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> From cce2d2e1b43ecee5f4af7cf116808b74b330080f Mon Sep 17 00:00:00 2001
> From: Christoph Hellwig <hch@xxxxxx>
> Date: Mon, 27 Jul 2020 17:42:27 +0200
> Subject: net: remove sockptr_advance
>
> sockptr_advance never properly worked. Replace it with _offset variants
> of copy_from_sockptr and copy_to_sockptr.
>
> Fixes: ba423fdaa589 ("net: add a new sockptr_t type")
> Reported-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
> Reported-by: Ido Schimmel <idosch@xxxxxxxxxx>
> Signed-off-by: Christoph Hellwig <hch@xxxxxx>
> ---
> drivers/crypto/chelsio/chtls/chtls_main.c | 12 +++++-----
> include/linux/sockptr.h | 27 +++++++++++------------
> net/dccp/proto.c | 5 ++---
> net/ipv4/netfilter/arp_tables.c | 8 +++----
> net/ipv4/netfilter/ip_tables.c | 8 +++----
> net/ipv4/tcp.c | 5 +++--
> net/ipv6/ip6_flowlabel.c | 11 ++++-----
> net/ipv6/netfilter/ip6_tables.c | 8 +++----
> net/netfilter/x_tables.c | 7 +++---
> net/tls/tls_main.c | 6 ++---
> 10 files changed, 49 insertions(+), 48 deletions(-)
>
> diff --git a/drivers/crypto/chelsio/chtls/chtls_main.c
> b/drivers/crypto/chelsio/chtls/chtls_main.c
> index c3058dcdb33c5c..66d247efd5615b 100644
> --- a/drivers/crypto/chelsio/chtls/chtls_main.c
> +++ b/drivers/crypto/chelsio/chtls/chtls_main.c
> @@ -525,9 +525,9 @@ static int do_chtls_setsockopt(struct sock *sk, int
> optname,
> /* Obtain version and type from previous copy */
> crypto_info[0] = tmp_crypto_info;
> /* Now copy the following data */
> - sockptr_advance(optval, sizeof(*crypto_info));
> - rc = copy_from_sockptr((char *)crypto_info +
> sizeof(*crypto_info),
> - optval,
> + rc = copy_from_sockptr_offset((char *)crypto_info +
> + sizeof(*crypto_info),
> + optval, sizeof(*crypto_info),
> sizeof(struct tls12_crypto_info_aes_gcm_128)
> - sizeof(*crypto_info));
>
> @@ -542,9 +542,9 @@ static int do_chtls_setsockopt(struct sock *sk, int
> optname,
> }
> case TLS_CIPHER_AES_GCM_256: {
> crypto_info[0] = tmp_crypto_info;
> - sockptr_advance(optval, sizeof(*crypto_info));
> - rc = copy_from_sockptr((char *)crypto_info +
> sizeof(*crypto_info),
> - optval,
> + rc = copy_from_sockptr_offset((char *)crypto_info +
> + sizeof(*crypto_info),
> + optval, sizeof(*crypto_info),
> sizeof(struct tls12_crypto_info_aes_gcm_256)
> - sizeof(*crypto_info));
>
> diff --git a/include/linux/sockptr.h b/include/linux/sockptr.h
> index b13ea1422f93a5..9e6c81d474cba8 100644
> --- a/include/linux/sockptr.h
> +++ b/include/linux/sockptr.h
> @@ -69,19 +69,26 @@ static inline bool sockptr_is_null(sockptr_t sockptr)
> return !sockptr.user;
> }
>
> -static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
> +static inline int copy_from_sockptr_offset(void *dst, sockptr_t src,
> + size_t offset, size_t size)
> {
> if (!sockptr_is_kernel(src))
> - return copy_from_user(dst, src.user, size);
> - memcpy(dst, src.kernel, size);
> + return copy_from_user(dst, src.user + offset, size);
> + memcpy(dst, src.kernel + offset, size);
> return 0;
> }
>
> -static inline int copy_to_sockptr(sockptr_t dst, const void *src, size_t
> size)
> +static inline int copy_from_sockptr(void *dst, sockptr_t src, size_t size)
> +{
> + return copy_from_sockptr_offset(dst, src, 0, size);
> +}
> +
> +static inline int copy_to_sockptr_offset(sockptr_t dst, size_t offset,
> + const void *src, size_t size)
> {
> if (!sockptr_is_kernel(dst))
> - return copy_to_user(dst.user, src, size);
> - memcpy(dst.kernel, src, size);
> + return copy_to_user(dst.user + offset, src, size);
> + memcpy(dst.kernel + offset, src, size);
> return 0;
> }
>
> @@ -112,14 +119,6 @@ static inline void *memdup_sockptr_nul(sockptr_t src,
> size_t len)
> return p;
> }
>
