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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [xen master] tools/xenstore: introduce dummy nodes for special watch paths
commit d6bb63924fc28a5bba53f5151db5c77f937879a5
Author: Juergen Gross <jgross@xxxxxxxx>
AuthorDate: Wed Jan 18 10:50:04 2023 +0100
Commit: Julien Grall <jgrall@xxxxxxxxxx>
CommitDate: Fri Jan 20 09:23:51 2023 +0000
tools/xenstore: introduce dummy nodes for special watch paths
Instead of special casing the permission handling and watch event
firing for the special watch paths "@introduceDomain" and
"@releaseDomain", use static dummy nodes added to the data base when
starting Xenstore.
The node accounting needs to reflect that change by adding the special
nodes in the domain_entry_fix() call in setup_structure().
Note that this requires to rework the calls of fire_watches() for the
special events in order to avoid leaking memory.
Move the check for a valid node name from get_node() to
get_node_canonicalized(), as it allows to use get_node() for the
special nodes, too.
In order to avoid read and write accesses to the special nodes use a
special variant for obtaining the current node data for the permission
handling.
This allows to simplify quite some code. In future sub-nodes of the
special nodes will be possible due to this change, allowing more fine
grained permission control of special events for specific domains.
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Julien Grall <jgrall@xxxxxxxxxx>
---
tools/xenstore/xenstored_control.c | 3 -
tools/xenstore/xenstored_core.c | 94 +++++++++++++--------
tools/xenstore/xenstored_domain.c | 164 ++++++-------------------------------
tools/xenstore/xenstored_domain.h | 6 --
tools/xenstore/xenstored_watch.c | 17 +---
5 files changed, 83 insertions(+), 201 deletions(-)
diff --git a/tools/xenstore/xenstored_control.c
b/tools/xenstore/xenstored_control.c
index d1aaa00bf4..41e6992591 100644
--- a/tools/xenstore/xenstored_control.c
+++ b/tools/xenstore/xenstored_control.c
@@ -676,9 +676,6 @@ static const char *lu_dump_state(const void *ctx, struct
connection *conn)
if (ret)
goto out;
ret = dump_state_connections(fp);
- if (ret)
- goto out;
- ret = dump_state_special_nodes(fp);
if (ret)
goto out;
ret = dump_state_nodes(fp, ctx);
diff --git a/tools/xenstore/xenstored_core.c b/tools/xenstore/xenstored_core.c
index d30f35e642..c82fb6e3d5 100644
--- a/tools/xenstore/xenstored_core.c
+++ b/tools/xenstore/xenstored_core.c
@@ -597,12 +597,13 @@ static void get_acc_data(TDB_DATA *key, struct
node_account_data *acc)
* Per-transaction nodes need to be accounted for the transaction owner.
* Those nodes are stored in the data base with the transaction generation
* count prepended (e.g. 123/local/domain/...). So testing for the node's
- * key not to start with "/" is sufficient.
+ * key not to start with "/" or "@" is sufficient.
*/
static unsigned int get_acc_domid(struct connection *conn, TDB_DATA *key,
unsigned int domid)
{
- return (!conn || key->dptr[0] == '/') ? domid : conn->id;
+ return (!conn || key->dptr[0] == '/' || key->dptr[0] == '@')
+ ? domid : conn->id;
}
int do_tdb_write(struct connection *conn, TDB_DATA *key, TDB_DATA *data,
@@ -944,10 +945,6 @@ static struct node *get_node(struct connection *conn,
{
struct node *node;
- if (!name || !is_valid_nodename(name)) {
- errno = EINVAL;
- return NULL;
- }
node = read_node(conn, ctx, name);
/* If we don't have permission, we don't have node. */
if (node) {
@@ -1236,9 +1233,23 @@ static struct node *get_node_canonicalized(struct
connection *conn,
*canonical_name = canonicalize(conn, ctx, name);
if (!*canonical_name)
return NULL;
+ if (!is_valid_nodename(*canonical_name)) {
+ errno = EINVAL;
+ return NULL;
+ }
return get_node(conn, ctx, *canonical_name, perm);
