Public bug reported: A requirement for snappy is that security sandbox violations against policy are logged. In this manner learning tools can be written to parse the logs, etc and make developing on snappy easier.
The current default seccomp action, in strict mode. is to kill the snap's thread that violated the policy but this is unfriendly to the developer and to the user. The desired action is to block the illegal system call and return an error with errno set to EPERM. However, seccomp does not emit log events when it takes that action. Seccomp should be updated to emit log events when taking the SECCOMP_RET_ERRNO action and then snappy can switch to the using that action when blocking illegal system calls. [Impact] Snapd needs a way to log SECCOMP_RET_ERRNO seccomp actions in order to have a more friendly strict mode. Such functionality has been merged upstream into 4.14-rc2. No libseccomp changes are needed at this time since snap-confine loads the BPF filter directly into the kernel without using libseccomp. [Test Case] Running the libseccomp "live" tests will exercise the kernel's seccomp enforcement and help to help catch any regressions. Note that on Artful, there's an existing test failure (20-live-basic_die%%002-00001): $ sudo apt build-dep -y libseccomp $ sudo apt install -y cython $ apt source libseccomp $ cd libseccomp-* $ autoreconf -ivf && ./configure --enable-python && make check-build $ (cd tests && ./regression -T live) All tests should pass on zesty (12 tests) and xenial (10 tests). On artful, you'll see one pre-existing failure: ... Test 20-live-basic_die%%002-00001 result: FAILURE 20-live-basic_die TRAP rc=159 ... Regression Test Summary tests run: 12 tests skipped: 0 tests passed: 11 tests failed: 1 tests errored: 0 ============================================================ [Regression Potential] The kernel patches received a lot of review between Kees and some others interested in improved seccomp logging. I authored the patches and feel comfortable/confident with my backported versions. They do not change the behavior of seccomp logging by default but offer ways applications to opt into more logging and, on the flipside, ways for the administrator to quite any additional logging. ** Affects: snappy Importance: Medium Assignee: Tyler Hicks (tyhicks) Status: In Progress ** Affects: linux (Ubuntu) Importance: Undecided Assignee: Tyler Hicks (tyhicks) Status: Fix Released ** Affects: linux (Ubuntu Xenial) Importance: Undecided Assignee: Tyler Hicks (tyhicks) Status: In Progress ** Affects: linux (Ubuntu Zesty) Importance: Undecided Assignee: Tyler Hicks (tyhicks) Status: In Progress ** Affects: linux (Ubuntu Artful) Importance: Undecided Assignee: Tyler Hicks (tyhicks) Status: Fix Released ** Also affects: linux (Ubuntu) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Artful) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Zesty) Importance: Undecided Status: New ** Also affects: linux (Ubuntu Xenial) Importance: Undecided Status: New ** Changed in: linux (Ubuntu Xenial) Status: New => In Progress ** Changed in: linux (Ubuntu Xenial) Assignee: (unassigned) => Tyler Hicks (tyhicks) ** Changed in: linux (Ubuntu Zesty) Status: New => In Progress ** Changed in: linux (Ubuntu Zesty) Assignee: (unassigned) => Tyler Hicks (tyhicks) ** Changed in: linux (Ubuntu Artful) Status: New => Fix Released ** Changed in: linux (Ubuntu Artful) Assignee: (unassigned) => Tyler Hicks (tyhicks) -- You received this bug notification because you are a member of नेपाली भाषा समायोजकहरुको समूह, which is subscribed to Xenial. Matching subscriptions: Ubuntu 16.04 Bugs https://bugs.launchpad.net/bugs/1721676 Title: implement errno action logging in seccomp for strict mode with snaps Status in Snappy: In Progress Status in linux package in Ubuntu: Fix Released Status in linux source package in Xenial: In Progress Status in linux source package in Zesty: In Progress Status in linux source package in Artful: Fix Released Bug description: A requirement for snappy is that security sandbox violations against policy are logged. In this manner learning tools can be written to parse the logs, etc and make developing on snappy easier. The current default seccomp action, in strict mode. is to kill the snap's thread that violated the policy but this is unfriendly to the developer and to the user. The desired action is to block the illegal system call and return an error with errno set to EPERM. However, seccomp does not emit log events when it takes that action. Seccomp should be updated to emit log events when taking the SECCOMP_RET_ERRNO action and then snappy can switch to the using that action when blocking illegal system calls. [Impact] Snapd needs a way to log SECCOMP_RET_ERRNO seccomp actions in order to have a more friendly strict mode. Such functionality has been merged upstream into 4.14-rc2. No libseccomp changes are needed at this time since snap-confine loads the BPF filter directly into the kernel without using libseccomp. [Test Case] Running the libseccomp "live" tests will exercise the kernel's seccomp enforcement and help to help catch any regressions. Note that on Artful, there's an existing test failure (20-live- basic_die%%002-00001): $ sudo apt build-dep -y libseccomp $ sudo apt install -y cython $ apt source libseccomp $ cd libseccomp-* $ autoreconf -ivf && ./configure --enable-python && make check-build $ (cd tests && ./regression -T live) All tests should pass on zesty (12 tests) and xenial (10 tests). On artful, you'll see one pre-existing failure: ... Test 20-live-basic_die%%002-00001 result: FAILURE 20-live-basic_die TRAP rc=159 ... Regression Test Summary tests run: 12 tests skipped: 0 tests passed: 11 tests failed: 1 tests errored: 0 ============================================================ [Regression Potential] The kernel patches received a lot of review between Kees and some others interested in improved seccomp logging. I authored the patches and feel comfortable/confident with my backported versions. They do not change the behavior of seccomp logging by default but offer ways applications to opt into more logging and, on the flipside, ways for the administrator to quite any additional logging. To manage notifications about this bug go to: https://bugs.launchpad.net/snappy/+bug/1721676/+subscriptions _______________________________________________ Mailing list: https://launchpad.net/~group.of.nepali.translators Post to : group.of.nepali.translators@lists.launchpad.net Unsubscribe : https://launchpad.net/~group.of.nepali.translators More help : https://help.launchpad.net/ListHelp