lib: Add per-user packet pools

The IRMd will now check the user UID and GID for privileged access,
avoiding unprivileged users being able to disrupt all IPC (e.g. by
shm_open the single pool and corrupting its metadata).

Non-privileged users are now limited to a PUP (per-user pool) for
sending/receiving packets. It is still created by the IRMd, but owned
by the user (uid) with 600 permissions. It does not add additional
copies for local IPC between their own processes (i.e. over the local
IPCP), but packets between processes owned by a different user or
destined over the network (other IPCPs) will incur a copy when
crossing the PUP / PUP or the PUP / GSPP boundary.

Privileged users and users in the ouroboros group still have direct
access to the GSPP (globally shared private pool) for packet transfer
that will avoid additional copies when processing packets between
processes owned by different users and to the network.

This aligns the security model with UNIX trust domains defined by UID
and GID by leveraging file permission on the pools in shared memory.

┌─────────────────────────────────────────────────────────────┐
│ Source Pool    │ Dest Pool      │ Operation    │ Copies     │
├─────────────────────────────────────────────────────────────┤
│ GSPP           │ GSPP           │ Zero-copy    │ 0          │
│ PUP.uid        │ PUP.uid        │ Zero-copy    │ 0          │
│ PUP.uid1       │ PUP.uid2       │ memcpy()     │ 1          │
│ PUP.uid        │ GSPP           │ memcpy()     │ 1          │
│ GSPP           │ PUP.uid        │ memcpy()     │ 1          │
└─────────────────────────────────────────────────────────────┘

This also renames the struct ai ("application instance") in dev.c to
struct proc (process).

Signed-off-by: Dimitri Staessens <dimitri@ouroboros.rocks>
Signed-off-by: Sander Vrijders <sander@ouroboros.rocks>

1 files changed, 102 insertions, 3 deletions

diff --git a/src/irmd/reg/reg.c b/src/irmd/reg/reg.c
index fd8285be..e89b492b 100644
--- a/src/irmd/reg/reg.c
+++ b/src/irmd/reg/reg.c
@@ -35,6 +35,7 @@ The IPC Resource Manager - Registry
 #include "flow.h"
 #include "ipcp.h"
 #include "name.h"
+#include "pool.h"
 #include "proc.h"
 #include "prog.h"
 
@@ -57,6 +58,9 @@ struct {
         struct list_head     names;     /* registered names known     */
         size_t               n_names;   /* number of names            */
 
+        struct list_head     pools;     /* per-user pools             */
+        size_t               n_pools;   /* number of pools            */
+
         struct list_head     procs;     /* processes                  */
         size_t               n_procs;   /* number of processes        */
 
@@ -235,6 +239,20 @@ static struct list_head * __reg_after_name(const char * name)
         return p;
 }
 
+static struct reg_pool * __reg_get_pool(uid_t uid)
+{
+        struct list_head * p;
+
+        list_for_each(p, &reg.pools) {
+                struct reg_pool * entry;
+                entry = list_entry(p, struct reg_pool, next);
+                if (entry->uid == uid)
+                        return entry;
+        }
+
+        return NULL;
+}
+
 static struct reg_proc * __reg_get_proc(pid_t pid)
 {
         struct list_head * p;
@@ -540,6 +558,7 @@ int reg_init(void)
         list_head_init(&reg.flows);
         list_head_init(&reg.ipcps);
         list_head_init(&reg.names);
+        list_head_init(&reg.pools);
         list_head_init(&reg.procs);
         list_head_init(&reg.progs);
         list_head_init(&reg.spawned);
@@ -589,6 +608,15 @@ void reg_clear(void)
                 reg.n_procs--;
         }
 
+        list_for_each_safe(p, h, &reg.pools) {
+                struct reg_pool * entry;
+                entry = list_entry(p, struct reg_pool, next);
+                list_del(&entry->next);
+                entry->refcount = 0; /* Force destroy during cleanup */
+                reg_pool_destroy(entry);
+                reg.n_pools--;
+        }
+
         list_for_each_safe(p, h, &reg.flows) {
                 struct reg_flow * entry;
                 entry = list_entry(p, struct reg_flow, next);
@@ -621,6 +649,7 @@ void reg_fini(void)
         assert(list_is_empty(&reg.spawned));
         assert(list_is_empty(&reg.progs));
         assert(list_is_empty(&reg.procs));
+        assert(list_is_empty(&reg.pools));
         assert(list_is_empty(&reg.names));
         assert(list_is_empty(&reg.ipcps));
         assert(list_is_empty(&reg.flows));
@@ -628,6 +657,7 @@ void reg_fini(void)
         assert(reg.n_spawned == 0);
         assert(reg.n_progs == 0);
         assert(reg.n_procs == 0);
+        assert(reg.n_pools == 0);
         assert(reg.n_names == 0);
         assert(reg.n_ipcps == 0);
         assert(reg.n_flows == 0);
@@ -1090,6 +1120,35 @@ int reg_list_names(name_info_msg_t *** names)
         return -ENOMEM;
 }
 
