From 0e433c11a21e58cc8ce28cef97bf96aad3523d4d Mon Sep 17 00:00:00 2001
From: mothcompute <mothcompute@protonmail.com>
Date: Tue, 28 Nov 2023 11:34:13 -0800
Subject: [PATCH] libc cleanup

---
 main.c | 54 +++++++++++++++++++++++++----------------------
 th.s   | 66 ----------------------------------------------------------
 2 files changed, 29 insertions(+), 91 deletions(-)

diff --git a/main.c b/main.c
index f60a3c3..26bf63e 100644
--- a/main.c
+++ b/main.c
@@ -11,10 +11,8 @@
 
 #define SYSCT_FBSD 588
 
-extern void trap(gregset_t);
 extern void cat(int fd, long sz);
-extern uint32_t trapsz;
-extern uint8_t sel;
+uint8_t sel = SYSCALL_DISPATCH_FILTER_ALLOW;
 
 uint16_t scmap[SYSCT_FBSD] = {
 	-1, // SYS_syscall needs args shifted
@@ -30,11 +28,31 @@ uint16_t scmap[SYSCT_FBSD] = {
 	SYS_unlink,
 	-1, // [obsolete] execv
 	SYS_chdir,
-	SYS_fchdir
+	SYS_fchdir,
+	-1, // [freebsd11] mknod
+	SYS_chmod,
+	SYS_chown,
+	-1, // break (no manual)
+	-1, // [freebsd4] getfsstat
+	-1, // [old] lseek
+	SYS_getpid,
 };
 
-void ftrp(int n, siginfo_t* s, ucontext_t* c) {
+// TODO also create trampoline for freebsd native signals
+void systrap(int n, siginfo_t* s, ucontext_t* c) {
 	sel = SYSCALL_DISPATCH_FILTER_ALLOW;
+	if(s->si_code != /* SYS_USER_DISPATCH - value from <asm-generic/siginfo.h> */ 2) {
+		// TODO chain old syscall handler
+	} else if(s->si_syscall > SYSCT_FBSD-1) {
+		// TODO fail - check how freebsd does this, esp. with nosys entries
+	} else if(scmap[s->si_syscall] == -1) {
+		switch(s->si_syscall) {
+			default:
+				abort();
+				break;
+		}
+	}
+	// TODO find max arg ct. and check stack if needed
 	c->uc_mcontext.gregs[13] = syscall(
 		scmap[s->si_syscall],
 		c->uc_mcontext.gregs[8],	
@@ -42,9 +60,7 @@ void ftrp(int n, siginfo_t* s, ucontext_t* c) {
 		c->uc_mcontext.gregs[12]	
 	);
 	//for(int i = 0; i < 23; i++) printf("%i: %lX\n", i, c->uc_mcontext.gregs[i]);
-	//printf("%u\n", s->si_arch);
 	sel = SYSCALL_DISPATCH_FILTER_BLOCK;
-	//trap(c->uc_mcontext.gregs);
 }
 
 typedef struct {
@@ -134,12 +150,12 @@ int main(int argc, char** argv) {
 	struct sigaction a, oa;
 	sigemptyset(&a.sa_mask);
 	a.sa_flags = SA_SIGINFO;
-	a.sa_sigaction = ftrp;
-	sigaction(SIGSYS, &a, &oa);
-	sel = SYSCALL_DISPATCH_FILTER_ALLOW;
+	a.sa_sigaction = (void(*)(int, siginfo_t*, void*))systrap;
 
 	int nm;
 	char** smaps = getmaps(&nm);
+
+	// TODO RW to only call stomap if strstr libc - saves memory and cycles
 	map maps[nm-1];
 	for(int i = 0; i < nm-1; i++) {
 		stomap(smaps[i], maps + i);
@@ -160,29 +176,17 @@ int main(int argc, char** argv) {
 			".X"[(maps[i].rwx >> 0) & 1]
 		);
 		*/
-		if(	(
-			strstr(maps[i].name, "libc")
-			//||strstr(maps[i].name, "ld-linux") ||
-			//strstr(maps[i].name, "fl") ||
-			//!strcmp(maps[i].name, "[vdso]") ||
-			//!strcmp(maps[i].name, "[vsyscall]")
-			) && (maps[i].rwx & 1)
-		) {
-			prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, maps[i].start, maps[i].len, &sel);
-		//	printf("enable sud bypass\n");
-		}
-		//printf("\n");
+		if(strstr(maps[i].name, "libc") && (maps[i].rwx & 1)) prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, maps[i].start, maps[i].len, &sel);
 	}
 	for(int i = 0; i < nm; i++) free(smaps[i]);
 	free(smaps);
+	// END RW
 
 	if(argc < 2) return printf("no file provided\n");
 	int fd = open(argv[1], O_RDONLY);
 	struct stat s;
 	fstat(fd, &s);
-	//printf("start cat() with freebsd syscalls\n");
-	//prctl(PR_SET_SYSCALL_USER_DISPATCH, PR_SYS_DISPATCH_ON, trap, trapsz, &sel);
-	//write(1, "fghgfgfg\n", 9);
+	sigaction(SIGSYS, &a, &oa);
 	sel = SYSCALL_DISPATCH_FILTER_BLOCK;
 	cat(fd, s.st_size);
 }
diff --git a/th.s b/th.s
index 3499db3..5d1e883 100644
--- a/th.s
+++ b/th.s
@@ -1,79 +1,13 @@
 bits 64
 default rel
 
-global trap
-global trapsz
 global cat
-global sel
-
-extern scmap
 
 section .data
-sel: db 1
-trapsz: dd cat-trap;
 buf: db 0
 
 section .text
 
-trap:
-	;mov rax, 60
-	;syscall
-	push r8
-	push r9
-	push r10
-	push r11
-	push r12
-	push r13
-	push r14
-	push r15
-	push rsi
-	push rbp
-	push rbx
-	push rdx
-	push rcx
-
-	mov r8, [rdi]
-	mov r9, [rdi+8]
-	mov r10, [rdi+16]
-	mov r11, [rdi+24]
-	mov r12, [rdi+32]
-	mov r13, [rdi+40]
-	mov r14, [rdi+48]
-	mov r15, [rdi+56]
-	mov rsi, [rdi+72]
-	mov rbp, [rdi+80]
-	mov rbx, [rdi+88]
-	mov rdx, [rdi+96]
-	mov rax, [rdi+104]
-	mov rcx, [rdi+112]
-
-	mov rdi, [rdi+64]
-	syscall
-	
-	pop rcx
-	pop rdx
-	pop rbx
-	pop rbp
-	pop rsi
-	pop r15
-	pop r14
-	pop r13
-	pop r12
-	pop r11
-	pop r10
-	pop r9
-	pop r8
-	ret
-
-
-
-	push rbx
-	;mov ax, word [rel scmap + 2*eax]
-	lea rbx, [scmap]
-	lea rax, [rbx + 2*rax]
-	movzx eax, ax
-	pop rbx
-	ret
 cat:
 	push r12
 	push rbx