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[104.198.60.80]) by smtp.gmail.com with ESMTPSA id g79sm1162957ilf.10.2019.12.18.15.55.51 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 18 Dec 2019 15:55:51 -0800 (PST) Date: Wed, 18 Dec 2019 23:55:50 +0000 From: Sargun Dhillon To: linux-kernel@vger.kernel.org, containers@lists.linux-foundation.org, linux-api@vger.kernel.org, linux-fsdevel@vger.kernel.org Cc: tycho@tycho.ws, jannh@google.com, cyphar@cyphar.com, christian.brauner@ubuntu.com, oleg@redhat.com, luto@amacapital.net, viro@zeniv.linux.org.uk, gpascutto@mozilla.com, ealvarez@mozilla.com, fweimer@redhat.com, jld@mozilla.com, arnd@arndb.de Subject: [PATCH v4 5/5] test: Add test for pidfd getfd Message-ID: <20191218235547.GA17298@ircssh-2.c.rugged-nimbus-611.internal> MIME-Version: 1.0 Content-Disposition: inline User-Agent: Mutt/1.5.24 (2015-08-30) Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org This adds four tests: * Fetch FD, and then compare via kcmp * Read data from FD to make sure it works * Make sure getfd can be blocked by blocking ptrace_may_access * Making sure fetching bad FDs fails Signed-off-by: Sargun Dhillon --- tools/testing/selftests/pidfd/.gitignore | 1 + tools/testing/selftests/pidfd/Makefile | 2 +- .../selftests/pidfd/pidfd_getfd_test.c | 231 ++++++++++++++++++ 3 files changed, 233 insertions(+), 1 deletion(-) create mode 100644 tools/testing/selftests/pidfd/pidfd_getfd_test.c diff --git a/tools/testing/selftests/pidfd/.gitignore b/tools/testing/selftests/pidfd/.gitignore index 8d069490e17b..3a779c084d96 100644 --- a/tools/testing/selftests/pidfd/.gitignore +++ b/tools/testing/selftests/pidfd/.gitignore @@ -2,3 +2,4 @@ pidfd_open_test pidfd_poll_test pidfd_test pidfd_wait +pidfd_getfd_test diff --git a/tools/testing/selftests/pidfd/Makefile b/tools/testing/selftests/pidfd/Makefile index 43db1b98e845..75a545861375 100644 --- a/tools/testing/selftests/pidfd/Makefile +++ b/tools/testing/selftests/pidfd/Makefile @@ -1,7 +1,7 @@ # SPDX-License-Identifier: GPL-2.0-only CFLAGS += -g -I../../../../usr/include/ -pthread -TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test pidfd_poll_test pidfd_wait +TEST_GEN_PROGS := pidfd_test pidfd_fdinfo_test pidfd_open_test pidfd_poll_test pidfd_wait pidfd_getfd_test include ../lib.mk diff --git a/tools/testing/selftests/pidfd/pidfd_getfd_test.c b/tools/testing/selftests/pidfd/pidfd_getfd_test.c new file mode 100644 index 000000000000..25c11a030afc --- /dev/null +++ b/tools/testing/selftests/pidfd/pidfd_getfd_test.c @@ -0,0 +1,231 @@ +// SPDX-License-Identifier: GPL-2.0 + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include "pidfd.h" +#include "../kselftest.h" + +#define WELL_KNOWN_CHILD_FD 100 +#define UNKNOWN_FD 111 +#define SECRET_MESSAGE "secret" + +static int kcmp(pid_t pid1, pid_t pid2, int type, unsigned long idx1, + unsigned long idx2) +{ + return syscall(SYS_kcmp, pid1, pid2, type, idx1, idx2); +} + +static int child(bool disable_ptrace, int sk) +{ + char buf[1024]; + int ret, fd; + + ret = prctl(PR_SET_PDEATHSIG, SIGKILL); + if (ret) + ksft_exit_fail_msg("%s: Child could not set DEATHSIG\n", + strerror(errno)); + + fd = syscall(SYS_memfd_create, "test", 0); + if (fd < 0) + ksft_exit_fail_msg("%s: Child could not create memfd\n", + strerror(errno)); + + ret = write(fd, SECRET_MESSAGE, sizeof(SECRET_MESSAGE)); + if (ret < 0) + ksft_exit_fail_msg("%s: Child could not write secret message\n", + strerror(errno)); + + ret = dup2(fd, WELL_KNOWN_CHILD_FD); + if (ret < 0) + ksft_exit_fail_msg("%s: Could not dup fd into well-known FD\n", + strerror(errno)); + + ret = close(fd); + if (ret < 0) + ksft_exit_fail_msg("%s: Child could close old fd\n", + strerror(errno)); + + if (disable_ptrace) { + ret = prctl(PR_SET_DUMPABLE, 0); + if (ret < 0) + ksft_exit_fail_msg("%s: Child failed to disable ptrace\n", + strerror(errno)); + } + ret = send(sk, "L", 