seccomp: simplify seccomp_prepare_filter and reuse bpf_prepare_filter

[cascardo/linux.git] / kernel / seccomp.c

diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 4f44028..93d40f7 100644 (file)
--- a/kernel/seccomp.c
+++ b/kernel/seccomp.c
@@ -347,15 +347,14 @@ static inline void seccomp_sync_threads(void)
 static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
 {
        struct seccomp_filter *filter;
-       unsigned long fp_size;
-       struct sock_filter *fp;
-       int new_len;
-       long ret;
+       struct bpf_prog *prog;
+       unsigned long fsize;
 
        if (fprog->len == 0 || fprog->len > BPF_MAXINSNS)
                return ERR_PTR(-EINVAL);
+
        BUG_ON(INT_MAX / fprog->len < sizeof(struct sock_filter));
-       fp_size = fprog->len * sizeof(struct sock_filter);
+       fsize = bpf_classic_proglen(fprog);
 
        /*
         * Installing a seccomp filter requires that the task has
@@ -368,60 +367,37 @@ static struct seccomp_filter *seccomp_prepare_filter(struct sock_fprog *fprog)
                                     CAP_SYS_ADMIN) != 0)
                return ERR_PTR(-EACCES);
 
-       fp = kzalloc(fp_size, GFP_KERNEL|__GFP_NOWARN);
-       if (!fp)
+       prog = bpf_prog_alloc(bpf_prog_size(fprog->len), 0);
+       if (!prog)
                return ERR_PTR(-ENOMEM);
 
        /* Copy the instructions from fprog. */
-       ret = -EFAULT;
-       if (copy_from_user(fp, fprog->filter, fp_size))
-               goto free_prog;
-
-       /* Check and rewrite the fprog via the skb checker */
-       ret = bpf_check_classic(fp, fprog->len);
-       if (ret)
-               goto free_prog;
+       if (copy_from_user(prog->insns, fprog->filter, fsize)) {
+               __bpf_prog_free(prog);
+               return ERR_PTR(-EFAULT);
+       }
 
-       /* Check and rewrite the fprog for seccomp use */
-       ret = seccomp_check_filter(fp, fprog->len);
-       if (ret)
-               goto free_prog;
+       prog->len = fprog->len;
 
-       /* Convert 'sock_filter' insns to 'bpf_insn' insns */
-       ret = bpf_convert_filter(fp, fprog->len, NULL, &new_len);
-       if (ret)
-               goto free_prog;
+       /* bpf_prepare_filter() already takes care of freeing
+        * memory in case something goes wrong.
+        */
+       prog = bpf_prepare_filter(prog, seccomp_check_filter);
+       if (IS_ERR(prog))
+               return ERR_CAST(prog);
 
        /* Allocate a new seccomp_filter */
-       ret = -ENOMEM;
        filter = kzalloc(sizeof(struct seccomp_filter),
                         GFP_KERNEL|__GFP_NOWARN);
-       if (!filter)
-               goto free_prog;
-
-       filter->prog = bpf_prog_alloc(bpf_prog_size(new_len), __GFP_NOWARN);
-       if (!filter->prog)
-               goto free_filter;
-
-       ret = bpf_convert_filter(fp, fprog->len, filter->prog->insnsi, &new_len);
-       if (ret)
-               goto free_filter_prog;
+       if (!filter) {
+               bpf_prog_destroy(prog);
+               return ERR_PTR(-ENOMEM);
+       }
 
-       kfree(fp);
+       filter->prog = prog;
        atomic_set(&filter->usage, 1);
-       filter->prog->len = new_len;
-
-       bpf_prog_select_runtime(filter->prog);
 
        return filter;
-
-free_filter_prog:
-       __bpf_prog_free(filter->prog);
-free_filter:
-       kfree(filter);
-free_prog:
-       kfree(fp);
-       return ERR_PTR(ret);
 }
 
 /**