SELinux 回归测试失败

SELinux 回归测试失败

我从以下位置克隆了 selinux-testsuite 回归测试:https://github.com/SELinuxProject/selinux-testsuite

我在 CentOS Linux 版本 7.6.1810 (Core) VM 中运行测试。我不认为这有相关性。

在我使用以下方法安装临时测试策略之前,SELinux 正在强制使用目标策略:

make -C policy load

sestatus 说

SELinux status:                 enabled
SELinuxfs mount:                /sys/fs/selinux
SELinux root directory:         /etc/selinux
Loaded policy name:             targeted
Current mode:                   enforcing
Mode from config file:          enforcing
Policy MLS status:              enabled
Policy deny_unknown status:     allowed
Max kernel policy version:      31

我相信我已经按照说明准确运行了测试套件。然而,当我运行它时,我发现了一个失败:

[snipped OK messages]

bounds/test ................. ok     
nnp_nosuid/test ............. ok     
mmap/test ................... 1/47 # Failed test 27 in mmap/test at line 143
#  mmap/test line 143 is:     ok($result);
mmap/test ................... Failed 1/47 subtests 
unix_socket/test ............ ok   
inet_socket/test ............ ok     

[more snipped OK messages]

Test Summary Report
-------------------
mmap/test                 (Wstat: 0 Tests: 47 Failed: 1)
  Failed test:  27
Files=51, Tests=520, 35 wallclock secs ( 0.11 usr  0.04 sys +  0.77 cusr  0.94 csys =  1.86 CPU)
Result: FAIL
Failed 1/51 test programs. 1/520 subtests failed.

我将有问题的测试从 mmap 测试组中分离出来:

#!/bin/bash

basedir=$(pwd)/tests/mmap

if [ ! -d $basedir ]; then
    printf "Error: missing basedir: $basedir\n"
    exit 1
fi

# Clean up from prior runs.
rm -f $basedir/temp_file

# Create temporary file.
dd if=/dev/zero of=$basedir/temp_file count=8 2>&1 > /dev/null
printf "\ncreate: OK\n"
chcon -t test_mmap_file_t $basedir/temp_file
printf "\nchcon: OK\n"

if [ ! -f $basedir/mmap_file_shared ]; then
    printf "Error - missing executable: $basedir/mmap_file_shared\n"
    exit 1
fi

if [ ! -f $basedir/temp_file ]; then
    printf "Error - missing temp file: $basedir/temp_file\n"
    exit 1
fi

/bin/runcon -t test_no_map_t -- $basedir/mmap_file_shared $basedir/temp_file

这会在 /var/log/audit/audit.log 中生成 AVC 消息:

type=AVC msg=audit(1556563573.950:2466): avc:  denied  { search } for  pid=16708 comm="mmap_file_share" name="vagrant" dev="dm-0" ino=81922 scontext=unconfined_u:unconfined_r:test_no_map_t:s0-s0:c0.c1023 tcontext=unconfined_u:object_r:user_home_dir_t:s0 tclass=dir permissive=0

我不完全确定这个 AVC 是否是测试套件有意为之(作为负面测试用例)。但我想了解这个失败的原因。

答案1

为了结束这个问题,selinux 邮件列表的 Ondrej Mosnacek 提供了答案:

Quoth Ondrej 说道:

RHEL 和 CentOS 7.6 默认将 domain_can_mmap_files SELinux 布尔值设置为“on” [1],这基本上意味着没有检查映射权限,这在逻辑上会导致测试失败,该测试检查映射权限在测试策略不允许时被拒绝。在 CentOS/RHEL 7.6 上运行测试套件时,您需要在测试执行期间关闭 domain_can_mmap_files 布尔值。

为了解决这个问题我做了:

# Get the original value of the bool
export OLD_MMAP_BOOL=$(getsebool domain_can_mmap_files | awk '{ print $3 }')
# Disable it
sudo setsebool domain_can_mmap_files off
# Run the test suite
make -C tests test
# Restore the previous state
sudo OLD_MMAP_BOOL=$OLD_MMAP_BOOL setsebool domain_can_mmap_files $OLD_MMAP_BOOL

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