diff mbox series

[2/2] net: socket: implement SO_DESCRIPTION

Message ID 20200815182344.7469-3-kalou@tfz.net
State RFC
Delegated to: David Miller
Headers show
Series proc,socket: attach description to sockets | expand

Commit Message

Pascal Bouchareine Aug. 15, 2020, 6:23 p.m. UTC 
This command attaches the zero terminated string in optval to the
socket for troubleshooting purposes. The free string is displayed in the
process fdinfo file for that fd (/proc/<pid>/fdinfo/<fd>).

One intended usage is to allow processes to self-document sockets
for netstat and friends to report

We ignore optlen and constrain the string to a static max size

Signed-off-by: Pascal Bouchareine <kalou@tfz.net>
---
 include/net/sock.h                |  4 ++++
 include/uapi/asm-generic/socket.h |  2 ++
 net/core/sock.c                   | 23 +++++++++++++++++++++++
 net/socket.c                      |  5 +++++
 4 files changed, 34 insertions(+)

Comments

kernel test robot Aug. 16, 2020, 5:02 a.m. UTC | #1 
Hi Pascal,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/perf/core]
[also build test WARNING on linux/master v5.8]
[cannot apply to security/next-testing linus/master next-20200814]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Pascal-Bouchareine/proc-socket-attach-description-to-sockets/20200816-090222
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git d903b6d029d66e6478562d75ea18d89098f7b7e8
config: m68k-allmodconfig (attached as .config)
compiler: m68k-linux-gcc (GCC) 9.3.0
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-9.3.0 make.cross ARCH=m68k 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

   In file included from arch/m68k/include/asm/io_mm.h:25,
                    from arch/m68k/include/asm/io.h:8,
                    from include/linux/scatterlist.h:9,
                    from include/linux/dma-mapping.h:11,
                    from include/linux/skbuff.h:31,
                    from include/linux/ip.h:16,
                    from include/net/ip.h:22,
                    from include/linux/errqueue.h:6,
                    from net/core/sock.c:91:
   arch/m68k/include/asm/raw_io.h: In function 'raw_rom_outsb':
   arch/m68k/include/asm/raw_io.h:83:7: warning: variable '__w' set but not used [-Wunused-but-set-variable]
      83 |  ({u8 __w, __v = (b);  u32 _addr = ((u32) (addr)); \
         |       ^~~
   arch/m68k/include/asm/raw_io.h:430:3: note: in expansion of macro 'rom_out_8'
     430 |   rom_out_8(port, *buf++);
         |   ^~~~~~~~~
   arch/m68k/include/asm/raw_io.h: In function 'raw_rom_outsw':
   arch/m68k/include/asm/raw_io.h:86:8: warning: variable '__w' set but not used [-Wunused-but-set-variable]
      86 |  ({u16 __w, __v = (w); u32 _addr = ((u32) (addr)); \
         |        ^~~
   arch/m68k/include/asm/raw_io.h:448:3: note: in expansion of macro 'rom_out_be16'
     448 |   rom_out_be16(port, *buf++);
         |   ^~~~~~~~~~~~
   arch/m68k/include/asm/raw_io.h: In function 'raw_rom_outsw_swapw':
   arch/m68k/include/asm/raw_io.h:90:8: warning: variable '__w' set but not used [-Wunused-but-set-variable]
      90 |  ({u16 __w, __v = (w); u32 _addr = ((u32) (addr)); \
         |        ^~~
   arch/m68k/include/asm/raw_io.h:466:3: note: in expansion of macro 'rom_out_le16'
     466 |   rom_out_le16(port, *buf++);
         |   ^~~~~~~~~~~~
   In file included from include/linux/kernel.h:11,
                    from include/linux/unaligned/access_ok.h:5,
                    from arch/m68k/include/asm/unaligned.h:18,
                    from net/core/sock.c:88:
   include/linux/scatterlist.h: In function 'sg_set_buf':
   arch/m68k/include/asm/page_mm.h:169:49: warning: ordered comparison of pointer with null pointer [-Wextra]
     169 | #define virt_addr_valid(kaddr) ((void *)(kaddr) >= (void *)PAGE_OFFSET && (void *)(kaddr) < high_memory)
         |                                                 ^~
   include/linux/compiler.h:78:42: note: in definition of macro 'unlikely'
      78 | # define unlikely(x) __builtin_expect(!!(x), 0)
         |                                          ^
   include/linux/scatterlist.h:143:2: note: in expansion of macro 'BUG_ON'
     143 |  BUG_ON(!virt_addr_valid(buf));
         |  ^~~~~~
   include/linux/scatterlist.h:143:10: note: in expansion of macro 'virt_addr_valid'
     143 |  BUG_ON(!virt_addr_valid(buf));
         |          ^~~~~~~~~~~~~~~
   In file included from arch/m68k/include/asm/bug.h:32,
                    from include/linux/bug.h:5,
                    from include/linux/thread_info.h:12,
                    from include/asm-generic/preempt.h:5,
                    from ./arch/m68k/include/generated/asm/preempt.h:1,
                    from include/linux/preempt.h:78,
                    from include/linux/spinlock.h:51,
                    from include/linux/seqlock.h:36,
                    from include/linux/time.h:6,
                    from include/linux/skbuff.h:15,
                    from include/linux/ip.h:16,
                    from include/net/ip.h:22,
                    from include/linux/errqueue.h:6,
                    from net/core/sock.c:91:
   include/linux/dma-mapping.h: In function 'dma_map_resource':
   arch/m68k/include/asm/page_mm.h:169:49: warning: ordered comparison of pointer with null pointer [-Wextra]
     169 | #define virt_addr_valid(kaddr) ((void *)(kaddr) >= (void *)PAGE_OFFSET && (void *)(kaddr) < high_memory)
         |                                                 ^~
   include/asm-generic/bug.h:144:27: note: in definition of macro 'WARN_ON_ONCE'
     144 |  int __ret_warn_once = !!(condition);   \
         |                           ^~~~~~~~~
   arch/m68k/include/asm/page_mm.h:170:25: note: in expansion of macro 'virt_addr_valid'
     170 | #define pfn_valid(pfn)  virt_addr_valid(pfn_to_virt(pfn))
         |                         ^~~~~~~~~~~~~~~
   include/linux/dma-mapping.h:352:19: note: in expansion of macro 'pfn_valid'
     352 |  if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr))))
         |                   ^~~~~~~~~
   net/core/sock.c: At top level:
>> net/core/sock.c:831:5: warning: no previous prototype for 'sock_set_description' [-Wmissing-prototypes]
     831 | int sock_set_description(struct sock *sk, char __user *user_desc)
         |     ^~~~~~~~~~~~~~~~~~~~

