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net: simplify cBPF setsockopt compat handling
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Add a helper that copies either a native or compat bpf_fprog from
userspace after verifying the length, and remove the compat setsockopt
handlers that now aren't required.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Christoph Hellwig authored and David S. Miller committed Jul 20, 2020
1 parent d8a9b38 commit 4d295e5
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Showing 6 changed files with 40 additions and 96 deletions.
4 changes: 2 additions & 2 deletions include/linux/filter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -502,13 +502,11 @@ static inline bool insn_is_zext(const struct bpf_insn *insn)
offsetof(TYPE, MEMBER); \
})

#ifdef CONFIG_COMPAT
/* A struct sock_filter is architecture independent. */
struct compat_sock_fprog {
u16 len;
compat_uptr_t filter; /* struct sock_filter * */
};
#endif

struct sock_fprog_kern {
u16 len;
Expand Down Expand Up @@ -1278,4 +1276,6 @@ struct bpf_sockopt_kern {
s32 retval;
};

int copy_bpf_fprog_from_user(struct sock_fprog *dst, void __user *src, int len);

#endif /* __LINUX_FILTER_H__ */
1 change: 0 additions & 1 deletion include/net/compat.h
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Original file line number Diff line number Diff line change
Expand Up @@ -61,7 +61,6 @@ int __get_compat_msghdr(struct msghdr *kmsg, struct compat_msghdr __user *umsg,
compat_size_t *len);
int get_compat_msghdr(struct msghdr *, struct compat_msghdr __user *,
struct sockaddr __user **, struct iovec **);
struct sock_fprog __user *get_compat_bpf_fprog(char __user *optval);
int put_cmsg_compat(struct msghdr*, int, int, int, void *);

int cmsghdr_from_user_compat_to_kern(struct msghdr *, struct sock *,
Expand Down
45 changes: 1 addition & 44 deletions net/compat.c
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Original file line number Diff line number Diff line change
Expand Up @@ -335,49 +335,6 @@ void scm_detach_fds_compat(struct msghdr *kmsg, struct scm_cookie *scm)
__scm_destroy(scm);
}

/* allocate a 64-bit sock_fprog on the user stack for duration of syscall. */
struct sock_fprog __user *get_compat_bpf_fprog(char __user *optval)
{
struct compat_sock_fprog __user *fprog32 = (struct compat_sock_fprog __user *)optval;
struct sock_fprog __user *kfprog = compat_alloc_user_space(sizeof(struct sock_fprog));
struct compat_sock_fprog f32;
struct sock_fprog f;

if (copy_from_user(&f32, fprog32, sizeof(*fprog32)))
return NULL;
memset(&f, 0, sizeof(f));
f.len = f32.len;
f.filter = compat_ptr(f32.filter);
if (copy_to_user(kfprog, &f, sizeof(struct sock_fprog)))
return NULL;

return kfprog;
}
EXPORT_SYMBOL_GPL(get_compat_bpf_fprog);

static int do_set_attach_filter(struct socket *sock, int level, int optname,
char __user *optval, unsigned int optlen)
{
struct sock_fprog __user *kfprog;

kfprog = get_compat_bpf_fprog(optval);
if (!kfprog)
return -EFAULT;

return sock_setsockopt(sock, level, optname, (char __user *)kfprog,
sizeof(struct sock_fprog));
}

static int compat_sock_setsockopt(struct socket *sock, int level, int optname,
char __user *optval, unsigned int optlen)
{
if (optname == SO_ATTACH_FILTER ||
optname == SO_ATTACH_REUSEPORT_CBPF)
return do_set_attach_filter(sock, level, optname,
optval, optlen);
return sock_setsockopt(sock, level, optname, optval, optlen);
}

static int __compat_sys_setsockopt(int fd, int level, int optname,
char __user *optval, unsigned int optlen)
{
Expand All @@ -396,7 +353,7 @@ static int __compat_sys_setsockopt(int fd, int level, int optname,
}

if (level == SOL_SOCKET)
err = compat_sock_setsockopt(sock, level,
err = sock_setsockopt(sock, level,
optname, optval, optlen);
else if (sock->ops->compat_setsockopt)
err = sock->ops->compat_setsockopt(sock, level,
Expand Down
23 changes: 23 additions & 0 deletions net/core/filter.c
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Original file line number Diff line number Diff line change
Expand Up @@ -77,6 +77,29 @@
#include <net/transp_v6.h>
#include <linux/btf_ids.h>

int copy_bpf_fprog_from_user(struct sock_fprog *dst, void __user *src, int len)
{
if (in_compat_syscall()) {
struct compat_sock_fprog f32;

if (len != sizeof(f32))
return -EINVAL;
if (copy_from_user(&f32, src, sizeof(f32)))
return -EFAULT;
memset(dst, 0, sizeof(*dst));
dst->len = f32.len;
dst->filter = compat_ptr(f32.filter);
} else {
if (len != sizeof(*dst))
return -EINVAL;
if (copy_from_user(dst, src, sizeof(*dst)))
return -EFAULT;
}

return 0;
}
EXPORT_SYMBOL_GPL(copy_bpf_fprog_from_user);