}
+static struct node *get_spec_node(struct connection *conn, const void *ctx,
+ const char *name, char **canonical_name,
+ unsigned int perm)
+{
+ if (name[0] == '@')
+ return get_node(conn, ctx, name, perm);
+
+ return get_node_canonicalized(conn, ctx, name, canonical_name, perm);
+}
+
static int send_directory(const void *ctx, struct connection *conn,
struct buffered_data *in)
{
@@ -1723,8 +1734,7 @@ static int do_get_perms(const void *ctx, struct
connection *conn,
char *strings;
unsigned int len;
- node = get_node_canonicalized(conn, ctx, onearg(in), NULL,
- XS_PERM_READ);
+ node = get_spec_node(conn, ctx, onearg(in), NULL, XS_PERM_READ);
if (!node)
return errno;
@@ -1766,17 +1776,9 @@ static int do_set_perms(const void *ctx, struct
connection *conn,
if (perms.p[0].perms & XS_PERM_IGNORE)
return ENOENT;
- /* First arg is node name. */
- if (strstarts(in->buffer, "@")) {
- if (set_perms_special(conn, in->buffer, &perms))
- return errno;
- send_ack(conn, XS_SET_PERMS);
- return 0;
- }
-
/* We must own node to do this (tools can do this too). */
- node = get_node_canonicalized(conn, ctx, in->buffer, &name,
- XS_PERM_WRITE | XS_PERM_OWNER);
+ node = get_spec_node(conn, ctx, in->buffer, &name,
+ XS_PERM_WRITE | XS_PERM_OWNER);
if (!node)
return errno;
@@ -2374,7 +2376,9 @@ void setup_structure(bool live_update)
manual_node("/", "tool");
manual_node("/tool", "xenstored");
manual_node("/tool/xenstored", NULL);
- domain_entry_fix(dom0_domid, 3, true);
+ manual_node("@releaseDomain", NULL);
+ manual_node("@introduceDomain", NULL);
+ domain_entry_fix(dom0_domid, 5, true);
}
check_store();
@@ -3156,6 +3160,23 @@ static int dump_state_node(const void *ctx, struct
connection *conn,
return WALK_TREE_OK;
}
+static int dump_state_special_node(FILE *fp, const void *ctx,
+ struct dump_node_data *data,
+ const char *name)
+{
+ struct node *node;
+ int ret;
+
+ node = read_node(NULL, ctx, name);
+ if (!node)
+ return dump_state_node_err(data, "Dump node read node error");
+
+ ret = dump_state_node(ctx, NULL, node, data);
+ talloc_free(node);
+
+ return ret;
+}
+
const char *dump_state_nodes(FILE *fp, const void *ctx)
{
struct dump_node_data data = {
@@ -3167,6 +3188,11 @@ const char *dump_state_nodes(FILE *fp, const void *ctx)
if (walk_node_tree(ctx, NULL, "/", &walkfuncs, &data))
return data.err;
+ if (dump_state_special_node(fp, ctx, &data, "@releaseDomain"))
+ return data.err;
+ if (dump_state_special_node(fp, ctx, &data, "@introduceDomain"))
+ return data.err;
+
return NULL;
}
@@ -3340,25 +3366,21 @@ void read_state_node(const void *ctx, const void *state)
node->perms.p[i].id = sn->perms[i].domid;
}
- if (strstarts(name, "@")) {
- set_perms_special(&conn, name, &node->perms);
- talloc_free(node);
- return;
- }
-
- parentname = get_parent(node, name);
- if (!parentname)
- barf("allocation error restoring node");
- parent = read_node(NULL, node, parentname);
- if (!parent)
- barf("read parent error restoring node");
+ if (!strstarts(name, "@")) {
+ parentname = get_parent(node, name);
+ if (!parentname)
+ barf("allocation error restoring node");
+ parent = read_node(NULL, node, parentname);
+ if (!parent)
+ barf("read parent error restoring node");
- if (add_child(node, parent, name))
- barf("allocation error restoring node");
+ if (add_child(node, parent, name))
+ barf("allocation error restoring node");
- set_tdb_key(parentname, &key);
- if (write_node_raw(NULL, &key, parent, true))
- barf("write parent error restoring node");
+ set_tdb_key(parentname, &key);
+ if (write_node_raw(NULL, &key, parent, true))
+ barf("write parent error restoring node");
+ }
set_tdb_key(name, &key);
if (write_node_raw(NULL, &key, node, true))
diff --git a/tools/xenstore/xenstored_domain.c
b/tools/xenstore/xenstored_domain.c
