From 110be3f9641cc5a95eae5cf6bc142245a1898545 Mon Sep 17 00:00:00 2001 From: Manu Bretelle Date: Tue, 24 Oct 2023 13:18:52 -0700 Subject: [PATCH] selftests/bpf: umount children of TDIR in test_bpffs Currently this tests tries to umount /sys/kernel/debug (TDIR) but the system it is running on may have mounts below. For example, danobi/vmtest [0] VMs have mount -t tracefs tracefs /sys/kernel/debug/tracing as part of their init. This change list mounts and will umount any mounts below TDIR before umounting TDIR itself. Note that it is not umounting recursively, so in the case of a sub-mount of TDIR having another sub-mount, this will fail as mtab is ordered. Test: Originally: $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs" => bzImage ===> Booting ===> Setting up VM ===> Running command [ 2.138818] bpf_testmod: loading out-of-tree module taints kernel. [ 2.140913] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel bpf_testmod.ko is already unloaded. Loading bpf_testmod.ko... Successfully loaded bpf_testmod.ko. test_test_bpffs:PASS:clone 0 nsec fn:PASS:unshare 0 nsec fn:PASS:mount / 0 nsec fn:FAIL:umount /sys/kernel/debug unexpected error: -1 (errno 16) bpf_testmod.ko is already unloaded. Loading bpf_testmod.ko... Successfully loaded bpf_testmod.ko. test_test_bpffs:PASS:clone 0 nsec test_test_bpffs:PASS:waitpid 0 nsec test_test_bpffs:FAIL:bpffs test failed 255#282 test_bpffs:FAIL Summary: 0/0 PASSED, 0 SKIPPED, 1 FAILED Successfully unloaded bpf_testmod.ko. Command failed with exit code: 1 After this change: $ vmtest -k $KERNEL_REPO/arch/x86_64/boot/bzImage "./test_progs -vv -a test_bpffs" => bzImage ===> Booting ===> Setting up VM ===> Running command [ 2.035210] bpf_testmod: loading out-of-tree module taints kernel. [ 2.036510] bpf_testmod: module verification failed: signature and/or required key missing - tainting kernel bpf_testmod.ko is already unloaded. Loading bpf_testmod.ko... Successfully loaded bpf_testmod.ko. test_test_bpffs:PASS:clone 0 nsec fn:PASS:unshare 0 nsec fn:PASS:mount / 0 nsec fn:PASS:accessing /etc/mtab 0 nsec fn:PASS:umount /sys/kernel/debug/tracing 0 nsec fn:PASS:umount /sys/kernel/debug 0 nsec fn:PASS:mount tmpfs 0 nsec fn:PASS:mkdir /sys/kernel/debug/fs1 0 nsec fn:PASS:mkdir /sys/kernel/debug/fs2 0 nsec fn:PASS:mount bpffs /sys/kernel/debug/fs1 0 nsec fn:PASS:mount bpffs /sys/kernel/debug/fs2 0 nsec fn:PASS:reading /sys/kernel/debug/fs1/maps.debug 0 nsec fn:PASS:reading /sys/kernel/debug/fs2/progs.debug 0 nsec fn:PASS:creating /sys/kernel/debug/fs1/a 0 nsec fn:PASS:creating /sys/kernel/debug/fs1/a/1 0 nsec fn:PASS:creating /sys/kernel/debug/fs1/b 0 nsec fn:PASS:create_map(ARRAY) 0 nsec fn:PASS:pin map 0 nsec fn:PASS:stat(/sys/kernel/debug/fs1/a) 0 nsec fn:PASS:renameat2(/fs1/a, /fs1/b, RENAME_EXCHANGE) 0 nsec fn:PASS:stat(/sys/kernel/debug/fs1/b) 0 nsec fn:PASS:b should have a's inode 0 nsec fn:PASS:access(/sys/kernel/debug/fs1/b/1) 0 nsec fn:PASS:stat(/sys/kernel/debug/fs1/map) 0 nsec fn:PASS:renameat2(/fs1/c, /fs1/b, RENAME_EXCHANGE) 0 nsec fn:PASS:stat(/sys/kernel/debug/fs1/b) 0 nsec fn:PASS:b should have c's inode 0 nsec fn:PASS:access(/sys/kernel/debug/fs1/c/1) 0 nsec fn:PASS:renameat2(RENAME_NOREPLACE) 0 nsec fn:PASS:access(/sys/kernel/debug/fs1/b) 0 nsec bpf_testmod.ko is already unloaded. Loading bpf_testmod.ko... Successfully loaded bpf_testmod.ko. test_test_bpffs:PASS:clone 0 nsec test_test_bpffs:PASS:waitpid 0 nsec test_test_bpffs:PASS:bpffs test 0 nsec #282 test_bpffs:OK Summary: 1/0 PASSED, 0 SKIPPED, 0 FAILED Successfully unloaded bpf_testmod.ko. [0] https://github.com/danobi/vmtest Signed-off-by: Manu Bretelle --- .../selftests/bpf/prog_tests/test_bpffs.c | 28 +++++++++++++++++++ 1 file changed, 28 insertions(+) diff --git a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c index 214d9f4a94a538..001bf694c2690f 100644 --- a/tools/testing/selftests/bpf/prog_tests/test_bpffs.c +++ b/tools/testing/selftests/bpf/prog_tests/test_bpffs.c @@ -3,12 +3,14 @@ #define _GNU_SOURCE #include #include +#include #include #include #include #include #define TDIR "/sys/kernel/debug" +#define MTAB "/etc/mtab" static int read_iter(char *file) { @@ -32,6 +34,8 @@ static int read_iter(char *file) static int fn(void) { + /* A buffer to store logging messages */ + char buf[1024]; struct stat a, b, c; int err, map; @@ -43,6 +47,30 @@ static int fn(void) if (!ASSERT_OK(err, "mount /")) goto out; + /* TDIR may have mounts below. unount them first */ + FILE *mtab = setmntent(MTAB, "r"); + + if (!ASSERT_TRUE(mtab != NULL, "accessing " MTAB)) { + err = errno; + goto out; + } + + struct mntent *mnt = NULL; + + while ((mnt = getmntent(mtab)) != NULL) { + if (strlen(mnt->mnt_dir) > strlen(TDIR) && + strncmp(TDIR, mnt->mnt_dir, strlen(TDIR)) == 0) { + snprintf(buf, sizeof(buf) - 1, "umount %s", mnt->mnt_dir); + err = umount(mnt->mnt_dir); + if (!ASSERT_OK(err, buf)) { + endmntent(mtab); + goto out; + } + } + } + // Ignore any error here + endmntent(mtab); + err = umount(TDIR); if (!ASSERT_OK(err, "umount " TDIR)) goto out;