From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Anthony Yznaga <anthony.yznaga@oracle.com>
Cc: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org,
mhocko@kernel.org, tglx@linutronix.de, mingo@redhat.com,
bp@alien8.de, x86@kernel.org, hpa@zytor.com,
viro@zeniv.linux.org.uk, akpm@linux-foundation.org,
arnd@arndb.de, ebiederm@xmission.com, keescook@chromium.org,
gerg@linux-m68k.org, ktkhai@virtuozzo.com,
christian.brauner@ubuntu.com, peterz@infradead.org,
esyr@redhat.com, jgg@ziepe.ca, christian@kellner.me,
areber@redhat.com, cyphar@cyphar.com, steven.sistare@oracle.com
Subject: Re: [RFC PATCH 3/5] mm: introduce VM_EXEC_KEEP
Date: Wed, 29 Jul 2020 16:52:11 +0300 [thread overview]
Message-ID: <20200729135211.zodforvnv2xvdchm@box> (raw)
In-Reply-To: <1595869887-23307-4-git-send-email-anthony.yznaga@oracle.com>
On Mon, Jul 27, 2020 at 10:11:25AM -0700, Anthony Yznaga wrote:
> A vma with the VM_EXEC_KEEP flag is preserved across exec. For anonymous
> vmas only. For safety, overlap with fixed address VMAs created in the new
> mm during exec (e.g. the stack and elf load segments) is not permitted and
> will cause the exec to fail.
> (We are studying how to guarantee there are no conflicts. Comments welcome.)
>
> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
> Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
> ---
> arch/x86/Kconfig | 1 +
> fs/exec.c | 20 ++++++++++++++++++++
> include/linux/mm.h | 5 +++++
> kernel/fork.c | 2 +-
> mm/mmap.c | 47 +++++++++++++++++++++++++++++++++++++++++++++++
> 5 files changed, 74 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 883da0abf779..fc36eb2f45c0 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -30,6 +30,7 @@ config X86_64
> select MODULES_USE_ELF_RELA
> select NEED_DMA_MAP_STATE
> select SWIOTLB
> + select ARCH_USES_HIGH_VMA_FLAGS
>
> config FORCE_DYNAMIC_FTRACE
> def_bool y
> diff --git a/fs/exec.c b/fs/exec.c
> index 262112e5f9f8..1de09c4eef00 100644
> --- a/fs/exec.c
> +++ b/fs/exec.c
> @@ -1069,6 +1069,20 @@ ssize_t read_code(struct file *file, unsigned long addr, loff_t pos, size_t len)
> EXPORT_SYMBOL(read_code);
> #endif
>
> +static int vma_dup_some(struct mm_struct *old_mm, struct mm_struct *new_mm)
> +{
> + struct vm_area_struct *vma;
> + int ret;
> +
> + for (vma = old_mm->mmap; vma; vma = vma->vm_next)
> + if (vma->vm_flags & VM_EXEC_KEEP) {
> + ret = vma_dup(vma, new_mm);
> + if (ret)
> + return ret;
> + }
> + return 0;
> +}
> +
> /*
> * Maps the mm_struct mm into the current task struct.
> * On success, this function returns with the mutex
> @@ -1104,6 +1118,12 @@ static int exec_mmap(struct mm_struct *mm)
> mutex_unlock(&tsk->signal->exec_update_mutex);
> return -EINTR;
> }
> + ret = vma_dup_some(old_mm, mm);
> + if (ret) {
> + mmap_read_unlock(old_mm);
> + mutex_unlock(&tsk->signal->exec_update_mutex);
> + return ret;
> + }
> }
>
> task_lock(tsk);
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index dc7b87310c10..1c538ba77f33 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -295,11 +295,15 @@ int overcommit_kbytes_handler(struct ctl_table *, int, void *, size_t *,
