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authorNicolas Schichan <nschichan@freebox.fr>2015-05-06 16:12:28 +0200
committerDavid S. Miller <davem@davemloft.net>2015-05-09 17:35:05 -0400
commitd9e12f42e58da475379b9080708b94f2095904af (patch)
tree91f92e7c45d77d993b39751df26989d53fe5698f /kernel/seccomp.c
parent4ae92bc77ac8e620f7c8d59b5882a4cb0d1c4ef1 (diff)
downloadlinux-d9e12f42e58da475379b9080708b94f2095904af.tar.bz2
seccomp: simplify seccomp_prepare_filter and reuse bpf_prepare_filter
Remove the calls to bpf_check_classic(), bpf_convert_filter() and bpf_migrate_runtime() and let bpf_prepare_filter() take care of that instead. seccomp_check_filter() is passed to bpf_prepare_filter() so that it gets called from there, after bpf_check_classic(). We can now remove exposure of two internal classic BPF functions previously used by seccomp. The export of bpf_check_classic() symbol, previously known as sk_chk_filter(), was there since pre git times, and no in-tree module was using it, therefore remove it. Joint work with Daniel Borkmann. Signed-off-by: Nicolas Schichan <nschichan@freebox.fr> Signed-off-by: Daniel Borkmann <daniel@iogearbox.net> Cc: Alexei Starovoitov <ast@plumgrid.com> Cc: Kees Cook <keescook@chromium.org> Acked-by: Alexei Starovoitov <ast@plumgrid.com> Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'kernel/seccomp.c')
-rw-r--r--kernel/seccomp.c68
1 files changed, 22 insertions, 46 deletions
diff --git a/kernel/seccomp.c b/kernel/seccomp.c
index 4f44028943e6..93d40f7f3683 100644
--- 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);
}
/**