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tools/xenstore: introduce node_perms structure

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There are several places in xenstored using a permission array and the
size of that array. Introduce a new struct node_perms containing both.

This is part of XSA-115.

Signed-off-by: Juergen Gross <jgross@suse.com>
Acked-by: Julien Grall <jgrall@amazon.com>
Reviewed-by: Paul Durrant <paul@xen.org>
This commit is contained in:
Juergen Gross authored and Jan Beulich committed 2020-12-15 14:06:12 +01:00
1 parent 3d0e1a15b3
commit 52593586d5
3 files changed
+50 -49
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tools/xenstore/xenstored_core.c
+38 -41
View File
@@ -403,14 +403,14 @@ static struct node *read_node(struct connection *conn, const void *ctx,
/* Datalen, childlen, number of permissions */
hdr = (void *)data.dptr;
node->generation = hdr->generation;
node->num_perms = hdr->num_perms;
node->perms.num = hdr->num_perms;
node->datalen = hdr->datalen;
node->childlen = hdr->childlen;
/* Permissions are struct xs_permissions. */
node->perms = hdr->perms;
node->perms.p = hdr->perms;
/* Data is binary blob (usually ascii, no nul). */
node->data = node->perms + node->num_perms;
node->data = node->perms.p + node->perms.num;
/* Children is strings, nul separated. */
node->children = node->data + node->datalen;
@@ -427,7 +427,7 @@ int write_node_raw(struct connection *conn, TDB_DATA *key, struct node *node,
struct xs_tdb_record_hdr *hdr;
data.dsize = sizeof(*hdr)
+ node->num_perms*sizeof(node->perms[0])
+ node->perms.num * sizeof(node->perms.p[0])
+ node->datalen + node->childlen;
if (!no_quota_check && domain_is_unprivileged(conn) &&
@@ -439,12 +439,13 @@ int write_node_raw(struct connection *conn, TDB_DATA *key, struct node *node,
data.dptr = talloc_size(node, data.dsize);
hdr = (void *)data.dptr;
hdr->generation = node->generation;
hdr->num_perms = node->num_perms;
hdr->num_perms = node->perms.num;
hdr->datalen = node->datalen;
hdr->childlen = node->childlen;
memcpy(hdr->perms, node->perms, node->num_perms*sizeof(node->perms[0]));
p = hdr->perms + node->num_perms;
memcpy(hdr->perms, node->perms.p,
node->perms.num * sizeof(*node->perms.p));
p = hdr->perms + node->perms.num;
memcpy(p, node->data, node->datalen);
p += node->datalen;
memcpy(p, node->children, node->childlen);
@@ -470,8 +471,7 @@ static int write_node(struct connection *conn, struct node *node,
}
static enum xs_perm_type perm_for_conn(struct connection *conn,
struct xs_permissions *perms,
unsigned int num)
const struct node_perms *perms)
{
unsigned int i;
enum xs_perm_type mask = XS_PERM_READ|XS_PERM_WRITE|XS_PERM_OWNER;
@@ -480,16 +480,16 @@ static enum xs_perm_type perm_for_conn(struct connection *conn,
mask &= ~XS_PERM_WRITE;
/* Owners and tools get it all... */
if (!domain_is_unprivileged(conn) || perms[0].id == conn->id
|| (conn->target && perms[0].id == conn->target->id))
if (!domain_is_unprivileged(conn) || perms->p[0].id == conn->id
|| (conn->target && perms->p[0].id == conn->target->id))
return (XS_PERM_READ|XS_PERM_WRITE|XS_PERM_OWNER) & mask;
for (i = 1; i < num; i++)
if (perms[i].id == conn->id
|| (conn->target && perms[i].id == conn->target->id))
return perms[i].perms & mask;
for (i = 1; i < perms->num; i++)
if (perms->p[i].id == conn->id
|| (conn->target && perms->p[i].id == conn->target->id))
return perms->p[i].perms & mask;
return perms[0].perms & mask;
return perms->p[0].perms & mask;
}
/*
@@ -536,7 +536,7 @@ static int ask_parents(struct connection *conn, const void *ctx,
return 0;
}
*perm = perm_for_conn(conn, node->perms, node->num_perms);
*perm = perm_for_conn(conn, &node->perms);
return 0;
}
@@ -582,8 +582,7 @@ struct node *get_node(struct connection *conn,
node = read_node(conn, ctx, name);
/* If we don't have permission, we don't have node. */
if (node) {
if ((perm_for_conn(conn, node->perms, node->num_perms) & perm)
!= perm) {
if ((perm_for_conn(conn, &node->perms) & perm) != perm) {
errno = EACCES;
node = NULL;
}
@@ -759,16 +758,15 @@ const char *onearg(struct buffered_data *in)
return in->buffer;
}
static char *perms_to_strings(const void *ctx,
struct xs_permissions *perms, unsigned int num,
static char *perms_to_strings(const void *ctx, const struct node_perms *perms,
unsigned int *len)
{
