[PATCH v2 02/12] tools/xenstored: add helper to parse domid

[Juergen Gross <jgross@xxxxxxxx>]

Today a domid passed in by a command is parsed using atoi(). This
will still "succeed" even with a domid like "x", resulting in "0" to
be used instead.

Use a common domid parser instead rejecting everything but integers
in the range 0..65535 like specified in docs/misc/xenstore.txt.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
V2:
- new patch (kind of suggested by Anthony Perard)
---
 tools/xenstored/domain.c | 47 +++++++++++++++++++++++++++++++++-------
 1 file changed, 39 insertions(+), 8 deletions(-)

diff --git a/tools/xenstored/domain.c b/tools/xenstored/domain.c
index e453b3061f..a70acddf94 100644
--- a/tools/xenstored/domain.c
+++ b/tools/xenstored/domain.c
@@ -732,6 +732,18 @@ static char *talloc_domain_path(const void *context, 
unsigned int domid)
        return talloc_asprintf(context, "/local/domain/%u", domid);
 }
 
+/* Parse a domid. Sets errno either to 0 or EINVAL. */
+static unsigned int parse_domid(const char *input)
+{
+       unsigned long domid;
+       char *endptr;
+
+       domid = strtoul(input, &endptr, 10);
+       errno = (*endptr != 0 || domid > 65535) ? EINVAL : 0;
+
+       return domid;
+}
+
 int domain_get_quota(const void *ctx, struct connection *conn,
                     unsigned int domid)
 {
@@ -1077,7 +1089,10 @@ int do_introduce(const void *ctx, struct connection 
*conn,
        if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec))
                return EINVAL;
 
-       domid = atoi(vec[0]);
+       domid = parse_domid(vec[0]);
+       if (errno)
+               return errno;
+
        /* Ignore the gfn, we don't need it. */
        port = atoi(vec[2]);
 
@@ -1124,8 +1139,12 @@ int do_set_target(const void *ctx, struct connection 
*conn,
        if (get_strings(in, vec, ARRAY_SIZE(vec)) < ARRAY_SIZE(vec))
                return EINVAL;
 
-       domid = atoi(vec[0]);
-       tdomid = atoi(vec[1]);
+       domid = parse_domid(vec[0]);
+       if (errno)
+               return errno;
+       tdomid = parse_domid(vec[1]);
+       if (errno)
+               return errno;
 
         domain = find_connected_domain(domid);
        if (IS_ERR(domain))
@@ -1152,7 +1171,9 @@ static struct domain *onearg_domain(struct connection 
*conn,
        if (!domid_str)
                return ERR_PTR(-EINVAL);
 
-       domid = atoi(domid_str);
+       domid = parse_domid(domid_str);
+       if (errno)
+               return ERR_PTR(-errno);
        if (domid == store_domid || domid == priv_domid)
                return ERR_PTR(-EINVAL);
 
@@ -1200,11 +1221,15 @@ int do_get_domain_path(const void *ctx, struct 
connection *conn,
 {
        char *path;
        const char *domid_str = onearg(in);
+       unsigned int domid;
 
        if (!domid_str)
                return EINVAL;
 
-       path = talloc_domain_path(ctx, atoi(domid_str));
+       domid = parse_domid(domid_str);
+       if (errno)
+               return errno;
+       path = talloc_domain_path(ctx, domid);
        if (!path)
                return errno;
 
@@ -1223,7 +1248,9 @@ int do_is_domain_introduced(const void *ctx, struct 
connection *conn,
        if (!domid_str)
                return EINVAL;
 
-       domid = atoi(domid_str);
+       domid = parse_domid(domid_str);
+       if (errno)
+               return errno;
        if (domid == DOMID_SELF)
                result = 1;
        else
@@ -1261,7 +1288,9 @@ int do_get_feature(const void *ctx, struct connection 
*conn,
                return EINVAL;
 
        if (n_args == 1) {
-               domid = atoi(vec[0]);
+               domid = parse_domid(vec[0]);
+               if (errno)
+                       return errno;
                domain = find_or_alloc_existing_domain(domid);
                if (!domain)
                        return ENOENT;
@@ -1289,7 +1318,9 @@ int do_set_feature(const void *ctx, struct connection 
*conn,
        if (get_strings(in, vec, ARRAY_SIZE(vec)) != ARRAY_SIZE(vec))
                return EINVAL;
 
-       domid = atoi(vec[0]);
+       domid = parse_domid(vec[0]);
+       if (errno)
+               return errno;
        features = atoi(vec[1]);
        domain = find_or_alloc_existing_domain(domid);
        if (!domain)
-- 
2.53.0