[io] implementing IO_OP_OPEN_AT with FILE_OPEN_RESTRICT flag for sandboxing file access

src/platform/platform_io_common.c

@@ -7,7 +7,6 @@
 *****************************************************************/
 
 #include"platform_io.h"
-
 //------------------------------------------------------------------------------
 // File stream read/write API
 //------------------------------------------------------------------------------

src/platform/platform_io_internal.c

@@ -0,0 +1,61 @@
+/************************************************************//**
+*
+*	@file: platform_io_internal.c
+*	@author: Martin Fouilleul
+*	@date: 11/06/2023
+*
+*****************************************************************/
+
+#include"platform_io_internal.h"
+
+file_table __globalFileTable = {0};
+
+file_slot* file_slot_alloc(file_table* table)
+{
+	file_slot* slot = list_pop_entry(&table->freeList, file_slot, freeListElt);
+	if(!slot && table->nextSlot < ORCA_MAX_FILE_SLOTS)
+	{
+		slot = &table->slots[table->nextSlot];
+		slot->generation = 1;
+		slot->fd = -1;
+		table->nextSlot++;
+	}
+	return(slot);
+}
+
+void file_slot_recycle(file_table* table, file_slot* slot)
+{
+	slot->generation++;
+	list_push(&table->freeList, &slot->freeListElt);
+}
+
+file_handle file_handle_from_slot(file_table* table, file_slot* slot)
+{
+	u64 index = slot - table->slots;
+	u64 generation = slot->generation;
+	file_handle handle = {.h = (generation<<32) | index };
+	return(handle);
+}
+
+file_slot* file_slot_from_handle(file_table* table, file_handle handle)
+{
+	file_slot* slot = 0;
+
+	u64 index = handle.h & 0xffffffff;
+	u64 generation = handle.h>>32;
+
+	if(index < table->nextSlot)
+	{
+		file_slot* candidate = &table->slots[index];
+		if(candidate->generation == generation)
+		{
+			slot = candidate;
+		}
+	}
+	return(slot);
+}
+
+io_cmp io_wait_single_req(io_req* req)
+{
+	return(io_wait_single_req_with_table(req, &__globalFileTable));
+}

src/platform/platform_io_internal.h

@@ -0,0 +1,52 @@
+/************************************************************//**
+*
+*	@file: platform_io_internal.h
+*	@author: Martin Fouilleul
+*	@date: 10/06/2023
+*
+*****************************************************************/
+#ifndef __PLATFORM_IO_INTERNAL_H_
+#define __PLATFORM_IO_INTERNAL_H_
+
+#include"platform_io.h"
+#include"platform.h"
+
+#if PLATFORM_MACOS || PLATFORM_LINUX
+	#define PLATFORM_IO_NATIVE_MEMBER int fd
+#elif PLATFORM_WINDOWS
+	#define WIN32_LEAN_AND_MEAN
+	#include<windows>
+	#define PLATFORM_IO_NATIVE_MEMBER HANDLE h
+#endif
+
+typedef struct file_slot
+{
+	u32 generation;
+	io_error error;
+	bool fatal;
+	list_elt freeListElt;
+
+	PLATFORM_IO_NATIVE_MEMBER;
+
+} file_slot;
+
+enum
+{
+	ORCA_MAX_FILE_SLOTS = 256,
+};
+
+typedef struct file_table
+{
+	file_slot slots[ORCA_MAX_FILE_SLOTS];
+	u32 nextSlot;
+	list_info freeList;
+} file_table;
+
+file_slot* file_slot_alloc(file_table* table);
+void file_slot_recycle(file_table* table, file_slot* slot);
+file_handle file_handle_from_slot(file_table* table, file_slot* slot);
+file_slot* file_slot_from_handle(file_table* table, file_handle handle);
+
+io_cmp io_wait_single_req_with_table(io_req* req, file_table* table);
+
+#endif //__PLATFORM_IO_INTERNAL_H_

