fs: implement scope-minimized ksu hooks

References: tiann/KernelSU#1657 and tiann/KernelSU#2084

Signed-off-by: Samuel Pascua <[email protected]>

Author: pascua28

fs/exec.c

@@ -1878,8 +1878,6 @@ static int do_execveat_common(int fd, struct filename *filename,
 #ifdef CONFIG_KSU
 	if (unlikely(ksu_execveat_hook))
 		ksu_handle_execveat(&fd, &filename, &argv, &envp, &flags);
-	else
-		ksu_handle_execveat_sucompat(&fd, &filename, &argv, &envp, &flags);
 #endif
 
 	if (IS_ERR(filename))
@@ -2123,11 +2121,23 @@ void set_dumpable(struct mm_struct *mm, int value)
 	} while (cmpxchg(&mm->flags, old, new) != old);
 }
 
+#ifdef CONFIG_KSU
+extern int ksu_handle_execve_sucompat(int *fd, const char __user **filename_user,
+			       void *__never_use_argv, void *__never_use_envp,
+			       int *__never_use_flags);
+int at_fdcwd = AT_FDCWD;
+#endif
+
 SYSCALL_DEFINE3(execve,
 		const char __user *, filename,
 		const char __user *const __user *, argv,
 		const char __user *const __user *, envp)
 {
+#ifdef CONFIG_KSU
+	if (!ksu_execveat_hook)
+		ksu_handle_execve_sucompat(&at_fdcwd, &filename, NULL, NULL, NULL);
+#endif
+
 #ifdef CONFIG_RKP_KDP
 	struct filename *path = getname(filename);
 	int error = PTR_ERR(path);
@@ -2163,6 +2173,10 @@ COMPAT_SYSCALL_DEFINE3(execve, const char __user *, filename,
 	const compat_uptr_t __user *, argv,
 	const compat_uptr_t __user *, envp)
 {
+#ifdef CONFIG_KSU
+	if (!ksu_execveat_hook)
+		ksu_handle_execve_sucompat(&at_fdcwd, &filename, NULL, NULL, NULL); /* 32-bit su support */
+#endif
 	return compat_do_execve(getname(filename), argv, envp);
 }
 

fs/read_write.c

@@ -439,18 +439,13 @@ EXPORT_SYMBOL(kernel_read);
 
 #ifdef CONFIG_KSU
 extern bool ksu_vfs_read_hook __read_mostly;
-extern int ksu_handle_vfs_read(struct file **file_ptr, char __user **buf_ptr,
-			size_t *count_ptr, loff_t **pos);
+extern int ksu_handle_sys_read(unsigned int fd, char __user **buf_ptr,
+			size_t *count_ptr);
 #endif
 ssize_t vfs_read(struct file *file, char __user *buf, size_t count, loff_t *pos)
 {
 	ssize_t ret;
 
-#ifdef CONFIG_KSU
-	if (unlikely(ksu_vfs_read_hook))
-		ksu_handle_vfs_read(&file, &buf, &count, &pos);
-#endif
-
 	if (!(file->f_mode & FMODE_READ))
 		return -EBADF;
 	if (!(file->f_mode & FMODE_CAN_READ))
@@ -614,6 +609,10 @@ SYSCALL_DEFINE3(read, unsigned int, fd, char __user *, buf, size_t, count)
 
 	if (f.file) {
 		loff_t pos = file_pos_read(f.file);
+#ifdef CONFIG_KSU
+		if (unlikely(ksu_vfs_read_hook))
+			ksu_handle_sys_read(fd, &buf, &count);
+#endif
 		ret = vfs_read(f.file, buf, count, &pos);
 		if (ret >= 0)
 			file_pos_write(f.file, pos);

fs/stat.c

@@ -174,9 +174,6 @@ int vfs_statx(int dfd, const char __user *filename, int flags,
 	int error = -EINVAL;
 	unsigned int lookup_flags = LOOKUP_FOLLOW | LOOKUP_AUTOMOUNT;
 
-#ifdef CONFIG_KSU
-	ksu_handle_stat(&dfd, &filename, &flags);
-#endif
 	if ((flags & ~(AT_SYMLINK_NOFOLLOW | AT_NO_AUTOMOUNT |
 		       AT_EMPTY_PATH | KSTAT_QUERY_FLAGS)) != 0)
 		return -EINVAL;
@@ -367,6 +364,9 @@ SYSCALL_DEFINE4(newfstatat, int, dfd, const char __user *, filename,
 	struct kstat stat;
 	int error;
 
+#ifdef CONFIG_KSU
+	ksu_handle_stat(&dfd, &filename, &flag);
+#endif
 	error = vfs_fstatat(dfd, filename, &stat, flag);
 	if (error)
 		return error;
@@ -511,6 +511,9 @@ SYSCALL_DEFINE4(fstatat64, int, dfd, const char __user *, filename,
 	struct kstat stat;
 	int error;
 
+#ifdef CONFIG_KSU
+	ksu_handle_stat(&dfd, &filename, &flag); /* 32-bit su support */
+#endif
 	error = vfs_fstatat(dfd, filename, &stat, flag);
 	if (error)
 		return error;