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