From: Steven Sistare <steven.sistare@oracle.com>
To: Kirill Tkhai <ktkhai@virtuozzo.com>,
Anthony Yznaga <anthony.yznaga@oracle.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-mm@kvack.org, linux-arch@vger.kernel.org
Cc: 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, christian.brauner@ubuntu.com,
peterz@infradead.org, esyr@redhat.com, jgg@ziepe.ca,
christian@kellner.me, areber@redhat.com, cyphar@cyphar.com
Subject: Re: [RFC PATCH 5/5] mm: introduce MADV_DOEXEC
Date: Tue, 28 Jul 2020 10:06:05 -0400 [thread overview]
Message-ID: <bd50a6f0-670e-6bd3-13f1-c7a96e56a9bb@oracle.com> (raw)
In-Reply-To: <743a51db-dc27-c49c-9c65-ac164f5283ba@virtuozzo.com>
On 7/28/2020 9:22 AM, Kirill Tkhai wrote:
> On 27.07.2020 20:11, Anthony Yznaga wrote:
>> madvise MADV_DOEXEC preserves a memory range across exec. Initially
>> only supported for non-executable, non-stack, anonymous memory.
>> MADV_DONTEXEC reverts the effect of a previous MADV_DOXEXEC call and
>> undoes the preservation of the range. After a successful exec call,
>> the behavior of all ranges reverts to MADV_DONTEXEC.
>>
>> Signed-off-by: Steve Sistare <steven.sistare@oracle.com>
>> Signed-off-by: Anthony Yznaga <anthony.yznaga@oracle.com>
>> ---
>> include/uapi/asm-generic/mman-common.h | 3 +++
>> mm/madvise.c | 25 +++++++++++++++++++++++++
>> 2 files changed, 28 insertions(+)
>>
>> diff --git a/include/uapi/asm-generic/mman-common.h b/include/uapi/asm-generic/mman-common.h
>> index f94f65d429be..7c5f616b28f7 100644
>> --- a/include/uapi/asm-generic/mman-common.h
>> +++ b/include/uapi/asm-generic/mman-common.h
>> @@ -72,6 +72,9 @@
>> #define MADV_COLD 20 /* deactivate these pages */
>> #define MADV_PAGEOUT 21 /* reclaim these pages */
>>
>> +#define MADV_DOEXEC 22 /* do inherit across exec */
>> +#define MADV_DONTEXEC 23 /* don't inherit across exec */
>> +
>> /* compatibility flags */
>> #define MAP_FILE 0
>>
>> diff --git a/mm/madvise.c b/mm/madvise.c
>> index dd1d43cf026d..b447fa748649 100644
>> --- a/mm/madvise.c
>> +++ b/mm/madvise.c
>> @@ -103,6 +103,26 @@ static long madvise_behavior(struct vm_area_struct *vma,
>> case MADV_KEEPONFORK:
>> new_flags &= ~VM_WIPEONFORK;
>> break;
>> + case MADV_DOEXEC:
>
> For me MADV_KEEPONEXEC sounds better as it's symmetric to MADV_KEEPONFORK.
We chose MADV_DOEXEC and MADV_DONTEXEC to match the precedent set by:
#define MADV_DONTFORK 10 /* don't inherit across fork */
#define MADV_DOFORK 11 /* do inherit across fork */
I do like "keep" as a concise description of the operation. KEEPONFORK is not a perfect
analog because its opposite is wipe ...
#define MADV_WIPEONFORK 18 /* Zero memory on fork, child only */
#define MADV_KEEPONFORK 19 /* Undo MADV_WIPEONFORK */
... but if folks are ok with that then IMO these are all good choices:
MADV_KEEPONEXEC
MADV_DROPONEXEC
MADV_KEEPEXEC (shorter)
MADV_DROPEXEC
MADV_KEEP_EXEC (more legible, but no existing MADV names use 2nd underscores)
MADV_DROP_EXEC
Whatever folks like best.
- Steve
>> + /*
>> + * MADV_DOEXEC is only supported on private, non-executable,
>> + * non-stack anonymous memory and if the VM_EXEC_KEEP flag
>> + * is available.
>> + */
>> + if (!VM_EXEC_KEEP || vma->vm_file || vma->vm_flags & (VM_EXEC|VM_SHARED|VM_STACK)) {
>> + error = -EINVAL;
>> + goto out;
>> + }
>> + new_flags |= (new_flags & ~VM_MAYEXEC) | VM_EXEC_KEEP;
>> + break;
>> + case MADV_DONTEXEC:
>> + if (!VM_EXEC_KEEP) {
>> + error = -EINVAL;
>> + goto out;
>> + }
>> + if (new_flags & VM_EXEC_KEEP)
>> + new_flags |= (new_flags & ~VM_EXEC_KEEP) | VM_MAYEXEC;
>> + break;
>> case MADV_DONTDUMP:
>> new_flags |= VM_DONTDUMP;
>> break;
>> @@ -983,6 +1003,8 @@ static int madvise_inject_error(int behavior,
>> case MADV_SOFT_OFFLINE:
>> case MADV_HWPOISON:
>> #endif
>> + case MADV_DOEXEC:
>> + case MADV_DONTEXEC:
>> return true;
>>
>> default:
>> @@ -1037,6 +1059,9 @@ static int madvise_inject_error(int behavior,
>> * MADV_DONTDUMP - the application wants to prevent pages in the given range
>> * from being included in its core dump.
>> * MADV_DODUMP - cancel MADV_DONTDUMP: no longer exclude from core dump.
>> + * MADV_DOEXEC - On exec, preserve and duplicate this area in the new process
>> + * if the new process allows it.
>> + * MADV_DONTEXEC - Undo the effect of MADV_DOEXEC.
>> *
>> * return values:
>> * zero - success
>>
>
next prev parent reply other threads:[~2020-07-28 14:07 UTC|newest]
Thread overview: 48+ 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
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 [this message]
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
2020-08-03 8:32 ` David Laight
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
2020-08-04 8:44 ` David Laight
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
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