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-rw-r--r--sys/kern/kern_jail.c163
1 files changed, 114 insertions, 49 deletions
diff --git a/sys/kern/kern_jail.c b/sys/kern/kern_jail.c
index 1bad2d7488c1..c29d966283f8 100644
--- a/sys/kern/kern_jail.c
+++ b/sys/kern/kern_jail.c
@@ -136,6 +136,7 @@ struct prisonlist allprison = TAILQ_HEAD_INITIALIZER(allprison);
LIST_HEAD(, prison_racct) allprison_racct;
int lastprid = 0;
+static int get_next_prid(struct prison **insprp);
static int do_jail_attach(struct thread *td, struct prison *pr);
static void prison_complete(void *context, int pending);
static void prison_deref(struct prison *pr, int flags);
@@ -506,7 +507,7 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
#endif
struct vfsopt *opt;
struct vfsoptlist *opts;
- struct prison *pr, *deadpr, *mypr, *ppr, *tpr;
+ struct prison *pr, *deadpr, *inspr, *mypr, *ppr, *tpr;
struct vnode *root;
char *domain, *errmsg, *host, *name, *namelc, *p, *path, *uuid;
char *g_path, *osrelstr;
@@ -977,6 +978,7 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
*/
pr = NULL;
ppr = mypr;
+ inspr = NULL;
if (cuflags == JAIL_CREATE && jid == 0 && name != NULL) {
namelc = strrchr(name, '.');
jid = strtoul(namelc != NULL ? namelc + 1 : name, &p, 10);
@@ -985,23 +987,36 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
}
sx_xlock(&allprison_lock);
if (jid != 0) {
- /*
- * See if a requested jid already exists. There is an
- * information leak here if the jid exists but is not within
- * the caller's jail hierarchy. Jail creators will get EEXIST
- * even though they cannot see the jail, and CREATE | UPDATE
- * will return ENOENT which is not normally a valid error.
- */
if (jid < 0) {
error = EINVAL;
vfs_opterror(opts, "negative jid");
goto done_unlock_list;
}
- pr = prison_find(jid);
+ /*
+ * See if a requested jid already exists. Keep track of
+ * where it can be inserted later.
+ */
+ TAILQ_FOREACH(inspr, &allprison, pr_list) {
+ if (inspr->pr_id == jid) {
+ mtx_lock(&inspr->pr_mtx);
+ if (inspr->pr_ref > 0) {
+ pr = inspr;
+ inspr = NULL;
+ } else
+ mtx_unlock(&inspr->pr_mtx);
+ break;
+ }
+ if (inspr->pr_id > jid)
+ break;
+ }
if (pr != NULL) {
ppr = pr->pr_parent;
/* Create: jid must not exist. */
if (cuflags == JAIL_CREATE) {
+ /*
+ * Even creators that cannot see the jail will
+ * get EEXIST.
+ */
mtx_unlock(&pr->pr_mtx);
error = EEXIST;
vfs_opterror(opts, "jail %d already exists",
@@ -1009,6 +1024,11 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
goto done_unlock_list;
}
if (!prison_ischild(mypr, pr)) {
+ /*
+ * Updaters get ENOENT if they cannot see the
+ * jail. This is true even for CREATE | UPDATE,
+ * which normally cannot give this error.
+ */
mtx_unlock(&pr->pr_mtx);
pr = NULL;
} else if (pr->pr_uref == 0) {
@@ -1175,52 +1195,26 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
ppr->pr_uref++;
mtx_unlock(&ppr->pr_mtx);
pr = malloc(sizeof(*pr), M_PRISON, M_WAITOK | M_ZERO);
- if (jid == 0) {
- /* Find the next free jid. */
- jid = lastprid + 1;
- findnext:
- if (jid == JAIL_MAX)
- jid = 1;
- TAILQ_FOREACH(tpr, &allprison, pr_list) {
- if (tpr->pr_id < jid)
- continue;
- if (tpr->pr_id > jid || tpr->pr_ref == 0) {
- TAILQ_INSERT_BEFORE(tpr, pr, pr_list);
- break;
- }
- if (jid == lastprid) {
- error = EAGAIN;
- vfs_opterror(opts,
- "no available jail IDs");
- free(pr, M_PRISON);
- prison_deref(ppr, PD_DEREF |
- PD_DEUREF | PD_LIST_XLOCKED);
- goto done_releroot;
- }
- jid++;
- goto findnext;
- }
- lastprid = jid;
- } else {
- /*
- * The jail already has a jid (that did not yet exist),
- * so just find where to insert it.