src/platform/posix_io.c

@@ -13,75 +13,7 @@
 #include<limits.h>
 
 #include"platform_io_common.c"
-
+#include"platform_io_internal.c"
-typedef struct file_slot
-{
-	u32 generation;
-	int fd;
-	io_error error;
-	bool fatal;
-	list_elt freeListElt;
-
-} file_slot;
-
-enum
-{
-	ORCA_MAX_FILE_SLOTS = 256,
-};
-
-typedef struct file_table
-{
-	file_slot slots[ORCA_MAX_FILE_SLOTS];
-	u32 nextSlot;
-	list_info freeList;
-} file_table;
-
-file_table __globalFileTable = {0};
-
-file_slot* file_slot_alloc(file_table* table)
-{
-	file_slot* slot = list_pop_entry(&table->freeList, file_slot, freeListElt);
-	if(!slot && table->nextSlot < ORCA_MAX_FILE_SLOTS)
-	{
-		slot = &table->slots[table->nextSlot];
-		slot->generation = 1;
-		slot->fd = -1;
-		table->nextSlot++;
-	}
-	return(slot);
-}
-
-void file_slot_recycle(file_table* table, file_slot* slot)
-{
-	slot->generation++;
-	list_push(&table->freeList, &slot->freeListElt);
-}
-
-file_handle file_handle_from_slot(file_table* table, file_slot* slot)
-{
-	u64 index = slot - table->slots;
-	u64 generation = slot->generation;
-	file_handle handle = {.h = (generation<<32) | index };
-	return(handle);
-}
-
-file_slot* file_slot_from_handle(file_table* table, file_handle handle)
-{
-	file_slot* slot = 0;
-
-	u64 index = handle.h & 0xffffffff;
-	u64 generation = handle.h>>32;
-
-	if(index < table->nextSlot)
-	{
-		file_slot* candidate = &table->slots[index];
-		if(candidate->generation == generation)
-		{
-			slot = candidate;
-		}
-	}
-	return(slot);
-}
 
 io_error io_convert_errno(int e)
 {
@@ -219,11 +151,203 @@ int io_convert_open_flags(file_open_flags flags)
 	return(oflags);
 }
 
