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    Subject[PATCHv9 3/5] syscalls: add selftest for execveat(2)
    Date
    Signed-off-by: David Drysdale <drysdale@google.com>
    ---
    tools/testing/selftests/Makefile | 1 +
    tools/testing/selftests/exec/.gitignore | 9 +
    tools/testing/selftests/exec/Makefile | 25 ++
    tools/testing/selftests/exec/execveat.c | 397 ++++++++++++++++++++++++++++++++
    4 files changed, 432 insertions(+)
    create mode 100644 tools/testing/selftests/exec/.gitignore
    create mode 100644 tools/testing/selftests/exec/Makefile
    create mode 100644 tools/testing/selftests/exec/execveat.c

    diff --git a/tools/testing/selftests/Makefile b/tools/testing/selftests/Makefile
    index 45f145c6f843..c14893b501a9 100644
    --- a/tools/testing/selftests/Makefile
    +++ b/tools/testing/selftests/Makefile
    @@ -15,6 +15,7 @@ TARGETS += user
    TARGETS += sysctl
    TARGETS += firmware
    TARGETS += ftrace
    +TARGETS += exec

    TARGETS_HOTPLUG = cpu-hotplug
    TARGETS_HOTPLUG += memory-hotplug
    diff --git a/tools/testing/selftests/exec/.gitignore b/tools/testing/selftests/exec/.gitignore
    new file mode 100644
    index 000000000000..64073e050c6a
    --- /dev/null
    +++ b/tools/testing/selftests/exec/.gitignore
    @@ -0,0 +1,9 @@
    +subdir*
    +script*
    +execveat
    +execveat.symlink
    +execveat.moved
    +execveat.path.ephemeral
    +execveat.ephemeral
    +execveat.denatured
    +xxxxxxxx*
    \ No newline at end of file
    diff --git a/tools/testing/selftests/exec/Makefile b/tools/testing/selftests/exec/Makefile
    new file mode 100644
    index 000000000000..66dfc2ce1788
    --- /dev/null
    +++ b/tools/testing/selftests/exec/Makefile
    @@ -0,0 +1,25 @@
    +CC = $(CROSS_COMPILE)gcc
    +CFLAGS = -Wall
    +BINARIES = execveat
    +DEPS = execveat.symlink execveat.denatured script subdir
    +all: $(BINARIES) $(DEPS)
    +
    +subdir:
    + mkdir -p $@
    +script:
    + echo '#!/bin/sh' > $@
    + echo 'exit $$*' >> $@
    + chmod +x $@
    +execveat.symlink: execveat
    + ln -s -f $< $@
    +execveat.denatured: execveat
    + cp $< $@
    + chmod -x $@
    +%: %.c
    + $(CC) $(CFLAGS) -o $@ $^
    +
    +run_tests: all
    + ./execveat
    +
    +clean:
    + rm -rf $(BINARIES) $(DEPS) subdir.moved execveat.moved xxxxx*
    diff --git a/tools/testing/selftests/exec/execveat.c b/tools/testing/selftests/exec/execveat.c
    new file mode 100644
    index 000000000000..33a5c06d95ca
    --- /dev/null
    +++ b/tools/testing/selftests/exec/execveat.c
    @@ -0,0 +1,397 @@
    +/*
    + * Copyright (c) 2014 Google, Inc.
    + *
    + * Licensed under the terms of the GNU GPL License version 2
    + *
    + * Selftests for execveat(2).