unsigned int i;
char *strings = NULL;
char buffer[MAX_STRLEN(unsigned int) + 1];
for (*len = 0, i = 0; i < num; i++) {
if (!xs_perm_to_string(&perms[i], buffer, sizeof(buffer)))
for (*len = 0, i = 0; i < perms->num; i++) {
if (!xs_perm_to_string(&perms->p[i], buffer, sizeof(buffer)))
return NULL;
strings = talloc_realloc(ctx, strings, char,
@@ -947,13 +945,13 @@ static struct node *construct_node(struct connection *conn, const void *ctx,
goto nomem;
/* Inherit permissions, except unprivileged domains own what they create */
node->num_perms = parent->num_perms;
node->perms = talloc_memdup(node, parent->perms,
node->num_perms * sizeof(node->perms[0]));
if (!node->perms)
node->perms.num = parent->perms.num;
node->perms.p = talloc_memdup(node, parent->perms.p,
node->perms.num * sizeof(*node->perms.p));
if (!node->perms.p)
goto nomem;
if (domain_is_unprivileged(conn))
node->perms[0].id = conn->id;
node->perms.p[0].id = conn->id;
/* No children, no data */
node->children = node->data = NULL;
@@ -1230,7 +1228,7 @@ static int do_get_perms(struct connection *conn, struct buffered_data *in)
if (!node)
return errno;
strings = perms_to_strings(node, node->perms, node->num_perms, &len);
strings = perms_to_strings(node, &node->perms, &len);
if (!strings)
return errno;
@@ -1241,13 +1239,12 @@ static int do_get_perms(struct connection *conn, struct buffered_data *in)
static int do_set_perms(struct connection *conn, struct buffered_data *in)
{
unsigned int num;
struct xs_permissions *perms;
struct node_perms perms;
char *name, *permstr;
struct node *node;
num = xs_count_strings(in->buffer, in->used);
if (num < 2)
perms.num = xs_count_strings(in->buffer, in->used);
if (perms.num < 2)
return EINVAL;
/* First arg is node name. */
@@ -1258,21 +1255,21 @@ static int do_set_perms(struct connection *conn, struct buffered_data *in)
return errno;
permstr = in->buffer + strlen(in->buffer) + 1;
num--;
perms.num--;
perms = talloc_array(node, struct xs_permissions, num);
if (!perms)
perms.p = talloc_array(node, struct xs_permissions, perms.num);
if (!perms.p)
return ENOMEM;
if (!xs_strings_to_perms(perms, num, permstr))
if (!xs_strings_to_perms(perms.p, perms.num, permstr))
return errno;
/* Unprivileged domains may not change the owner. */
if (domain_is_unprivileged(conn) && perms[0].id != node->perms[0].id)
if (domain_is_unprivileged(conn) &&
perms.p[0].id != node->perms.p[0].id)
return EPERM;
domain_entry_dec(conn, node);
node->perms = perms;
node->num_perms = num;
domain_entry_inc(conn, node);
if (write_node(conn, node, false))
@@ -1547,8 +1544,8 @@ static void manual_node(const char *name, const char *child)
barf_perror("Could not allocate initial node %s", name);
node->name = name;
node->perms = &perms;
node->num_perms = 1;
node->perms.p = &perms;
node->perms.num = 1;
node->children = (char *)child;
if (child)
node->childlen = strlen(child) + 1;
tools/xenstore/xenstored_core.h
+6 -2
View File
@@ -109,6 +109,11 @@ struct connection
};
extern struct list_head connections;
struct node_perms {
unsigned int num;
struct xs_permissions *p;
};
struct node {
const char *name;
@@ -120,8 +125,7 @@ struct node {
#define NO_GENERATION ~((uint64_t)0)
/* Permissions. */
unsigned int num_perms;
struct xs_permissions *perms;
struct node_perms perms;
/* Contents. */
unsigned int datalen;
tools/xenstore/xenstored_domain.c
+6 -6
View File
@@ -650,12 +650,12 @@ void domain_entry_inc(struct connection *conn, struct node *node)
if (!conn)
return;
if (node->perms && node->perms[0].id != conn->id) {
if (node->perms.p && node->perms.p[0].id != conn->id) {
if (conn->transaction) {
transaction_entry_inc(conn->transaction,
node->perms[0].id);
node->perms.p[0].id);
} else {
d = find_domain_by_domid(node->perms[0].id);
d = find_domain_by_domid(node->perms.p[0].id);
if (d)
d->nbentry++;
}
@@ -676,12 +676,12 @@ void domain_entry_dec(struct connection *conn, struct node *node)
if (!conn)
return;
if (node->perms && node->perms[0].id != conn->id) {
if (node->perms.p && node->perms.p[0].id != conn->id) {
if (conn->transaction) {
transaction_entry_dec(conn->transaction,
node->perms[0].id);
node->perms.p[0].id);
} else {
d = find_domain_by_domid(node->perms[0].id);
d = find_domain_by_domid(node->perms.p[0].id);
if (d && d->nbentry)
d->nbentry--;
}
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