Permissive mode #17
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enhancement
New feature or request
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Related to landlock-lsm/rust-landlock#36, but this would be implemented kernel-side. Both implementation are valuables and complementary for different use cases:
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l0kod
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Sep 9, 2024
[ Upstream commit a699781 ] A sysfs reader can race with a device reset or removal, attempting to read device state when the device is not actually present. eg: [exception RIP: qed_get_current_link+17] #8 [ffffb9e4f2907c48] qede_get_link_ksettings at ffffffffc07a994a [qede] #9 [ffffb9e4f2907cd8] __rh_call_get_link_ksettings at ffffffff992b01a3 #10 [ffffb9e4f2907d38] __ethtool_get_link_ksettings at ffffffff992b04e4 #11 [ffffb9e4f2907d90] duplex_show at ffffffff99260300 #12 [ffffb9e4f2907e38] dev_attr_show at ffffffff9905a01c #13 [ffffb9e4f2907e50] sysfs_kf_seq_show at ffffffff98e0145b #14 [ffffb9e4f2907e68] seq_read at ffffffff98d902e3 #15 [ffffb9e4f2907ec8] vfs_read at ffffffff98d657d1 #16 [ffffb9e4f2907f00] ksys_read at ffffffff98d65c3f #17 [ffffb9e4f2907f38] do_syscall_64 at ffffffff98a052fb crash> struct net_device.state ffff9a9d21336000 state = 5, state 5 is __LINK_STATE_START (0b1) and __LINK_STATE_NOCARRIER (0b100). The device is not present, note lack of __LINK_STATE_PRESENT (0b10). This is the same sort of panic as observed in commit 4224cfd ("net-sysfs: add check for netdevice being present to speed_show"). There are many other callers of __ethtool_get_link_ksettings() which don't have a device presence check. Move this check into ethtool to protect all callers. Fixes: d519e17 ("net: export device speed and duplex via sysfs") Fixes: 4224cfd ("net-sysfs: add check for netdevice being present to speed_show") Signed-off-by: Jamie Bainbridge <[email protected]> Link: https://patch.msgid.link/8bae218864beaa44ed01628140475b9bf641c5b0.1724393671.git.jamie.bainbridge@gmail.com Signed-off-by: Jakub Kicinski <[email protected]> Signed-off-by: Sasha Levin <[email protected]>
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Before enforcing a sandbox on a fleet with potential different configurations and states, it would be useful to know whether a restriction would have an effect on legitimate use cases. By being able to have a permissive/not-enforcing mode and thanks to #3, telemetry can inform us of all access requests that would have been denied. We can then improve the sandbox configuration and get guarantees that it will not break current workstream.
This should be configurable with a new
LANDLOCK_RESTRICT_SELF_PERMISSIVEflag passed tolandlock_restrict_self(). Of course, this flag must only apply to the new domain layer, the inherited restrictions and the future nested restrictions will still be enforced.The text was updated successfully, but these errors were encountered: