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Diffstat (limited to 'security/safesetid/lsm.c')
-rw-r--r--security/safesetid/lsm.c190
1 files changed, 143 insertions, 47 deletions
diff --git a/security/safesetid/lsm.c b/security/safesetid/lsm.c
index 7760019ad35d..8a176b6adbe5 100644
--- a/security/safesetid/lsm.c
+++ b/security/safesetid/lsm.c
@@ -24,20 +24,36 @@
/* Flag indicating whether initialization completed */
int safesetid_initialized;
-struct setuid_ruleset __rcu *safesetid_setuid_rules;
+struct setid_ruleset __rcu *safesetid_setuid_rules;
+struct setid_ruleset __rcu *safesetid_setgid_rules;
+
/* Compute a decision for a transition from @src to @dst under @policy. */
-enum sid_policy_type _setuid_policy_lookup(struct setuid_ruleset *policy,
- kuid_t src, kuid_t dst)
+enum sid_policy_type _setid_policy_lookup(struct setid_ruleset *policy,
+ kid_t src, kid_t dst)
{
- struct setuid_rule *rule;
+ struct setid_rule *rule;
enum sid_policy_type result = SIDPOL_DEFAULT;
- hash_for_each_possible(policy->rules, rule, next, __kuid_val(src)) {
- if (!uid_eq(rule->src_uid, src))
- continue;
- if (uid_eq(rule->dst_uid, dst))
- return SIDPOL_ALLOWED;
+ if (policy->type == UID) {
+ hash_for_each_possible(policy->rules, rule, next, __kuid_val(src.uid)) {
+ if (!uid_eq(rule->src_id.uid, src.uid))
+ continue;
+ if (uid_eq(rule->dst_id.uid, dst.uid))
+ return SIDPOL_ALLOWED;
+ result = SIDPOL_CONSTRAINED;
+ }
+ } else if (policy->type == GID) {
+ hash_for_each_possible(policy->rules, rule, next, __kgid_val(src.gid)) {
+ if (!gid_eq(rule->src_id.gid, src.gid))
+ continue;
+ if (gid_eq(rule->dst_id.gid, dst.gid)){
+ return SIDPOL_ALLOWED;
+ }
+ result = SIDPOL_CONSTRAINED;
+ }
+ } else {
+ /* Should not reach here, report the ID as contrainsted */
result = SIDPOL_CONSTRAINED;
}
return result;
@@ -47,15 +63,26 @@ enum sid_policy_type _setuid_policy_lookup(struct setuid_ruleset *policy,
* Compute a decision for a transition from @src to @dst under the active
* policy.
*/
-static enum sid_policy_type setuid_policy_lookup(kuid_t src, kuid_t dst)
+static enum sid_policy_type setid_policy_lookup(kid_t src, kid_t dst, enum setid_type new_type)
{
enum sid_policy_type result = SIDPOL_DEFAULT;
- struct setuid_ruleset *pol;
+ struct setid_ruleset *pol;
rcu_read_lock();
- pol = rcu_dereference(safesetid_setuid_rules);
- if (pol)
- result = _setuid_policy_lookup(pol, src, dst);
+ if (new_type == UID)
+ pol = rcu_dereference(safesetid_setuid_rules);
+ else if (new_type == GID)
+ pol = rcu_dereference(safesetid_setgid_rules);
+ else { /* Should not reach here */
+ result = SIDPOL_CONSTRAINED;
+ rcu_read_unlock();
+ return result;
+ }
+
+ if (pol) {
+ pol->type = new_type;
+ result = _setid_policy_lookup(pol, src, dst);
+ }
rcu_read_unlock();
return result;
}
@@ -65,57 +92,101 @@ static int safesetid_security_capable(const struct cred *cred,
int cap,
unsigned int opts)
{
- /* We're only interested in CAP_SETUID. */
- if (cap != CAP_SETUID)
+ /* We're only interested in CAP_SETUID and CAP_SETGID. */
+ if (cap != CAP_SETUID && cap != CAP_SETGID)
return 0;
/*
- * If CAP_SETUID is currently used for a set*uid() syscall, we want to
+ * If CAP_SET{U/G}ID is currently used for a setid() syscall, we want to
* let it go through here; the real security check happens later, in the
- * task_fix_setuid hook.
