From ecf724116488651a0dba3880fb89aca308e2251b Mon Sep 17 00:00:00 2001
From: dzwdz
Date: Tue, 24 Jan 2023 16:09:14 +0100
Subject: kernel/procfs: allow reading memory of descendants

I'm suprised how short this patch is. It also feels like I've
introducted a vulnerability somewhere with it. Hopefully it's a false
feeling.
---
 src/kernel/vfs/procfs.c  | 11 +++++++++++
 src/user/app/init/init.c |  3 ++-
 2 files changed, 13 insertions(+), 1 deletion(-)

diff --git a/src/kernel/vfs/procfs.c b/src/kernel/vfs/procfs.c
index 7ca8c14..a417606 100644
--- a/src/kernel/vfs/procfs.c
+++ b/src/kernel/vfs/procfs.c
@@ -9,6 +9,7 @@
 enum phandle_type {
 	PhDir,
 	PhIntr,
+	PhMem,
 };
 
 struct phandle {
@@ -57,6 +58,8 @@ openpath(const char *path, size_t len, struct process *p)
 		type = PhDir;
 	} else if (len == 4 && memcmp(path, "intr", 4) == 0) {
 		type = PhIntr;
+	} else if (len == 3 && memcmp(path, "mem", 3) == 0) {
+		type = PhMem;
 	} else {
 		return NULL;
 	}
@@ -105,6 +108,7 @@ procfs_accept(struct vfs_request *req)
 			return;
 		}
 		pos += snprintf(buf + pos, 512 - pos, "intr")+1;
+		pos += snprintf(buf + pos, 512 - pos, "mem")+1;
 		for (struct process *iter = p->child; iter; iter = iter->sibling) {
 			assert(pos < 512);
 			// processes could possibly be identified by unique identifiers instead
@@ -118,6 +122,13 @@ procfs_accept(struct vfs_request *req)
 		assert(0 <= pos && (size_t)pos <= sizeof buf);
 		virt_cpy_to(req->caller->pages, req->output.buf, buf, pos);
 		vfsreq_finish_short(req, pos);
+	} else if (req->type == VFSOP_READ && h->type == PhMem) {
+		size_t res = virt_cpy(
+				req->caller->pages, req->output.buf,
+				p->pages, (__user void*)req->offset,
+				req->output.len, NULL
+		);
+		vfsreq_finish_short(req, res);
 	} else if (req->type == VFSOP_WRITE && h->type == PhIntr) {
 		process_intr(p);
 		vfsreq_finish_short(req, req->input.len);
diff --git a/src/user/app/init/init.c b/src/user/app/init/init.c
index 0114ac5..73e863e 100644
--- a/src/user/app/init/init.c
+++ b/src/user/app/init/init.c
@@ -36,11 +36,12 @@ void redirect(const char *exe, const char *out, const char *in) {
 }
 
 int main(void) {
+	const char *teststr = "I am teststr.\n";
 	handle_t killswitch_pipe[2];
 
 	freopen("/kdev/com1", "a+", stdout);
 	freopen("/kdev/com1", "a+", stderr);
-	printf("[init] stage 2, main at %p\n", &main);
+	printf("[init] stage 2, main at %p, testtr at %p\n", &main, teststr);
 
 	MOUNT_AT("/keyboard") {
 		MOUNT_AT("/") { fs_whitelist((const char*[]){"/kdev/ps2/kb", NULL}); }
-- 
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