanT9S1TB71UUUUU7qnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvjb4IE77IF4wAFF20E14v26ryj6rWUM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28lY4IEw2IIxxk0rwA2F7IY1VAKz4 vEj48ve4kI8wA2z4x0Y4vE2Ix0cI8IcVAFwI0_Jr0_JF4l84ACjcxK6xIIjxv20xvEc7Cj xVAFwI0_Gr0_Cr1l84ACjcxK6I8E87Iv67AKxVW8JVWxJwA2z4x0Y4vEx4A2jsIEc7CjxV AFwI0_Gr0_Gr1UM2AIxVAIcxkEcVAq07x20xvEncxIr21l5I8CrVACY4xI64kE6c02F40E x7xfMcIj6xIIjxv20xvE14v26r1j6r18McIj6I8E87Iv67AKxVWUJVW8JwAm72CE4IkC6x 0Yz7v_Jr0_Gr1lF7xvr2IY64vIr41lFIxGxcIEc7CjxVA2Y2ka0xkIwI1lc7CjxVAaw2AF wI0_GFv_Wryl42xK82IYc2Ij64vIr41l4I8I3I0E4IkC6x0Yz7v_Jr0_Gr1lx2IqxVAqx4 xG67AKxVWUJVWUGwC20s026x8GjcxK67AKxVWUGVWUWwC2zVAF1VAY17CE14v26r4a6rW5 MIIYrxkI7VAKI48JMIIF0xvE2Ix0cI8IcVAFwI0_Jr0_JF4lIxAIcVC0I7IYx2IY6xkF7I 0E14v26r4j6F4UMIIF0xvE42xK8VAvwI8IcIk0rVWUJVWUCwCI42IY6I8E87Iv67AKxVWU JVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r4j6r4UJbIYCTnIWIevJa73UjIFyTuYvjxUIa 0PDUUUU X-CM-SenderInfo: purev21wro2thvvxqx5xdzvxpfor3voofrz/1tbiAgAABGcRxH8JsgAAsw X-Rspam-User: X-Rspamd-Queue-Id: 30D0D1A0017 X-Rspamd-Server: rspam01 X-Stat-Signature: oux3sogf3kyif6zxxj5yno8tsn15trwt X-HE-Tag: 1729258153-214149 X-HE-Meta: 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 sIkrbEpR s7LdiH1coJMOVkXjv3B4+p54le5XkQ7Ew/XvXFHtWuCI/iAG46q9HtT/GG65l3qcHP/1zbxZGIN2JHvfsKo7kjxIf6/o7RJaxbuHQXWLGDmvXF9AqKmo1JvgfSa8QxBhB8dtQc3ew0XCKTOeBHynBGghp3BrfnzOZjrJbEUP+TaQ6K8SZ40yxNVTixZys7uQSaGpq X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, 2024-10-18 at 14:05 +0300, Kirill A. Shutemov wrote: > On Fri, Oct 18, 2024 at 12:00:22PM +0100, Lorenzo Stoakes wrote: > > + Liam, Jann > >=20 > > On Fri, Oct 18, 2024 at 01:49:06PM +0300, Kirill A. Shutemov wrote: > > > On Fri, Oct 18, 2024 at 11:24:06AM +0200, Roberto Sassu wrote: > > > > Probably it is hard, @Kirill would there be any way to safely move > > > > security_mmap_file() out of the mmap_lock lock? > > >=20 > > > What about something like this (untested): > > >=20 > > > diff --git a/mm/mmap.c b/mm/mmap.c > > > index dd4b35a25aeb..03473e77d356 100644 > > > --- a/mm/mmap.c > > > +++ b/mm/mmap.c > > > @@ -1646,6 +1646,26 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned lon= g, start, unsigned long, size, > > > if (pgoff + (size >> PAGE_SHIFT) < pgoff) > > > return ret; > > >=20 > > > + if (mmap_read_lock_killable(mm)) > > > + return -EINTR; > > > + > > > + vma =3D vma_lookup(mm, start); > > > + > > > + if (!vma || !(vma->vm_flags & VM_SHARED)) { > > > + mmap_read_unlock(mm); > > > + return -EINVAL; > > > + } > > > + > > > + file =3D get_file(vma->vm_file); > > > + > > > + mmap_read_unlock(mm); > > > + > > > + ret =3D security_mmap_file(vma->vm_file, prot, flags); > >=20 > > Accessing VMA fields without any kind of lock is... very much not advis= ed. > >=20 > > I'm guessing you meant to say: > >=20 > > ret =3D security_mmap_file(file, prot, flags); > >=20 > > Here? :) >=20 > Sure. My bad. >=20 > Patch with all fixups: >=20 > diff --git a/mm/mmap.c b/mm/mmap.c > index dd4b35a25aeb..541787d526b6 100644 > --- a/mm/mmap.c > +++ b/mm/mmap.c > @@ -1646,14 +1646,41 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, = start, unsigned long, size, > if (pgoff + (size >> PAGE_SHIFT) < pgoff) > return ret; > =20 > - if (mmap_write_lock_killable(mm)) > + if (mmap_read_lock_killable(mm)) > return -EINTR; > =20 > vma =3D vma_lookup(mm, start); > =20 > + if (!vma || !(vma->vm_flags & VM_SHARED)) { > + mmap_read_unlock(mm); > + return -EINVAL; > + } > + > + file =3D get_file(vma->vm_file); > + > + mmap_read_unlock(mm); > + > + ret =3D security_mmap_file(file, prot, flags); Uhm, I have to calculate prot and flags before. I can check if what I used here changed in the next lock, and refuse. Roberto > + if (ret) { > + fput(file); > + return ret; > + } > + > + ret =3D -EINVAL; > + > + if (mmap_write_lock_killable(mm)) { > + fput(file); > + return -EINTR; > + } > + > + vma =3D vma_lookup(mm, start); > + > if (!vma || !(vma->vm_flags & VM_SHARED)) > goto out; > =20 > + if (vma->vm_file !=3D file) > + goto out; > + > if (start + size > vma->vm_end) { > VMA_ITERATOR(vmi, mm, vma->vm_end); > struct vm_area_struct *next, *prev =3D vma; > @@ -1688,16 +1715,11 @@ SYSCALL_DEFINE5(remap_file_pages, unsigned long, = start, unsigned long, size, > if (vma->vm_flags & VM_LOCKED) > flags |=3D MAP_LOCKED; > =20 > - file =3D get_file(vma->vm_file); > - ret =3D security_mmap_file(vma->vm_file, prot, flags); > - if (ret) > - goto out_fput; > ret =3D do_mmap(vma->vm_file, start, size, > prot, flags, 0, pgoff, &populate, NULL); > -out_fput: > - fput(file); > out: > mmap_write_unlock(mm); > + fput(file); > if (populate) > mm_populate(ret, populate); > if (!IS_ERR_VALUE(ret))