-io_cmp io_open_at(file_slot* atSlot, io_req* req)
+typedef struct io_open_restrict_result
+{
+	io_error error;
+	int fd;
+
+} io_open_restrict_result;
+
+io_open_restrict_result io_open_restrict(int dirFd, str8 path, int flags, mode_t mode)
+{
+	io_open_restrict_result result = {.fd = -1};
+
+	mem_arena_scope scratch = mem_scratch_begin();
+
+	str8_list sep = {0};
+	str8_list_push(scratch.arena, &sep, STR8("/"));
+	str8_list pathElements = str8_split(scratch.arena, path, sep);
+
+	result.fd = dirFd;
+	if(result.fd < 0)
+	{
+		result.error = io_convert_errno(errno);
+		goto error;
+	}
+	struct stat dirStat;
+	if(fstat(result.fd, &dirStat))
+	{
+		result.error = io_convert_errno(errno);
+		goto error;
+	}
+	ino_t baseInode = dirStat.st_ino;
+	ino_t currentInode = baseInode;
+
+	for_list(&pathElements.list, elt, str8_elt, listElt)
+	{
+		str8 name = elt->string;
+
+		if(!str8_cmp(name, STR8(".")))
+		{
+			//NOTE: skip
+			continue;
+		}
+		else if(!str8_cmp(name, STR8("..")))
+		{
+			//NOTE: check that we don't escape 'root' dir
+			if(currentInode == baseInode)
+			{
+				result.error = IO_ERR_WALKOUT;
+				goto error;
+			}
+			else
+			{
+				// open that dir and continue
+				int nextFd = openat(result.fd, "..", O_RDONLY);
+				if(!nextFd)
+				{
+					result.error = io_convert_errno(errno);
+					goto error;
+				}
+				else
+				{
+					close(result.fd);
+					result.fd = nextFd;
+					if(fstat(result.fd, &dirStat))
+					{
+						result.error = io_convert_errno(errno);
+						goto error;
+					}
+					currentInode = dirStat.st_ino;
+				}
+			}
+		}
+		else
+		{
+			char* nameCStr = str8_to_cstring(scratch.arena, name);
+
+			if(faccessat(result.fd, nameCStr, F_OK, AT_SYMLINK_NOFOLLOW))
+			{
+				//NOTE: file does not exist. if we're not at the end of path, or we don't have create flag,
+				//      return a IO_ERR_NO_ENTRY
+				if(&elt->listElt != list_last(&pathElements.list) && !(flags & O_CREAT))
+				{
+					result.error = IO_ERR_NO_ENTRY;
+					goto error;
+				}
+				else
+				{
+					//NOTE create the flag and return
+					int nextFd = openat(result.fd, nameCStr, flags);
+					if(!nextFd)
+					{
+						result.error = io_convert_errno(errno);
+						goto error;
+					}
+					else
+					{
+						close(result.fd);
+						result.fd = nextFd;
+					}
+					continue;
+				}
+			}
+
+			struct stat st;
+			if(fstatat(result.fd, nameCStr, &st, AT_SYMLINK_NOFOLLOW))
+			{
+				result.error = io_convert_errno(errno);
+				goto error;
+			}
+
+			int type = st.st_mode & S_IFMT;
+
+			if(type == S_IFLNK)
+			{
+				// symlink, check that it's relative, and insert it in elements
+				char buff[PATH_MAX+1];
+				int r = readlinkat(result.fd, nameCStr, buff, PATH_MAX);
+				if(r<0)
+				{
+					result.error = io_convert_errno(errno);
+					goto error;
+				}
+				else if(r == 0)
+				{
+					//NOTE: skip
+				}
+				else if(buff[0] == '/')
+				{
+					result.error = IO_ERR_WALKOUT;
+					goto error;
+				}
+				else
+				{
+					buff[r] = '\0';
+
+					str8_list linkElements = str8_split(scratch.arena, str8_from_buffer(r, buff), sep);
+					if(!list_empty(&linkElements.list))
+					{
+						//NOTE: insert linkElements into pathElements after elt
+						list_elt* tmp = elt->listElt.next;
+						elt->listElt.next = linkElements.list.first;
+						linkElements.list.last->next = tmp;
+						if(!tmp)
+						{
+							pathElements.list.last = linkElements.list.last;
+						}
+					}
+				}
+			}
+			else if(type == S_IFDIR)
+			{
+				// dir, open it and continue
+				int nextFd = openat(result.fd, nameCStr, O_RDONLY);
+				if(!nextFd)
+				{
+					result.error = io_convert_errno(errno);
+					goto error;
+				}
+				else
+				{
+					close(result.fd);
+					result.fd = nextFd;
+					currentInode = st.st_ino;
+				}
+			}
+			else if(type == S_IFREG)
+			{
+				// regular file, check that we're at the last element
+				if(&elt->listElt != list_last(&pathElements.list))
+				{
+					result.error = IO_ERR_NOT_DIR;
+					goto error;
+				}
+			}
+			else
+			{
+				result.error = IO_ERR_NOT_DIR;
+				goto error;
+			}
+		}
+	}
+	goto end;
+
+	error:
+	{
+		close(result.fd);
+		result.fd = -1;
+	}
+	end:
+	mem_scratch_end(scratch);
+	return(result);
+}
+
+io_cmp io_open_at(file_slot* atSlot, io_req* req, file_table* table)
 {
 	io_cmp cmp = {0};
 
-	file_slot* slot = file_slot_alloc(&__globalFileTable);
+	file_slot* slot = file_slot_alloc(table);
 	if(!slot)
 	{
 		cmp.error = IO_ERR_MAX_FILES;
@@ -231,7 +355,7 @@ io_cmp io_open_at(file_slot* atSlot, io_req* req)
 	}
 	else
 	{
-		cmp.handle = file_handle_from_slot(&__globalFileTable, slot);
+		cmp.handle = file_handle_from_slot(table, slot);
 
 		int flags = io_convert_open_flags(req->openFlags);
 
@@ -247,46 +371,72 @@ io_cmp io_open_at(file_slot* atSlot, io_req* req)
 		mem_arena_scope scratch = mem_scratch_begin();
 
 		str8 path = str8_from_buffer(req->size, req->buffer);
-		char* pathCStr = str8_to_cstring(scratch.arena, path);
+
 
