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Notes for TOMOYO Linux project |
Notes for TOMOYO Linux project |
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This is a handy Mandatory Access Control patch for Linux kernels. |
This is a handy Mandatory Access Control patch for Linux kernels. |
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This patch is released under the GPL. |
This patch is released under the GPLv2. |
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Project URL: http://tomoyo.sourceforge.jp/ |
Project URL: http://tomoyo.sourceforge.jp/ |
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By default, this handler does nothing (i.e. merely reject execve() |
By default, this handler does nothing (i.e. merely reject execve() |
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request). You can specify any program to start what you want to do. |
request). You can specify any program to start what you want to do. |
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You can redirect attackers to somewhere else (e.g. honeypot). |
You can redirect attackers to somewhere else (e.g. honey pot). |
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This makes it possible to act your Linux box as an on-demand honeypot |
This makes it possible to act your Linux box as an on-demand honey pot |
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while keeping regular services for your usage. |
while keeping regular services for your usage. |
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You can collect information of the attacker (e.g. IP address) and |
You can collect information of the attacker (e.g. IP address) and |
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0 -> disabled |
0 -> disabled |
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1 -> enabled |
1 -> enabled |
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Fix 2008/03/10 |
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@ Rename "force_alt_exec" keyword to "execute_handler". |
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To be able to use different programs for validating execve() parameters, |
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I moved the location to specify the program's pathname from profile |
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to domain policy. |
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The "execute_handler" keyword takes one pathname which is |
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invoked whenever execve() request is issued. Thus, any "allow_execute" |
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keywords in a domain with "execute_handler" are ignored. |
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This keyword is designed for validating expected/desirable execve() |
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requests in userspace, although there is no way to tell the caller |
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that the execve() request was rejected. |
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@ Rename "alt_exec" keyword to "denied_execute_handler". |
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The "denied_execute_handler" keyword takes one pathname which is |
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invoked only when execve() request was rejected. In other words, |
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this program is invoked only when the following conditions are met. |
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(1) None of "allow_execute" keywords in the domain matched. |
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(2) The execve() request was rejected in enforcing mode. |
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(3) "execute_handler" keyword is not used by the domain. |
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This keyword is designed for handling unexpected/undesirable execve() |
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requests, to redirect the process issuing such requests to somewhere. |
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Fix 2008/03/18 |
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@ Fix wrong/redundant locks in pre-vfs functions. |
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lock_kernel()/unlock_kernel() in pre_vfs_rename() were redundant for |
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2.6 kernels. |
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Locking order in pre_vfs_link() and pre_vfs_unlink() for 2.4 kernels |
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after 2.4.33 were different from before 2.4.32 . |
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Fix 2008/03/28 |
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@ Disable execute handler loop. |
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To be able to use "execute_handler" in a "keep_domain" domain, |
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ignore "execute_handler" and "denied_execute_handler" keywords |
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if the current process is executing programs specified by |
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"execute_handler" or "denied_execute_handler" keyword. |
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This exception is needed to avoid infinite execute handler loop. |
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If a domain has both "keep_domain" and "execute_handler", |
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any execute request by that domain is handled by an execute handler, |
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and the execute handler attempts to process original execute request. |
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But the original execute request is handled by the same execute handler |
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unless the execute handler ignores "execute_handler". |
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@ Update coding style. |
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I rewrote the code to pass scripts/checkpatch.pl as much as possible. |
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Function names were changed to use only lower letters. |
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Version 1.6.0 2008/04/01 Feature enhancement release. |
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Fix 2008/04/14 |
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@ Fix "Compilation failures" and "Initialization ordering bugs" |
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with kernels before 2.4.30/2.6.11 . |
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2.6 kernels before 2.6.9 didn't have include/linux/hardirq.h , |
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resulting compilation error at #include <linux/hardirq.h> . |
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I added #elif condition. |
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CentOS 4.6's 2.6.9 kernel calls do_execve() before initialization of |
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ccs_alloc(), resulting NULL pointer dereference. |
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I changed __initcall to core_initcall. |
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CentOS 4.6's 2.6.9 kernel backported kzalloc() from 2.6.14 , |
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resulting compilation error at kzalloc(). |
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I modified prototype of kzalloc(). |
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Fix 2008/04/20 |
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@ Fix "Compilation failures" with kernels before 2.4.30/2.6.11 . |
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Turbolinux 10 Server's 2.6.8 kernel backported kzalloc() as an inlined |
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function, resulting compilation error at kzalloc(). |
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I converted kzalloc() from an inlined function into a macro. |
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Fix 2008/04/21 |
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@ Add workaround for gcc 3.2.2's inline bug. |
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RedHat Linux 9's gcc 3.2.2 generated a bad code |
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if ((var_of_u8 & 0x000000BF) & 0x80000000) { } |
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where the expected code is |
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if ((var_of_u8 & 0xBF) & 0x80) { } |
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when embedding ccs_acl_type2() into print_entry(), |
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resulting runtime BUG(). |
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I added the expected code explicitly as a workaround. |
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Fix 2008/05/06 |
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@ Add memory quota. |
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1.5.x returns -ENOMEM when FindNextDomain() failed to create a new |
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domain, but I forgot to return -ENOMEM when find_next_domain() failed to |
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create a new domain. |
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A domain is automatically created by find_next_domain() only if |
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the domain for the requested program doesn't exist. |
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This behavior is for the administrator's convenience. |
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The administrator needn't to know how many domains are needed for running |
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the whole programs in the system beforehand when developing the policy. |
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But the administrator does not want the kernel to reject execution of the |
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requested program when developing the policy. |
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So, I think it is better to grant execution of programs even if |
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find_next_domain() failed to create a new domain than reject execution. |
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Thus, I decided not to return -ENOMEM when find_next_domain() failed to |
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create a new domain. This exception breaks the domain transition rules, |
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so I print "transition_failed" warning in /proc/ccs/domain_policy |
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when this exception happened. |
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Also, to prevent the system from being halted by unexpectedly allocating |
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all kernel memory for the policy, I added memory quota. |
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This quota is configurable via /proc/ccs/meminfo like |
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echo Shared: 1048576 > /proc/ccs/meminfo |
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echo Private: 1048576 > /proc/ccs/meminfo |
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Version 1.6.1 2008/05/?? Bug fix release. |
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