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Noux: move ELF signature check into 'Child_env'

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Fixes #2703
This commit is contained in:
Christian Prochaska 2018-03-01 19:33:56 +01:00 committed by Christian Helmuth
parent bad002acb1
commit 6986b6ca95
6 changed files with 135 additions and 97 deletions
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7
repos/ports/include/noux_session/sysio.h
View File

@ -319,9 +319,10 @@ struct Noux::Sysio
SYMLINK_ERR_NO_SPACE, SYMLINK_ERR_NO_PERM,
SYMLINK_ERR_NAME_TOO_LONG };
enum Execve_error { EXECVE_NONEXISTENT = Vfs::Directory_service::NUM_GENERAL_ERRORS,
EXECVE_NOMEM,
EXECVE_NOEXEC };
enum Execve_error { EXECVE_ERR_NO_ENTRY = Vfs::Directory_service::NUM_GENERAL_ERRORS,
EXECVE_ERR_NO_MEMORY,
EXECVE_ERR_NO_EXEC,
EXECVE_ERR_ACCESS};
enum Fork_error { FORK_NOMEM = Vfs::Directory_service::NUM_GENERAL_ERRORS };
enum Select_error { SELECT_ERR_INTERRUPT };

7
repos/ports/src/lib/libc_noux/plugin.cc
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@ -1099,9 +1099,10 @@ namespace {
if (!noux_syscall(Noux::Session::SYSCALL_EXECVE)) {
warning("exec syscall failed for path \"", filename, "\"");
switch (sysio()->error.execve) {
case Noux::Sysio::EXECVE_NONEXISTENT: errno = ENOENT; break;
case Noux::Sysio::EXECVE_NOMEM: errno = ENOMEM; break;
case Noux::Sysio::EXECVE_NOEXEC: errno = ENOEXEC; break;
case Noux::Sysio::EXECVE_ERR_NO_ENTRY: errno = ENOENT; break;
case Noux::Sysio::EXECVE_ERR_NO_MEMORY: errno = ENOMEM; break;
case Noux::Sysio::EXECVE_ERR_NO_EXEC: errno = ENOEXEC; break;
case Noux::Sysio::EXECVE_ERR_ACCESS: errno = EACCES; break;
}
return -1;
}

5
repos/ports/src/noux/child.h
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@ -300,7 +300,6 @@ class Noux::Child : public Rpc_object<Session>,
public:
struct Binary_does_not_exist : Exception { };
struct Insufficient_memory : Exception { };
/**
@ -311,10 +310,6 @@ class Noux::Child : public Rpc_object<Session>,
* or children created via execve, or
* true if the child is a fork from another child
*
* \throw Binary_does_not_exist if child is not a fork and the
* specified name could not be
* looked up at the virtual file
* system
* \throw Insufficent_memory if the child could not be started by
* the parent
*/

120
repos/ports/src/noux/child_env.h
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@ -48,38 +48,79 @@ class Noux::Child_env
memcpy(_env, env, sizeof(Sysio::Env));
}
/**
* Verify that the file exists and return its size
*/
Vfs::file_size _file_size(Vfs::Dir_file_system &root_dir,
char const *binary_name)
{
Vfs::Directory_service::Stat stat_out;
Vfs::Directory_service::Stat_result stat_result;
stat_result = root_dir.stat(binary_name, stat_out);
switch (stat_result) {
case Vfs::Directory_service::STAT_OK:
break;
case Vfs::Directory_service::STAT_ERR_NO_ENTRY:
throw Binary_does_not_exist();
case Vfs::Directory_service::STAT_ERR_NO_PERM:
throw Binary_is_not_accessible();
}
return stat_out.size;
}
/**
* Verify that the file is a valid ELF executable
*/
void _verify_elf(char const *file)
{
if ((file[0] != 0x7f) ||
(file[1] != 'E') ||
(file[2] != 'L') ||
(file[3] != 'F'))
throw Binary_is_not_executable();
}
/**
* Handle the case that the given binary needs an interpreter
*/
void _process_binary_name_and_args(Region_map &local_rm,
const char *binary_name,
Dataspace_capability binary_ds,
const char *args)
void _process_binary_name_and_args(char const *binary_name,
char const *args,
Vfs::Dir_file_system &root_dir,
Vfs_io_waiter_registry &vfs_io_waiter_registry,
Ram_session &ram,
Region_map &rm,
Allocator &alloc)
{
bool interpretable = true;
Vfs::file_size binary_size = _file_size(root_dir, binary_name);
const size_t binary_size = Dataspace_client(binary_ds).size();
if (binary_size == 0)
throw Binary_is_not_executable();
if (binary_size < 4)
interpretable = false;
/*
* We may have to check the dataspace twice because the binary
* could be a script that uses an interpreter which might not
* exist.
*/
Reconstructible<Vfs_dataspace> binary_ds {
root_dir, vfs_io_waiter_registry,
binary_name, ram, rm, alloc
};
const char *binary_addr = 0;
if (interpretable)
try {
binary_addr = local_rm.attach(binary_ds);
} catch(...) {
warning("could not attach dataspace");
interpretable = false;
}
if (!binary_ds->ds.valid())
throw Binary_is_not_executable();
if (interpretable &&
((binary_addr[0] != '#') || (binary_addr[1] != '!')))
interpretable = false;
Reconstructible<Attached_dataspace> attached_binary_ds(rm, binary_ds->ds);
if (!interpretable) {
local_rm.detach(binary_addr);
char const *binary_addr = attached_binary_ds->local_addr<char const>();
/* look for '#!' */
if ((binary_addr[0] != '#') || (binary_addr[1] != '!')) {
_binary_name = binary_name;
Genode::memcpy(_args, args, ARGS_SIZE);
_verify_elf(binary_addr);
return;
}
@ -102,7 +143,7 @@ class Noux::Child_env
/* no interpreter name found */
if (interpreter_line_cursor == eol)
throw Child::Binary_does_not_exist();
throw Binary_does_not_exist();
int interpreter_name_start = interpreter_line_cursor;
@ -142,16 +183,43 @@ class Noux::Child_env
Genode::memcpy(&_args[args_buf_cursor],
args, ARGS_SIZE);
local_rm.detach(binary_addr);
/* check if interpreter exists and is executable */
binary_size = _file_size(root_dir, _binary_name);
if (binary_size == 0)
throw Binary_is_not_executable();
binary_ds.construct(root_dir, vfs_io_waiter_registry,
_binary_name, ram,
rm, alloc);
if (!binary_ds->ds.valid())
throw Binary_is_not_executable();
attached_binary_ds.construct(rm, binary_ds->ds);
_verify_elf(attached_binary_ds->local_addr<char const>());
}
public:
Child_env(Region_map &local_rm, const char *binary_name,
Dataspace_capability binary_ds, const char *args, Sysio::Env env)
struct Binary_does_not_exist : Exception { };
struct Binary_is_not_accessible : Exception { };
struct Binary_is_not_executable : Exception { };
Child_env(char const *binary_name,
char const *args, Sysio::Env env,
Vfs::Dir_file_system &root_dir,
Vfs_io_waiter_registry &vfs_io_waiter_registry,
Ram_session &ram,
Region_map &rm,
Allocator &alloc)
{
_process_env(env);
_process_binary_name_and_args(local_rm, binary_name, binary_ds, args);
_process_binary_name_and_args(binary_name, args, root_dir,
vfs_io_waiter_registry,
ram, rm, alloc);
}
char const *binary_name() const { return _binary_name; }

