On 1/11/21 1:23 PM, KP Singh wrote:
It was found in [1] that bpf_inode_storage_get helper did not check
the nullness of the passed owner ptr which caused an oops when
dereferenced. This change incorporates the example suggested in [1] into
the local storage selftest.
The test is updated to create a temporary directory instead of just
using a tempfile. In order to replicate the issue this copied rm binary
is renamed tiggering the inode_rename with a null pointer for the
new_inode. The logic to verify the setting and deletion of the inode
local storage of the old inode is also moved to this LSM hook.
The change also removes the copy_rm function and simply shells out
to copy files and recursively delete directories and consolidates the
logic of setting the initial inode storage to the bprm_committed_creds
hook and removes the file_open hook.
[1]: https://lore.kernel.org/bpf/CANaYP3HWkH91SN=wTNO9FL_2ztHfqcXKX38SSE-JJ2voh+vssw@xxxxxxxxxxxxxx
Suggested-by: Gilad Reti <gilad.reti@xxxxxxxxx>
Signed-off-by: KP Singh <kpsingh@xxxxxxxxxx>
Ack with one nit below.
Acked-by: Yonghong Song <yhs@xxxxxx>
---
.../bpf/prog_tests/test_local_storage.c | 96 +++++--------------
.../selftests/bpf/progs/local_storage.c | 62 ++++++------
2 files changed, 61 insertions(+), 97 deletions(-)
diff --git a/tools/testing/selftests/bpf/prog_tests/test_local_storage.c b/tools/testing/selftests/bpf/prog_tests/test_local_storage.c
index c0fe73a17ed1..338475fe9ffb 100644
--- a/tools/testing/selftests/bpf/prog_tests/test_local_storage.c
+++ b/tools/testing/selftests/bpf/prog_tests/test_local_storage.c
@@ -34,61 +34,6 @@ struct storage {
struct bpf_spin_lock lock;
};
-/* Copies an rm binary to a temp file. dest is a mkstemp template */
-static int copy_rm(char *dest)
-{
- int fd_in, fd_out = -1, ret = 0;
- struct stat stat;
- char *buf = NULL;
-
- fd_in = open("/bin/rm", O_RDONLY);
- if (fd_in < 0)
- return -errno;
-
- fd_out = mkstemp(dest);
- if (fd_out < 0) {
- ret = -errno;
- goto out;
- }
-
- ret = fstat(fd_in, &stat);
- if (ret == -1) {
- ret = -errno;
- goto out;
- }
-
- buf = malloc(stat.st_blksize);
- if (!buf) {
- ret = -errno;
- goto out;
- }
-
- while (ret = read(fd_in, buf, stat.st_blksize), ret > 0) {
- ret = write(fd_out, buf, ret);
- if (ret < 0) {
- ret = -errno;
- goto out;
-
- }
- }
- if (ret < 0) {
- ret = -errno;
- goto out;
-
- }
-
- /* Set executable permission on the copied file */
- ret = chmod(dest, 0100);
- if (ret == -1)
- ret = -errno;
-
-out:
- free(buf);
- close(fd_in);
- close(fd_out);
- return ret;
-}
-
/* Fork and exec the provided rm binary and return the exit code of the
* forked process and its pid.
*/
@@ -168,9 +113,11 @@ static bool check_syscall_operations(int map_fd, int obj_fd)
void test_test_local_storage(void)
{
- char tmp_exec_path[PATH_MAX] = "/tmp/copy_of_rmXXXXXX";
+ char tmp_dir_path[64] = "/tmp/local_storageXXXXXX";
int err, serv_sk = -1, task_fd = -1, rm_fd = -1;
struct local_storage *skel = NULL;
+ char tmp_exec_path[64];
+ char cmd[256];
skel = local_storage__open_and_load();
if (CHECK(!skel, "skel_load", "lsm skeleton failed\n"))
@@ -189,18 +136,24 @@ void test_test_local_storage(void)
task_fd))
goto close_prog;
- err = copy_rm(tmp_exec_path);
- if (CHECK(err < 0, "copy_rm", "err %d errno %d\n", err, errno))
+ mkdtemp(tmp_dir_path);
+ if (CHECK(errno < 0, "mkdtemp", "unable to create tmpdir: %d\n", errno))
I think checking mkdtemp return value is more reliable than checking
errno. It is possible mkdtemp returns 0 and errno is not 0 (inheritted
from previous syscall).
goto close_prog;
+ snprintf(tmp_exec_path, sizeof(tmp_exec_path), "%s/copy_of_rm",
+ tmp_dir_path);
+ snprintf(cmd, sizeof(cmd), "cp /bin/rm %s", tmp_exec_path);
+ if (CHECK_FAIL(system(cmd)))
+ goto close_prog_rmdir;
+
[...]