+int reg_prepare_pool(uid_t uid,
+                     gid_t gid)
+{
+        struct reg_pool * pool;
+
+        if (is_ouroboros_member_uid(uid))
+                return 0;
+
+        pthread_mutex_lock(&reg.mtx);
+
+        pool = __reg_get_pool(uid);
+        if (pool == NULL) {
+                pool = reg_pool_create(uid, gid);
+                if (pool == NULL) {
+                        log_err("Failed to create pool for uid %d.", uid);
+                        pthread_mutex_unlock(&reg.mtx);
+                        return -1;
+                }
+                list_add(&pool->next, &reg.pools);
+                reg.n_pools++;
+        }
+
+        reg_pool_ref(pool);
+
+        pthread_mutex_unlock(&reg.mtx);
+
+        return 0;
+}
+
 int reg_create_proc(const struct proc_info * info)
 {
         struct reg_proc * proc;
@@ -1100,13 +1159,13 @@ int reg_create_proc(const struct proc_info * info)
 
         if (__reg_get_proc(info->pid) != NULL) {
                 log_err("Process %d already exists.", info->pid);
-                goto fail_proc;
+                goto fail;
         }
 
         proc = reg_proc_create(info);
         if (proc == NULL) {
                 log_err("Failed to create process %d.", info->pid);
-                goto fail_proc;
+                goto fail;
         }
 
         __reg_proc_update_names(proc);
@@ -1121,7 +1180,7 @@ int reg_create_proc(const struct proc_info * info)
 
         return 0;
 
- fail_proc:
+ fail:
         pthread_mutex_unlock(&reg.mtx);
         return -1;
 }
@@ -1129,6 +1188,7 @@ int reg_create_proc(const struct proc_info * info)
 int reg_destroy_proc(pid_t pid)
 {
         struct reg_proc *  proc;
+        struct reg_pool *  pool = NULL;
         struct pid_entry * spawn;
         struct reg_ipcp *  ipcp;
 
@@ -1136,11 +1196,18 @@ int reg_destroy_proc(pid_t pid)
 
         proc = __reg_get_proc(pid);
         if (proc != NULL) {
+                if (!is_ouroboros_member_uid(proc->info.uid))
+                        pool = __reg_get_pool(proc->info.uid);
                 list_del(&proc->next);
                 reg.n_procs--;
                 reg_proc_destroy(proc);
                 __reg_del_proc_from_names(pid);
                 __reg_cancel_flows_for_proc(pid);
+                if (pool != NULL && reg_pool_unref(pool) == 0) {
+                        list_del(&pool->next);
+                        reg.n_pools--;
+                        reg_pool_destroy(pool);
+                }
         }
 
         spawn = __reg_get_spawned(pid);
@@ -1175,6 +1242,38 @@ bool reg_has_proc(pid_t pid)
         return ret;
 }
 
+bool reg_is_proc_privileged(pid_t pid)
+{
+        struct reg_proc * proc;
+        bool              ret = false;
+
+        pthread_mutex_lock(&reg.mtx);
+
+        proc = __reg_get_proc(pid);
+        if (proc != NULL)
+                ret = reg_proc_is_privileged(proc);
+
+        pthread_mutex_unlock(&reg.mtx);
+
+        return ret;
+}
+
+uid_t reg_get_proc_uid(pid_t pid)
+{
+        struct reg_proc * proc;
+        uid_t             ret = 0;
+
+        pthread_mutex_lock(&reg.mtx);
+
+        proc = __reg_get_proc(pid);
+        if (proc != NULL && !is_ouroboros_member_uid(proc->info.uid))
+                ret = proc->info.uid;
+
+        pthread_mutex_unlock(&reg.mtx);
+
+        return ret;
+}
+
 void reg_kill_all_proc(int signal)
 {
         pthread_mutex_lock(&reg.mtx);