    + */
    +
    +#define _GNU_SOURCE /* to get O_PATH, AT_EMPTY_PATH */
    +#include <sys/sendfile.h>
    +#include <sys/stat.h>
    +#include <sys/syscall.h>
    +#include <sys/types.h>
    +#include <sys/wait.h>
    +#include <errno.h>
    +#include <fcntl.h>
    +#include <limits.h>
    +#include <stdio.h>
    +#include <stdlib.h>
    +#include <string.h>
    +#include <unistd.h>
    +
    +static char longpath[2 * PATH_MAX] = "";
    +static char *envp[] = { "IN_TEST=yes", NULL, NULL };
    +static char *argv[] = { "execveat", "99", NULL };
    +
    +static int execveat_(int fd, const char *path, char **argv, char **envp,
    + int flags)
    +{
    +#ifdef __NR_execveat
    + return syscall(__NR_execveat, fd, path, argv, envp, flags);
    +#else
    + errno = -ENOSYS;
    + return -1;
    +#endif
    +}
    +
    +#define check_execveat_fail(fd, path, flags, errno) \
    + _check_execveat_fail(fd, path, flags, errno, #errno)
    +static int _check_execveat_fail(int fd, const char *path, int flags,
    + int expected_errno, const char *errno_str)
    +{
    + int rc;
    +
    + errno = 0;
    + printf("Check failure of execveat(%d, '%s', %d) with %s... ",
    + fd, path?:"(null)", flags, errno_str);
    + rc = execveat_(fd, path, argv, envp, flags);
    +
    + if (rc > 0) {
    + printf("[FAIL] (unexpected success from execveat(2))\n");
    + return 1;
    + }
    + if (errno != expected_errno) {
    + printf("[FAIL] (expected errno %d (%s) not %d (%s)\n",
    + expected_errno, strerror(expected_errno),
    + errno, strerror(errno));
    + return 1;
    + }
    + printf("[OK]\n");
    + return 0;
    +}
    +
    +static int check_execveat_invoked_rc(int fd, const char *path, int flags,
    + int expected_rc)
    +{
    + int status;
    + int rc;
    + pid_t child;
    + int pathlen = path ? strlen(path) : 0;
    +
    + if (pathlen > 40)
    + printf("Check success of execveat(%d, '%.20s...%s', %d)... ",
    + fd, path, (path + pathlen - 20), flags);
    + else
    + printf("Check success of execveat(%d, '%s', %d)... ",
    + fd, path?:"(null)", flags);
    + child = fork();
    + if (child < 0) {
    + printf("[FAIL] (fork() failed)\n");
    + return 1;
    + }
    + if (child == 0) {
    + /* Child: do execveat(). */
    + rc = execveat_(fd, path, argv, envp, flags);
    + printf("[FAIL]: execveat() failed, rc=%d errno=%d (%s)\n",
    + rc, errno, strerror(errno));
    + exit(1); /* should not reach here */
    + }
    + /* Parent: wait for & check child's exit status. */
    + rc = waitpid(child, &status, 0);
    + if (rc != child) {
    + printf("[FAIL] (waitpid(%d,...) returned %d)\n", child, rc);
    + return 1;
    + }
    + if (!WIFEXITED(status)) {
    + printf("[FAIL] (child %d did not exit cleanly, status=%08x)\n",
    + child, status);
    + return 1;
    + }
    + if (WEXITSTATUS(status) != expected_rc) {
    + printf("[FAIL] (child %d exited with %d not %d)\n",
    + child, WEXITSTATUS(status), expected_rc);
    + return 1;
    + }
    + printf("[OK]\n");
    + return 0;
    +}
    +
    +static int check_execveat(int fd, const char *path, int flags)
    +{
    + return check_execveat_invoked_rc(fd, path, flags, 99);
    +}
    +
    +static char *concat(const char *left, const char *right)
    +{
    + char *result = malloc(strlen(left) + strlen(right) + 1);
    +
    + strcpy(result, left);
    + strcat(result, right);
    + return result;
    +}
    +
    +static int open_or_die(const char *filename, int flags)
    +{
    + int fd = open(filename, flags);
    +
