From: Mark Wielaard <mark@klomp.org>
To: Carlos O'Donell <carlos@redhat.com>
Cc: libc-alpha@sourceware.org, Mark Wielaard <mark@klomp.org>,
Adhemerval Zanella <adhemerval.zanella@linaro.org>
Subject: [PATCHv5] tst-pidfd.c: UNSUPPORTED if we get EPERM on valid pidfd_getfd call
Date: Tue, 19 Jul 2022 15:14:19 +0200 [thread overview]
Message-ID: <20220719131419.21312-1-mark@klomp.org> (raw)
pidfd_getfd can fail for a valid pidfd with errno EPERM for various
reasons in a restricted environment. Use FAIL_UNSUPPORTED in that case.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
---
v5: Add comment why the EPERM check is needed and which credential
checks are performed
v4: Drop all EPERM checks except on the actual (valid) pidfd_getfd
v3: Also test for EPERM on pidfd_open, don't mention
PTRACE_MODE_ATTACH_REALCREDS since it is just one reason for
getting EPERM.
v2: separate ENOSYS and EPERM checks and FAIL_UNSUPPORTED messages
https://code.wildebeest.org/git/user/mjw/glibc/commit/?h=container-perms&id=435a8361ef3e2ce64bb7a48760adea577797967e
sysdeps/unix/sysv/linux/tst-pidfd.c | 7 +++++++
1 file changed, 7 insertions(+)
diff --git a/sysdeps/unix/sysv/linux/tst-pidfd.c b/sysdeps/unix/sysv/linux/tst-pidfd.c
index d93b6faa6f..037af22290 100644
--- a/sysdeps/unix/sysv/linux/tst-pidfd.c
+++ b/sysdeps/unix/sysv/linux/tst-pidfd.c
@@ -142,6 +142,13 @@ do_test (void)
xrecvfrom (sockets[0], &remote_fd, sizeof (remote_fd), 0, NULL, 0);
int fd = pidfd_getfd (pidfd, remote_fd, 0);
+ /* pidfd_getfd may fail with EPERM if the process does not have
+ PTRACE_MODE_ATTACH_REALCREDS permissions. This means the call
+ may be denied if the process doesn't have CAP_SYS_PTRACE or
+ if a LSM security_ptrace_access_check denies access. */
+ if (fd == -1 && errno == EPERM)
+ FAIL_UNSUPPORTED ("don't have permission to use pidfd_getfd on pidfd, "
+ "skipping test");
TEST_VERIFY (fd > 0);
char *path = xasprintf ("/proc/%d/fd/%d", pid, remote_fd);
--
2.30.2
next reply other threads:[~2022-07-19 13:14 UTC|newest]
Thread overview: 2+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-07-19 13:14 Mark Wielaard [this message]
2022-07-29 15:53 ` Carlos O'Donell
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