vim +/sock_set_description +831 net/core/sock.c

   830	
 > 831	int sock_set_description(struct sock *sk, char __user *user_desc)
   832	{
   833		char *old, *desc;
   834	
   835		desc = strndup_user(user_desc, SK_MAX_DESC_SIZE, GFP_KERNEL_ACCOUNT);
   836		if (IS_ERR(desc))
   837			return PTR_ERR(desc);
   838	
   839		lock_sock(sk);
   840		old = sk->sk_description;
   841		sk->sk_description = desc;
   842		release_sock(sk);
   843	
   844		kfree(old);
   845	
   846		return 0;
   847	}
   848	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Aug. 16, 2020, 7:33 a.m. UTC | #2 
Hi Pascal,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/perf/core]
[also build test WARNING on linux/master v5.8]
[cannot apply to security/next-testing linus/master next-20200814]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Pascal-Bouchareine/proc-socket-attach-description-to-sockets/20200816-090222
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git d903b6d029d66e6478562d75ea18d89098f7b7e8
config: i386-randconfig-s002-20200816 (attached as .config)
compiler: gcc-9 (Debian 9.3.0-15) 9.3.0
reproduce:
        # apt-get install sparse
        # sparse version: v0.6.2-168-g9554805c-dirty
        # save the attached .config to linux build tree
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__' ARCH=i386 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>


sparse warnings: (new ones prefixed by >>)

>> net/core/sock.c:831:5: sparse: sparse: symbol 'sock_set_description' was not declared. Should it be static?
   net/core/sock.c:2028:9: sparse: sparse: context imbalance in 'sk_clone_lock' - wrong count at exit
   net/core/sock.c:2032:6: sparse: sparse: context imbalance in 'sk_free_unlock_clone' - unexpected unlock
   net/core/sock.c:3117:6: sparse: sparse: context imbalance in 'lock_sock_fast' - different lock contexts for basic block
   net/core/sock.c:3611:13: sparse: sparse: context imbalance in 'proto_seq_start' - wrong count at exit
   net/core/sock.c:3623:13: sparse: sparse: context imbalance in 'proto_seq_stop' - wrong count at exit

Please review and possibly fold the followup patch.

