On 03/09/2018 08:28 AM, Stephen Smalley wrote: > On 03/09/2018 08:14 AM, Vit Mojzis wrote: >> >> >> On 7.3.2018 15:59, Stephen Smalley wrote: >>> On 03/06/2018 06:58 AM, Vit Mojzis wrote: >>>> access() uses real UID instead of effective UID which causes false >>>> negative checks in setuid programs. >>>> Replace access(,F_OK) (i.e. tests for file existence) by stat(). >>>> And access(,R_OK) by fopen(,"r") >>>> >>>> Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431 >>>> >>>> Signed-off-by: Vit Mojzis <vmojzis@xxxxxxxxxx> >>>> --- >>>> libsemanage/src/direct_api.c | 133 +++++++++++++++++++++++++-------------- >>>> libsemanage/src/semanage_store.c | 16 ++++- >>>> 2 files changed, 99 insertions(+), 50 deletions(-) >>>> >>>> diff --git a/libsemanage/src/direct_api.c b/libsemanage/src/direct_api.c >>>> index 49cac14f..4e2af810 100644 >>>> --- a/libsemanage/src/direct_api.c >>>> +++ b/libsemanage/src/direct_api.c >>>> @@ -140,6 +140,7 @@ int semanage_direct_is_managed(semanage_handle_t * sh) >>>> int semanage_direct_connect(semanage_handle_t * sh) >>>> { >>>> const char *path; >>>> + struct stat sb; >>>> if (semanage_check_init(sh, sh->conf->store_root_path)) >>>> goto err; >>>> @@ -302,10 +303,16 @@ int semanage_direct_connect(semanage_handle_t * sh) >>>> /* set the disable dontaudit value */ >>>> path = semanage_path(SEMANAGE_ACTIVE, SEMANAGE_DISABLE_DONTAUDIT); >>>> - if (access(path, F_OK) == 0) >>>> + >>>> + if (stat(path, &sb) == 0) >>>> sepol_set_disable_dontaudit(sh->sepolh, 1); >>>> - else >>>> + else if (errno == ENOENT) { >>>> + /* The file does not exist */ >>>> sepol_set_disable_dontaudit(sh->sepolh, 0); >>>> + } else { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + goto err; >>>> + } >>>> return STATUS_SUCCESS; >>>> @@ -1139,6 +1146,7 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh, >>>> int status = 0; >>>> int i; >>>> char cil_path[PATH_MAX]; >>>> + struct stat sb; >>>> assert(sh); >>>> assert(modinfos); >>>> @@ -1155,9 +1163,13 @@ static int semanage_compile_hll_modules(semanage_handle_t *sh, >>>> } >>>> if (semanage_get_ignore_module_cache(sh) == 0 && >>>> - access(cil_path, F_OK) == 0) { >>>> + (status = stat(cil_path, &sb)) == 0) { >>>> continue; >>>> } >>>> + if (status != 0 && errno != ENOENT) { >>>> + ERR(sh, "Unable to access %s: %s\n", cil_path, strerror(errno)); >>>> + goto cleanup; //an error in the "stat" call >>>> + } >>>> status = semanage_compile_module(sh, &modinfos[i]); >>>> if (status < 0) { >>>> @@ -1196,6 +1208,7 @@ static int semanage_direct_commit(semanage_handle_t * sh) >>>> struct cil_db *cildb = NULL; >>>> semanage_module_info_t *modinfos = NULL; >>>> mode_t mask = umask(0077); >>>> + struct stat sb; >>>> int do_rebuild, do_write_kernel, do_install; >>>> int fcontexts_modified, ports_modified, seusers_modified, >>>> @@ -1234,10 +1247,15 @@ static int semanage_direct_commit(semanage_handle_t * sh) >>>> /* Create or remove the disable_dontaudit flag file. */ >>>> path = semanage_path(SEMANAGE_TMP, SEMANAGE_DISABLE_DONTAUDIT); >>>> - if (access(path, F_OK) == 0) >>>> + if (stat(path, &sb) == 0) >>>> do_rebuild |= !