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get rid of compat_mc_getsockopt()

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now we can do MCAST_MSFILTER in compat ->getsockopt() without
playing silly buggers with copying things back and forth.
We can form a native struct group_filter (sans the variable-length
tail) on stack, pass that + pointer to the tail of original request
to the helper doing the bulk of the work, then do the rest of
copyout - same as the native getsockopt() does.

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
This commit is contained in:
Al Viro
2020-03-29 22:08:59 -04:00
parent 931ca7ab7f
commit 0dfe6581a7
4 changed files with 79 additions and 88 deletions
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79
net/compat.c
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@@ -538,85 +538,6 @@ int compat_mc_setsockopt(struct sock *sock, int level, int optname,
}
EXPORT_SYMBOL(compat_mc_setsockopt);
int compat_mc_getsockopt(struct sock *sock, int level, int optname,
char __user *optval, int __user *optlen,
int (*getsockopt)(struct sock *, int, int, char __user *, int __user *))
{
struct compat_group_filter __user *gf32 = (void __user *)optval;
struct group_filter __user *kgf;
int __user *koptlen;
u32 interface, fmode, numsrc;
int klen, ulen, err;
if (optname != MCAST_MSFILTER)
return getsockopt(sock, level, optname, optval, optlen);
koptlen = compat_alloc_user_space(sizeof(*koptlen));
if (!access_ok(optlen, sizeof(*optlen)) ||
__get_user(ulen, optlen))
return -EFAULT;
/* adjust len for pad */
klen = ulen + sizeof(*kgf) - sizeof(*gf32);
if (klen < GROUP_FILTER_SIZE(0))
return -EINVAL;
if (!access_ok(koptlen, sizeof(*koptlen)) ||
__put_user(klen, koptlen))
return -EFAULT;
/* have to allow space for previous compat_alloc_user_space, too */
kgf = compat_alloc_user_space(klen+sizeof(*optlen));
if (!access_ok(gf32, __COMPAT_GF0_SIZE) ||
__get_user(interface, &gf32->gf_interface) ||
__get_user(fmode, &gf32->gf_fmode) ||
__get_user(numsrc, &gf32->gf_numsrc) ||
__put_user(interface, &kgf->gf_interface) ||
__put_user(fmode, &kgf->gf_fmode) ||
__put_user(numsrc, &kgf->gf_numsrc) ||
copy_in_user(&kgf->gf_group, &gf32->gf_group, sizeof(kgf->gf_group)))
return -EFAULT;
err = getsockopt(sock, level, optname, (char __user *)kgf, koptlen);
if (err)
return err;
if (!access_ok(koptlen, sizeof(*koptlen)) ||
__get_user(klen, koptlen))
return -EFAULT;
ulen = klen - (sizeof(*kgf)-sizeof(*gf32));
if (!access_ok(optlen, sizeof(*optlen)) ||
__put_user(ulen, optlen))
return -EFAULT;
if (!access_ok(kgf, klen) ||
!access_ok(gf32, ulen) ||
__get_user(interface, &kgf->gf_interface) ||
__get_user(fmode, &kgf->gf_fmode) ||
__get_user(numsrc, &kgf->gf_numsrc) ||
__put_user(interface, &gf32->gf_interface) ||
__put_user(fmode, &gf32->gf_fmode) ||
__put_user(numsrc, &gf32->gf_numsrc))
return -EFAULT;
if (numsrc) {
int copylen;
klen -= GROUP_FILTER_SIZE(0);
copylen = numsrc * sizeof(gf32->gf_slist[0]);
if (copylen > klen)
copylen = klen;
if (copy_in_user(gf32->gf_slist, kgf->gf_slist, copylen))
return -EFAULT;
}
return err;
}
EXPORT_SYMBOL(compat_mc_getsockopt);
/* Argument list sizes for compat_sys_socketcall */
#define AL(x) ((x) * sizeof(u32))
static unsigned char nas[21] = {