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Diffstat (limited to 'Documentation/admin-guide/sysctl/vm.rst')
| -rw-r--r-- | Documentation/admin-guide/sysctl/vm.rst | 15 |
1 files changed, 10 insertions, 5 deletions
diff --git a/Documentation/admin-guide/sysctl/vm.rst b/Documentation/admin-guide/sysctl/vm.rst index 82b5e7ad3e91..e35a3f2fb006 100644 --- a/Documentation/admin-guide/sysctl/vm.rst +++ b/Documentation/admin-guide/sysctl/vm.rst @@ -873,12 +873,17 @@ file-backed pages is less than the high watermark in a zone. unprivileged_userfaultfd ======================== -This flag controls whether unprivileged users can use the userfaultfd -system calls. Set this to 1 to allow unprivileged users to use the -userfaultfd system calls, or set this to 0 to restrict userfaultfd to only -privileged users (with SYS_CAP_PTRACE capability). +This flag controls the mode in which unprivileged users can use the +userfaultfd system calls. Set this to 0 to restrict unprivileged users +to handle page faults in user mode only. In this case, users without +SYS_CAP_PTRACE must pass UFFD_USER_MODE_ONLY in order for userfaultfd to +succeed. Prohibiting use of userfaultfd for handling faults from kernel +mode may make certain vulnerabilities more difficult to exploit. -The default value is 1. +Set this to 1 to allow unprivileged users to use the userfaultfd system +calls without any restrictions. + +The default value is 0. user_reserve_kbytes |