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Merge branch 'wip/smcv/but-what-if-capabilities' into 'master'
Make tests pass if we are euid != 0 with capabilities Closes #2029, #2028, and #2027 See merge request GNOME/glib!1363
This commit is contained in:
Philip Withnall
commit
4a153abebe
@ -22,6 +22,7 @@
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#include <glib/glib.h>
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#include <gio/gio.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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@ -115,6 +116,65 @@ static gboolean write_test;
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static gboolean verbose;
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static gboolean posix_compat;
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#ifdef G_OS_UNIX
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/*
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* check_cap_dac_override:
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* @tmpdir: A temporary directory in which we can create and delete files
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*
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* Check whether the current process can bypass DAC permissions.
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*
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* Traditionally, "privileged" processes (those with effective uid 0)
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* could do this (and bypass many other checks), and "unprivileged"
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* processes could not.
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*
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* In Linux, the special powers of euid 0 are divided into many
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* capabilities: see `capabilities(7)`. The one we are interested in
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* here is `CAP_DAC_OVERRIDE`.
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*
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* We do this generically instead of actually looking at the capability
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* bits, so that the right thing will happen on non-Linux Unix
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* implementations, in particular if they have something equivalent to
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* but not identical to Linux permissions.
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*
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* Returns: %TRUE if we have Linux `CAP_DAC_OVERRIDE` or equivalent
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* privileges
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*/
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static gboolean
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check_cap_dac_override (const char *tmpdir)
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{
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gchar *dac_denies_write;
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gchar *inside;
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gboolean have_cap;
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dac_denies_write = g_build_filename (tmpdir, "dac-denies-write", NULL);
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inside = g_build_filename (dac_denies_write, "inside", NULL);
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g_assert_cmpint (mkdir (dac_denies_write, S_IRWXU) == 0 ? 0 : errno, ==, 0);
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g_assert_cmpint (chmod (dac_denies_write, 0) == 0 ? 0 : errno, ==, 0);
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if (mkdir (inside, S_IRWXU) == 0)
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{
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g_test_message ("Looks like we have CAP_DAC_OVERRIDE or equivalent");
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g_assert_cmpint (rmdir (inside) == 0 ? 0 : errno, ==, 0);
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have_cap = TRUE;
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}
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else
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{
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int saved_errno = errno;
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g_test_message ("We do not have CAP_DAC_OVERRIDE or equivalent");
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g_assert_cmpint (saved_errno, ==, EACCES);
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have_cap = FALSE;
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}
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g_assert_cmpint (chmod (dac_denies_write, S_IRWXU) == 0 ? 0 : errno, ==, 0);
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g_assert_cmpint (rmdir (dac_denies_write) == 0 ? 0 : errno, ==, 0);
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g_free (dac_denies_write);
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g_free (inside);
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return have_cap;
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}
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#endif
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#ifdef G_HAVE_ISO_VARARGS
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#define log(...) if (verbose) g_printerr (__VA_ARGS__)
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#elif defined(G_HAVE_GNUC_VARARGS)
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@ -708,6 +768,9 @@ do_copy_move (GFile * root, struct StructureItem item, const char *target_dir,
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GFile *dst_dir, *src_file, *dst_file;
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gboolean res;
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GError *error;
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#ifdef G_OS_UNIX
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gboolean have_cap_dac_override = check_cap_dac_override (g_file_peek_path (root));
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#endif
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log (" do_copy_move: '%s' --> '%s'\n", item.filename, target_dir);
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@ -768,12 +831,17 @@ do_copy_move (GFile * root, struct StructureItem item, const char *target_dir,
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(extra_flags == TEST_NO_ACCESS))
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{
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/* This works for root, see bug #552912 */
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if (test_suite && getuid () == 0)
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#ifdef G_OS_UNIX
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if (have_cap_dac_override)
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{
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g_test_message ("Unable to exercise g_file_copy() or g_file_move() "
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"failing with EACCES: we probably have "
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"CAP_DAC_OVERRIDE");
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g_assert_true (res);
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g_assert_no_error (error);
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}
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else
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#endif
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{
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g_assert_false (res);
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g_assert_error (error, G_IO_ERROR, G_IO_ERROR_PERMISSION_DENIED);
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@ -1121,6 +1189,9 @@ test_make_directory_with_parents (gconstpointer test_data)
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GFile *root, *child, *grandchild, *greatgrandchild;
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gboolean res;
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GError *error = NULL;