> -static inline void sockptr_advance(sockptr_t sockptr, size_t len)
> -{
> - if (sockptr_is_kernel(sockptr))
> - sockptr.kernel += len;
> - else
> - sockptr.user += len;
> -}
> -
> static inline long strncpy_from_sockptr(char *dst, sockptr_t src, size_t
> count)
> {
> if (sockptr_is_kernel(src)) {
> diff --git a/net/dccp/proto.c b/net/dccp/proto.c
> index 2e9e8449698fb4..d148ab1530e57b 100644
> --- a/net/dccp/proto.c
> +++ b/net/dccp/proto.c
> @@ -426,9 +426,8 @@ static int dccp_setsockopt_service(struct sock *sk, const
> __be32 service,
> return -ENOMEM;
>
> sl->dccpsl_nr = optlen / sizeof(u32) - 1;
> - sockptr_advance(optval, sizeof(service));
> - if (copy_from_sockptr(sl->dccpsl_list, optval,
> - optlen - sizeof(service)) ||
> + if (copy_from_sockptr_offset(sl->dccpsl_list, optval,
> + sizeof(service), optlen - sizeof(service)) ||
> dccp_list_has_service(sl, DCCP_SERVICE_INVALID_VALUE)) {
> kfree(sl);
> return -EFAULT;
> diff --git a/net/ipv4/netfilter/arp_tables.c b/net/ipv4/netfilter/arp_tables.c
> index 9a1567dbc022b6..d1e04d2b5170ec 100644
> --- a/net/ipv4/netfilter/arp_tables.c
> +++ b/net/ipv4/netfilter/arp_tables.c
> @@ -971,8 +971,8 @@ static int do_replace(struct net *net, sockptr_t arg,
> unsigned int len)
> return -ENOMEM;
>
> loc_cpu_entry = newinfo->entries;
> - sockptr_advance(arg, sizeof(tmp));
> - if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
> + tmp.size) != 0) {
> ret = -EFAULT;
> goto free_newinfo;
> }
> @@ -1267,8 +1267,8 @@ static int compat_do_replace(struct net *net, sockptr_t
> arg, unsigned int len)
> return -ENOMEM;
>
> loc_cpu_entry = newinfo->entries;
> - sockptr_advance(arg, sizeof(tmp));
> - if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
> + tmp.size) != 0) {
> ret = -EFAULT;
> goto free_newinfo;
> }
> diff --git a/net/ipv4/netfilter/ip_tables.c b/net/ipv4/netfilter/ip_tables.c
> index f2a9680303d8c0..f15bc21d730164 100644
> --- a/net/ipv4/netfilter/ip_tables.c
> +++ b/net/ipv4/netfilter/ip_tables.c
> @@ -1126,8 +1126,8 @@ do_replace(struct net *net, sockptr_t arg, unsigned int
> len)
> return -ENOMEM;
>
> loc_cpu_entry = newinfo->entries;
> - sockptr_advance(arg, sizeof(tmp));
> - if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
> + tmp.size) != 0) {
> ret = -EFAULT;
> goto free_newinfo;
> }
> @@ -1508,8 +1508,8 @@ compat_do_replace(struct net *net, sockptr_t arg,
> unsigned int len)
> return -ENOMEM;
>
> loc_cpu_entry = newinfo->entries;
> - sockptr_advance(arg, sizeof(tmp));
> - if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
> + tmp.size) != 0) {
> ret = -EFAULT;
> goto free_newinfo;
> }
> diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
> index 27de9380ed140e..4afec552f211b9 100644
> --- a/net/ipv4/tcp.c
> +++ b/net/ipv4/tcp.c
> @@ -2801,12 +2801,13 @@ static int tcp_repair_options_est(struct sock *sk,
> sockptr_t optbuf,
> {
> struct tcp_sock *tp = tcp_sk(sk);
> struct tcp_repair_opt opt;
> + size_t offset = 0;
>
> while (len >= sizeof(opt)) {
> - if (copy_from_sockptr(&opt, optbuf, sizeof(opt)))
> + if (copy_from_sockptr_offset(&opt, optbuf, offset,
> sizeof(opt)))
> return -EFAULT;
>
> - sockptr_advance(optbuf, sizeof(opt));
> + offset += sizeof(opt);
> len -= sizeof(opt);
>
> switch (opt.opt_code) {
> diff --git a/net/ipv6/ip6_flowlabel.c b/net/ipv6/ip6_flowlabel.c
> index 215b6f5e733ec9..2d655260dedc75 100644
> --- a/net/ipv6/ip6_flowlabel.c
> +++ b/net/ipv6/ip6_flowlabel.c
> @@ -401,8 +401,8 @@ fl_create(struct net *net, struct sock *sk, struct
> in6_flowlabel_req *freq,
> memset(fl->opt, 0, sizeof(*fl->opt));
> fl->opt->tot_len = sizeof(*fl->opt) + olen;
> err = -EFAULT;
> - sockptr_advance(optval, CMSG_ALIGN(sizeof(*freq)));
> - if (copy_from_sockptr(fl->opt + 1, optval, olen))
