TOMOYO: Add environment variable name restriction support.
This patch adds support for checking environment variable's names.
Although TOMOYO already provides ability to check argv[]/envp[] passed to
execve() requests,
file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="bar"
will reject execution of /bin/sh if environment variable LD_LIBRARY_PATH is not
defined. To grant execution of /bin/sh if LD_LIBRARY_PATH is not defined,
administrators have to specify like
file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]="/system/lib"
file execute /bin/sh exec.envp["LD_LIBRARY_PATH"]=NULL
. Since there are many environment variables whereas conditional checks are
applied as "&&", it is difficult to cover all combinations. Therefore, this
patch supports conditional checks that are applied as "||", by specifying like
file execute /bin/sh
misc env LD_LIBRARY_PATH exec.envp["LD_LIBRARY_PATH"]="/system/lib"
which means "grant execution of /bin/sh if environment variable is not defined
or is defined and its value is /system/lib".
Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index cd0f92d..5931fb1 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -563,6 +563,92 @@
}
/**
+ * tomoyo_environ - Check permission for environment variable names.
+ *
+ * @ee: Pointer to "struct tomoyo_execve".
+ *
+ * Returns 0 on success, negative value otherwise.
+ */
+static int tomoyo_environ(struct tomoyo_execve *ee)
+{
+ struct tomoyo_request_info *r = &ee->r;
+ struct linux_binprm *bprm = ee->bprm;
+ /* env_page.data is allocated by tomoyo_dump_page(). */
+ struct tomoyo_page_dump env_page = { };
+ char *arg_ptr; /* Size is TOMOYO_EXEC_TMPSIZE bytes */
+ int arg_len = 0;
+ unsigned long pos = bprm->p;
+ int offset = pos % PAGE_SIZE;
+ int argv_count = bprm->argc;
+ int envp_count = bprm->envc;
+ int error = -ENOMEM;
+
+ ee->r.type = TOMOYO_MAC_ENVIRON;
+ ee->r.profile = r->domain->profile;
+ ee->r.mode = tomoyo_get_mode(r->domain->ns, ee->r.profile,
+ TOMOYO_MAC_ENVIRON);
+ if (!r->mode || !envp_count)
+ return 0;
+ arg_ptr = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
+ if (!arg_ptr)
+ goto out;
+ while (error == -ENOMEM) {
+ if (!tomoyo_dump_page(bprm, pos, &env_page))
+ goto out;
+ pos += PAGE_SIZE - offset;
+ /* Read. */
+ while (argv_count && offset < PAGE_SIZE) {
+ if (!env_page.data[offset++])
+ argv_count--;
+ }
+ if (argv_count) {
+ offset = 0;
+ continue;
+ }
+ while (offset < PAGE_SIZE) {
+ const unsigned char c = env_page.data[offset++];
+
+ if (c && arg_len < TOMOYO_EXEC_TMPSIZE - 10) {
+ if (c == '=') {
+ arg_ptr[arg_len++] = '\0';
+ } else if (c == '\\') {
+ arg_ptr[arg_len++] = '\\';
+ arg_ptr[arg_len++] = '\\';
+ } else if (c > ' ' && c < 127) {
+ arg_ptr[arg_len++] = c;
+ } else {
+ arg_ptr[arg_len++] = '\\';
+ arg_ptr[arg_len++] = (c >> 6) + '0';
+ arg_ptr[arg_len++]
+ = ((c >> 3) & 7) + '0';
+ arg_ptr[arg_len++] = (c & 7) + '0';
+ }
+ } else {
+ arg_ptr[arg_len] = '\0';
+ }
+ if (c)
+ continue;
+ if (tomoyo_env_perm(r, arg_ptr)) {
+ error = -EPERM;
+ break;
+ }
+ if (!--envp_count) {
+ error = 0;
+ break;
+ }
+ arg_len = 0;
+ }
+ offset = 0;
+ }
+out:
+ if (r->mode != TOMOYO_CONFIG_ENFORCING)
+ error = 0;
+ kfree(env_page.data);
+ kfree(arg_ptr);
+ return error;
+}
+
+/**
* tomoyo_find_next_domain - Find a domain.
*
* @bprm: Pointer to "struct linux_binprm".
@@ -581,6 +667,7 @@
bool reject_on_transition_failure = false;
struct tomoyo_path_info rn = { }; /* real name */
struct tomoyo_execve *ee = kzalloc(sizeof(*ee), GFP_NOFS);
+
if (!ee)
return -ENOMEM;
ee->tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
@@ -713,6 +800,10 @@
bprm->cred->security = domain;
if (need_kfree)
kfree(rn.name);
+ if (!retval) {
+ ee->r.domain = domain;
+ retval = tomoyo_environ(ee);
+ }
kfree(ee->tmp);
kfree(ee->dump.data);
kfree(ee);
@@ -732,7 +823,8 @@
struct tomoyo_page_dump *dump)
{
struct page *page;
- /* dump->data is released by tomoyo_finish_execve(). */
+
+ /* dump->data is released by tomoyo_find_next_domain(). */
if (!dump->data) {
dump->data = kzalloc(PAGE_SIZE, GFP_NOFS);
if (!dump->data)
@@ -753,6 +845,7 @@
* So do I.
*/
char *kaddr = kmap_atomic(page, KM_USER0);
+
dump->page = page;
memcpy(dump->data + offset, kaddr + offset,
PAGE_SIZE - offset);