close_range() test type conflicts with close_range() library call in
x86_64-linux-gnu/bits/unistd_ext.h. Fix it by changing the name to
core_close_range().
gcc -g -I../../../../usr/include/ close_range_test.c -o ../tools/testing/selftests/core/close_range_test
In file included from close_range_test.c:16:
close_range_test.c:57:6: error: conflicting types for ‘close_range’; have ‘void(struct __test_metadata *)’
57 | TEST(close_range)
| ^~~~~~~~~~~
../kselftest_harness.h:181:21: note: in definition of macro ‘__TEST_IMPL’
181 | static void test_name(struct __test_metadata *_metadata); \
| ^~~~~~~~~
close_range_test.c:57:1: note: in expansion of macro ‘TEST’
57 | TEST(close_range)
| ^~~~
In file included from /usr/include/unistd.h:1204,
from close_range_test.c:13:
/usr/include/x86_64-linux-gnu/bits/unistd_ext.h:56:12: note: previous declaration of ‘close_range’ with type ‘int(unsigned int, unsigned int, int)’
56 | extern int close_range (unsigned int __fd, unsigned int __max_fd,
| ^~~~~~~~~~~
Signed-off-by: Shuah Khan <[email protected]>
This test is a minimalized version of the reproducer given by syzbot
(cf. [1]).
After introducing CLOSE_RANGE_CLOEXEC syzbot reported a crash when
CLOSE_RANGE_CLOEXEC is specified in conjunction with
CLOSE_RANGE_UNSHARE. When CLOSE_RANGE_UNSHARE is specified the caller
will receive a private file descriptor table in case their file
descriptor table is currently shared.
For the case where the caller has requested all file descriptors to be
actually closed via e.g. close_range(3, ~0U, 0) the kernel knows that
the caller does not need any of the file descriptors anymore and will
optimize the close operation by only copying all files in the range from
0 to 3 and no others.
However, if the caller requested CLOSE_RANGE_CLOEXEC together with
CLOSE_RANGE_UNSHARE the caller wants to still make use of the file
descriptors so the kernel needs to copy all of them and can't optimize.
The original patch didn't account for this and thus could cause oopses
as evidenced by the syzbot report. Add tests for this regression.
We first create a huge gap in the fd table. When we now call
CLOSE_RANGE_UNSHARE with a shared fd table and and with ~0U as upper
bound the kernel will only copy up to fd1 file descriptors into the new
fd table. If the kernel is buggy and doesn't handle CLOSE_RANGE_CLOEXEC
correctly it will not have copied all file descriptors and we will oops!
This test passes on a fixed kernel and will trigger an oops on a buggy
kernel.
[1]: https://syzkaller.appspot.com/text?tag=KernelConfig&x=db720fe37a6a41d8
Cc: Giuseppe Scrivano <[email protected]>
Cc: [email protected]
Link: [email protected]
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Christian Brauner <[email protected]>
check that close_range(initial_fd, last_fd, CLOSE_RANGE_CLOEXEC)
correctly sets the close-on-exec bit for the specified file
descriptors.
Open 100 file descriptors and set the close-on-exec flag for a subset
of them first, then set it for every file descriptor above 2. Make
sure RLIMIT_NOFILE doesn't affect the result.
Signed-off-by: Giuseppe Scrivano <[email protected]>
Link: https://lore.kernel.org/r/[email protected]
Signed-off-by: Christian Brauner <[email protected]>
This adds basic tests for the new close_range() syscall.
- test that no invalid flags can be passed
- test that a range of file descriptors is correctly closed
- test that a range of file descriptors is correctly closed if there there
are already closed file descriptors in the range
- test that max_fd is correctly capped to the current fdtable maximum
Signed-off-by: Christian Brauner <[email protected]>
Cc: Arnd Bergmann <[email protected]>
Cc: Jann Horn <[email protected]>
Cc: David Howells <[email protected]>
Cc: Dmitry V. Levin <[email protected]>
Cc: Oleg Nesterov <[email protected]>
Cc: Linus Torvalds <[email protected]>
Cc: Florian Weimer <[email protected]>
Cc: Shuah Khan <[email protected]>
Cc: [email protected]
Cc: [email protected]
Shuah Khan