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https://github.com/checkpoint-restore/criu
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d7c86c8b02
Flag `noexecstack' for ld implies `EXSTACK_DISABLE_X' ELF flag on CRIU binary. Without this flag the kernel ELF loader will set `READ_IMPLIES_EXEC' personality bit: > if (elf_read_implies_exec(loc->elf_ex, executable_stack)) > current->personality |= READ_IMPLIES_EXEC; This flag is checked by sys_mmap(): > if ((prot & PROT_READ) && (current->personality & READ_IMPLIES_EXEC)) > if (!(file && path_noexec(&file->f_path))) > prot |= PROT_EXEC; Which results in each mmap() syscall returning +x mapping for any readable mapping for CRIU binary, e.g: Before C/R: 76fc4000-76fc5000 r--p 0001f000 b3:02 131656 /usr/lib/ld-2.25.so 76fc5000-76fc6000 rw-p 00020000 b3:02 131656 /usr/lib/ld-2.25.so After restore: 76fc4000-76fc5000 r-xp 0001f000 b3:02 131656 /usr/lib/ld-2.25.so 76fc5000-76fc6000 rwxp 00020000 b3:02 131656 /usr/lib/ld-2.25.so Which also makes ZDTM very sad: 1: Old maps lost: set(["76f80000-76f81000 ['rw-p', '0120400']", "25000-26000 ['rw-p', '0120400']", "76f7d000-76f7f000 ['rw-p']", "14a8000-14c9000 ['rw-p']", "76f4a000-76f4c000 ['r--p', '0120400']", "7ed3d000-7ed7f000 ['rw-p']", "76f7f000-76f80000 ['r--p', '0120400']", "24000-25000 ['r--p', '0120400']", "76f4c000-76f50000 ['rw-p', '0120400']"]) 1: New maps appeared: set(["76f7f000-76f80000 ['r-xp', '0120400']", "7ed3d000-7ed7f000 ['rwxp']", "76f4a000-76f4c000 ['r-xp', '0120400']", "76f80000-76f81000 ['rwxp', '0120400']", "24000-25000 ['r-xp', '0120400']", "14a8000-14c9000 ['rwxp']", "25000-26000 ['rwxp', '0120400']", "76f7d000-76f7f000 ['rwxp']", "76f4c000-76f50000 ['rwxp', '0120400']"]) Maybe we also need to set it for arm64 or even for all archs, but that needs to be tested in the first place, so add it now to arm32, x86 already has it. Acked-by: Cyrill Gorcunov <gorcunov@openvz.org> Signed-off-by: Dmitry Safonov <dsafonov@virtuozzo.com> Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>
CRIU (Checkpoint and Restore in Userspace)
An utility to checkpoint/restore tasks. Using this tool, you can freeze a running application (or part of it) and checkpoint it to a hard drive as a collection of files. You can then use the files to restore and run the application from the point it was frozen at. The distinctive feature of the CRIU project is that it is mainly implemented in user space.
The project home is at http://criu.org.
Pages worth starting with are:
- Kernel configuration, compilation, etc
- A simple example of usage
- More sophisticated example with graphical app
A video tour on basic CRIU features
How to contribute
- How to submit patches;
- Send all bug reports to mailing list;
- Spread the word about CRIU in social networks;