net: filter: sk_chk_filter() no longer mangles filter

Add const attribute to filter argument to make clear it is no
longer modified.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Acked-by: Daniel Borkmann <dborkman@redhat.com>
Acked-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/linux/filter.h b/include/linux/filter.h
index b885dcb..c43c825 100644 (file)
--- a/include/linux/filter.h
+++ b/include/linux/filter.h
@@ -362,7 +362,7 @@ void sk_unattached_filter_destroy(struct sk_filter *fp);
 int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk);
 int sk_detach_filter(struct sock *sk);
 
-int sk_chk_filter(struct sock_filter *filter, unsigned int flen);
+int sk_chk_filter(const struct sock_filter *filter, unsigned int flen);
 int sk_get_filter(struct sock *sk, struct sock_filter __user *filter,
                  unsigned int len);
 

diff --git a/net/core/filter.c b/net/core/filter.c
index 87af1e3..b90ae7f 100644 (file)
--- a/net/core/filter.c
+++ b/net/core/filter.c
@@ -1085,7 +1085,7 @@ err:
  * a cell if not previously written, and we check all branches to be sure
  * a malicious user doesn't try to abuse us.
  */
-static int check_load_and_stores(struct sock_filter *filter, int flen)
+static int check_load_and_stores(const struct sock_filter *filter, int flen)
 {
        u16 *masks, memvalid = 0; /* One bit per cell, 16 cells */
        int pc, ret = 0;
@@ -1218,7 +1218,7 @@ static bool chk_code_allowed(u16 code_to_probe)
  *
  * Returns 0 if the rule set is legal or -EINVAL if not.
  */
-int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
+int sk_chk_filter(const struct sock_filter *filter, unsigned int flen)
 {
        bool anc_found;
        int pc;
@@ -1228,7 +1228,7 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen)
 
        /* Check the filter code now */
        for (pc = 0; pc < flen; pc++) {
-               struct sock_filter *ftest = &filter[pc];
+               const struct sock_filter *ftest = &filter[pc];
 
                /* May we actually operate on this code? */
                if (!chk_code_allowed(ftest->code))