> + if (copy_from_sockptr_offset(fl->opt + 1, optval,
> + CMSG_ALIGN(sizeof(*freq)), olen))
> goto done;
>
> msg.msg_controllen = olen;
> @@ -703,9 +703,10 @@ static int ipv6_flowlabel_get(struct sock *sk, struct
> in6_flowlabel_req *freq,
> goto recheck;
>
> if (!freq->flr_label) {
> - sockptr_advance(optval,
> - offsetof(struct in6_flowlabel_req,
> flr_label));
> - if (copy_to_sockptr(optval, &fl->label, sizeof(fl->label))) {
> + size_t offset = offsetof(struct in6_flowlabel_req, flr_label);
> +
> + if (copy_to_sockptr_offset(optval, offset, &fl->label,
> + sizeof(fl->label))) {
> /* Intentionally ignore fault. */
> }
> }
> diff --git a/net/ipv6/netfilter/ip6_tables.c b/net/ipv6/netfilter/ip6_tables.c
> index 1d52957a413f4a..2e2119bfcf1373 100644
> --- a/net/ipv6/netfilter/ip6_tables.c
> +++ b/net/ipv6/netfilter/ip6_tables.c
> @@ -1143,8 +1143,8 @@ do_replace(struct net *net, sockptr_t arg, unsigned int
> len)
> return -ENOMEM;
>
> loc_cpu_entry = newinfo->entries;
> - sockptr_advance(arg, sizeof(tmp));
> - if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
> + tmp.size) != 0) {
> ret = -EFAULT;
> goto free_newinfo;
> }
> @@ -1517,8 +1517,8 @@ compat_do_replace(struct net *net, sockptr_t arg,
> unsigned int len)
> return -ENOMEM;
>
> loc_cpu_entry = newinfo->entries;
> - sockptr_advance(arg, sizeof(tmp));
> - if (copy_from_sockptr(loc_cpu_entry, arg, tmp.size) != 0) {
> + if (copy_from_sockptr_offset(loc_cpu_entry, arg, sizeof(tmp),
> + tmp.size) != 0) {
> ret = -EFAULT;
> goto free_newinfo;
> }
> diff --git a/net/netfilter/x_tables.c b/net/netfilter/x_tables.c
> index b97eb4b538fd4e..91bf6635ea9ee4 100644
> --- a/net/netfilter/x_tables.c
> +++ b/net/netfilter/x_tables.c
> @@ -1050,6 +1050,7 @@ EXPORT_SYMBOL_GPL(xt_check_target);
> void *xt_copy_counters(sockptr_t arg, unsigned int len,
> struct xt_counters_info *info)
> {
> + size_t offset;
> void *mem;
> u64 size;
>
> @@ -1067,7 +1068,7 @@ void *xt_copy_counters(sockptr_t arg, unsigned int len,
>
> memcpy(info->name, compat_tmp.name, sizeof(info->name) - 1);
> info->num_counters = compat_tmp.num_counters;
> - sockptr_advance(arg, sizeof(compat_tmp));
> + offset = sizeof(compat_tmp);
> } else
> #endif
> {
> @@ -1078,7 +1079,7 @@ void *xt_copy_counters(sockptr_t arg, unsigned int len,
> if (copy_from_sockptr(info, arg, sizeof(*info)) != 0)
> return ERR_PTR(-EFAULT);
>
> - sockptr_advance(arg, sizeof(*info));
> + offset = sizeof(*info);
> }
> info->name[sizeof(info->name) - 1] = '\0';
>
> @@ -1092,7 +1093,7 @@ void *xt_copy_counters(sockptr_t arg, unsigned int len,
> if (!mem)
> return ERR_PTR(-ENOMEM);
>
> - if (copy_from_sockptr(mem, arg, len) == 0)
> + if (copy_from_sockptr_offset(mem, arg, offset, len) == 0)
> return mem;
>
> vfree(mem);
> diff --git a/net/tls/tls_main.c b/net/tls/tls_main.c
> index d77f7d821130db..bbc52b088d2968 100644
> --- a/net/tls/tls_main.c
> +++ b/net/tls/tls_main.c
> @@ -522,9 +522,9 @@ static int do_tls_setsockopt_conf(struct sock *sk,
> sockptr_t optval,
> goto err_crypto_info;
> }
>
> - sockptr_advance(optval, sizeof(*crypto_info));
> - rc = copy_from_sockptr(crypto_info + 1, optval,
> - optlen - sizeof(*crypto_info));
> + rc = copy_from_sockptr_offset(crypto_info + 1, optval,
> + sizeof(*crypto_info),
> + optlen - sizeof(*crypto_info));
> if (rc) {
> rc = -EFAULT;
> goto err_crypto_info;
> --
> 2.27.0
Getting rid of sockptr_advance entirely seems like the right decision
here. You still might want to make sure the addition in
copy_from_sockptr_offset doesn't overflow, and return -EFAULT if it
does.
But this indeed fixes the bug, so:
Acked-by: Jason A. Donenfeld <Jason@xxxxxxxxx>
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