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#ifdef G_OS_UNIX
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gboolean have_cap_dac_override = check_cap_dac_override (test_data);
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#endif
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g_assert_nonnull (test_data);
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@ -1171,9 +1242,16 @@ test_make_directory_with_parents (gconstpointer test_data)
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if (!posix_compat)
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goto out;
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#ifndef G_PLATFORM_WIN32
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if (getuid() == 0) /* permissions are ignored for root */
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goto out;
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#ifdef G_OS_UNIX
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/* Permissions are ignored if we have CAP_DAC_OVERRIDE or equivalent,
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* and in particular if we're root */
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if (have_cap_dac_override)
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{
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g_test_skip ("Unable to exercise g_file_make_directory_with_parents "
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"failing with EACCES: we probably have "
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"CAP_DAC_OVERRIDE");
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goto out;
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}
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#endif
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g_file_make_directory (child, NULL, NULL);
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@ -1343,7 +1421,7 @@ main (int argc, char *argv[])
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}
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g_option_context_free (context);
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/* Write test - clean target directory first */
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/* this can be also considered as a test - enumerate + delete */
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if (write_test || only_create_struct)
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@ -522,6 +522,65 @@ test_mkdir_with_parents (void)
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g_assert_cmpint (errno, ==, EINVAL);
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}
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#ifdef G_OS_UNIX
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/*
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* check_cap_dac_override:
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* @tmpdir: A temporary directory in which we can create and delete files
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*
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* Check whether the current process can bypass DAC permissions.
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*
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* Traditionally, "privileged" processes (those with effective uid 0)
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* could do this (and bypass many other checks), and "unprivileged"
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* processes could not.
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*
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* In Linux, the special powers of euid 0 are divided into many
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* capabilities: see `capabilities(7)`. The one we are interested in
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* here is `CAP_DAC_OVERRIDE`.
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*
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* We do this generically instead of actually looking at the capability
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* bits, so that the right thing will happen on non-Linux Unix
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* implementations, in particular if they have something equivalent to
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* but not identical to Linux permissions.
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*
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* Returns: %TRUE if we have Linux `CAP_DAC_OVERRIDE` or equivalent
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* privileges
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*/
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static gboolean
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check_cap_dac_override (const char *tmpdir)
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{
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gchar *dac_denies_write;
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gchar *inside;
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gboolean have_cap;
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dac_denies_write = g_build_filename (tmpdir, "dac-denies-write", NULL);
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inside = g_build_filename (dac_denies_write, "inside", NULL);
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g_assert_cmpint (mkdir (dac_denies_write, S_IRWXU) == 0 ? 0 : errno, ==, 0);
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g_assert_cmpint (chmod (dac_denies_write, 0) == 0 ? 0 : errno, ==, 0);
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if (mkdir (inside, S_IRWXU) == 0)
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{
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g_test_message ("Looks like we have CAP_DAC_OVERRIDE or equivalent");
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g_assert_cmpint (rmdir (inside) == 0 ? 0 : errno, ==, 0);
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have_cap = TRUE;
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}
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else
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{
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int saved_errno = errno;
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g_test_message ("We do not have CAP_DAC_OVERRIDE or equivalent");
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g_assert_cmpint (saved_errno, ==, EACCES);
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have_cap = FALSE;
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}
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g_assert_cmpint (chmod (dac_denies_write, S_IRWXU) == 0 ? 0 : errno, ==, 0);
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g_assert_cmpint (rmdir (dac_denies_write) == 0 ? 0 : errno, ==, 0);
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g_free (dac_denies_write);
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g_free (inside);
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return have_cap;
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}
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#endif
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/* Reproducer for https://gitlab.gnome.org/GNOME/glib/issues/1852 */
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static void
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test_mkdir_with_parents_permission (void)
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@ -534,21 +593,23 @@ test_mkdir_with_parents_permission (void)
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GError *error = NULL;
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int result;
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int saved_errno;
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gboolean have_cap_dac_override;
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tmpdir = g_dir_make_tmp ("test-fileutils.XXXXXX", &error);
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g_assert_no_error (error);
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g_assert_nonnull (tmpdir);
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have_cap_dac_override = check_cap_dac_override (tmpdir);
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subdir = g_build_filename (tmpdir, "sub", NULL);