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
kernel test robot Aug. 16, 2020, 9 a.m. UTC | #3 
Hi Pascal,

Thank you for the patch! Perhaps something to improve:

[auto build test WARNING on tip/perf/core]
[also build test WARNING on linux/master v5.8]
[cannot apply to security/next-testing linus/master next-20200814]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch]

url:    https://github.com/0day-ci/linux/commits/Pascal-Bouchareine/proc-socket-attach-description-to-sockets/20200816-090222
base:   https://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git d903b6d029d66e6478562d75ea18d89098f7b7e8
config: x86_64-randconfig-r006-20200816 (attached as .config)
compiler: clang version 12.0.0 (https://github.com/llvm/llvm-project ab9fc8bae805c785066779e76e7846aabad5609e)
reproduce (this is a W=1 build):
        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        # install x86_64 cross compiling tool for clang build
        # apt-get install binutils-x86-64-linux-gnu
        # save the attached .config to linux build tree
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang make.cross ARCH=x86_64 

If you fix the issue, kindly add following tag as appropriate
Reported-by: kernel test robot <lkp@intel.com>

All warnings (new ones prefixed by >>):

>> net/core/sock.c:831:5: warning: no previous prototype for function 'sock_set_description' [-Wmissing-prototypes]
   int sock_set_description(struct sock *sk, char __user *user_desc)
       ^
   net/core/sock.c:831:1: note: declare 'static' if the function is not intended to be used outside of this translation unit
   int sock_set_description(struct sock *sk, char __user *user_desc)
   ^
   static 
   1 warning generated.

vim +/sock_set_description +831 net/core/sock.c

   830	
 > 831	int sock_set_description(struct sock *sk, char __user *user_desc)
   832	{
   833		char *old, *desc;
   834	
   835		desc = strndup_user(user_desc, SK_MAX_DESC_SIZE, GFP_KERNEL_ACCOUNT);
   836		if (IS_ERR(desc))
   837			return PTR_ERR(desc);
   838	
   839		lock_sock(sk);
   840		old = sk->sk_description;
   841		sk->sk_description = desc;
   842		release_sock(sk);
   843	
   844		kfree(old);
   845	
   846		return 0;
   847	}
   848	

---
0-DAY CI Kernel Test Service, Intel Corporation
https://lists.01.org/hyperkitty/list/kbuild-all@lists.01.org
Eric Dumazet Aug. 16, 2020, 6:15 p.m. UTC | #4 
On 8/15/20 11:23 AM, Pascal Bouchareine wrote:
> This command attaches the zero terminated string in optval to the
> socket for troubleshooting purposes. The free string is displayed in the
> process fdinfo file for that fd (/proc/<pid>/fdinfo/<fd>).
> 
> One intended usage is to allow processes to self-document sockets
> for netstat and friends to report
> 
> We ignore optlen and constrain the string to a static max size
> 
>

1) You also ignored what would happen at accept() time.

Please test your patches with ASAN.

2) Also, why is that description specific to sockets ?

3) When a new socket option is added, it is customary to implement both setsockopt() and getsockopt()
  for things like CRIU.
Pascal Bouchareine Aug. 16, 2020, 7:30 p.m. UTC | #5 
On Sun, Aug 16, 2020 at 11:15 AM Eric Dumazet <eric.dumazet@gmail.com> wrote:
>
> 1) You also ignored what would happen at accept() time.
>
> Please test your patches with ASAN.