/**
* sk_filter_trim_cap - run a packet through a socket filter
* @sk: sock associated with &sk_buff
Expand Down
30 changes: 10 additions & 20 deletions net/core/sock.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1059,19 +1059,14 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
ret = sock_set_timeout(&sk->sk_sndtimeo, optval, optlen, optname == SO_SNDTIMEO_OLD);
break;

case SO_ATTACH_FILTER:
ret = -EINVAL;
if (optlen == sizeof(struct sock_fprog)) {
struct sock_fprog fprog;

ret = -EFAULT;
if (copy_from_user(&fprog, optval, sizeof(fprog)))
break;
case SO_ATTACH_FILTER: {
struct sock_fprog fprog;

ret = copy_bpf_fprog_from_user(&fprog, optval, optlen);
if (!ret)
ret = sk_attach_filter(&fprog, sk);
}
break;

}
case SO_ATTACH_BPF:
ret = -EINVAL;
if (optlen == sizeof(u32)) {
Expand All @@ -1085,19 +1080,14 @@ int sock_setsockopt(struct socket *sock, int level, int optname,
}
break;

case SO_ATTACH_REUSEPORT_CBPF:
ret = -EINVAL;
if (optlen == sizeof(struct sock_fprog)) {
struct sock_fprog fprog;

ret = -EFAULT;
if (copy_from_user(&fprog, optval, sizeof(fprog)))
break;
case SO_ATTACH_REUSEPORT_CBPF: {
struct sock_fprog fprog;

ret = copy_bpf_fprog_from_user(&fprog, optval, optlen);
if (!ret)
ret = sk_reuseport_attach_filter(&fprog, sk);
}
break;

}
case SO_ATTACH_REUSEPORT_EBPF:
ret = -EINVAL;
if (optlen == sizeof(u32)) {
Expand Down
33 changes: 4 additions & 29 deletions net/packet/af_packet.c
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Original file line number Diff line number Diff line change
Expand Up @@ -1545,10 +1545,10 @@ static int fanout_set_data_cbpf(struct packet_sock *po, char __user *data,

if (sock_flag(&po->sk, SOCK_FILTER_LOCKED))
return -EPERM;
if (len != sizeof(fprog))
return -EINVAL;
if (copy_from_user(&fprog, data, len))
return -EFAULT;

ret = copy_bpf_fprog_from_user(&fprog, data, len);
if (ret)
return ret;

ret = bpf_prog_create_from_user(&new, &fprog, NULL, false);
if (ret)
Expand Down Expand Up @@ -4040,28 +4040,6 @@ static int packet_getsockopt(struct socket *sock, int level, int optname,
return 0;
}


#ifdef CONFIG_COMPAT
static int compat_packet_setsockopt(struct socket *sock, int level, int optname,
char __user *optval, unsigned int optlen)
{
struct packet_sock *po = pkt_sk(sock->sk);

if (level != SOL_PACKET)
return -ENOPROTOOPT;

if (optname == PACKET_FANOUT_DATA &&
po->fanout && po->fanout->type == PACKET_FANOUT_CBPF) {
optval = (char __user *)get_compat_bpf_fprog(optval);
if (!optval)
return -EFAULT;
optlen = sizeof(struct sock_fprog);
}

return packet_setsockopt(sock, level, optname, optval, optlen);
}
#endif

static int packet_notifier(struct notifier_block *this,
unsigned long msg, void *ptr)
{
Expand Down Expand Up @@ -4549,9 +4527,6 @@ static const struct proto_ops packet_ops = {
.shutdown = sock_no_shutdown,
.setsockopt = packet_setsockopt,
.getsockopt = packet_getsockopt,
#ifdef CONFIG_COMPAT
.compat_setsockopt = compat_packet_setsockopt,
#endif
.sendmsg = packet_sendmsg,
.recvmsg = packet_recvmsg,
.mmap = packet_mmap,
Expand Down

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