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subdir2 = g_build_filename (subdir, "sub2", NULL);
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subdir3 = g_build_filename (subdir2, "sub3", NULL);
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g_assert_cmpint (g_mkdir (subdir, 0700) == 0 ? 0 : errno, ==, 0);
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g_assert_cmpint (g_chmod (subdir, 0) == 0 ? 0 : errno, ==, 0);
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if (g_mkdir (subdir2, 0700) == 0)
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if (have_cap_dac_override)
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{
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g_test_skip ("have CAP_DAC_OVERRIDE or equivalent, cannot test");
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g_remove (subdir2);
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}
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else
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{
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@ -949,14 +1010,8 @@ test_stdio_wrappers (void)
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GError *error = NULL;
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GStatBuf path_statbuf, cwd_statbuf;
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time_t now;
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/* The permissions tests here don’t work when running as root. */
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#ifdef G_OS_UNIX
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if (getuid () == 0 || geteuid () == 0)
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{
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g_test_skip ("File permissions tests cannot be run as root");
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return;
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}
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gboolean have_cap_dac_override;
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#endif
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g_remove ("mkdir-test/test-create");
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@ -973,13 +1028,32 @@ test_stdio_wrappers (void)
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cwd = g_get_current_dir ();
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path = g_build_filename (cwd, "mkdir-test", NULL);
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g_free (cwd);
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#ifndef G_OS_WIN32
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/* 0666 on directories means nothing to Windows, it only obeys ACLs */
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ret = g_chdir (path);
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g_assert_cmpint (errno, ==, EACCES);
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g_assert_cmpint (ret, ==, -1);
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#ifdef G_OS_UNIX
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have_cap_dac_override = check_cap_dac_override (cwd);
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#endif
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g_free (cwd);
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/* 0666 on directories means nothing to Windows, it only obeys ACLs.
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* It doesn't necessarily mean anything on Unix either: if we have
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* Linux CAP_DAC_OVERRIDE or equivalent (in particular if we're root),
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* then we ignore filesystem permissions. */
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#ifdef G_OS_UNIX
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if (have_cap_dac_override)
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{
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g_test_message ("Cannot test g_chdir() failing with EACCES: we "
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"probably have CAP_DAC_OVERRIDE or equivalent");
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}
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else
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{
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ret = g_chdir (path);
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g_assert_cmpint (ret == 0 ? 0 : errno, ==, EACCES);
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g_assert_cmpint (ret, ==, -1);
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}
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#else
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g_test_message ("Cannot test g_chdir() failing with EACCES: "
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"it's Unix-specific behaviour");
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#endif
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ret = g_chmod (path, 0777);
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g_assert_cmpint (ret, ==, 0);
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ret = g_chdir (path);
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@ -138,12 +138,6 @@ test_thread4 (void)
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GError *error;
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gint ret;
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/* Linux CAP_SYS_RESOURCE overrides RLIMIT_NPROC, and probably similar
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* things are true on other systems.
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*/
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if (getuid () == 0 || geteuid () == 0)
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return;
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getrlimit (RLIMIT_NPROC, &nl);
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nl.rlim_cur = 1;
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@ -152,9 +146,26 @@ test_thread4 (void)
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error = NULL;
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thread = g_thread_try_new ("a", thread1_func, NULL, &error);
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g_assert (thread == NULL);
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g_assert_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN);
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g_error_free (error);
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if (thread != NULL)
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{
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gpointer result;
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/* Privileged processes might be able to create new threads even
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* though the rlimit is too low. There isn't much we can do about
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* this; we just can't test this failure mode in this situation. */
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g_test_skip ("Unable to test g_thread_try_new() failing with EAGAIN "
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"while privileged (CAP_SYS_RESOURCE, CAP_SYS_ADMIN or "
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"euid 0?)");
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result = g_thread_join (thread);
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g_assert_cmpint (GPOINTER_TO_INT (result), ==, 1);
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}
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else
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{
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g_assert (thread == NULL);
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g_assert_error (error, G_THREAD_ERROR, G_THREAD_ERROR_AGAIN);
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g_error_free (error);
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}
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if ((ret = prlimit (getpid (), RLIMIT_NPROC, &ol, NULL)) != 0)
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g_error ("resetting RLIMIT_NPROC failed: %s", g_strerror (errno));
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