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authorKees Cook <keescook@chromium.org>2020-09-19 00:14:31 -0700
committerKees Cook <keescook@chromium.org>2020-10-08 13:16:00 -0700
commit71c87fbe720038007543abff7540ef0376c519f5 (patch)
tree533a8361436b35436f46ee72ad0eb4e79e0e3e2a /tools
parent46138329faeac3598f5a4dc991a174386b6de833 (diff)
downloadlinux-71c87fbe720038007543abff7540ef0376c519f5.tar.bz2
selftests/seccomp: Record syscall during ptrace entry
In preparation for performing actions during ptrace syscall exit, save the syscall number during ptrace syscall entry. Some architectures do no have the syscall number available during ptrace syscall exit. Suggested-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com> Link: https://lore.kernel.org/linux-kselftest/20200911181012.171027-1-cascardo@canonical.com/ Acked-by: Christian Brauner <christian.brauner@ubuntu.com> Link: https://lore.kernel.org/lkml/20200921074354.6shkt2e5yhzhj3sn@wittgenstein/ Signed-off-by: Kees Cook <keescook@chromium.org>
Diffstat (limited to 'tools')
-rw-r--r--tools/testing/selftests/seccomp/seccomp_bpf.c40
1 files changed, 27 insertions, 13 deletions
diff --git a/tools/testing/selftests/seccomp/seccomp_bpf.c b/tools/testing/selftests/seccomp/seccomp_bpf.c
index bc0fb463c709..c0311b4c736b 100644
--- a/tools/testing/selftests/seccomp/seccomp_bpf.c
+++ b/tools/testing/selftests/seccomp/seccomp_bpf.c
@@ -1949,12 +1949,19 @@ void tracer_seccomp(struct __test_metadata *_metadata, pid_t tracee,
}
+FIXTURE(TRACE_syscall) {
+ struct sock_fprog prog;
+ pid_t tracer, mytid, mypid, parent;
+ long syscall_nr;
+};
+
void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee,
int status, void *args)
{
- int ret, nr;
+ int ret;
unsigned long msg;
static bool entry;
+ FIXTURE_DATA(TRACE_syscall) *self = args;
/*
* The traditional way to tell PTRACE_SYSCALL entry/exit
@@ -1968,24 +1975,31 @@ void tracer_ptrace(struct __test_metadata *_metadata, pid_t tracee,
EXPECT_EQ(entry ? PTRACE_EVENTMSG_SYSCALL_ENTRY
: PTRACE_EVENTMSG_SYSCALL_EXIT, msg);
- if (!entry)
+ /*
+ * Some architectures only support setting return values during
+ * syscall exit under ptrace, and on exit the syscall number may
+ * no longer be available. Therefore, save the initial sycall
+ * number here, so it can be examined during both entry and exit
+ * phases.
+ */
+ if (entry)
+ self->syscall_nr = get_syscall(_metadata, tracee);
+ else
return;
- nr = get_syscall(_metadata, tracee);
-
- if (nr == __NR_getpid)
+ switch (self->syscall_nr) {
+ case __NR_getpid:
change_syscall(_metadata, tracee, __NR_getppid, 0);
- if (nr == __NR_gettid)
+ break;
+ case __NR_gettid:
change_syscall(_metadata, tracee, -1, 45000);
- if (nr == __NR_openat)
+ break;
+ case __NR_openat:
change_syscall(_metadata, tracee, -1, -ESRCH);
+ break;
+ }
}
-FIXTURE(TRACE_syscall) {
- struct sock_fprog prog;
- pid_t tracer, mytid, mypid, parent;
-};
-
FIXTURE_VARIANT(TRACE_syscall) {
/*
* All of the SECCOMP_RET_TRACE behaviors can be tested with either
@@ -2044,7 +2058,7 @@ FIXTURE_SETUP(TRACE_syscall)
self->tracer = setup_trace_fixture(_metadata,
variant->use_ptrace ? tracer_ptrace
: tracer_seccomp,
- NULL, variant->use_ptrace);
+ self, variant->use_ptrace);
ret = prctl(PR_SET_NO_NEW_PRIVS, 1, 0, 0, 0);
ASSERT_EQ(0, ret);