Move meta file usage to a file backed hashtable

src/GNUmakefile

@@ -16,7 +16,7 @@ OBJDUMP  ?= $(CROSS_COMPILE)objdump
 
 CPPFLAGS += -D_FILE_OFFSET_BITS=64 -D_GNU_SOURCE -I. -I$(VPATH)
 CFLAGS   += -Wall -Wextra -O2
-LDFLAGS  += -ltalloc -Wl,-z,noexecstack
+LDFLAGS  += -lleveldb -ltalloc -Wl,-z,noexecstack
 
 OBJECTS += \
 	cli/cli.o		\
@@ -66,8 +66,6 @@ OBJECTS += \
 	extension/fake_id0/utimensat.o \
 	extension/fake_id0/access.o \
 	extension/fake_id0/exec.o \
-	extension/fake_id0/link.o \
-	extension/fake_id0/symlink.o \
 	extension/fake_id0/mk.o \
 	extension/fake_id0/stat.o \
         extension/fake_id0/helper_functions.o \

src/extension/fake_id0/access.c

@@ -6,39 +6,25 @@
 #include "extension/fake_id0/helper_functions.h"
 
 /** Handles the access and faccessat syscalls. Checks permissions according to
- *  a meta file if it exists. See access(2) for returned errors.
+ *  the meta info if it exists. See access(2) for returned errors.
  */
 int handle_access_enter_end(Tracee *tracee, Reg path_sysarg,
 	Reg mode_sysarg, Reg dirfd_sysarg, Config *config)
 {
 	int status, mode, perms, mask;
 	char path[PATH_MAX];
-	char rel_path[PATH_MAX];
-	char meta_path[PATH_MAX];
 
 	status = read_sysarg_path(tracee, path, path_sysarg, CURRENT);
 	if(status < 0)
 		return status;
 	if(status == 1)
 		return 0;
 
-	status = get_fd_path(tracee, rel_path, dirfd_sysarg, CURRENT);
-	if(status < 0)
-		return status;
-
-	status = check_dir_perms(tracee, 'r', path, rel_path, config);
-	if(status < 0) 
-		return status;
-
 	// Only care about calls checking permissions.
 	mode = peek_reg(tracee, ORIGINAL, mode_sysarg);
 	if(mode & F_OK) 
 		return 0;
 
-	status = get_meta_path(path, meta_path);
-	if(status < 0)
-		return status;
-
 	mask = 0;
 	if((mode & R_OK) == R_OK)
 		mask += 4;
@@ -47,7 +33,7 @@ int handle_access_enter_end(Tracee *tracee, Reg path_sysarg,
 	if((mode & X_OK) == X_OK)
 		mask += 1; 
 
-	perms = get_permissions(meta_path, config, 1);
+	perms = get_permissions(path, config, 1);
 	if((perms & mask) != mask) 
 		return -EACCES;
 

src/extension/fake_id0/chmod.c

@@ -6,8 +6,8 @@
 
 #include "extension/fake_id0/helper_functions.h"
 
-/** Handles chmod, fchmod, and fchmodat syscalls. Changes meta files to the new
- *  permissions if the meta file exists. See chmod(2) for returned permission
+/** Handles chmod, fchmod, and fchmodat syscalls. Changes meta info to the new
+ *  permissions if the meta info exists. See chmod(2) for returned permission
  *  errors. 
  */
 int handle_chmod_enter_end(Tracee *tracee, Reg path_sysarg, Reg mode_sysarg, 
@@ -18,8 +18,6 @@ int handle_chmod_enter_end(Tracee *tracee, Reg path_sysarg, Reg mode_sysarg,
 	uid_t owner;
 	gid_t group;
 	char path[PATH_MAX];
-	char rel_path[PATH_MAX];
-	char meta_path[PATH_MAX];
 
 	// When path_sysarg is set to IGNORE, the call being handled is fchmod.
 	if(path_sysarg == IGNORE_SYSARG) 
@@ -34,23 +32,11 @@ int handle_chmod_enter_end(Tracee *tracee, Reg path_sysarg, Reg mode_sysarg,
 		return 0;
 	}
 
-	status = get_meta_path(path, meta_path);
-	if(path_exists(meta_path) < 0)
-		return 0;
-
-	status = get_fd_path(tracee, rel_path, dirfd_sysarg, CURRENT);
-	if(status < 0)
-		return status;
-
-	status = check_dir_perms(tracee, 'r', path, rel_path, config);
-	if(status < 0) 
-		return status;
-
-	read_meta_file(meta_path, &read_mode, &owner, &group, config);
+	read_meta_info(path, &read_mode, &owner, &group, config);
 	if(config->euid != owner && config->euid != 0) 
 		return -EPERM;
 
 	call_mode = peek_reg(tracee, ORIGINAL, mode_sysarg);
 	set_sysnum(tracee, PR_getuid);
-	return write_meta_file(meta_path, call_mode, owner, group, 0, config);
+	return write_meta_info(path, call_mode, owner, group, 0, config);
 }

src/extension/fake_id0/chown.c

@@ -26,8 +26,8 @@ int handle_chown_enter_end(Tracee *tracee, Config *config, Reg uid_sysarg, Reg g
 #endif /* ifndef USERLAND */
 