    + if (fd < 0) {
    + printf("Failed to open '%s'; "
    + "check prerequisites are available\n", filename);
    + exit(1);
    + }
    + return fd;
    +}
    +
    +static void exe_cp(const char *src, const char *dest)
    +{
    + int in_fd = open_or_die(src, O_RDONLY);
    + int out_fd = open(dest, O_RDWR|O_CREAT|O_TRUNC, 0755);
    + struct stat info;
    +
    + fstat(in_fd, &info);
    + sendfile(out_fd, in_fd, NULL, info.st_size);
    + close(in_fd);
    + close(out_fd);
    +}
    +
    +#define XX_DIR_LEN 200
    +static int check_execveat_pathmax(int dot_dfd, const char *src, int is_script)
    +{
    + int fail = 0;
    + int ii, count, len;
    + char longname[XX_DIR_LEN + 1];
    + int fd;
    +
    + if (*longpath == '\0') {
    + /* Create a filename close to PATH_MAX in length */
    + memset(longname, 'x', XX_DIR_LEN - 1);
    + longname[XX_DIR_LEN - 1] = '/';
    + longname[XX_DIR_LEN] = '\0';
    + count = (PATH_MAX - 3) / XX_DIR_LEN;
    + for (ii = 0; ii < count; ii++) {
    + strcat(longpath, longname);
    + mkdir(longpath, 0755);
    + }
    + len = (PATH_MAX - 3) - (count * XX_DIR_LEN);
    + if (len <= 0)
    + len = 1;
    + memset(longname, 'y', len);
    + longname[len] = '\0';
    + strcat(longpath, longname);
    + }
    + exe_cp(src, longpath);
    +
    + /*
    + * Execute as a pre-opened file descriptor, which works whether this is
    + * a script or not (because the interpreter sees a filename like
    + * "/dev/fd/20").
    + */
    + fd = open(longpath, O_RDONLY);
    + if (fd > 0) {
    + printf("Invoke copy of '%s' via filename of length %lu:\n",
    + src, strlen(longpath));
    + fail += check_execveat(fd, "", AT_EMPTY_PATH);
    + } else {
    + printf("Failed to open length %lu filename, errno=%d (%s)\n",
    + strlen(longpath), errno, strerror(errno));
    + fail++;
    + }
    +
    + /*
    + * Execute as a long pathname relative to ".". If this is a script,
    + * the interpreter will launch but fail to open the script because its
    + * name ("/dev/fd/5/xxx....") is bigger than PATH_MAX.
    + */
    + if (is_script)
    + fail += check_execveat_invoked_rc(dot_dfd, longpath, 0, 127);
    + else
    + fail += check_execveat(dot_dfd, longpath, 0);
    +
    + return fail;
    +}
    +
    +static int run_tests(void)
    +{
    + int fail = 0;
    + char *fullname = realpath("execveat", NULL);
    + char *fullname_script = realpath("script", NULL);
    + char *fullname_symlink = concat(fullname, ".symlink");
    + int subdir_dfd = open_or_die("subdir", O_DIRECTORY|O_RDONLY);
    + int subdir_dfd_ephemeral = open_or_die("subdir.ephemeral",
    + O_DIRECTORY|O_RDONLY);
    + int dot_dfd = open_or_die(".", O_DIRECTORY|O_RDONLY);
    + int dot_dfd_path = open_or_die(".", O_DIRECTORY|O_RDONLY|O_PATH);
    + int dot_dfd_cloexec = open_or_die(".", O_DIRECTORY|O_RDONLY|O_CLOEXEC);
    + int fd = open_or_die("execveat", O_RDONLY);
    + int fd_path = open_or_die("execveat", O_RDONLY|O_PATH);
    + int fd_symlink = open_or_die("execveat.symlink", O_RDONLY);
    + int fd_denatured = open_or_die("execveat.denatured", O_RDONLY);
    + int fd_denatured_path = open_or_die("execveat.denatured",
    + O_RDONLY|O_PATH);
    + int fd_script = open_or_die("script", O_RDONLY);
    + int fd_ephemeral = open_or_die("execveat.ephemeral", O_RDONLY);
    + int fd_ephemeral_path = open_or_die("execveat.path.ephemeral",
    + O_RDONLY|O_PATH);
    + int fd_script_ephemeral = open_or_die("script.ephemeral", O_RDONLY);
    + int fd_cloexec = open_or_die("execveat", O_RDONLY|O_CLOEXEC);
