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    Subject[PATCH RFC 1/5] mm: Add process_vm_mmap() syscall declaration
    From
    Date
    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.

    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 4cd5f982b1e5..bf8cc5de918f 100644
    --- a/arch/x86/entry/syscalls/syscall_32.tbl
    +++ b/arch/x86/entry/syscalls/syscall_32.tbl
    @@ -438,3 +438,4 @@
    425 i386 io_uring_setup sys_io_uring_setup __ia32_sys_io_uring_setup
    426 i386 io_uring_enter sys_io_uring_enter __ia32_sys_io_uring_enter
    427 i386 io_uring_register sys_io_uring_register __ia32_sys_io_uring_register
    +428 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 64ca0d06259a..5af619c2d512 100644
    --- a/arch/x86/entry/syscalls/syscall_64.tbl
    +++ b/arch/x86/entry/syscalls/syscall_64.tbl
    @@ -355,6 +355,7 @@
    425 common io_uring_setup __x64_sys_io_uring_setup
    426 common io_uring_enter __x64_sys_io_uring_enter
    427 common io_uring_register __x64_sys_io_uring_register
    +428 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 dee7292e1df6..1273d86bf546 100644
    --- a/include/uapi/asm-generic/unistd.h
    +++ b/include/uapi/asm-generic/unistd.h
    @@ -832,9 +832,12 @@ __SYSCALL(__NR_io_uring_setup, sys_io_uring_setup)
    __SYSCALL(__NR_io_uring_enter, sys_io_uring_enter)
    #define __NR_io_uring_register 427
    __SYSCALL(__NR_io_uring_register, sys_io_uring_register)
    +#define __NR_process_vm_mmap 428
    +__SC_COMP(__NR_process_vm_mmap, sys_process_vm_mmap, \
    + compat_sys_process_vm_mmap)

    #undef __NR_syscalls
    -#define __NR_syscalls 428
    +#define __NR_syscalls 429

    /*
    * 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);
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