1, 0); + if (ret < 0) + ksft_exit_fail_msg("%s: Child failed to send launched message\n", + strerror(errno)); + if (ret == 0) + ksft_exit_fail_msg("Failed to send launch message; other side is closed\n"); + + close(sk); + pause(); + + return EXIT_SUCCESS; +} + +static int start_child(bool disable_ptrace, pid_t *childpid) +{ + int pidfd, ret, sk_pair[2]; + char buf[1]; + + if (socketpair(PF_LOCAL, SOCK_SEQPACKET, 0, sk_pair) < 0) + ksft_exit_fail_msg("%s: failed to create socketpair\n", + strerror(errno)); + *childpid = fork(); + if (*childpid < 0) + ksft_exit_fail_msg("%s: failed to fork a child process\n", + strerror(errno)); + + if (*childpid == 0) + exit(child(disable_ptrace, sk_pair[1])); + + close(sk_pair[1]); + + pidfd = sys_pidfd_open(*childpid, 0); + if (pidfd < 0) + ksft_exit_fail_msg("%s: failed to pidfd_open\n", + strerror(errno)); + + ret = recv(sk_pair[0], &buf, 1, 0); + if (ret < 0) + ksft_exit_fail_msg("%s: failed read from launch socket\n", + strerror(errno)); + if (ret == 0) + ksft_exit_fail_msg("Failed to read from launch socket, child failed\n"); + + return pidfd; +} + +static void test_kcmp_and_fetch_fd(void) +{ + char buf[sizeof(SECRET_MESSAGE)]; + int fd, pidfd, ret; + pid_t child_pid; + + pidfd = start_child(false, &child_pid); + + fd = ioctl(pidfd, PIDFD_IOCTL_GETFD, WELL_KNOWN_CHILD_FD); + if (fd < 0) + ksft_exit_fail_msg("%s: getfd failed\n", strerror(errno)); + + ret = kcmp(getpid(), child_pid, KCMP_FILE, fd, WELL_KNOWN_CHILD_FD); + if (ret != 0) + ksft_exit_fail_msg("Our FD not equal to child FD\n"); + + ksft_test_result_pass("kcmp\n"); + + ret = lseek(fd, 0, SEEK_SET); + if (ret < 0) + ksft_exit_fail_msg("%s: seek failed\n", strerror(errno)); + if (ret != 0) + ksft_exit_fail_msg("%d: unexpected seek position\n", ret); + + ret = read(fd, buf, sizeof(buf)); + if (ret < 0) + ksft_exit_fail_msg("%s: failed to read secret message\n", + strerror(errno)); + + if (strncmp(SECRET_MESSAGE, buf, sizeof(buf)) != 0) + ksft_exit_fail_msg("%s: Secret message not correct\n", buf); + + ret = sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0); + close(pidfd); + if (ret < 0) + ksft_exit_fail_msg("%s: failed to send kill to child\n", + strerror(errno)); + + ksft_test_result_pass("fetch_and_read\n"); +} + +static void test_no_ptrace(void) +{ + int fd, pidfd, ret, uid; + pid_t child_pid; + + /* turn into nobody if we're root, to avoid CAP_SYS_PTRACE */ + uid = getuid(); + if (uid == 0) + seteuid(USHRT_MAX); + + pidfd = start_child(true, &child_pid); + + fd = ioctl(pidfd, PIDFD_IOCTL_GETFD, WELL_KNOWN_CHILD_FD); + if (fd != -1) + ksft_exit_fail_msg("%s: getfd succeeded when ptrace blocked\n", + strerror(errno)); + if (errno != EPERM) + ksft_exit_fail_msg("%s: getfd did not get EPERM\n", + strerror(errno)); + + ret = sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0); + close(pidfd); + if (ret < 0) + ksft_exit_fail_msg("%s: failed to send kill to child\n", + strerror(errno)); + + if (uid == 0) + seteuid(0); + + ksft_test_result_pass("no_ptrace\n"); +} + +static void test_unknown_fd(void) +{ + int fd, pidfd, ret; + pid_t child_pid; + + pidfd = start_child(false, &child_pid); + + fd = ioctl(pidfd, PIDFD_IOCTL_GETFD, UNKNOWN_FD); + if (fd != -1) + ksft_exit_fail_msg("%s: getfd succeeded when fetching unknown FD\n", + strerror(errno)); + if (errno != EBADF) + ksft_exit_fail_msg("%s: getfd did not get EBADF\n", + strerror(errno)); + + ret = sys_pidfd_send_signal(pidfd, SIGKILL, NULL, 0); + close(pidfd); + if (ret < 0) + ksft_exit_fail_msg("%s: failed to send kill to child\n", + strerror(errno)); + + ksft_test_result_pass("unknown_fd\n"); +} + +int main(int argc, char **argv) +{ + char buf[sizeof(SECRET_MESSAGE)]; + int ret, status, fd, pidfd; + pid_t child_pid; + + ksft_print_header(); + ksft_set_plan(4); + + test_kcmp_and_fetch_fd(); + test_unknown_fd(); + test_no_ptrace(); + + return ksft_exit_pass(); +}