Ouch, I will look into it - thanks for pointing that out & 3/

>
> 2) Also, why is that description specific to sockets ?

fcntl on struct file was deemed too intrusive - as far as fds are
concerned, regular files and pipes have names and local processes to
match against anyway
we're left with mostly remote targets - one example was to preserve
target host names after resolution (alas, I don't think there's a
clean flow to hook that transparently)
diff mbox series

Patch

diff --git a/include/net/sock.h b/include/net/sock.h
index 1183507df95b..6b4fd1383282 100644
--- a/include/net/sock.h
+++ b/include/net/sock.h
@@ -342,6 +342,7 @@  struct bpf_sk_storage;
   *	@sk_txtime_deadline_mode: set deadline mode for SO_TXTIME
   *	@sk_txtime_report_errors: set report errors mode for SO_TXTIME
   *	@sk_txtime_unused: unused txtime flags
+  *	@sk_description: user supplied with SO_DESCRIPTION
   */
 struct sock {
 	/*
@@ -519,6 +520,9 @@  struct sock {
 	struct bpf_sk_storage __rcu	*sk_bpf_storage;
 #endif
 	struct rcu_head		sk_rcu;
+
+#define	SK_MAX_DESC_SIZE	256
+	char			*sk_description;
 };
 
 enum sk_pacing {
diff --git a/include/uapi/asm-generic/socket.h b/include/uapi/asm-generic/socket.h
index 77f7c1638eb1..fb51c4bb7a12 100644
--- a/include/uapi/asm-generic/socket.h
+++ b/include/uapi/asm-generic/socket.h
@@ -119,6 +119,8 @@ 
 
 #define SO_DETACH_REUSEPORT_BPF 68
 
+#define SO_DESCRIPTION		69
+
 #if !defined(__KERNEL__)
 
 #if __BITS_PER_LONG == 64 || (defined(__x86_64__) && defined(__ILP32__))
diff --git a/net/core/sock.c b/net/core/sock.c
index 2e5b7870e5d3..2cb44a0e38b7 100644
--- a/net/core/sock.c
+++ b/net/core/sock.c
@@ -828,6 +828,24 @@  void sock_set_rcvbuf(struct sock *sk, int val)
 }
 EXPORT_SYMBOL(sock_set_rcvbuf);
 
+int sock_set_description(struct sock *sk, char __user *user_desc)
+{
+	char *old, *desc;
+
+	desc = strndup_user(user_desc, SK_MAX_DESC_SIZE, GFP_KERNEL_ACCOUNT);
+	if (IS_ERR(desc))
+		return PTR_ERR(desc);
+
+	lock_sock(sk);
+	old = sk->sk_description;
+	sk->sk_description = desc;
+	release_sock(sk);
+
+	kfree(old);
+
+	return 0;
+}
+
 /*
  *	This is meant for all protocols to use and covers goings on
  *	at the socket level. Everything here is generic.
@@ -850,6 +868,9 @@  int sock_setsockopt(struct socket *sock, int level, int optname,
 	if (optname == SO_BINDTODEVICE)
 		return sock_setbindtodevice(sk, optval, optlen);
 
+	if (optname == SO_DESCRIPTION)
+		return sock_set_description(sk, optval);
+
 	if (optlen < sizeof(int))
 		return -EINVAL;
 
@@ -1792,6 +1813,8 @@  static void __sk_destruct(struct rcu_head *head)
 		RCU_INIT_POINTER(sk->sk_filter, NULL);
 	}
 
+	kfree(sk->sk_description);
+
 	sock_disable_timestamp(sk, SK_FLAGS_TIMESTAMP);
 
 #ifdef CONFIG_BPF_SYSCALL
diff --git a/net/socket.c b/net/socket.c
index 976426d03f09..4f2c1a7744b0 100644
--- a/net/socket.c
+++ b/net/socket.c
@@ -134,6 +134,11 @@  static void sock_show_fdinfo(struct seq_file *m, struct file *f)
 {
 	struct socket *sock = f->private_data;
 
+	lock_sock(sock->sk);
+	if (sock->sk->sk_description)
+		seq_printf(m, "desc:\t%s\n", sock->sk->sk_description);
+	release_sock(sock->sk);
+
 	if (sock->ops->show_fdinfo)
 		sock->ops->show_fdinfo(m, sock);
 }