Commit 9ca71874 authored by Francis Laniel's avatar Francis Laniel Committed by Jakub Kicinski

Modify return value of nla_strlcpy to match that of strscpy.

nla_strlcpy now returns -E2BIG if src was truncated when written to dst.
It also returns this error value if dstsize is 0 or higher than INT_MAX.

For example, if src is "foo\0" and dst is 3 bytes long, the result will be:
1. "foG" after memcpy (G means garbage).
2. "fo\0" after memset.
3. -E2BIG is returned because src was not completely written into dst.

The callers of nla_strlcpy were modified to take into account this modification.
Signed-off-by: default avatarFrancis Laniel <laniel_francis@privacyrequired.com>
Reviewed-by: default avatarKees Cook <keescook@chromium.org>
Signed-off-by: default avatarJakub Kicinski <kuba@kernel.org>
parent 8eeb99bc
......@@ -506,7 +506,7 @@ int __nla_parse(struct nlattr **tb, int maxtype, const struct nlattr *head,
struct netlink_ext_ack *extack);
int nla_policy_len(const struct nla_policy *, int);
struct nlattr *nla_find(const struct nlattr *head, int len, int attrtype);
size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize);
ssize_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize);
char *nla_strdup(const struct nlattr *nla, gfp_t flags);
int nla_memcpy(void *dest, const struct nlattr *src, int count);
int nla_memcmp(const struct nlattr *nla, const void *data, size_t size);
......
......@@ -512,7 +512,7 @@ tcf_change_indev(struct net *net, struct nlattr *indev_tlv,
char indev[IFNAMSIZ];
struct net_device *dev;
if (nla_strlcpy(indev, indev_tlv, IFNAMSIZ) >= IFNAMSIZ) {
if (nla_strlcpy(indev, indev_tlv, IFNAMSIZ) < 0) {
NL_SET_ERR_MSG_ATTR(extack, indev_tlv,
"Interface name too long");
return -EINVAL;
......
......@@ -710,33 +710,44 @@ EXPORT_SYMBOL(nla_find);
/**
* nla_strlcpy - Copy string attribute payload into a sized buffer
* @dst: where to copy the string to
* @nla: attribute to copy the string from
* @dstsize: size of destination buffer
* @dst: Where to copy the string to.
* @nla: Attribute to copy the string from.
* @dstsize: Size of destination buffer.
*
* Copies at most dstsize - 1 bytes into the destination buffer.
* The result is always a valid NUL-terminated string. Unlike
* strlcpy the destination buffer is always padded out.
* Unlike strlcpy the destination buffer is always padded out.
*
* Returns the length of the source buffer.
* Return:
* * srclen - Returns @nla length (not including the trailing %NUL).
* * -E2BIG - If @dstsize is 0 or greater than U16_MAX or @nla length greater
* than @dstsize.
*/
size_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
ssize_t nla_strlcpy(char *dst, const struct nlattr *nla, size_t dstsize)
{
size_t srclen = nla_len(nla);
char *src = nla_data(nla);
ssize_t ret;
size_t len;
if (dstsize == 0 || WARN_ON_ONCE(dstsize > U16_MAX))
return -E2BIG;
if (srclen > 0 && src[srclen - 1] == '\0')
srclen--;
if (dstsize > 0) {
size_t len = (srclen >= dstsize) ? dstsize - 1 : srclen;
memcpy(dst, src, len);
/* Zero pad end of dst. */
memset(dst + len, 0, dstsize - len);
if (srclen >= dstsize) {
len = dstsize - 1;
ret = -E2BIG;
} else {
len = srclen;
ret = len;
}
return srclen;
memcpy(dst, src, len);
/* Zero pad end of dst. */
memset(dst + len, 0, dstsize - len);
return ret;
}
EXPORT_SYMBOL(nla_strlcpy);
......
......@@ -939,7 +939,7 @@ struct tc_action *tcf_action_init_1(struct net *net, struct tcf_proto *tp,
NL_SET_ERR_MSG(extack, "TC action kind must be specified");
goto err_out;
}
if (nla_strlcpy(act_name, kind, IFNAMSIZ) >= IFNAMSIZ) {
if (nla_strlcpy(act_name, kind, IFNAMSIZ) < 0) {
NL_SET_ERR_MSG(extack, "TC action name too long");
goto err_out;
}
......
......@@ -223,7 +223,7 @@ static inline u32 tcf_auto_prio(struct tcf_proto *tp)
static bool tcf_proto_check_kind(struct nlattr *kind, char *name)
{
if (kind)
return nla_strlcpy(name, kind, IFNAMSIZ) >= IFNAMSIZ;
return nla_strlcpy(name, kind, IFNAMSIZ) < 0;
memset(name, 0, IFNAMSIZ);
return false;
}
......
......@@ -1170,7 +1170,7 @@ static struct Qdisc *qdisc_create(struct net_device *dev,
#ifdef CONFIG_MODULES
if (ops == NULL && kind != NULL) {
char name[IFNAMSIZ];
if (nla_strlcpy(name, kind, IFNAMSIZ) < IFNAMSIZ) {
if (nla_strlcpy(name, kind, IFNAMSIZ) >= 0) {
/* We dropped the RTNL semaphore in order to
* perform the module load. So, even if we
* succeeded in loading the module we have to
......
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