Matthew Ahrens e59a377a8f filesystem_limit/snapshot_limit is incorrectly enforced against root ... The filesystem_limit and snapshot_limit properties limit the number of filesystems or snapshots that can be created below this dataset. According to the manpage, "The limit is not enforced if the user is allowed to change the limit." Two types of users are allowed to change the limit: 1. Those that have been delegated the `filesystem_limit` or `snapshot_limit` permission, e.g. with `zfs allow USER filesystem_limit DATASET`. This works properly. 2. A user with elevated system privileges (e.g. root). This does not work - the root user will incorrectly get an error when trying to create a snapshot/filesystem, if it exceeds the `_limit` property. The problem is that `priv_policy_ns()` does not work if the `cred_t` is not that of the current process. This happens when `dsl_enforce_ds_ss_limits()` is called in syncing context (as part of a sync task's check func) to determine the permissions of the corresponding user process. This commit fixes the issue by passing the `task_struct` (typedef'ed as a `proc_t`) to syncing context, and then using `has_capability()` to determine if that process is privileged. Note that we still need to pass the `cred_t` to syncing context so that we can check if the user was delegated this permission with `zfs allow`. This problem only impacts Linux. Wrappers are added to FreeBSD but it continues to use `priv_check_cred()`, which works on arbitrary `cred_t`. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Ryan Moeller <ryan@ixsystems.com> Signed-off-by: Matthew Ahrens <mahrens@delphix.com> Closes #8226 Closes #10545		2020-07-11 17:18:02 -07:00
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freebsd	filesystem_limit/snapshot_limit is incorrectly enforced against root	2020-07-11 17:18:02 -07:00
linux	filesystem_limit/snapshot_limit is incorrectly enforced against root	2020-07-11 17:18:02 -07:00