index 3ad1028edb..494694fd30 100644
--- a/tools/xenstore/xenstored_domain.c
+++ b/tools/xenstore/xenstored_domain.c
@@ -43,9 +43,6 @@ static evtchn_port_t virq_port;
xenevtchn_handle *xce_handle = NULL;
-static struct node_perms dom_release_perms;
-static struct node_perms dom_introduce_perms;
-
struct domain
{
/* The id of this domain */
@@ -225,27 +222,6 @@ static void unmap_interface(void *interface)
xengnttab_unmap(*xgt_handle, interface, 1);
}
-static void remove_domid_from_perm(struct node_perms *perms,
- struct domain *domain)
-{
- unsigned int cur, new;
-
- if (perms->p[0].id == domain->domid)
- perms->p[0].id = priv_domid;
-
- for (cur = new = 1; cur < perms->num; cur++) {
- if (perms->p[cur].id == domain->domid)
- continue;
-
- if (new != cur)
- perms->p[new] = perms->p[cur];
-
- new++;
- }
-
- perms->num = new;
-}
-
static int domain_tree_remove_sub(const void *ctx, struct connection *conn,
struct node *node, void *arg)
{
@@ -297,8 +273,26 @@ static void domain_tree_remove(struct domain *domain)
"error when looking for orphaned nodes\n");
}
- remove_domid_from_perm(&dom_release_perms, domain);
- remove_domid_from_perm(&dom_introduce_perms, domain);
+ walk_node_tree(domain, NULL, "@releaseDomain", &walkfuncs, domain);
+ walk_node_tree(domain, NULL, "@introduceDomain", &walkfuncs, domain);
+}
+
+static void fire_special_watches(const char *name)
+{
+ void *ctx = talloc_new(NULL);
+ struct node *node;
+
+ if (!ctx)
+ return;
+
+ node = read_node(NULL, ctx, name);
+
+ if (node)
+ fire_watches(NULL, ctx, name, node, true, NULL);
+ else
+ log("special node %s not found\n", name);
+
+ talloc_free(ctx);
}
static int destroy_domain(void *_domain)
@@ -326,7 +320,7 @@ static int destroy_domain(void *_domain)
unmap_interface(domain->interface);
}
- fire_watches(NULL, domain, "@releaseDomain", NULL, true, NULL);
+ fire_special_watches("@releaseDomain");
wrl_domain_destroy(domain);
@@ -384,7 +378,7 @@ void check_domains(void)
;
if (notify)
- fire_watches(NULL, NULL, "@releaseDomain", NULL, true, NULL);
+ fire_special_watches("@releaseDomain");
}
/* We scan all domains rather than use the information given here. */
@@ -633,8 +627,7 @@ static struct domain *introduce_domain(const void *ctx,
}
if (!is_master_domain && !restore)
- fire_watches(NULL, ctx, "@introduceDomain", NULL,
- true, NULL);
+ fire_special_watches("@introduceDomain");
} else {
/* Use XS_INTRODUCE for recreating the xenbus event-channel. */
if (domain->port)
@@ -840,59 +833,6 @@ const char *get_implicit_path(const struct connection
*conn)
return conn->domain->path;
}
-static int set_dom_perms_default(struct node_perms *perms)
-{
- perms->num = 1;
- perms->p = talloc_array(NULL, struct xs_permissions, perms->num);
- if (!perms->p)
- return -1;
- perms->p->id = 0;
- perms->p->perms = XS_PERM_NONE;
-
- return 0;
-}
-
-static struct node_perms *get_perms_special(const char *name)
-{
- if (!strcmp(name, "@releaseDomain"))
- return &dom_release_perms;
- if (!strcmp(name, "@introduceDomain"))
- return &dom_introduce_perms;
- return NULL;
-}
-
-int set_perms_special(struct connection *conn, const char *name,
- struct node_perms *perms)
-{
- struct node_perms *p;
-
- p = get_perms_special(name);
- if (!p)
- return EINVAL;
-
- if ((perm_for_conn(conn, p) & (XS_PERM_WRITE | XS_PERM_OWNER)) !=
- (XS_PERM_WRITE | XS_PERM_OWNER))
- return EACCES;
-
- p->num = perms->num;
- talloc_free(p->p);
- p->p = perms->p;
- talloc_steal(NULL, perms->p);
-
- return 0;
-}
-
-bool check_perms_special(const char *name, struct connection *conn)
-{
- struct node_perms *p;
-
- p = get_perms_special(name);
- if (!p)
- return false;
-
- return perm_for_conn(conn, p) & XS_PERM_READ;
-}
-
void dom0_init(void)
{
evtchn_port_t port;
@@ -962,10 +902,6 @@ void domain_init(int evtfd)
if (xce_handle == NULL)
