From 12dd3dc0894fa592233111e4dca1796638bf0da3 Mon Sep 17 00:00:00 2001
From: Matheus <matheusuky@gmail.com>
Date: Sun, 25 Aug 2024 11:58:09 -0300
Subject: [PATCH] mmap: check file permissions before allowing it to be mapped

---
 kernel-src/sys/syscalls/mmap.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/kernel-src/sys/syscalls/mmap.c b/kernel-src/sys/syscalls/mmap.c
index d0b0fd02..27b163d6 100644
--- a/kernel-src/sys/syscalls/mmap.c
+++ b/kernel-src/sys/syscalls/mmap.c
@@ -68,6 +68,14 @@ syscallret_t syscall_mmap(context_t *context, void *hint, size_t len, int prot,
 			return ret;
 		}
 
+		int type = file->vnode->type;
+		if ((type != V_TYPE_REGULAR && type != V_TYPE_BLKDEV && type != V_TYPE_CHDEV)
+			|| ((prot & PROT_READ) && (file->flags & FILE_READ) == 0)
+			|| ((flags & MAP_SHARED) && (prot & PROT_WRITE) && (file->flags & FILE_WRITE) == 0)) {
+			ret.errno = EACCES;
+			goto cleanup;
+		}
+
 		vfd.node = file->vnode;
 		vfd.offset = offset;
 	}
@@ -79,6 +87,7 @@ syscallret_t syscall_mmap(context_t *context, void *hint, size_t len, int prot,
 	if (ret.ret == 0)
 		ret.errno = ENOMEM;
 
+	cleanup:
 	if (isfile)
 		fd_release(file);