+ * task_fix_set{u/g}id hook.
+ *
+ * NOTE:
+ * Until we add support for restricting setgroups() calls, GID security
+ * policies offer no meaningful security since we always return 0 here
+ * when called from within the setgroups() syscall and there is no
+ * additional hook later on to enforce security policies for setgroups().
*/
if ((opts & CAP_OPT_INSETID) != 0)
return 0;
- /*
- * If no policy applies to this task, allow the use of CAP_SETUID for
- * other purposes.
- */
- if (setuid_policy_lookup(cred->uid, INVALID_UID) == SIDPOL_DEFAULT)
+ switch (cap) {
+ case CAP_SETUID:
+ /*
+ * If no policy applies to this task, allow the use of CAP_SETUID for
+ * other purposes.
+ */
+ if (setid_policy_lookup((kid_t){.uid = cred->uid}, INVALID_ID, UID) == SIDPOL_DEFAULT)
+ return 0;
+ /*
+ * Reject use of CAP_SETUID for functionality other than calling
+ * set*uid() (e.g. setting up userns uid mappings).
+ */
+ pr_warn("Operation requires CAP_SETUID, which is not available to UID %u for operations besides approved set*uid transitions\n",
+ __kuid_val(cred->uid));
+ return -EPERM;
+ break;
+ case CAP_SETGID:
+ /*
+ * If no policy applies to this task, allow the use of CAP_SETGID for
+ * other purposes.
+ */
+ if (setid_policy_lookup((kid_t){.gid = cred->gid}, INVALID_ID, GID) == SIDPOL_DEFAULT)
+ return 0;
+ /*
+ * Reject use of CAP_SETUID for functionality other than calling
+ * set*gid() (e.g. setting up userns gid mappings).
+ */
+ pr_warn("Operation requires CAP_SETGID, which is not available to GID %u for operations besides approved set*gid transitions\n",
+ __kuid_val(cred->uid));
+ return -EPERM;
+ break;
+ default:
+ /* Error, the only capabilities were checking for is CAP_SETUID/GID */
return 0;
-
- /*
- * Reject use of CAP_SETUID for functionality other than calling
- * set*uid() (e.g. setting up userns uid mappings).
- */
- pr_warn("Operation requires CAP_SETUID, which is not available to UID %u for operations besides approved set*uid transitions\n",
- __kuid_val(cred->uid));
- return -EPERM;
+ break;
+ }
+ return 0;
}
/*
* Check whether a caller with old credentials @old is allowed to switch to
- * credentials that contain @new_uid.
+ * credentials that contain @new_id.
*/
-static bool uid_permitted_for_cred(const struct cred *old, kuid_t new_uid)
+static bool id_permitted_for_cred(const struct cred *old, kid_t new_id, enum setid_type new_type)
{
bool permitted;
- /* If our old creds already had this UID in it, it's fine. */
- if (uid_eq(new_uid, old->uid) || uid_eq(new_uid, old->euid) ||
- uid_eq(new_uid, old->suid))
- return true;
+ /* If our old creds already had this ID in it, it's fine. */
+ if (new_type == UID) {
+ if (uid_eq(new_id.uid, old->uid) || uid_eq(new_id.uid, old->euid) ||
+ uid_eq(new_id.uid, old->suid))
+ return true;
+ } else if (new_type == GID){
+ if (gid_eq(new_id.gid, old->gid) || gid_eq(new_id.gid, old->egid) ||
+ gid_eq(new_id.gid, old->sgid))
+ return true;
+ } else /* Error, new_type is an invalid type */
+ return false;
/*
* Transitions to new UIDs require a check against the policy of the old
* RUID.