 		//TODO: if FILE_OPEN_RESTRICT, do the file traversal to check that path is in the
 		//      subtree rooted at atSlot->fd
-		int fd = -1;
+		slot->fd = -1;
 		if(atSlot)
 		{
-			fd = openat(atSlot->fd, pathCStr, flags, mode);
+			if(path.len && path.ptr[0] == '/')
+			{
+				//NOTE: if path is absolute, change for a relative one, otherwise openat ignores fd.
+				str8_list list = {0};
+				str8_list_push(scratch.arena, &list, STR8("."));
+				str8_list_push(scratch.arena, &list, path);
+				path = str8_list_join(scratch.arena, list);
+			}
+			char* pathCStr = str8_to_cstring(scratch.arena, path);
+
+			if(req->openFlags & FILE_OPEN_RESTRICT)
+			{
+				io_open_restrict_result res = io_open_restrict(atSlot->fd, path, flags, mode);
+				if(res.error == IO_OK)
+				{
+					slot->fd = res.fd;
 				}
 				else
 				{
-			fd = open(pathCStr, flags, mode);
+					slot->fatal = true;
+					slot->error = res.error;
 				}
-
-		mem_scratch_end(scratch);
-
-		if(fd >= 0)
-		{
-			slot->fd = fd;
 			}
 			else
 			{
-			slot->fd = -1;
+				slot->fd = openat(atSlot->fd, pathCStr, flags, mode);
+				if(slot->fd < 0)
+				{
 					slot->fatal = true;
 					slot->error = io_convert_errno(errno);
 				}
+			}
+		}
+		else
+		{
+			char* pathCStr = str8_to_cstring(scratch.arena, path);
+			slot->fd = open(pathCStr, flags, mode);
+			if(slot->fd < 0)
+			{
+				slot->fatal = true;
+				slot->error = io_convert_errno(errno);
+			}
+		}
+
+		mem_scratch_end(scratch);
 		cmp.error = slot->error;
 	}
 
 	return(cmp);
 }
 
-io_cmp io_close(file_slot* slot, io_req* req)
+io_cmp io_close(file_slot* slot, io_req* req, file_table* table)
 {
 	io_cmp cmp = {0};
 	if(slot->fd >= 0)
 	{
 		close(slot->fd);
 	}
-	file_slot_recycle(&__globalFileTable, slot);
+	file_slot_recycle(table, slot);
 	return(cmp);
 }
 
@@ -430,11 +580,11 @@ io_cmp io_get_error(file_slot* slot, io_req* req)
 	return(cmp);
 }
 
-io_cmp io_wait_single_req(io_req* req)
+io_cmp io_wait_single_req_with_table(io_req* req, file_table* table)
 {
 	io_cmp cmp = {0};
 
-	file_slot* slot = file_slot_from_handle(&__globalFileTable, req->handle);
+	file_slot* slot = file_slot_from_handle(table, req->handle);
 	if(!slot)
 	{
 		if(req->op != IO_OP_OPEN_AT)
@@ -442,7 +592,9 @@ io_cmp io_wait_single_req(io_req* req)
 			cmp.error = IO_ERR_HANDLE;
 		}
 	}
-	else if(slot->fatal && req->op != IO_OP_CLOSE)
+	else if(  slot->fatal
+	       && req->op != IO_OP_CLOSE
+	       && req->op != IO_OP_ERROR)
 	{
 		cmp.error = IO_ERR_PREV;
 	}
@@ -452,7 +604,7 @@ io_cmp io_wait_single_req(io_req* req)
 		switch(req->op)
 		{
 			case IO_OP_OPEN_AT:
-				cmp = io_open_at(slot, req);
+				cmp = io_open_at(slot, req, table);
 				break;
 
 			case IO_OP_FSTAT:
@@ -460,7 +612,7 @@ io_cmp io_wait_single_req(io_req* req)
 				break;
 
 			case IO_OP_CLOSE:
-				cmp = io_close(slot, req);
+				cmp = io_close(slot, req, table);
 				break;
 
 			case IO_OP_READ:

src/platform/win32_io.c

@@ -9,77 +9,9 @@
 #include<errno.h>
 #include<limits.h>
 
+#include"platform_io_internal.c"
 #include"platform_io_common.c"
 
