f3c3a1aa33
execute_no_trans controls whether a domain can execve a program without switching to another domain. Exclude this permission from unconfineddomain, add it back to init, init_shell, and recovery for files in / and /system, and to kernel for files in / (to permit execution of init prior to setcon). Prohibit it otherwise for the kernel domain via neverallow. This ensures that if a kernel task attempts to execute a kernel usermodehelper for which no domain transition is defined, the exec will fail. Change-Id: Ie7b2349923672dd4f5faf7c068a6e5994fd0e4e3 Signed-off-by: Stephen Smalley <sds@tycho.nsa.gov>
56 lines
2.1 KiB
Text
56 lines
2.1 KiB
Text
# Life begins with the kernel.
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type kernel, domain;
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# Run /init before we have switched domains.
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allow kernel rootfs:file execute_no_trans;
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# setcon to init domain.
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allow kernel self:process setcurrent;
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allow kernel init:process dyntransition;
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# The kernel is unconfined.
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unconfined_domain(kernel)
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# cgroup filesystem initialization prior to setting the cgroup root directory label.
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allow kernel unlabeled:dir search;
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# Mount usbfs.
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allow kernel usbfs:filesystem mount;
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# init direct restorecon calls prior to switching to init domain
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# /dev and /dev/socket
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allow kernel { device socket_device }:dir relabelto;
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# /dev/__properties__
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allow kernel properties_device:file relabelto;
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# /sys
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allow kernel sysfs:{ dir file lnk_file } relabelfrom;
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allow kernel sysfs_type:{ dir file lnk_file } relabelto;
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# Initial setenforce by init prior to switching to init domain.
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# We use dontaudit instead of allow to prevent a kernel spawned userspace
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# process from turning off SELinux once enabled.
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dontaudit kernel self:security setenforce;
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# Set checkreqprot by init.rc prior to switching to init domain.
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allow kernel self:security setcheckreqprot;
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###
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### neverallow rules
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###
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# The initial task starts in the kernel domain (assigned via
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# initial_sid_contexts), but nothing ever transitions to it.
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neverallow domain kernel:process { transition dyntransition };
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# The kernel domain is never entered via an exec, nor should it
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# ever execute a program outside the rootfs without changing to another domain.
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# If you encounter an execute_no_trans denial on the kernel domain, then
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# possible causes include:
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# - The program is a kernel usermodehelper. In this case, define a domain
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# for the program and domain_auto_trans() to it.
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# - You failed to setcon u:r:init:s0 in your init.rc and thus your init
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# program was left in the kernel domain and is now trying to execute
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# some other program. Fix your init.rc file.
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# - You are running an exploit which switched to the init task credentials
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# and is then trying to exec a shell or other program. You lose!
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neverallow kernel { file_type fs_type -rootfs }:file { entrypoint execute_no_trans };
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