*/
permitted =
- setuid_policy_lookup(old->uid, new_uid) != SIDPOL_CONSTRAINED;
+ setid_policy_lookup((kid_t){.uid = old->uid}, new_id, new_type) != SIDPOL_CONSTRAINED;
+
if (!permitted) {
- pr_warn("UID transition ((%d,%d,%d) -> %d) blocked\n",
- __kuid_val(old->uid), __kuid_val(old->euid),
- __kuid_val(old->suid), __kuid_val(new_uid));
+ if (new_type == UID) {
+ pr_warn("UID transition ((%d,%d,%d) -> %d) blocked\n",
+ __kuid_val(old->uid), __kuid_val(old->euid),
+ __kuid_val(old->suid), __kuid_val(new_id.uid));
+ } else if (new_type == GID) {
+ pr_warn("GID transition ((%d,%d,%d) -> %d) blocked\n",
+ __kgid_val(old->gid), __kgid_val(old->egid),
+ __kgid_val(old->sgid), __kgid_val(new_id.gid));
+ } else /* Error, new_type is an invalid type */
+ return false;
}
return permitted;
}
@@ -131,18 +202,42 @@ static int safesetid_task_fix_setuid(struct cred *new,
{
/* Do nothing if there are no setuid restrictions for our old RUID. */
- if (setuid_policy_lookup(old->uid, INVALID_UID) == SIDPOL_DEFAULT)
+ if (setid_policy_lookup((kid_t){.uid = old->uid}, INVALID_ID, UID) == SIDPOL_DEFAULT)
+ return 0;
+
+ if (id_permitted_for_cred(old, (kid_t){.uid = new->uid}, UID) &&
+ id_permitted_for_cred(old, (kid_t){.uid = new->euid}, UID) &&
+ id_permitted_for_cred(old, (kid_t){.uid = new->suid}, UID) &&
+ id_permitted_for_cred(old, (kid_t){.uid = new->fsuid}, UID))
+ return 0;
+
+ /*
+ * Kill this process to avoid potential security vulnerabilities
+ * that could arise from a missing allowlist entry preventing a
+ * privileged process from dropping to a lesser-privileged one.
+ */
+ force_sig(SIGKILL);
+ return -EACCES;
+}
+
+static int safesetid_task_fix_setgid(struct cred *new,
+ const struct cred *old,
+ int flags)
+{
+
+ /* Do nothing if there are no setgid restrictions for our old RGID. */
+ if (setid_policy_lookup((kid_t){.gid = old->gid}, INVALID_ID, GID) == SIDPOL_DEFAULT)
return 0;
- if (uid_permitted_for_cred(old, new->uid) &&
- uid_permitted_for_cred(old, new->euid) &&
- uid_permitted_for_cred(old, new->suid) &&
- uid_permitted_for_cred(old, new->fsuid))
+ if (id_permitted_for_cred(old, (kid_t){.gid = new->gid}, GID) &&
+ id_permitted_for_cred(old, (kid_t){.gid = new->egid}, GID) &&
+ id_permitted_for_cred(old, (kid_t){.gid = new->sgid}, GID) &&
+ id_permitted_for_cred(old, (kid_t){.gid = new->fsgid}, GID))
return 0;
/*
* Kill this process to avoid potential security vulnerabilities
- * that could arise from a missing whitelist entry preventing a
+ * that could arise from a missing allowlist entry preventing a
* privileged process from dropping to a lesser-privileged one.
*/
force_sig(SIGKILL);
@@ -151,6 +246,7 @@ static int safesetid_task_fix_setuid(struct cred *new,
static struct security_hook_list safesetid_security_hooks[] = {
LSM_HOOK_INIT(task_fix_setuid, safesetid_task_fix_setuid),
+ LSM_HOOK_INIT(task_fix_setgid, safesetid_task_fix_setgid),
LSM_HOOK_INIT(capable, safesetid_security_capable)
};