lkml.org 
[lkml]   [2016]   [Jun]   [22]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.4 75/75] netfilter: x_tables: dont reject valid target size on some architectures
    Date
    4.4-stable review patch.  If anyone has any objections, please let me know.

    ------------------

    From: Florian Westphal <fw@strlen.de>

    commit 7b7eba0f3515fca3296b8881d583f7c1042f5226 upstream.

    Quoting John Stultz:
    In updating a 32bit arm device from 4.6 to Linus' current HEAD, I
    noticed I was having some trouble with networking, and realized that
    /proc/net/ip_tables_names was suddenly empty.
    Digging through the registration process, it seems we're catching on the:

    if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
    target_offset + sizeof(struct xt_standard_target) != next_offset)
    return -EINVAL;

    Where next_offset seems to be 4 bytes larger then the
    offset + standard_target struct size.

    next_offset needs to be aligned via XT_ALIGN (so we can access all members
    of ip(6)t_entry struct).

    This problem didn't show up on i686 as it only needs 4-byte alignment for
    u64, but iptables userspace on other 32bit arches does insert extra padding.

    Reported-by: John Stultz <john.stultz@linaro.org>
    Tested-by: John Stultz <john.stultz@linaro.org>
    Fixes: 7ed2abddd20cf ("netfilter: x_tables: check standard target size too")
    Signed-off-by: Florian Westphal <fw@strlen.de>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
    Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

    ---
    net/netfilter/x_tables.c | 4 ++--
    1 file changed, 2 insertions(+), 2 deletions(-)

    --- a/net/netfilter/x_tables.c
    +++ b/net/netfilter/x_tables.c
    @@ -608,7 +608,7 @@ int xt_compat_check_entry_offsets(const
    return -EINVAL;

    if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
    - target_offset + sizeof(struct compat_xt_standard_target) != next_offset)
    + COMPAT_XT_ALIGN(target_offset + sizeof(struct compat_xt_standard_target)) != next_offset)
    return -EINVAL;

    /* compat_xt_entry match has less strict aligment requirements,
    @@ -690,7 +690,7 @@ int xt_check_entry_offsets(const void *b
    return -EINVAL;

    if (strcmp(t->u.user.name, XT_STANDARD_TARGET) == 0 &&
    - target_offset + sizeof(struct xt_standard_target) != next_offset)
    + XT_ALIGN(target_offset + sizeof(struct xt_standard_target)) != next_offset)
    return -EINVAL;

    return xt_check_entry_match(elems, base + target_offset,

    \
     
     \ /
      Last update: 2016-06-23 01:21    [W:4.067 / U:0.096 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site