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author | Daniel Borkmann <dborkman@redhat.com> | 2014-03-28 18:58:19 +0100 |
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committer | David S. Miller <davem@davemloft.net> | 2014-03-31 00:45:09 -0400 |
commit | a3ea269b8bcdbb0c5fa2fd449a436e7987446975 (patch) | |
tree | 9e118e381c14f9a065cc4136be2a9bf6e5257dfb /net/core/filter.c | |
parent | f8bbbfc3b97f4c7a6c7c23185e520b22bfc3a21d (diff) | |
download | op-kernel-dev-a3ea269b8bcdbb0c5fa2fd449a436e7987446975.zip op-kernel-dev-a3ea269b8bcdbb0c5fa2fd449a436e7987446975.tar.gz |
net: filter: keep original BPF program around
In order to open up the possibility to internally transform a BPF program
into an alternative and possibly non-trivial reversible representation, we
need to keep the original BPF program around, so that it can be passed back
to user space w/o the need of a complex decoder.
The reason for that use case resides in commit a8fc92778080 ("sk-filter:
Add ability to get socket filter program (v2)"), that is, the ability
to retrieve the currently attached BPF filter from a given socket used
mainly by the checkpoint-restore project, for example.
Therefore, we add two helpers sk_{store,release}_orig_filter for taking
care of that. In the sk_unattached_filter_create() case, there's no such
possibility/requirement to retrieve a loaded BPF program. Therefore, we
can spare us the work in that case.
This approach will simplify and slightly speed up both, sk_get_filter()
and sock_diag_put_filterinfo() handlers as we won't need to successively
decode filters anymore through sk_decode_filter(). As we still need
sk_decode_filter() later on, we're keeping it around.
Joint work with Alexei Starovoitov.
Signed-off-by: Alexei Starovoitov <ast@plumgrid.com>
Signed-off-by: Daniel Borkmann <dborkman@redhat.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'net/core/filter.c')
-rw-r--r-- | net/core/filter.c | 86 |
1 files changed, 70 insertions, 16 deletions
diff --git a/net/core/filter.c b/net/core/filter.c index bb3c764..9730e7f 100644 --- a/net/core/filter.c +++ b/net/core/filter.c @@ -629,6 +629,37 @@ int sk_chk_filter(struct sock_filter *filter, unsigned int flen) } EXPORT_SYMBOL(sk_chk_filter); +static int sk_store_orig_filter(struct sk_filter *fp, + const struct sock_fprog *fprog) +{ + unsigned int fsize = sk_filter_proglen(fprog); + struct sock_fprog_kern *fkprog; + + fp->orig_prog = kmalloc(sizeof(*fkprog), GFP_KERNEL); + if (!fp->orig_prog) + return -ENOMEM; + + fkprog = fp->orig_prog; + fkprog->len = fprog->len; + fkprog->filter = kmemdup(fp->insns, fsize, GFP_KERNEL); + if (!fkprog->filter) { + kfree(fp->orig_prog); + return -ENOMEM; + } + + return 0; +} + +static void sk_release_orig_filter(struct sk_filter *fp) +{ + struct sock_fprog_kern *fprog = fp->orig_prog; + + if (fprog) { + kfree(fprog->filter); + kfree(fprog); + } +} + /** * sk_filter_release_rcu - Release a socket filter by rcu_head * @rcu: rcu_head that contains the sk_filter to free @@ -637,6 +668,7 @@ void sk_filter_release_rcu(struct rcu_head *rcu) { struct sk_filter *fp = container_of(rcu, struct sk_filter, rcu); + sk_release_orig_filter(fp); bpf_jit_free(fp); } EXPORT_SYMBOL(sk_filter_release_rcu); @@ -669,8 +701,8 @@ static int __sk_prepare_filter(struct sk_filter *fp) int sk_unattached_filter_create(struct sk_filter **pfp, struct sock_fprog *fprog) { + unsigned int fsize = sk_filter_proglen(fprog); struct sk_filter *fp; - unsigned int fsize = sizeof(struct sock_filter) * fprog->len; int err; /* Make sure new filter is there and in the right amounts. */ @@ -680,10 +712,16 @@ int sk_unattached_filter_create(struct sk_filter **pfp, fp = kmalloc(sk_filter_size(fprog->len), GFP_KERNEL); if (!fp) return -ENOMEM; + memcpy(fp->insns, fprog->filter, fsize); atomic_set(&fp->refcnt, 1); fp->len = fprog->len; + /* Since unattached filters are not copied back to user + * space through sk_get_filter(), we do not need to hold + * a copy here, and can spare us the work. + */ + fp->orig_prog = NULL; err = __sk_prepare_filter(fp); if (err) @@ -716,7 +754,7 @@ EXPORT_SYMBOL_GPL(sk_unattached_filter_destroy); int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) { struct sk_filter *fp, *old_fp; - unsigned int fsize = sizeof(struct sock_filter) * fprog->len; + unsigned int fsize = sk_filter_proglen(fprog); unsigned int sk_fsize = sk_filter_size(fprog->len); int err; @@ -730,6 +768,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) fp = sock_kmalloc(sk, sk_fsize, GFP_KERNEL); if (!fp) return -ENOMEM; + if (copy_from_user(fp->insns, fprog->filter, fsize)) { sock_kfree_s(sk, fp, sk_fsize); return -EFAULT; @@ -738,6 +777,12 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) atomic_set(&fp->refcnt, 1); fp->len = fprog->len; + err = sk_store_orig_filter(fp, fprog); + if (err) { + sk_filter_uncharge(sk, fp); + return -ENOMEM; + } + err = __sk_prepare_filter(fp); if (err) { sk_filter_uncharge(sk, fp); @@ -750,6 +795,7 @@ int sk_attach_filter(struct sock_fprog *fprog, struct sock *sk) if (old_fp) sk_filter_uncharge(sk, old_fp); + return 0; } EXPORT_SYMBOL_GPL(sk_attach_filter); @@ -769,6 +815,7 @@ int sk_detach_filter(struct sock *sk) sk_filter_uncharge(sk, filter); ret = 0; } + return ret; } EXPORT_SYMBOL_GPL(sk_detach_filter); @@ -851,34 +898,41 @@ void sk_decode_filter(struct sock_filter *filt, struct sock_filter *to) to->k = filt->k; } -int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, unsigned int len) +int sk_get_filter(struct sock *sk, struct sock_filter __user *ubuf, + unsigned int len) { + struct sock_fprog_kern *fprog; struct sk_filter *filter; - int i, ret; + int ret = 0; lock_sock(sk); filter = rcu_dereference_protected(sk->sk_filter, - sock_owned_by_user(sk)); - ret = 0; + sock_owned_by_user(sk)); if (!filter) goto out; - ret = filter->len; + + /* We're copying the filter that has been originally attached, + * so no conversion/decode needed anymore. + */ + fprog = filter->orig_prog; + + ret = fprog->len; if (!len) + /* User space only enquires number of filter blocks. */ goto out; + ret = -EINVAL; - if (len < filter->len) + if (len < fprog->len) goto out; ret = -EFAULT; - for (i = 0; i < filter->len; i++) { - struct sock_filter fb; - - sk_decode_filter(&filter->insns[i], &fb); - if (copy_to_user(&ubuf[i], &fb, sizeof(fb))) - goto out; - } + if (copy_to_user(ubuf, fprog->filter, sk_filter_proglen(fprog))) + goto out; - ret = filter->len; + /* Instead of bytes, the API requests to return the number + * of filter blocks. + */ + ret = fprog->len; out: release_sock(sk); return ret; |