4747da3a5b Add syscall sandboxing (seccomp-bpf) (practicalswift)
Pull request description:
Add experimental syscall sandboxing using seccomp-bpf (Linux secure computing mode).
Enable filtering of system calls using seccomp-bpf: allow only explicitly allowlisted (expected) syscalls to be called.
The syscall sandboxing implemented in this PR is an experimental feature currently available only under Linux x86-64.
To enable the experimental syscall sandbox the `-sandbox=<mode>` option must be passed to `bitcoind`:
```
-sandbox=<mode>
Use the experimental syscall sandbox in the specified mode
(-sandbox=log-and-abort or -sandbox=abort). Allow only expected
syscalls to be used by bitcoind. Note that this is an
experimental new feature that may cause bitcoind to exit or crash
unexpectedly: use with caution. In the "log-and-abort" mode the
invocation of an unexpected syscall results in a debug handler
being invoked which will log the incident and terminate the
program (without executing the unexpected syscall). In the
"abort" mode the invocation of an unexpected syscall results in
the entire process being killed immediately by the kernel without
executing the unexpected syscall.
```
The allowed syscalls are defined on a per thread basis.
I've used this feature since summer 2020 and I find it to be a helpful testing/debugging addition which makes it much easier to reason about the actual capabilities required of each type of thread in Bitcoin Core.
---
Quick start guide:
```
$ ./configure
$ src/bitcoind -regtest -debug=util -sandbox=log-and-abort
…
2021-06-09T12:34:56Z Experimental syscall sandbox enabled (-sandbox=log-and-abort): bitcoind will terminate if an unexpected (not allowlisted) syscall is invoked.
…
2021-06-09T12:34:56Z Syscall filter installed for thread "addcon"
2021-06-09T12:34:56Z Syscall filter installed for thread "dnsseed"
2021-06-09T12:34:56Z Syscall filter installed for thread "net"
2021-06-09T12:34:56Z Syscall filter installed for thread "msghand"
2021-06-09T12:34:56Z Syscall filter installed for thread "opencon"
2021-06-09T12:34:56Z Syscall filter installed for thread "init"
…
# A simulated execve call to show the sandbox in action:
2021-06-09T12:34:56Z ERROR: The syscall "execve" (syscall number 59) is not allowed by the syscall sandbox in thread "msghand". Please report.
…
Aborted (core dumped)
$
```
---
[About seccomp and seccomp-bpf](https://en.wikipedia.org/wiki/Seccomp):
> In computer security, seccomp (short for secure computing mode) is a facility in the Linux kernel. seccomp allows a process to make a one-way transition into a "secure" state where it cannot make any system calls except exit(), sigreturn(), and read() and write() to already-open file descriptors. Should it attempt any other system calls, the kernel will terminate the process with SIGKILL or SIGSYS. In this sense, it does not virtualize the system's resources but isolates the process from them entirely.
>
> […]
>
> seccomp-bpf is an extension to seccomp that allows filtering of system calls using a configurable policy implemented using Berkeley Packet Filter rules. It is used by OpenSSH and vsftpd as well as the Google Chrome/Chromium web browsers on Chrome OS and Linux. (In this regard seccomp-bpf achieves similar functionality, but with more flexibility and higher performance, to the older systrace—which seems to be no longer supported for Linux.)
ACKs for top commit:
laanwj:
Code review and lightly tested ACK 4747da3a5b
Tree-SHA512: e1c28e323eb4409a46157b7cc0fc29a057ba58d1ee2de268962e2ade28ebd4421b5c2536c64a3af6e9bd3f54016600fec88d016adb49864b63edea51ad838e17
fa9b48549c test: Add test for -blockversion (MarcoFalke)
fa7fb0e442 test: Default blockversion to 4 in feature_block (MarcoFalke)
fa2b778d0c test: Remove unused -blockversion from tests (MarcoFalke)
Pull request description:
`-blockversion` is currently untested, as in: The setting could be made a no-op without any tests failing. Fix that by adding an explicit test for it. Also, related minor cleanups.
ACKs for top commit:
guggero:
ACK fa9b48549c.
Tree-SHA512: 1b2e792f7ed0ec1db163476ee8a938f8f7cb3691f797c721bbe55fdeed92487c2ff83b55467440096917999406c86430cb3a615383cefb4f621828309ff6a1e7
-BEGIN VERIFY SCRIPT-
# max-depth=0 excludes test/functional/test_framework/...
FILES=$(git grep -l --max-depth 0 "connect_nodes" test/functional)
# Replace (dis)?connect_nodes(self.nodes[a], b) with self.(dis)?connect_nodes(a, b)
sed -i 's/\b\(dis\)\?connect_nodes(self\.nodes\[\(.*\)\]/self.\1connect_nodes(\2/g' $FILES
# Remove imports in the middle of a line
sed -i 's/\(dis\)\?connect_nodes, //g' $FILES
sed -i 's/, \(dis\)\?connect_nodes//g' $FILES
# Remove imports on a line by themselves
sed -i '/^\s*\(dis\)\?connect_nodes,\?$/d' $FILES
sed -i '/^from test_framework\.util import connect_nodes$/d' $FILES
-END VERIFY SCRIPT-
Co-authored-by: Elliott Jin <elliott.jin@gmail.com>
- Get rid of hardcoded wallet "" names and -wallet="" args
- Get rid of setup_nodes (-wallet, -nowallet, -disablewallet) argument rewriting
Motivation:
- Simplify test framework behavior so it's easier to write new tests without
having arguments mangled by the framework
- Make tests more readable, replacing unexplained "" string literals with
default_wallet_name references
- Make it trivial to update default wallet name and wallet data filename for
sqlite #19077 testing
- Stop relying on -wallet arguments to create wallets, so it is easy to change
-wallet option in the future to only load existing wallets not create new
ones (to avoid accidental wallet creation, and encourage use of wallet
encryption and descriptor features)
This fix is a based on the fix by Antoine Riard <ariard@student.42.fr> in
https://github.com/bitcoin/bitcoin/pull/18600.
Unlike that PR, which implements some new behavior, this just restores previous
wallet notification and status behavior for transactions removed from the
mempool because they conflict with transactions in a block. The behavior was
accidentally changed in two `CWallet::BlockConnected` updates:
a31be09bfd and
7e89994133 from
https://github.com/bitcoin/bitcoin/pull/16624, causing issue
https://github.com/bitcoin/bitcoin/issues/18325.
The change here could be improved and replaced with a more comprehensive
cleanup, so it includes a detailed comment explaining future considerations.
Fixes#18325
Co-authored-by: Antoine Riard <ariard@student.42.fr>
Due to miners inserting garbage into the version numbers, the current
version signalling has become completely useless. This removes the
"unknown block versions" warning which has the tendency to scare
users unnecessarily (and might get them to "update" to something
bad).
It preserves the warning in the logs. Whether this is desirable can
be a point of discussion.
W. J. van der Laan