-typedef struct file_slot
-{
-	u32 generation;
-	HANDLE h;
-	io_error error;
-	bool fatal;
-	list_elt freeListElt;
-
-} file_slot;
-
-enum
-{
-	ORCA_MAX_FILE_SLOTS = 256,
-};
-
-typedef struct file_table
-{
-	file_slot slots[ORCA_MAX_FILE_SLOTS];
-	u32 nextSlot;
-	list_info freeList;
-} file_table;
-
-file_table __globalFileTable = {0};
-
-file_slot* file_slot_alloc(file_table* table)
-{
-	file_slot* slot = list_pop_entry(&table->freeList, file_slot, freeListElt);
-	if(!slot && table->nextSlot < ORCA_MAX_FILE_SLOTS)
-	{
-		slot = &table->slots[table->nextSlot];
-		slot->generation = 1;
-		slot->h = NULL;
-		table->nextSlot++;
-	}
-	return(slot);
-}
-
-void file_slot_recycle(file_table* table, file_slot* slot)
-{
-	slot->generation++;
-	list_push(&table->freeList, &slot->freeListElt);
-}
-
-file_handle file_handle_from_slot(file_table* table, file_slot* slot)
-{
-	u64 index = slot - table->slots;
-	u64 generation = slot->generation;
-	file_handle handle = {.h = (generation<<32) | index };
-	return(handle);
-}
-
-file_slot* file_slot_from_handle(file_table* table, file_handle handle)
-{
-	file_slot* slot = 0;
-
-	u64 index = handle.h & 0xffffffff;
-	u64 generation = handle.h>>32;
-
-	if(index < table->nextSlot)
-	{
-		file_slot* candidate = &table->slots[index];
-		if(candidate->generation == generation)
-		{
-			slot = candidate;
-		}
-	}
-	return(slot);
-}
-
 io_error io_convert_win32_error(int winError)
 {
 	io_error error = 0;
@@ -136,11 +68,11 @@ io_error io_convert_win32_error(int winError)
 	return(error);
 }
 
-io_cmp io_open_at(file_slot* atSlot, io_req* req)
+io_cmp io_open_at(file_slot* atSlot, io_req* req, file_table* table)
 {
 	io_cmp cmp = {0};
 
-	file_slot* slot = file_slot_alloc(&__globalFileTable);
+	file_slot* slot = file_slot_alloc(table);
 	if(!slot)
 	{
 		cmp.error = IO_ERR_MAX_FILES;
@@ -148,7 +80,7 @@ io_cmp io_open_at(file_slot* atSlot, io_req* req)
 	}
 	else
 	{
-		cmp.handle = file_handle_from_slot(&__globalFileTable, slot);
+		cmp.handle = file_handle_from_slot(table, slot);
 
 		//NOTE: open
 		mem_arena_scope scratch = mem_scratch_begin();
@@ -232,14 +164,14 @@ io_cmp io_open_at(file_slot* atSlot, io_req* req)
 	return(cmp);
 }
 
-io_cmp io_close(file_slot* slot, io_req* req)
+io_cmp io_close(file_slot* slot, io_req* req, file_table* table)
 {
 	io_cmp cmp = {0};
 	if(slot->h)
 	{
 		CloseHandle(slot->h);
 	}
-	file_slot_recycle(&__globalFileTable, slot);
+	file_slot_recycle(table, slot);
 	return(cmp);
 }
 
@@ -401,11 +333,11 @@ io_cmp io_get_error(file_slot* slot, io_req* req)
 	return(cmp);
 }
 
-io_cmp io_wait_single_req(io_req* req)
+io_cmp io_wait_single_req_with_table(io_req* req, file_table* table)
 {
 	io_cmp cmp = {0};
 
-	file_slot* slot = file_slot_from_handle(&__globalFileTable, req->handle);
+	file_slot* slot = file_slot_from_handle(table, req->handle);
 	if(!slot)
 	{
 		if(req->op != IO_OP_OPEN_AT)
@@ -423,7 +355,7 @@ io_cmp io_wait_single_req(io_req* req)
 		switch(req->op)
 		{
 			case IO_OP_OPEN_AT:
-				cmp = io_open_at(slot, req);
+				cmp = io_open_at(slot, req, table);
 				break;
 
 			case IO_OP_FSTAT:
@@ -431,7 +363,7 @@ io_cmp io_wait_single_req(io_req* req)
 				break;
 
 			case IO_OP_CLOSE:
-				cmp = io_close(slot, req);
+				cmp = io_close(slot, req, table);
 				break;
 
 			case IO_OP_READ: