Commit Graph

13 Commits

Author SHA1 Message Date
Stefan Thöni
78497c03ca base-linux: enabled seccomp
base-linux uses seccomp to reduce the available system calls
to the minimum set needed to run base-linux. There are still
some syscalls that allow accessing global state which should
be further reduced.

The combination of seccomp and socket descriptor caps should
provide an intermediate level of security for base-linux
thereby enabling base-linux as a migration path from using
the Linux kernel to the use of microkernel-based Genode.

Fixes #3581
2020-05-27 11:56:46 +02:00
Norman Feske
132569d12b base-linux: socket descriptor caps for RPC
On Linux, Genode used to represent each RPC object by a socket
descriptor of the receiving thread (entrypoint) and a globally-unique
value that identifies the object. Because the latter was transferred as
plain message payload, clients had to be trusted to not forge the
values. For this reason, Linux could not be considered as a productive
Genode base platform but remained merely a development vehicle.

This patch changes the RPC mechanism such that each RPC object is
represented by a dedicated socket pair. Entrypoints wait on a set of
the local ends of the socket pairs of all RPC objects managed by the
respective entrypoint. The epoll kernel interface is used as the
underlying mechanism to wait for a set of socket descriptors at the
server side.

When delegating a capability, the remote end of the socket pair is
transferred to the recipient along with a plaintext copy of the
socket-descriptor value of the local end. The latter value serves as a
hint for re-identifiying a capability whenever it is delegated back to
its origin. Note that the client is not trusted to preserve this
information. The integrity of the hint value is protected by comparing
the inode values of incoming and already present capablities at the
originating site (whenever the capability is invoked or presented to the
owner of the RPC object).

The new mechanism effectively equips base-linux with Genode's capablity
model as described in the Chapter 3 of the Genode Foundations book.
That said, the sandboxing of components cannot be assumed at this point
because each component has still direct access to the Linux system-call
interface.

This patch is based on the extensive exploration work conducted by
Stefan Thoeni who strongly motivated the inclusion of this feature into
Genode.

Issue #3581
2020-04-17 12:40:13 +02:00
Norman Feske
aa66b5d62f base: remove dependency from deprecated APIs
This patch adjusts the implementation of the base library and core such
that the code no longer relies on deprecated APIs except for very few
cases, mainly to keep those deprecated APIs in tact for now.

The most prominent changes are:

- Removing the use of base/printf.h

- Removing of the log backend for printf. The 'Console' with the
  format-string parser is still there along with 'snprintf.h' because
  the latter is still used at a few places, most prominently the
  'Connection' classes.

- Removing the notion of a RAM session, which does not exist in
  Genode anymore. Still the types were preserved (by typedefs to
  PD session) to keep up compatibility. But this transition should
  come to an end now.

- Slight rennovation of core's tracing service, e.g., the use of an
  Attached_dataspace as the Argument_buffer.

- Reducing the reliance on global accessors like deprecated_env() or
  core_env(). Still there is a longish way to go to eliminate all such
  calls. A useful pattern (or at least a stop-gap solution) is to
  pass the 'Env' to the individual compilation units via init functions.

- Avoiding the use of the old 'Child_policy::resolve_session_request'
  interface that returned a 'Service' instead of a 'Route'.

Issue #1987
2019-02-19 11:08:17 +01:00
Norman Feske
f93294975b base-linux: avoid double define of __always_inline
This patch fixes the following build problem that occurs on recent
GNU/Linux systems:

  /usr/include/x86_64-linux-gnu/sys/cdefs.h:307:0: error: "__always_inline" redefined
  ...
  /usr/include/linux/stddef.h:5:0: note: this is the location of the previous definition

The code in 'cdefs.h' does not check if the '__always_inline' is already
defined. The patch works around the problem by including the 'sys/cdefs.h'
first.
2018-11-16 14:37:20 +01:00
Johannes Schlatow
684052df5e base-linux: implement lx_sigmask/lx_sigword explicitly
In newer glibc versions, the '__sigword' and '__sigmask' macros are only
available in sigsetops.h which is not installed. These macros are not
system-specific, hence we implement them explicitly ourselves.

Fixes #2616
2017-12-21 15:01:51 +01:00
Norman Feske
29b8d609c9 Adjust file headers to refer to the AGPLv3 2017-02-28 12:59:29 +01:00
Norman Feske
e370e08e01 Define Genode::size_t as unsigned long
Fixes #2105
2016-10-21 12:39:29 +02:00
Norman Feske
17c79a9e23 base: avoid use of deprecated base/printf.h
Besides adapting the components to the use of base/log.h, the patch
cleans up a few base headers, i.e., it removes unused includes from
root/component.h, specifically base/heap.h and
ram_session/ram_session.h. Hence, components that relied on the implicit
inclusion of those headers have to manually include those headers now.

While adjusting the log messages, I repeatedly stumbled over the problem
that printing char * arguments is ambiguous. It is unclear whether to
print the argument as pointer or null-terminated string. To overcome
this problem, the patch introduces a new type 'Cstring' that allows the
caller to express that the argument should be handled as null-terminated
string. As a nice side effect, with this type in place, the optional len
argument of the 'String' class could be removed. Instead of supplying a
pair of (char const *, size_t), the constructor accepts a 'Cstring'.
This, in turn, clears the way let the 'String' constructor use the new
output mechanism to assemble a string from multiple arguments (and
thereby getting rid of snprintf within Genode in the near future).

To enforce the explicit resolution of the char * ambiguity, the 'char *'
overload of the 'print' function is marked as deleted.

Issue #1987
2016-08-29 17:27:10 +02:00
Christian Helmuth
4eb58730c0 linux: fix raw-string output in PRAW() 2016-08-10 11:07:47 +02:00
Christian Helmuth
d7ddc83fa9 linux: place alternate signal stack in stack area
The alternate stack must use the stack area as, e.g., Thread::myself()
depends on this property. Hybrid components do not depend on this
property and, therefore, use a static stack buffer.

Fixes #1935
2016-06-28 11:09:28 +02:00
Norman Feske
2030ae678e Supplement base/log.h with raw output function
This patch introduces the Genode::raw function that prints output
directly via a low-level kernel mechanism, if available.

On base-linux, it replaces the former 'raw_write_str' function.
On base-hw, it replaces the former kernel/log.h interface.

Fixes #2012
2016-06-22 12:21:42 +02:00
Christian Helmuth
14f1ac497e linux: improve exception-signal handling
First, we use an alternate stack for signal handling now. The stack is
shared among all threads of the component, which is okay as we only
handle exceptions with log output and pass on to the default handler
(that terminates the execution). The primary motivation for the
alternate stack is the detection of SIGSEGV due to stack overflows.

Also, hybrid components now handle exception signals by logging and the
support for multi-threaded applications was improved.

Fixes #1935
2016-04-11 11:53:00 +02:00
Stefan Kalkowski
ed52d5a211 Introduce 'spec' subdirectories to outline aspects
Instead of holding SPEC-variable dependent files and directories inline
within the repository structure, move them into 'spec' subdirectories
at the corresponding levels, e.g.:

  repos/base/include/spec
  repos/base/mk/spec
  repos/base/lib/mk/spec
  repos/base/src/core/spec
  ...

Moreover, this commit removes the 'platform' directories. That term was
used in an overloaded sense. All SPEC-relative 'platform' directories are
now named 'spec'. Other files, like for instance those related to the
kernel/architecture specific startup library, where moved from 'platform'
directories to explicit, more meaningful places like e.g.: 'src/lib/startup'.

Fix #1673
2015-09-16 13:58:50 +02:00