4
repos/ports/src/noux/rom_session_component.h
View File

@ -63,9 +63,13 @@ struct Noux::Vfs_dataspace
got_ds_from_vfs = false;
Vfs::Directory_service::Stat stat_out;
if (root_dir.stat(name.string(), stat_out) != Vfs::Directory_service::STAT_OK)
return;
if (stat_out.size == 0)
return;
Vfs::Vfs_handle *file;
if (root_dir.open(name.string(),
Vfs::Directory_service::OPEN_MODE_RDONLY,

89
repos/ports/src/noux/syscall.cc
View File

@ -266,69 +266,38 @@ bool Noux::Child::syscall(Noux::Session::Syscall sc)
break;
case SYSCALL_EXECVE:
{
typedef Child_env<sizeof(_sysio.execve_in.args)> Execve_child_env;
try {
Execve_child_env child_env(_sysio.execve_in.filename,
_sysio.execve_in.args,
_sysio.execve_in.env,
_root_dir, _vfs_io_waiter_registry,
_env.ram(), _env.rm(), _heap);
_parent_execve.execve_child(*this,
child_env.binary_name(),
child_env.args(),
child_env.env());
/*
* We have to check the dataspace twice because the binary
* could be a script that uses an interpreter which maybe
* does not exist.
* 'return' instead of 'break' to skip possible signal delivery,
* which might cause the old child process to exit itself
*/
Genode::Reconstructible<Vfs_dataspace> binary_ds {
_root_dir, _vfs_io_waiter_registry,
_sysio.execve_in.filename, _env.ram(), _env.rm(), _heap
};
if (!binary_ds->ds.valid()) {
_sysio.error.execve = Sysio::EXECVE_NONEXISTENT;
break;
}
Child_env<sizeof(_sysio.execve_in.args)>
child_env(_env.rm(),
_sysio.execve_in.filename, binary_ds->ds,
_sysio.execve_in.args, _sysio.execve_in.env);
binary_ds.construct(_root_dir, _vfs_io_waiter_registry,
child_env.binary_name(), _env.ram(),
_env.rm(), _heap);
if (!binary_ds->ds.valid()) {
_sysio.error.execve = Sysio::EXECVE_NONEXISTENT;
break;
}
{
Attached_dataspace attached_binary_ds(_env.rm(), binary_ds->ds);
char const *binary_addr = attached_binary_ds.local_addr<char const>();
if ((binary_addr[0] != 0x7f) ||
(binary_addr[1] != 'E') ||
(binary_addr[2] != 'L') ||
(binary_addr[3] != 'F')) {
_sysio.error.execve = Sysio::EXECVE_NOEXEC;
break;
}
}
binary_ds.destruct();
try {
_parent_execve.execve_child(*this,
child_env.binary_name(),
child_env.args(),
child_env.env());
/*
* 'return' instead of 'break' to skip possible signal delivery,
* which might cause the old child process to exit itself
*/
return true;
}
catch (Child::Binary_does_not_exist) {
_sysio.error.execve = Sysio::EXECVE_NONEXISTENT; }
catch (Child::Insufficient_memory) {
_sysio.error.execve = Sysio::EXECVE_NOMEM; }
break;
return true;
}
catch (Execve_child_env::Binary_does_not_exist) {
_sysio.error.execve = Sysio::EXECVE_ERR_NO_ENTRY; }
catch (Execve_child_env::Binary_is_not_accessible) {
_sysio.error.execve = Sysio::EXECVE_ERR_ACCESS; }
catch (Execve_child_env::Binary_is_not_executable) {
_sysio.error.execve = Sysio::EXECVE_ERR_NO_EXEC; }
catch (Child::Insufficient_memory) {
_sysio.error.execve = Sysio::EXECVE_ERR_NO_MEMORY; }
break;
case SYSCALL_SELECT:
{