lkml.org 
[lkml]   [2018]   [Apr]   [6]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 4.14 33/67] netfilter: x_tables: add and use xt_check_proc_name
    Date
    4.14-stable review patch.  If anyone has any objections, please let me know.

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

    From: Florian Westphal <fw@strlen.de>

    commit b1d0a5d0cba4597c0394997b2d5fced3e3841b4e upstream.

    recent and hashlimit both create /proc files, but only check that
    name is 0 terminated.

    This can trigger WARN() from procfs when name is "" or "/".
    Add helper for this and then use it for both.

    Cc: Eric Dumazet <eric.dumazet@gmail.com>
    Reported-by: Eric Dumazet <eric.dumazet@gmail.com>
    Reported-by: <syzbot+0502b00edac2a0680b61@syzkaller.appspotmail.com>
    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>

    ---
    include/linux/netfilter/x_tables.h | 2 ++
    net/netfilter/x_tables.c | 30 ++++++++++++++++++++++++++++++
    net/netfilter/xt_hashlimit.c | 16 ++++++++++------
    net/netfilter/xt_recent.c | 6 +++---
    4 files changed, 45 insertions(+), 9 deletions(-)

    --- a/include/linux/netfilter/x_tables.h
    +++ b/include/linux/netfilter/x_tables.h
    @@ -285,6 +285,8 @@ unsigned int *xt_alloc_entry_offsets(uns
    bool xt_find_jump_offset(const unsigned int *offsets,
    unsigned int target, unsigned int size);

    +int xt_check_proc_name(const char *name, unsigned int size);
    +
    int xt_check_match(struct xt_mtchk_param *, unsigned int size, u_int8_t proto,
    bool inv_proto);
    int xt_check_target(struct xt_tgchk_param *, unsigned int size, u_int8_t proto,
    --- a/net/netfilter/x_tables.c
    +++ b/net/netfilter/x_tables.c
    @@ -423,6 +423,36 @@ textify_hooks(char *buf, size_t size, un
    return buf;
    }

    +/**
    + * xt_check_proc_name - check that name is suitable for /proc file creation
    + *
    + * @name: file name candidate
    + * @size: length of buffer
    + *
    + * some x_tables modules wish to create a file in /proc.
    + * This function makes sure that the name is suitable for this
    + * purpose, it checks that name is NUL terminated and isn't a 'special'
    + * name, like "..".
    + *
    + * returns negative number on error or 0 if name is useable.
    + */
    +int xt_check_proc_name(const char *name, unsigned int size)
    +{
    + if (name[0] == '\0')
    + return -EINVAL;
    +
    + if (strnlen(name, size) == size)
    + return -ENAMETOOLONG;
    +
    + if (strcmp(name, ".") == 0 ||
    + strcmp(name, "..") == 0 ||
    + strchr(name, '/'))
    + return -EINVAL;
    +
    + return 0;
    +}
    +EXPORT_SYMBOL(xt_check_proc_name);
    +
    int xt_check_match(struct xt_mtchk_param *par,
    unsigned int size, u_int8_t proto, bool inv_proto)
    {
    --- a/net/netfilter/xt_hashlimit.c
    +++ b/net/netfilter/xt_hashlimit.c
    @@ -915,8 +915,9 @@ static int hashlimit_mt_check_v1(const s
    struct hashlimit_cfg3 cfg = {};
    int ret;

    - if (info->name[sizeof(info->name) - 1] != '\0')
    - return -EINVAL;
    + ret = xt_check_proc_name(info->name, sizeof(info->name));
    + if (ret)
    + return ret;

    ret = cfg_copy(&cfg, (void *)&info->cfg, 1);

    @@ -933,8 +934,9 @@ static int hashlimit_mt_check_v2(const s
    struct hashlimit_cfg3 cfg = {};
    int ret;

    - if (info->name[sizeof(info->name) - 1] != '\0')
    - return -EINVAL;
    + ret = xt_check_proc_name(info->name, sizeof(info->name));
    + if (ret)
    + return ret;

    ret = cfg_copy(&cfg, (void *)&info->cfg, 2);

    @@ -948,9 +950,11 @@ static int hashlimit_mt_check_v2(const s
    static int hashlimit_mt_check(const struct xt_mtchk_param *par)
    {
    struct xt_hashlimit_mtinfo3 *info = par->matchinfo;
    + int ret;

    - if (info->name[sizeof(info->name) - 1] != '\0')
    - return -EINVAL;
    + ret = xt_check_proc_name(info->name, sizeof(info->name));
    + if (ret)
    + return ret;

    return hashlimit_mt_check_common(par, &info->hinfo, &info->cfg,
    info->name, 3);
    --- a/net/netfilter/xt_recent.c
    +++ b/net/netfilter/xt_recent.c
    @@ -361,9 +361,9 @@ static int recent_mt_check(const struct
    info->hit_count, XT_RECENT_MAX_NSTAMPS - 1);
    return -EINVAL;
    }
    - if (info->name[0] == '\0' ||
    - strnlen(info->name, XT_RECENT_NAME_LEN) == XT_RECENT_NAME_LEN)
    - return -EINVAL;
    + ret = xt_check_proc_name(info->name, sizeof(info->name));
    + if (ret)
    + return ret;

    if (ip_pkt_list_tot && info->hit_count < ip_pkt_list_tot)
    nstamp_mask = roundup_pow_of_two(ip_pkt_list_tot) - 1;

    \
     
     \ /
      Last update: 2018-04-06 16:18    [W:4.174 / U:0.064 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site