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libsemanage: replace access() checks to make setuid programs work
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access() uses real UID instead of effective UID which causes false
negative checks in setuid programs.
Replace access() calls (mostly tests for file existence) by stat().

Fixes: https://bugzilla.redhat.com/show_bug.cgi?id=1186431

Signed-off-by: Vit Mojzis <vmojzis@redhat.com>
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@vmojzis @bachradsusi
vmojzis authored and bachradsusi committed Mar 13, 2018
1 parent 29d84c6 commit 6bb8282
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Showing 2 changed files with 98 additions and 50 deletions.
137 changes: 89 additions & 48 deletions libsemanage/src/direct_api.c
View file
Expand Up @@ -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;
Expand Down Expand Up @@ -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;

Expand Down Expand Up @@ -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);
Expand All @@ -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) {
Expand Down Expand Up @@ -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,
Expand Down Expand Up @@ -1234,10 +1247,16 @@ 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));
retval = -1;
goto cleanup;
}
if (sepol_get_disable_dontaudit(sh->sepolh) == 1) {
FILE *touch;
touch = fopen(path, "w");
Expand All @@ -1259,10 +1278,17 @@ 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));
retval = -1;
goto cleanup;
}

if (sepol_get_preserve_tunables(sh->sepolh) == 1) {
FILE *touch;
touch = fopen(path, "w");
Expand Down Expand Up @@ -1299,40 +1325,25 @@ 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));
retval = -1;
goto cleanup;
}

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;
}
}
}

Expand Down Expand Up @@ -1465,29 +1476,39 @@ static int semanage_direct_commit(semanage_handle_t * sh)
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),
sh->conf->file_mode);
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));
retval = -1;
goto cleanup;
}

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),
sh->conf->file_mode);
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));
retval = -1;
goto cleanup;
}
}

Expand Down Expand Up @@ -1817,6 +1838,7 @@ 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(
Expand All @@ -1829,8 +1851,8 @@ 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;
}
Expand Down Expand Up @@ -1859,7 +1881,13 @@ 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));
rc = -1;
goto cleanup;
}

rc = semanage_compile_module(sh, _modinfo);
if (rc < 0) {
goto cleanup;
Expand Down Expand Up @@ -2004,6 +2032,12 @@ 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 {
Expand Down Expand Up @@ -2330,6 +2364,12 @@ 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;
Expand Down Expand Up @@ -2738,6 +2778,7 @@ 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);
Expand Down Expand Up @@ -2838,7 +2879,7 @@ 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));
Expand Down
11 changes: 9 additions & 2 deletions libsemanage/src/semanage_store.c
View file
Expand Up @@ -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));
Expand All @@ -522,7 +523,7 @@ 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 && errno == ENOENT) {
snprintf(semanage_conf, len + 1, "%s%s", selinux_path(), SEMANAGE_CONF_FILE);
}

Expand Down Expand Up @@ -1508,8 +1509,14 @@ 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;
}

Expand Down

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