(sepol_get_disable_dontaudit(sh->sepolh) == 1); >>>> - else >>>> + else if (errno == ENOENT) { >>>> + /* The file does not exist */ >>>> do_rebuild |= (sepol_get_disable_dontaudit(sh->sepolh) == 1); >>>> + } else { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>> We need to ensure that retval is set in all of these cases. Safest to always set it before goto cleanup, >>> either explicitly to -1 or to return value of stat() call above. >> Thank you. >> The retval is actually initialized to -1 (and stat() returns -1 for any error) so it's not necessary to set it here. It will be necessary a little bit down the road after the first assignment to retval, you're right. >> Should I set it to -1 here anyway to make it less prone to breaking due to future changes in the code (what about the other ERR calls in this section of the code)? > > Yes, I would do that for safety here and in any other case where we didn't just set retval and test it. IOW, any case where we have: > retval = foo(args); > if (retval < 0) { > ERR(...) > goto cleanup; > } > is fine as is, but any case where we have: > if (some-condition-other-than-retval-less-than-0) { > ERR(...) > goto cleanup; > } > likely ought to explicitly set retval. > > If we have too many of those, then maybe we ought to have an err: label that sets retval to -1 explicitly and goto it instead. That said, you don't have to fix cases that you didn't introduce in your patch; that's up to you, and you can fix pre-existing cases via a separate patch if desired. > >> >>>> + goto cleanup; >>>> + } >>>> if (sepol_get_disable_dontaudit(sh->sepolh) == 1) { >>>> FILE *touch; >>>> touch = fopen(path, "w"); >>>> @@ -1259,10 +1277,16 @@ static int semanage_direct_commit(semanage_handle_t * sh) >>>> /* Create or remove the preserve_tunables flag file. */ >>>> path = semanage_path(SEMANAGE_TMP, SEMANAGE_PRESERVE_TUNABLES); >>>> - if (access(path, F_OK) == 0) >>>> + if (stat(path, &sb) == 0) >>>> do_rebuild |= !(sepol_get_preserve_tunables(sh->sepolh) == 1); >>>> - else >>>> + else if (errno == ENOENT) { >>>> + /* The file does not exist */ >>>> do_rebuild |= (sepol_get_preserve_tunables(sh->sepolh) == 1); >>>> + } else { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + goto cleanup; >>>> + } >>> Ditto >>> >>>> + >>>> if (sepol_get_preserve_tunables(sh->sepolh) == 1) { >>>> FILE *touch; >>>> touch = fopen(path, "w"); >>>> @@ -1299,40 +1323,24 @@ static int semanage_direct_commit(semanage_handle_t * sh) >>>> * a rebuild. >>>> */ >>>> if (!do_rebuild) { >>>> - path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_KERNEL); >>>> - if (access(path, F_OK) != 0) { >>>> - do_rebuild = 1; >>>> - goto rebuild; >>>> - } >>>> - >>>> - path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_FC); >>>> - if (access(path, F_OK) != 0) { >>>> - do_rebuild = 1; >>>> - goto rebuild; >>>> - } >>>> - >>>> - path = semanage_path(SEMANAGE_TMP, SEMANAGE_STORE_SEUSERS); >>>> - if (access(path, F_OK) != 0) { >>>> - do_rebuild = 1; >>>> - goto rebuild; >>>> - } >>>> - >>>> - path = semanage_path(SEMANAGE_TMP, SEMANAGE_LINKED); >>>> - if (access(path, F_OK) != 0) { >>>> - do_rebuild = 1; >>>> - goto rebuild; >>>> - } >>>> - >>>> - path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED); >>>> - if (access(path, F_OK) != 0) { >>>> - do_rebuild = 1; >>>> - goto rebuild; >>>> - } >>>> + int files[] = {SEMANAGE_STORE_KERNEL, >>>> + SEMANAGE_STORE_FC, >>>> + SEMANAGE_STORE_SEUSERS, >>>> + SEMANAGE_LINKED, >>>> + SEMANAGE_SEUSERS_LINKED, >>>> + SEMANAGE_USERS_EXTRA_LINKED}; >>>> + >>>> + for (i = 0; i < (int) sizeof(files); i++) { >>>> + path = semanage_path(SEMANAGE_TMP, files[i]); >>>> + if (stat(path, &sb) != 0) { >>>> + if (errno != ENOENT) { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + goto cleanup; >>> Ditto >>> >>>> + } >>>> - path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED); >>>> - if (access(path, F_OK) != 0) { >>>> - do_rebuild = 1; >>>> - goto rebuild; >>>> + do_rebuild = 1; >>>> + goto rebuild; >>>> + } >>>> } >>>> } >>>> @@ -1465,7 +1473,7 @@ rebuild: >>>> goto cleanup; >>>> path = semanage_path(SEMANAGE_TMP, SEMANAGE_SEUSERS_LINKED); >>>> - if (access(path, F_OK) == 0) { >>>> + if (stat(path, &sb) == 0) { >>>> retval = semanage_copy_file(path, >>>> semanage_path(SEMANAGE_TMP, >>>> SEMANAGE_STORE_SEUSERS), >>>> @@ -1473,12 +1481,18 @@ rebuild: >>>> if (retval < 0) >>>> goto cleanup; >>>> pseusers->dtable->drop_cache(pseusers->dbase); >>>> - } else { >>>> + } else if (errno == ENOENT) { >>>> + /* The file does not exist */ >>>> pseusers->dtable->clear(sh, pseusers->dbase); >>>> + } else { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + goto cleanup; >>> Ditto >>> >>>> } >>>> + >>>> + >>>> path = semanage_path(SEMANAGE_TMP, SEMANAGE_USERS_EXTRA_LINKED); >>>> - if (access(path, F_OK) == 0) { >>>> + if (stat(path, &sb) == 0) { >>>> retval = semanage_copy_file(path, >>>> semanage_path(SEMANAGE_TMP, >>>> SEMANAGE_USERS_EXTRA), >>>> @@ -1486,8 +1500,12 @@ rebuild: >>>> if (retval < 0) >>>> goto cleanup; >>>> pusers_extra->dtable->drop_cache(pusers_extra->dbase); >>>> - } else { >>>> + } else if (errno == ENOENT) { >>>> + /* The file does not exist */ >>>> pusers_extra->dtable->clear(sh, pusers_extra->dbase); >>>> + } else { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + goto cleanup; >>> Ditto >>> >>>> } >>>> } >>>> @@ -1817,6 +1835,7 @@ static int semanage_direct_extract(semanage_handle_t * sh, >>>> ssize_t _data_len; >>>> char *_data; >>>> int compressed; >>>> + struct stat sb; >>>> /* get path of module */ >>>> rc = semanage_module_get_path( >>>> @@ -1829,8 +1848,8 @@ static int semanage_direct_extract(semanage_handle_t * sh, >>>> goto cleanup; >>>> } >>>> - if (access(module_path, F_OK) != 0) { >>>> - ERR(sh, "Module does not exist: %s", module_path); >>>> + if (stat(module_path, &sb) != 0) { >>>> + ERR(sh, "Unable to access %s: %s\n", module_path, strerror(errno)); >>>> rc = -1; >>>> goto cleanup; >>>> } >>>> @@ -1859,7 +1878,12 @@ static int semanage_direct_extract(semanage_handle_t * sh, >>>> goto cleanup; >>>> } >>>> - if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && access(input_file, F_OK) != 0) { >>>> + if (extract_cil == 1 && strcmp(_modinfo->lang_ext, "cil") && stat(input_file, &sb) != 0) { >>>> + if (errno != ENOENT) { >>>> + ERR(sh, "Unable to access %s: %s\n", input_file, strerror(errno)); >>> Ditto >>> >>>> + goto cleanup; >>>> + >>>> + >>>> rc = semanage_compile_module(sh, _modinfo); >>>> if (rc < 0) { >>>> goto cleanup; >>>> @@ -2004,6 +2028,12 @@ static int semanage_direct_get_enabled(semanage_handle_t *sh, >>>> } >>>> if (stat(path, &sb) < 0) { >>>> + if (errno != ENOENT) { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + status = -1; >>>> + goto cleanup; >>>> + } >>>> + >>>> *enabled = 1; >>>> } >>>> else { >>>> @@ -2330,6 +2360,12 @@ static int semanage_direct_get_module_info(semanage_handle_t *sh, >>>> /* set enabled/disabled status */ >>>> if (stat(fn, &sb) < 0) { >>>> + if (errno != ENOENT) { >>>> + ERR(sh, "Unable to access %s: %s\n", fn, strerror(errno)); >>>> + status = -1; >>>> + goto cleanup; >>>> + } >>>> + >>>> ret = semanage_module_info_set_enabled(sh, *modinfo, 1); >>>> if (ret != 0) { >>>> status = -1; >>>> @@ -2738,6 +2774,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh, >>>> int status = 0; >>>> int ret = 0; >>>> int type; >>>> + struct stat sb; >>>> char path[PATH_MAX]; >>>> mode_t mask = umask(0077); >>>> @@ -2838,7 +2875,7 @@ static int semanage_direct_install_info(semanage_handle_t *sh, >>>> goto cleanup; >>>> } >>>> - if (access(path, F_OK) == 0) { >>>> + if (stat(path, &sb) == 0) { >>>> ret = unlink(path); >>>> if (ret != 0) { >>>> ERR(sh, "Error while removing cached CIL file %s: %s", path, strerror(errno)); >>>> diff --git a/libsemanage/src/semanage_store.c b/libsemanage/src/semanage_store.c >>>> index 4bd1d651..10f8b306 100644 >>>> --- a/libsemanage/src/semanage_store.c >>>> +++ b/libsemanage/src/semanage_store.c >>>> @@ -514,6 +514,7 @@ char *semanage_conf_path(void) >>>> { >>>> char *semanage_conf = NULL; >>>> int len; >>>> + struct stat sb; >>>> len = strlen(semanage_root()) + strlen(selinux_path()) + strlen(SEMANAGE_CONF_FILE); >>>> semanage_conf = calloc(len + 1, sizeof(char)); >>>> @@ -522,7 +523,12 @@ char *semanage_conf_path(void) >>>> snprintf(semanage_conf, len + 1, "%s%s%s", semanage_root(), selinux_path(), >>>> SEMANAGE_CONF_FILE); >>>> - if (access(semanage_conf, R_OK) != 0) { >>>> + if (stat(semanage_conf, &sb) != 0) { >>>> + if (errno != ENOENT) { >>>> + /* semanage_conf exists but can't be accessed */ >>>> + return NULL; >>> Not sure this is what we want. I think we'd just return semanage_conf here, and then let the caller fail when it tries to access it, so that we get a useful error message with the pathname. >>> >>>> + } >>>> + >>>> snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE); >>>> } >>>> @@ -1508,8 +1514,14 @@ int semanage_split_fc(semanage_handle_t * sh) >>>> static int sefcontext_compile(semanage_handle_t * sh, const char *path) { >>>> int r; >>>> + struct stat sb; >>>> + >>>> + if (stat(path, &sb) < 0) { >>>> + if (errno != ENOENT) { >>>> + ERR(sh, "Unable to access %s: %s\n", path, strerror(errno)); >>>> + return -1; >>>> + } >>>> - if (access(path, F_OK) != 0) { >>>> return 0; >>>> } >>>> >> >> >
