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* [glibc] linux: Fail as unsupported if personality call is filtered
@ 2023-06-05 15:53 Adhemerval Zanella
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From: Adhemerval Zanella @ 2023-06-05 15:53 UTC (permalink / raw)
To: glibc-cvs
https://sourceware.org/git/gitweb.cgi?p=glibc.git;h=d4963a844dc72c4ac14da3395cf511f3d191d689
commit d4963a844dc72c4ac14da3395cf511f3d191d689
Author: Adhemerval Zanella <adhemerval.zanella@linaro.org>
Date: Fri Jun 2 10:19:48 2023 -0300
linux: Fail as unsupported if personality call is filtered
Container management default seccomp filter [1] only accepts
personality(2) with PER_LINUX, (0x0), UNAME26 (0x20000),
PER_LINUX32 (0x8), UNAME26 | PER_LINUX32, and 0xffffffff (to query
current personality)
Although the documentation only state it is blocked to prevent
'enabling BSD emulation' (PER_BSD, not implemented by Linux), checking
on repository log the real reason is to block ASLR disable flag
(ADDR_NO_RANDOMIZE) and other poorly support emulations.
So handle EPERM and fail as UNSUPPORTED if we can really check for
BZ#19408.
Checked on aarch64-linux-gnu.
[1] https://github.com/moby/moby/blob/master/profiles/seccomp/default.json
Reviewed-by: Florian Weimer <fweimer@redhat.com>
Diff:
---
sysdeps/unix/sysv/linux/tst-personality.c | 33 ++++++++++++++++++++-----------
1 file changed, 21 insertions(+), 12 deletions(-)
diff --git a/sysdeps/unix/sysv/linux/tst-personality.c b/sysdeps/unix/sysv/linux/tst-personality.c
index e730650e5b..5e59627826 100644
--- a/sysdeps/unix/sysv/linux/tst-personality.c
+++ b/sysdeps/unix/sysv/linux/tst-personality.c
@@ -19,27 +19,36 @@
#include <errno.h>
#include <sys/personality.h>
+#include <support/check.h>
static int
do_test (void)
{
- int rc = 0;
unsigned int test_persona = -EINVAL;
unsigned int saved_persona;
errno = 0xdefaced;
saved_persona = personality (0xffffffff);
- if (personality (test_persona) != saved_persona
- || personality (0xffffffff) == -1
- || personality (PER_LINUX) == -1
- || personality (0xffffffff) != PER_LINUX
- || 0xdefaced != errno)
- rc = 1;
-
- (void) personality (saved_persona);
- return rc;
+ unsigned int r = personality (test_persona);
+ if (r == -1)
+ {
+ /* The syscall argument might be filtered by kernel, so the
+ test can not check for the bug issue. */
+ if (errno == EPERM)
+ FAIL_UNSUPPORTED ("personality syscall argument are filtered");
+ FAIL_EXIT1 ("personality (%#x) failed: %m", test_persona);
+ }
+
+ TEST_COMPARE (r, saved_persona);
+ TEST_VERIFY (personality (0xffffffff) != -1);
+ TEST_VERIFY (personality (PER_LINUX) != -1);
+ TEST_COMPARE (personality (0xffffffff), PER_LINUX);
+ TEST_COMPARE (0xdefaced, errno);
+
+ personality (saved_persona);
+
+ return 0;
}
-#define TEST_FUNCTION do_test ()
-#include "../test-skeleton.c"
+#include <support/test-driver.c>
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