 #ifdef USERLAND
-/** Handles chown, lchown, fchown, and fchownat syscalls. Changes the meta file
- *  to reflect arguments sent to the syscall if the meta file exists. See
+/** Handles chown, lchown, fchown, and fchownat syscalls. Changes the meta info 
+ *  to reflect arguments sent to the syscall if the meta info exists. See
  *  chown(2) for returned permission errors.
  */
 int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
@@ -38,8 +38,6 @@ int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
 	uid_t owner, read_owner;
 	gid_t group, read_group;
 	char path[PATH_MAX];
-	char rel_path[PATH_MAX];
-	char meta_path[PATH_MAX];
 
 	if(path_sysarg == IGNORE_SYSARG)
 		status = get_fd_path(tracee, path, fd_sysarg, CURRENT);
@@ -53,38 +51,23 @@ int handle_chown_enter_end(Tracee *tracee, Reg path_sysarg, Reg owner_sysarg,
 		return 0;
 	}
 
-	status = get_meta_path(path, meta_path);
-	if(status < 0)
-		return status;
-
-	if(path_exists(meta_path) != 0)
-		return 0;
-
-	status = get_fd_path(tracee, rel_path, dirfd_sysarg, CURRENT);
-	if(status < 0)
-		return status;
-
-	status = check_dir_perms(tracee, 'r', path, rel_path, config);
-	if(status < 0)
-		return status;
-
-	read_meta_file(meta_path, &mode, &read_owner, &read_group, config);
+	read_meta_info(path, &mode, &read_owner, &read_group, config);
 	owner = peek_reg(tracee, ORIGINAL, owner_sysarg);
 	/** When chown is called without an owner specified, eg 
 	 *  chown :1000 'file', the owner argument to the system call is implicitly
 	 *  set to -1. To avoid this, the owner argument is replaced with the owner
-	 *  according to the meta file if it exists, or the current euid.
+	 *  according to the meta info if it exists, or the current euid.
 	 */
 	if((int) owner == -1)
 		owner = read_owner;
 	group = peek_reg(tracee, ORIGINAL, group_sysarg);
 	if(config->euid == 0) 
-		write_meta_file(meta_path, mode, owner, group, 0, config);
+		write_meta_info(path, mode, owner, group, 0, config);
 
 	//TODO Handle chown properly: owner can only change the group of
 	//  a file to another group they belong to.
 	else if(config->euid == read_owner) {
-		write_meta_file(meta_path, mode, read_owner, group, 0, config);
+		write_meta_info(path, mode, read_owner, group, 0, config);
 		poke_reg(tracee, owner_sysarg, read_owner);	
 	}
 

src/extension/fake_id0/exec.c

@@ -6,14 +6,13 @@
 
 #include "extension/fake_id0/helper_functions.h"
 
-/** Handles execve system calls. Checks permissions in a meta file if it exists
+/** Handles execve system calls. Checks permissions from the meta info if it exists
  *  and returns errors matching those in execve(2).
  */
 int handle_exec_enter_end(Tracee *tracee, Reg filename_sysarg, Config *config)
 {
 	int status, perms;
 	char path[PATH_MAX];
-	char meta_path[PATH_MAX];
 	uid_t uid;
 	gid_t gid;
 	mode_t mode;
@@ -24,26 +23,13 @@ int handle_exec_enter_end(Tracee *tracee, Reg filename_sysarg, Config *config)
 	if(status == 1) 
 		return 0;
 
-	status = get_meta_path(path, meta_path);
-	if(status < 0) 
-		return status;
-
-	/* If metafile doesn't exist, get out, but don't error. */
-	if(path_exists(meta_path) != 0)
-		return 0;
-
-	/* Check perms relative to / since there is no dirfd argument to execve */
-	status = check_dir_perms(tracee, 'r', meta_path, "/", config);
-	if(status < 0) 
-		return status;
-
 	/* Check whether the file has execute permission. */
-	perms = get_permissions(meta_path, config, 0);
+	perms = get_permissions(path, config, 0);
 	if((perms & 1) != 1) 
 		return -EACCES;
 
 	/* If the setuid or setgid bits are on, change config accordingly. */
-	read_meta_file(meta_path, &mode, &uid, &gid, config);
+	read_meta_info(path, &mode, &uid, &gid, config);
 	if ((mode & S_ISUID) != 0) {
 		config->ruid = 0;
 		config->euid = 0;