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tools/testing/selftests/sysctl: validate sysctl_writes_strict

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This adds several behavioral tests to sysctl string and number writing
to detect unexpected cases that behaved differently when the sysctl
kernel.sysctl_writes_strict != 1.

[ original ]
    root@localhost:~# make test_num
    == Testing sysctl behavior against /proc/sys/kernel/domainname ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... FAIL
    Writing beyond end of sysctl ... FAIL
    Writing sysctl with multiple long writes ... FAIL
    Writing entire sysctl in short writes ... FAIL
    Writing middle of sysctl after unsynchronized seek ... ok
    Checking sysctl maxlen is at least 65 ... ok
    Checking sysctl keeps original string on overflow append ... FAIL
    Checking sysctl stays NULL terminated on write ... ok
    Checking sysctl stays NULL terminated on overwrite ... ok
    make: *** [test_num] Error 1
    root@localhost:~# make test_string
    == Testing sysctl behavior against /proc/sys/vm/swappiness ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... FAIL
    Writing beyond end of sysctl ... FAIL
    Writing sysctl with multiple long writes ... ok
    make: *** [test_string] Error 1

[ with CONFIG_PROC_SYSCTL_STRICT_WRITES ]
    root@localhost:~# make run_tests
    == Testing sysctl behavior against /proc/sys/kernel/domainname ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... ok
    Writing beyond end of sysctl ... ok
    Writing sysctl with multiple long writes ... ok
    Writing entire sysctl in short writes ... ok
    Writing middle of sysctl after unsynchronized seek ... ok
    Checking sysctl maxlen is at least 65 ... ok
    Checking sysctl keeps original string on overflow append ... ok
    Checking sysctl stays NULL terminated on write ... ok
    Checking sysctl stays NULL terminated on overwrite ... ok
    == Testing sysctl behavior against /proc/sys/vm/swappiness ==
    Writing test file ... ok
    Checking sysctl is not set to test value ... ok
    Writing sysctl from shell ... ok
    Resetting sysctl to original value ... ok
    Writing entire sysctl in single write ... ok
    Writing middle of sysctl after synchronized seek ... ok
    Writing beyond end of sysctl ... ok
    Writing sysctl with multiple long writes ... ok

Signed-off-by: Kees Cook <keescook@chromium.org>
Cc: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Kees Cook 2014-06-06 14:37:21 -07:00 committed by Linus Torvalds
parent f4aacea2f5
commit 24fe831c17
5 changed files with 216 additions and 0 deletions
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1
tools/testing/selftests/Makefile
View file

@ -10,6 +10,7 @@ TARGETS += timers
TARGETS += vm
TARGETS += powerpc
TARGETS += user
TARGETS += sysctl
all:
for TARGET in $(TARGETS); do \

19
tools/testing/selftests/sysctl/Makefile Normal file
View file

@ -0,0 +1,19 @@
# Makefile for sysctl selftests.
# Expects kernel.sysctl_writes_strict=1.
# No binaries, but make sure arg-less "make" doesn't trigger "run_tests".
all:
# Allow specific tests to be selected.
test_num:
@/bin/sh ./run_numerictests
test_string:
@/bin/sh ./run_stringtests
run_tests: all test_num test_string
# Nothing to clean up.
clean:
.PHONY: all run_tests clean test_num test_string

109
tools/testing/selftests/sysctl/common_tests Normal file
View file

@ -0,0 +1,109 @@
#!/bin/sh
TEST_FILE=$(mktemp)
echo "== Testing sysctl behavior against ${TARGET} =="
set_orig()
{
echo "${ORIG}" > "${TARGET}"
}
set_test()
{
echo "${TEST_STR}" > "${TARGET}"
}
verify()
{
local seen
seen=$(cat "$1")
if [ "${seen}" != "${TEST_STR}" ]; then
return 1
fi
return 0
}
trap 'set_orig; rm -f "${TEST_FILE}"' EXIT
rc=0
echo -n "Writing test file ... "
echo "${TEST_STR}" > "${TEST_FILE}"
if ! verify "${TEST_FILE}"; then
echo "FAIL" >&2
exit 1
else
echo "ok"
fi
echo -n "Checking sysctl is not set to test value ... "
if verify "${TARGET}"; then
echo "FAIL" >&2
exit 1
else
echo "ok"
fi
echo -n "Writing sysctl from shell ... "
set_test
if ! verify "${TARGET}"; then
echo "FAIL" >&2
exit 1
else
echo "ok"
fi
echo -n "Resetting sysctl to original value ... "
set_orig
if verify "${TARGET}"; then
echo "FAIL" >&2
exit 1
else
echo "ok"
fi
# Now that we've validated the sanity of "set_test" and "set_orig",
# we can use those functions to set starting states before running
# specific behavioral tests.
echo -n "Writing entire sysctl in single write ... "
set_orig
dd if="${TEST_FILE}" of="${TARGET}" bs=4096 2>/dev/null
if ! verify "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Writing middle of sysctl after synchronized seek ... "
set_test
dd if="${TEST_FILE}" of="${TARGET}" bs=1 seek=1 skip=1 2>/dev/null
if ! verify "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Writing beyond end of sysctl ... "
set_orig
dd if="${TEST_FILE}" of="${TARGET}" bs=20 seek=2 2>/dev/null
if verify "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Writing sysctl with multiple long writes ... "
set_orig
(perl -e 'print "A" x 50;'; echo "${TEST_STR}") | \
dd of="${TARGET}" bs=50 2>/dev/null
if verify "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi

10
tools/testing/selftests/sysctl/run_numerictests Normal file
View file

@ -0,0 +1,10 @@
#!/bin/sh
SYSCTL="/proc/sys"
TARGET="${SYSCTL}/vm/swappiness"
ORIG=$(cat "${TARGET}")
TEST_STR=$(( $ORIG + 1 ))
. ./common_tests
exit $rc

77
tools/testing/selftests/sysctl/run_stringtests Normal file
View file

@ -0,0 +1,77 @@
#!/bin/sh
SYSCTL="/proc/sys"
TARGET="${SYSCTL}/kernel/domainname"
ORIG=$(cat "${TARGET}")
TEST_STR="Testing sysctl"
. ./common_tests
# Only string sysctls support seeking/appending.
MAXLEN=65
echo -n "Writing entire sysctl in short writes ... "
set_orig
dd if="${TEST_FILE}" of="${TARGET}" bs=1 2>/dev/null
if ! verify "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Writing middle of sysctl after unsynchronized seek ... "
set_test
dd if="${TEST_FILE}" of="${TARGET}" bs=1 seek=1 2>/dev/null
if verify "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Checking sysctl maxlen is at least $MAXLEN ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-2), "B";' | \
dd of="${TARGET}" bs="${MAXLEN}" 2>/dev/null
if ! grep -q B "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Checking sysctl keeps original string on overflow append ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-1), "B";' | \
dd of="${TARGET}" bs=$(( MAXLEN - 1 )) 2>/dev/null
if grep -q B "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Checking sysctl stays NULL terminated on write ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-1), "B";' | \
dd of="${TARGET}" bs="${MAXLEN}" 2>/dev/null
if grep -q B "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
echo -n "Checking sysctl stays NULL terminated on overwrite ... "
set_orig
perl -e 'print "A" x ('"${MAXLEN}"'-1), "BB";' | \
dd of="${TARGET}" bs=$(( $MAXLEN + 1 )) 2>/dev/null
if grep -q B "${TARGET}"; then
echo "FAIL" >&2
rc=1
else
echo "ok"
fi
exit $rc