- */
- TAILQ_FOREACH(tpr, &allprison, pr_list)
- if (tpr->pr_id >= jid) {
- TAILQ_INSERT_BEFORE(tpr, pr, pr_list);
- break;
- }
+
+ if (jid == 0 && (jid = get_next_prid(&inspr)) == 0) {
+ error = EAGAIN;
+ vfs_opterror(opts, "no available jail IDs");
+ free(pr, M_PRISON);
+ prison_deref(ppr,
+ PD_DEREF | PD_DEUREF | PD_LIST_XLOCKED);
+ goto done_releroot;
}
- if (tpr == NULL)
+ pr->pr_id = jid;
+ if (inspr != NULL)
+ TAILQ_INSERT_BEFORE(inspr, pr, pr_list);
+ else
TAILQ_INSERT_TAIL(&allprison, pr, pr_list);
+
+ pr->pr_parent = ppr;
LIST_INSERT_HEAD(&ppr->pr_children, pr, pr_sibling);
for (tpr = ppr; tpr != NULL; tpr = tpr->pr_parent)
tpr->pr_childcount++;
- pr->pr_parent = ppr;
- pr->pr_id = jid;
-
/* Set some default values, and inherit some from the parent. */
if (namelc == NULL)
namelc = "";
@@ -1914,6 +1908,70 @@ kern_jail_set(struct thread *td, struct uio *optuio, int flags)
}
/*
+ * Find the next available prison ID. Return the ID on success, or zero
+ * on failure. Also set a pointer to the allprison list entry the prison
+ * should be inserted before.
+ */
+static int
+get_next_prid(struct prison **insprp)
+{
+ struct prison *inspr;
+ int jid, maxid;
+
+ jid = lastprid % JAIL_MAX + 1;
+ if (TAILQ_EMPTY(&allprison) ||
+ TAILQ_LAST(&allprison, prisonlist)->pr_id < jid) {
+ /*
+ * A common case is for all jails to be implicitly numbered,
+ * which means they'll go on the end of the list, at least
+ * for the first JAIL_MAX times.
+ */
+ inspr = NULL;
+ } else {
+ /*
+ * Take two passes through the allprison list: first starting
+ * with the proposed jid, then ending with it.
+ */
+ for (maxid = JAIL_MAX; maxid != 0; ) {
+ TAILQ_FOREACH(inspr, &allprison, pr_list) {
+ if (inspr->pr_id < jid)
+ continue;
+ if (inspr->pr_id > jid || inspr->pr_ref == 0) {
+ /*
+ * Found an opening. This may be a gap
+ * in the list, or a dead jail with the
+ * same ID.
+ */
+ maxid = 0;
+ break;
+ }
+ if (++jid > maxid) {
+ if (lastprid == maxid || lastprid == 0)
+ {
+ /*
+ * The entire legal range
+ * has been traversed
+ */
+ return 0;
+ }
+ /* Try again from the start. */
+ jid = 1;
+ maxid = lastprid;
+ break;
+ }
+ }
+ if (inspr == NULL) {
+ /* Found room at the end of the list. */
+ break;
+ }
+ }
+ }
+ *insprp = inspr;
+ lastprid = jid;
+ return (jid);
+}
+
+/*
* struct jail_get_args {
* struct iovec *iovp;
* unsigned int iovcnt;
@@ -2453,8 +2511,15 @@ prison_find(int prid)
mtx_lock(&pr->pr_mtx);
if (pr->pr_ref > 0)
return (pr);
+ /*
+ * Any active prison with the same ID would have
+ * been inserted before a dead one.
+ */
mtx_unlock(&pr->pr_mtx);
+ break;
}
+ if (pr->pr_id > prid)
+ break;
}
return (NULL);
}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-01 00:27:10 +0000