    + int fd_script_cloexec = open_or_die("script", O_RDONLY|O_CLOEXEC);
    +
    + /* Change file position to confirm it doesn't affect anything */
    + lseek(fd, 10, SEEK_SET);
    +
    + /* Normal executable file: */
    + /* dfd + path */
    + fail += check_execveat(subdir_dfd, "../execveat", 0);
    + fail += check_execveat(dot_dfd, "execveat", 0);
    + fail += check_execveat(dot_dfd_path, "execveat", 0);
    + /* absolute path */
    + fail += check_execveat(AT_FDCWD, fullname, 0);
    + /* absolute path with nonsense dfd */
    + fail += check_execveat(99, fullname, 0);
    + /* fd + no path */
    + fail += check_execveat(fd, "", AT_EMPTY_PATH);
    + /* O_CLOEXEC fd + no path */
    + fail += check_execveat(fd_cloexec, "", AT_EMPTY_PATH);
    + /* O_PATH fd */
    + fail += check_execveat(fd_path, "", AT_EMPTY_PATH);
    +
    + /* Mess with executable file that's already open: */
    + /* fd + no path to a file that's been renamed */
    + rename("execveat.ephemeral", "execveat.moved");
    + fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
    + /* fd + no path to a file that's been deleted */
    + unlink("execveat.moved"); /* remove the file now fd open */
    + fail += check_execveat(fd_ephemeral, "", AT_EMPTY_PATH);
    +
    + /* Mess with executable file that's already open with O_PATH */
    + /* fd + no path to a file that's been deleted */
    + unlink("execveat.path.ephemeral");
    + fail += check_execveat(fd_ephemeral_path, "", AT_EMPTY_PATH);
    +
    + /* Invalid argument failures */
    + fail += check_execveat_fail(fd, "", 0, ENOENT);
    + fail += check_execveat_fail(fd, NULL, AT_EMPTY_PATH, EFAULT);
    +
    + /* Symlink to executable file: */
    + /* dfd + path */
    + fail += check_execveat(dot_dfd, "execveat.symlink", 0);
    + fail += check_execveat(dot_dfd_path, "execveat.symlink", 0);
    + /* absolute path */
    + fail += check_execveat(AT_FDCWD, fullname_symlink, 0);
    + /* fd + no path, even with AT_SYMLINK_NOFOLLOW (already followed) */
    + fail += check_execveat(fd_symlink, "", AT_EMPTY_PATH);
    + fail += check_execveat(fd_symlink, "",
    + AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
    +
    + /* Symlink fails when AT_SYMLINK_NOFOLLOW set: */
    + /* dfd + path */
    + fail += check_execveat_fail(dot_dfd, "execveat.symlink",
    + AT_SYMLINK_NOFOLLOW, ELOOP);
    + fail += check_execveat_fail(dot_dfd_path, "execveat.symlink",
    + AT_SYMLINK_NOFOLLOW, ELOOP);
    + /* absolute path */
    + fail += check_execveat_fail(AT_FDCWD, fullname_symlink,
    + AT_SYMLINK_NOFOLLOW, ELOOP);
    +
    + /* Shell script wrapping executable file: */
    + /* dfd + path */
    + fail += check_execveat(subdir_dfd, "../script", 0);
    + fail += check_execveat(dot_dfd, "script", 0);
    + fail += check_execveat(dot_dfd_path, "script", 0);
    + /* absolute path */
    + fail += check_execveat(AT_FDCWD, fullname_script, 0);
    + /* fd + no path */
    + fail += check_execveat(fd_script, "", AT_EMPTY_PATH);
    + fail += check_execveat(fd_script, "",
    + AT_EMPTY_PATH|AT_SYMLINK_NOFOLLOW);
    + /* O_CLOEXEC fd fails for a script (as script file inaccessible) */
    + fail += check_execveat_fail(fd_script_cloexec, "", AT_EMPTY_PATH,
    + ENOENT);
    + fail += check_execveat_fail(dot_dfd_cloexec, "script", 0, ENOENT);
    +
    + /* Mess with script file that's already open: */
    + /* fd + no path to a file that's been renamed */
    + rename("script.ephemeral", "script.moved");
    + fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