> #define VM_HIGH_ARCH_BIT_2 34 /* bit only usable on 64-bit architectures */
> #define VM_HIGH_ARCH_BIT_3 35 /* bit only usable on 64-bit architectures */
> #define VM_HIGH_ARCH_BIT_4 36 /* bit only usable on 64-bit architectures */
> +#define VM_HIGH_ARCH_BIT_5 37 /* bit only usable on 64-bit architectures */
> #define VM_HIGH_ARCH_0 BIT(VM_HIGH_ARCH_BIT_0)
> #define VM_HIGH_ARCH_1 BIT(VM_HIGH_ARCH_BIT_1)
> #define VM_HIGH_ARCH_2 BIT(VM_HIGH_ARCH_BIT_2)
> #define VM_HIGH_ARCH_3 BIT(VM_HIGH_ARCH_BIT_3)
> #define VM_HIGH_ARCH_4 BIT(VM_HIGH_ARCH_BIT_4)
> +#define VM_EXEC_KEEP BIT(VM_HIGH_ARCH_BIT_5) /* preserve VMA across exec */
> +#else
> +#define VM_EXEC_KEEP VM_NONE
> #endif /* CONFIG_ARCH_USES_HIGH_VMA_FLAGS */
>
> #ifdef CONFIG_ARCH_HAS_PKEYS
> @@ -2534,6 +2538,7 @@ extern struct vm_area_struct *copy_vma(struct vm_area_struct **,
> unsigned long addr, unsigned long len, pgoff_t pgoff,
> bool *need_rmap_locks);
> extern void exit_mmap(struct mm_struct *);
> +extern int vma_dup(struct vm_area_struct *vma, struct mm_struct *mm);
>
> static inline int check_data_rlimit(unsigned long rlim,
> unsigned long new,
> diff --git a/kernel/fork.c b/kernel/fork.c
> index efc5493203ae..15ead613714f 100644
> --- a/kernel/fork.c
> +++ b/kernel/fork.c
> @@ -564,7 +564,7 @@ static __latent_entropy int dup_mmap(struct mm_struct *mm,
> tmp->anon_vma = NULL;
> } else if (anon_vma_fork(tmp, mpnt))
> goto fail_nomem_anon_vma_fork;
> - tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT);
> + tmp->vm_flags &= ~(VM_LOCKED | VM_LOCKONFAULT | VM_EXEC_KEEP);
> file = tmp->vm_file;
> if (file) {
> struct inode *inode = file_inode(file);
> diff --git a/mm/mmap.c b/mm/mmap.c
> index 59a4682ebf3f..be2ff53743c3 100644
> --- a/mm/mmap.c
> +++ b/mm/mmap.c
> @@ -3279,6 +3279,53 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
> return NULL;
> }
>
> +int vma_dup(struct vm_area_struct *old_vma, struct mm_struct *mm)
> +{
> + unsigned long npages;
> + struct mm_struct *old_mm = old_vma->vm_mm;
> + struct vm_area_struct *vma;
> + int ret = -ENOMEM;
> +
> + if (WARN_ON(old_vma->vm_file || old_vma->vm_ops))
> + return -EINVAL;
> +
> + vma = find_vma(mm, old_vma->vm_start);
> + if (vma && vma->vm_start < old_vma->vm_end)
> + return -EEXIST;
> +
> + npages = vma_pages(old_vma);
> + mm->total_vm += npages;
Why only total_vm? Where's exec_vm/stack_vm/data_vm?
> +
> + vma = vm_area_dup(old_vma);
> + if (!vma)
> + goto fail_nomem;
> +
> + ret = vma_dup_policy(old_vma, vma);
> + if (ret)
> + goto fail_nomem_policy;
> +
> + vma->vm_mm = mm;
> + ret = anon_vma_fork(vma, old_vma);
> + if (ret)
> + goto fail_nomem_anon_vma_fork;
Looks like a duplication of code form dup_mmap().
Any chance to get in one place?
> + vma->vm_flags &= ~(VM_LOCKED|VM_UFFD_MISSING|VM_UFFD_WP|VM_EXEC_KEEP);
> + vma->vm_next = vma->vm_prev = NULL;
No need. vm_area_dup() takes care of it.
> + vma->vm_userfaultfd_ctx = NULL_VM_UFFD_CTX;
Semantics of VM_EXEC_KEEP vs userfaultfd() deserves a detailed explanation.
I feel these flags has to be mutually exclusive.
