lkml.org 
[lkml]   [2021]   [Nov]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    Patch in this message
    /
    From
    Subject[PATCH 1/5] tcp/md5: Don't BUG_ON() failed kmemdup()
    Date
    static_branch_unlikely(&tcp_md5_needed) is enabled by
    tcp_alloc_md5sig_pool(), so as long as the code doesn't change
    tcp_md5sig_pool has been already populated if this code is being
    executed.

    In case tcptw->tw_md5_key allocaion failed - no reason to crash kernel:
    tcp_{v4,v6}_send_ack() will send unsigned segment, the connection won't be
    established, which is bad enough, but in OOM situation totally
    acceptable and better than kernel crash.

    Introduce tcp_md5sig_pool_ready() helper.
    tcp_alloc_md5sig_pool() usage is intentionally avoided here as it's
    fast-path here and it's check for sanity rather than point of actual
    pool allocation. That will allow to have generic slow-path allocator
    for tcp crypto pool.

    Signed-off-by: Dmitry Safonov <dima@arista.com>
    ---
    include/net/tcp.h | 1 +
    net/ipv4/tcp.c | 5 +++++
    net/ipv4/tcp_minisocks.c | 5 +++--
    3 files changed, 9 insertions(+), 2 deletions(-)

    diff --git a/include/net/tcp.h b/include/net/tcp.h
    index 4da22b41bde6..3e5423a10a74 100644
    --- a/include/net/tcp.h
    +++ b/include/net/tcp.h
    @@ -1672,6 +1672,7 @@ tcp_md5_do_lookup(const struct sock *sk, int l3index,
    #endif

    bool tcp_alloc_md5sig_pool(void);
    +bool tcp_md5sig_pool_ready(void);

    struct tcp_md5sig_pool *tcp_get_md5sig_pool(void);
    static inline void tcp_put_md5sig_pool(void)
    diff --git a/net/ipv4/tcp.c b/net/ipv4/tcp.c
    index b7796b4cf0a0..c0856a6af9f5 100644
    --- a/net/ipv4/tcp.c
    +++ b/net/ipv4/tcp.c
    @@ -4314,6 +4314,11 @@ bool tcp_alloc_md5sig_pool(void)
    }
    EXPORT_SYMBOL(tcp_alloc_md5sig_pool);

    +bool tcp_md5sig_pool_ready(void)
    +{
    + return tcp_md5sig_pool_populated;
    +}
    +EXPORT_SYMBOL(tcp_md5sig_pool_ready);

    /**
    * tcp_get_md5sig_pool - get md5sig_pool for this user
    diff --git a/net/ipv4/tcp_minisocks.c b/net/ipv4/tcp_minisocks.c
    index cf913a66df17..c99cdb529902 100644
    --- a/net/ipv4/tcp_minisocks.c
    +++ b/net/ipv4/tcp_minisocks.c
    @@ -293,11 +293,12 @@ void tcp_time_wait(struct sock *sk, int state, int timeo)
    tcptw->tw_md5_key = NULL;
    if (static_branch_unlikely(&tcp_md5_needed)) {
    struct tcp_md5sig_key *key;
    + bool err = WARN_ON(!tcp_md5sig_pool_ready());

    key = tp->af_specific->md5_lookup(sk, sk);
    - if (key) {
    + if (key && !err) {
    tcptw->tw_md5_key = kmemdup(key, sizeof(*key), GFP_ATOMIC);
    - BUG_ON(tcptw->tw_md5_key && !tcp_alloc_md5sig_pool());
    + WARN_ON_ONCE(tcptw->tw_md5_key == NULL);
    }
    }
    } while (0);
    --
    2.33.1
    \
     
     \ /
      Last update: 2021-11-05 02:50    [W:8.047 / U:0.060 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site