    + /* fd + no path to a file that's been deleted */
    + unlink("script.moved"); /* remove the file while fd open */
    + fail += check_execveat(fd_script_ephemeral, "", AT_EMPTY_PATH);
    +
    + /* Rename a subdirectory in the path: */
    + rename("subdir.ephemeral", "subdir.moved");
    + fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
    + fail += check_execveat(subdir_dfd_ephemeral, "script", 0);
    + /* Remove the subdir and its contents */
    + unlink("subdir.moved/script");
    + unlink("subdir.moved");
    + /* Shell loads via deleted subdir OK because name starts with .. */
    + fail += check_execveat(subdir_dfd_ephemeral, "../script", 0);
    + fail += check_execveat_fail(subdir_dfd_ephemeral, "script", 0, ENOENT);
    +
    + /* Flag values other than AT_SYMLINK_NOFOLLOW => EINVAL */
    + fail += check_execveat_fail(dot_dfd, "execveat", 0xFFFF, EINVAL);
    + /* Invalid path => ENOENT */
    + fail += check_execveat_fail(dot_dfd, "no-such-file", 0, ENOENT);
    + fail += check_execveat_fail(dot_dfd_path, "no-such-file", 0, ENOENT);
    + fail += check_execveat_fail(AT_FDCWD, "no-such-file", 0, ENOENT);
    + /* Attempt to execute directory => EACCES */
    + fail += check_execveat_fail(dot_dfd, "", AT_EMPTY_PATH, EACCES);
    + /* Attempt to execute non-executable => EACCES */
    + fail += check_execveat_fail(dot_dfd, "Makefile", 0, EACCES);
    + fail += check_execveat_fail(fd_denatured, "", AT_EMPTY_PATH, EACCES);
    + fail += check_execveat_fail(fd_denatured_path, "", AT_EMPTY_PATH,
    + EACCES);
    + /* Attempt to execute nonsense FD => EBADF */
    + fail += check_execveat_fail(99, "", AT_EMPTY_PATH, EBADF);
    + fail += check_execveat_fail(99, "execveat", 0, EBADF);
    + /* Attempt to execute relative to non-directory => ENOTDIR */
    + fail += check_execveat_fail(fd, "execveat", 0, ENOTDIR);
    +
    + fail += check_execveat_pathmax(dot_dfd, "execveat", 0);
    + fail += check_execveat_pathmax(dot_dfd, "script", 1);
    + return fail;
    +}
    +
    +static void prerequisites(void)
    +{
    + int fd;
    + const char *script = "#!/bin/sh\nexit $*\n";
    +
    + /* Create ephemeral copies of files */
    + exe_cp("execveat", "execveat.ephemeral");
    + exe_cp("execveat", "execveat.path.ephemeral");
    + exe_cp("script", "script.ephemeral");
    + mkdir("subdir.ephemeral", 0755);
    +
    + fd = open("subdir.ephemeral/script", O_RDWR|O_CREAT|O_TRUNC, 0755);
    + write(fd, script, strlen(script));
    + close(fd);
    +}
    +
    +int main(int argc, char **argv)
    +{
    + int ii;
    + int rc;
    + const char *verbose = getenv("VERBOSE");
    +
    + if (argc >= 2) {
    + /* If we are invoked with an argument, don't run tests. */
    + const char *in_test = getenv("IN_TEST");
    +
    + if (verbose) {
    + printf(" invoked with:");
    + for (ii = 0; ii < argc; ii++)
    + printf(" [%d]='%s'", ii, argv[ii]);
    + printf("\n");
    + }
    +
    + /* Check expected environment transferred. */
    + if (!in_test || strcmp(in_test, "yes") != 0) {
    + printf("[FAIL] (no IN_TEST=yes in env)\n");
    + return 1;
    + }
    +
    + /* Use the final argument as an exit code. */
    + rc = atoi(argv[argc - 1]);
    + fflush(stdout);
    + } else {
    + prerequisites();
    + if (verbose)
    + envp[1] = "VERBOSE=1";
    + rc = run_tests();
    + if (rc > 0)
    + printf("%d tests failed\n", rc);
    + }
    + return rc;
    +}
    --
    2.1.0.rc2.206.gedb03e5


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