> + if (is_vm_hugetlb_page(vma))
> + reset_vma_resv_huge_pages(vma);
> + __insert_vm_struct(mm, vma);
> + ret = copy_page_range(mm, old_mm, old_vma);
> + return ret;
> +
> +fail_nomem_anon_vma_fork:
> + mpol_put(vma_policy(vma));
> +fail_nomem_policy:
> + vm_area_free(vma);
> +fail_nomem:
> + return -ENOMEM;
> +}
> +
> /*
> * Return true if the calling process may expand its vm space by the passed
> * number of pages
> --
> 1.8.3.1
>
>
--
Kirill A. Shutemov
next prev parent reply other threads:[~2020-07-29 13:52 UTC|newest]
Thread overview: 74+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-07-27 17:11 [RFC PATCH 0/5] madvise MADV_DOEXEC Anthony Yznaga
2020-07-27 17:07 ` Eric W. Biederman
2020-07-27 18:00 ` Steven Sistare
2020-07-28 13:40 ` Christian Brauner
2020-07-27 17:11 ` [RFC PATCH 1/5] elf: reintroduce using MAP_FIXED_NOREPLACE for elf executable mappings Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 2/5] mm: do not assume only the stack vma exists in setup_arg_pages() Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 3/5] mm: introduce VM_EXEC_KEEP Anthony Yznaga
2020-07-28 13:38 ` Eric W. Biederman
2020-07-28 17:44 ` Anthony Yznaga
2020-07-29 13:52 ` Kirill A. Shutemov [this message]
2020-07-29 23:20 ` Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 4/5] exec, elf: require opt-in for accepting preserved mem Anthony Yznaga
2020-07-27 17:11 ` [RFC PATCH 5/5] mm: introduce MADV_DOEXEC Anthony Yznaga
2020-07-28 13:22 ` Kirill Tkhai
2020-07-28 14:06 ` Steven Sistare
2020-07-28 11:34 ` [RFC PATCH 0/5] madvise MADV_DOEXEC Kirill Tkhai
2020-07-28 17:28 ` Anthony Yznaga
2020-07-28 14:23 ` Andy Lutomirski
2020-07-28 14:30 ` Steven Sistare
2020-07-30 15:22 ` Matthew Wilcox
2020-07-30 15:27 ` Christian Brauner
2020-07-30 15:34 ` Matthew Wilcox
2020-07-30 15:54 ` Christian Brauner
2020-07-31 9:12 ` Stefan Hajnoczi
2020-07-30 15:59 ` Steven Sistare
2020-07-30 17:12 ` Matthew Wilcox
2020-07-30 17:35 ` Steven Sistare
2020-07-30 17:49 ` Matthew Wilcox
2020-07-30 18:27 ` Steven Sistare
2020-07-30 21:58 ` Eric W. Biederman
2020-07-31 14:57 ` Steven Sistare
2020-07-31 15:27 ` Matthew Wilcox
2020-07-31 16:11 ` Steven Sistare
2020-07-31 16:56 ` Jason Gunthorpe
2020-07-31 17:15 ` Steven Sistare
2020-07-31 17:48 ` Jason Gunthorpe
2020-07-31 17:55 ` Steven Sistare
2020-07-31 17:23 ` Matthew Wilcox
2020-08-03 15:28 ` Eric W. Biederman
2020-08-03 15:42 ` James Bottomley
2020-08-03 20:03 ` Steven Sistare
[not found] ` <9371b8272fd84280ae40b409b260bab3@AcuMS.aculab.com>
2020-08-04 11:13 ` Matthew Wilcox
2020-08-03 19:29 ` Steven Sistare
2020-07-31 19:41 ` Steven Sistare
2021-07-08 9:52 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-07-08 12:48 ` Steven Sistare
2021-07-12 1:05 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-07-12 1:30 ` Matthew Wilcox
2021-07-13 0:57 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-13 19:49 ` Khalid Aziz
2021-08-14 20:07 ` David Laight
2021-08-16 0:26 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-16 8:07 ` David Laight
2021-08-16 6:54 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-16 8:02 ` David Hildenbrand
2021-08-16 12:07 ` Matthew Wilcox
2021-08-16 12:20 ` David Hildenbrand
2021-08-16 12:42 ` David Hildenbrand
2021-08-16 12:46 ` Matthew Wilcox
2021-08-16 13:24 ` David Hildenbrand
2021-08-16 13:32 ` Matthew Wilcox
2021-08-16 14:10 ` David Hildenbrand
2021-08-16 14:27 ` Matthew Wilcox
2021-08-16 14:33 ` David Hildenbrand
2021-08-16 14:40 ` Matthew Wilcox
2021-08-16 15:01 ` David Hildenbrand
2021-08-16 15:59 ` Matthew Wilcox
2021-08-16 16:06 ` Khalid Aziz
2021-08-16 16:15 ` Matthew Wilcox
2021-08-16 16:13 ` David Hildenbrand
2021-08-16 12:27 ` [private] " David Hildenbrand
2021-08-16 12:30 ` David Hildenbrand
2021-08-17 0:47 ` Longpeng (Mike, Cloud Infrastructure Service Product Dept.)
2021-08-17 0:55 ` Matthew Wilcox
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