barf_perror("Failed to open evtchn device");
- if (set_dom_perms_default(&dom_release_perms) ||
- set_dom_perms_default(&dom_introduce_perms))
- barf_perror("Failed to set special permissions");
-
if ((rc = xenevtchn_bind_virq(xce_handle, VIRQ_DOM_EXC)) == -1)
barf_perror("Failed to bind to domain exception virq port");
virq_port = rc;
@@ -1535,60 +1471,6 @@ const char *dump_state_connections(FILE *fp)
return ret;
}
-static const char *dump_state_special_node(FILE *fp, const char *name,
- const struct node_perms *perms)
-{
- struct xs_state_record_header head;
- struct xs_state_node sn;
- unsigned int pathlen;
- const char *ret;
-
- pathlen = strlen(name) + 1;
-
- head.type = XS_STATE_TYPE_NODE;
- head.length = sizeof(sn);
-
- sn.conn_id = 0;
- sn.ta_id = 0;
- sn.ta_access = 0;
- sn.perm_n = perms->num;
- sn.path_len = pathlen;
- sn.data_len = 0;
- head.length += perms->num * sizeof(*sn.perms);
- head.length += pathlen;
- head.length = ROUNDUP(head.length, 3);
- if (fwrite(&head, sizeof(head), 1, fp) != 1)
- return "Dump special node error";
- if (fwrite(&sn, sizeof(sn), 1, fp) != 1)
- return "Dump special node error";
-
- ret = dump_state_node_perms(fp, perms->p, perms->num);
- if (ret)
- return ret;
-
- if (fwrite(name, pathlen, 1, fp) != 1)
- return "Dump special node path error";
-
- ret = dump_state_align(fp);
-
- return ret;
-}
-
-const char *dump_state_special_nodes(FILE *fp)
-{
- const char *ret;
-
- ret = dump_state_special_node(fp, "@releaseDomain",
- &dom_release_perms);
- if (ret)
- return ret;
-
- ret = dump_state_special_node(fp, "@introduceDomain",
- &dom_introduce_perms);
-
- return ret;
-}
-
void read_state_connection(const void *ctx, const void *state)
{
const struct xs_state_connection *sc = state;
diff --git a/tools/xenstore/xenstored_domain.h
b/tools/xenstore/xenstored_domain.h
index b38c82991d..630641d620 100644
--- a/tools/xenstore/xenstored_domain.h
+++ b/tools/xenstore/xenstored_domain.h
@@ -99,11 +99,6 @@ void domain_outstanding_domid_dec(unsigned int domid);
int domain_get_quota(const void *ctx, struct connection *conn,
unsigned int domid);
-/* Special node permission handling. */
-int set_perms_special(struct connection *conn, const char *name,
- struct node_perms *perms);
-bool check_perms_special(const char *name, struct connection *conn);
-
/* Write rate limiting */
#define WRL_FACTOR 1000 /* for fixed-point arithmetic */
@@ -132,7 +127,6 @@ void wrl_apply_debit_direct(struct connection *conn);
void wrl_apply_debit_trans_commit(struct connection *conn);
const char *dump_state_connections(FILE *fp);
-const char *dump_state_special_nodes(FILE *fp);
void read_state_connection(const void *ctx, const void *state);
diff --git a/tools/xenstore/xenstored_watch.c b/tools/xenstore/xenstored_watch.c
index 316c08b7f7..75748ac109 100644
--- a/tools/xenstore/xenstored_watch.c
+++ b/tools/xenstore/xenstored_watch.c
@@ -46,13 +46,6 @@ struct watch
char *node;
};
-static bool check_special_event(const char *name)
-{
- assert(name);
-
- return strstarts(name, "@");
-}
-
/* Is child a subnode of parent, or equal? */
static bool is_child(const char *child, const char *parent)
{
@@ -153,14 +146,8 @@ void fire_watches(struct connection *conn, const void
*ctx, const char *name,
/* Create an event for each watch. */
list_for_each_entry(i, &connections, list) {
- /* introduce/release domain watches */
- if (check_special_event(name)) {
- if (!check_perms_special(name, i))
- continue;
- } else {
- if (!watch_permitted(i, ctx, name, node, perms))
- continue;
- }
+ if (!watch_permitted(i, ctx, name, node, perms))
+ continue;
list_for_each_entry(watch, &i->watches, list) {
if (exact) {
--
generated by git-patchbot for /home/xen/git/xen.git#master
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