x86: hook up execveat system call

Hook up x86-64, i386 and x32 ABIs.

Signed-off-by: David Drysdale <drysdale@google.com>
Cc: Meredydd Luff <meredydd@senatehouse.org>
Cc: Shuah Khan <shuah.kh@samsung.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Kees Cook <keescook@chromium.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Rich Felker <dalias@aerifal.cx>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: Michael Kerrisk <mtk.manpages@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

arch/x86/ia32/audit.c

@@ -35,6 +35,7 @@ int ia32_classify_syscall(unsigned syscall)
 	case __NR_socketcall:
 		return 4;
 	case __NR_execve:
+	case __NR_execveat:
 		return 5;
 	default:
 		return 1;

arch/x86/ia32/ia32entry.S

@@ -480,6 +480,7 @@ GLOBAL(\label)
 	PTREGSCALL stub32_rt_sigreturn, sys32_rt_sigreturn
 	PTREGSCALL stub32_sigreturn, sys32_sigreturn
 	PTREGSCALL stub32_execve, compat_sys_execve
+	PTREGSCALL stub32_execveat, compat_sys_execveat
 	PTREGSCALL stub32_fork, sys_fork
 	PTREGSCALL stub32_vfork, sys_vfork
 

arch/x86/kernel/audit_64.c

@@ -50,6 +50,7 @@ int audit_classify_syscall(int abi, unsigned syscall)
 	case __NR_openat:
 		return 3;
 	case __NR_execve:
+	case __NR_execveat:
 		return 5;
 	default:
 		return 0;

arch/x86/kernel/entry_64.S

@@ -652,6 +652,20 @@ ENTRY(stub_execve)
 	CFI_ENDPROC
 END(stub_execve)
 
+ENTRY(stub_execveat)
+	CFI_STARTPROC
+	addq $8, %rsp
+	PARTIAL_FRAME 0
+	SAVE_REST
+	FIXUP_TOP_OF_STACK %r11
+	call sys_execveat
+	RESTORE_TOP_OF_STACK %r11
+	movq %rax,RAX(%rsp)
+	RESTORE_REST
+	jmp int_ret_from_sys_call
+	CFI_ENDPROC
+END(stub_execveat)
+
 /*
  * sigreturn is special because it needs to restore all registers on return.
  * This cannot be done with SYSRET, so use the IRET return path instead.
@@ -697,6 +711,20 @@ ENTRY(stub_x32_execve)
 	CFI_ENDPROC
 END(stub_x32_execve)
 
+ENTRY(stub_x32_execveat)
+	CFI_STARTPROC
+	addq $8, %rsp
+	PARTIAL_FRAME 0
+	SAVE_REST
+	FIXUP_TOP_OF_STACK %r11
+	call compat_sys_execveat
+	RESTORE_TOP_OF_STACK %r11
+	movq %rax,RAX(%rsp)
+	RESTORE_REST
+	jmp int_ret_from_sys_call
+	CFI_ENDPROC
+END(stub_x32_execveat)
+
 #endif
 
 /*

arch/x86/syscalls/syscall_32.tbl

@@ -364,3 +364,4 @@
 355	i386	getrandom		sys_getrandom
 356	i386	memfd_create		sys_memfd_create
 357	i386	bpf			sys_bpf
+358	i386	execveat		sys_execveat			stub32_execveat

arch/x86/syscalls/syscall_64.tbl

@@ -328,6 +328,7 @@
 319	common	memfd_create		sys_memfd_create
 320	common	kexec_file_load		sys_kexec_file_load
 321	common	bpf			sys_bpf
+322	64	execveat		stub_execveat
 
 #
 # x32-specific system call numbers start at 512 to avoid cache impact
@@ -366,3 +367,4 @@
 542	x32	getsockopt		compat_sys_getsockopt
 543	x32	io_setup		compat_sys_io_setup
 544	x32	io_submit		compat_sys_io_submit
+545	x32	execveat		stub_x32_execveat

arch/x86/um/sys_call_table_64.c

@@ -31,6 +31,7 @@
 #define stub_fork sys_fork
 #define stub_vfork sys_vfork
 #define stub_execve sys_execve
+#define stub_execveat sys_execveat
 #define stub_rt_sigreturn sys_rt_sigreturn
 
 #define __SYSCALL_COMMON(nr, sym, compat) __SYSCALL_64(nr, sym, compat)