Re: [PATCH v2 1/7] mm: Add process_vm_mmap() syscall declaration

Ira Weiny
2019-05-21T00:28:27Z

On Mon, May 20, 2019 at 05:00:07PM +0300, Kirill Tkhai wrote:
> Similar to process_vm_readv() and process_vm_writev(),
> add declarations of a new syscall, which will allow
> to map memory from or to another process.

Shouldn't this be the last patch in the series so that the syscall is actually
implemented first?

Ira

>
> Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
> ---
> arch/x86/entry/syscalls/syscall_32.tbl | 1 +
> arch/x86/entry/syscalls/syscall_64.tbl | 2 ++
> include/linux/syscalls.h | 5 +++++
> include/uapi/asm-generic/unistd.h | 5 ++++-
> init/Kconfig | 9 +++++----
> kernel/sys_ni.c | 2 ++
> 6 files changed, 19 insertions(+), 5 deletions(-)
>
> diff --git a/arch/x86/entry/syscalls/syscall_32.tbl b/arch/x86/entry/syscalls/syscall_32.tbl
> index ad968b7bac72..99d6e0085576 100644
> --- a/arch/x86/entry/syscalls/syscall_32.tbl
> +++ b/arch/x86/entry/syscalls/syscall_32.tbl
> @@ -438,3 +438,4 @@
> 431 i386 fsconfig sys_fsconfig __ia32_sys_fsconfig
> 432 i386 fsmount sys_fsmount __ia32_sys_fsmount
> 433 i386 fspick sys_fspick __ia32_sys_fspick
> +434 i386 process_vm_mmap sys_process_vm_mmap __ia32_compat_sys_process_vm_mmap
> diff --git a/arch/x86/entry/syscalls/syscall_64.tbl b/arch/x86/entry/syscalls/syscall_64.tbl
> index b4e6f9e6204a..46d7d2898f7a 100644
> --- a/arch/x86/entry/syscalls/syscall_64.tbl
> +++ b/arch/x86/entry/syscalls/syscall_64.tbl
> @@ -355,6 +355,7 @@
> 431 common fsconfig __x64_sys_fsconfig
> 432 common fsmount __x64_sys_fsmount
> 433 common fspick __x64_sys_fspick
> +434 common process_vm_mmap __x64_sys_process_vm_mmap
>
> #
> # x32-specific system call numbers start at 512 to avoid cache impact
> @@ -398,3 +399,4 @@
> 545 x32 execveat __x32_compat_sys_execveat/ptregs
> 546 x32 preadv2 __x32_compat_sys_preadv64v2
> 547 x32 pwritev2 __x32_compat_sys_pwritev64v2
> +548 x32 process_vm_mmap __x32_compat_sys_process_vm_mmap
> diff --git a/include/linux/syscalls.h b/include/linux/syscalls.h
> index e2870fe1be5b..7d8ae36589cf 100644
> --- a/include/linux/syscalls.h
> +++ b/include/linux/syscalls.h
> @@ -997,6 +997,11 @@ asmlinkage long sys_fspick(int dfd, const char __user *path, unsigned int flags)
> asmlinkage long sys_pidfd_send_signal(int pidfd, int sig,
> siginfo_t __user *info,
> unsigned int flags);
> +asmlinkage long sys_process_vm_mmap(pid_t pid,
> + unsigned long src_addr,
> + unsigned long len,
> + unsigned long dst_addr,
> + unsigned long flags);
>
> /*
> * Architecture-specific system calls
> diff --git a/include/uapi/asm-generic/unistd.h b/include/uapi/asm-generic/unistd.h
> index a87904daf103..b7aaa5ae02da 100644
> --- a/include/uapi/asm-generic/unistd.h
> +++ b/include/uapi/asm-generic/unistd.h
> @@ -844,9 +844,12 @@ __SYSCALL(__NR_fsconfig, sys_fsconfig)
> __SYSCALL(__NR_fsmount, sys_fsmount)
> #define __NR_fspick 433
> __SYSCALL(__NR_fspick, sys_fspick)
> +#define __NR_process_vm_mmap 424
> +__SC_COMP(__NR_process_vm_mmap, sys_process_vm_mmap, \
> + compat_sys_process_vm_mmap)
>
> #undef __NR_syscalls
> -#define __NR_syscalls 434
> +#define __NR_syscalls 435
>
> /*
> * 32 bit systems traditionally used different
> diff --git a/init/Kconfig b/init/Kconfig
> index 8b9ffe236e4f..604db5f14718 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -320,13 +320,14 @@ config POSIX_MQUEUE_SYSCTL
> default y
>
> config CROSS_MEMORY_ATTACH
> - bool "Enable process_vm_readv/writev syscalls"
> + bool "Enable process_vm_readv/writev/mmap syscalls"
> depends on MMU
> default y
> help
> - Enabling this option adds the system calls process_vm_readv and
> - process_vm_writev which allow a process with the correct privileges
> - to directly read from or write to another process' address space.
> + Enabling this option adds the system calls process_vm_readv,
> + process_vm_writev and process_vm_mmap, which allow a process
> + with the correct privileges to directly read from or write to
> + or mmap another process' address space.
> See the man page for more details.
>
> config USELIB
> diff --git a/kernel/sys_ni.c b/kernel/sys_ni.c
> index 4d9ae5ea6caf..6f51634f4f7e 100644
> --- a/kernel/sys_ni.c
> +++ b/kernel/sys_ni.c
> @@ -316,6 +316,8 @@ COND_SYSCALL(process_vm_readv);
> COND_SYSCALL_COMPAT(process_vm_readv);
> COND_SYSCALL(process_vm_writev);
> COND_SYSCALL_COMPAT(process_vm_writev);
> +COND_SYSCALL(process_vm_mmap);
> +COND_SYSCALL_COMPAT(process_vm_mmap);
>
> /* compare kernel pointers */
> COND_SYSCALL(kcmp);
>