* Re: [PATCH v2 man-pages] bpf.2: new page documenting bpf(2)
@ 2015-03-12 15:20 Alexei Starovoitov
[not found] ` <CAMEtUuxZrmqUvgBX5zNbEdExqPaNw0LUhFyGP=N9erVqeKwhSQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
0 siblings, 1 reply; 5+ messages in thread
From: Alexei Starovoitov @ 2015-03-12 15:20 UTC (permalink / raw)
To: wharms-fPG8STNUNVg; +Cc: linux-man
On Thu, Mar 12, 2015 at 3:09 AM, walter harms <wharms-fPG8STNUNVg@public.gmane.org> wrote:
>
>
>> +.SH DESCRIPTION
>> +.BR bpf()
>> +syscall is a multiplexor for a range of different operations on extended BPF
> syscall is a multiplexor for a range of different operations on extended
> Berkeley Packet Filter (eBPF).
>
> just introduce the abv. early as possible,
>
I'd rather not. The universal feedback from everyone was
that eBPF name is ugly, awkward, hard to pronounce, hard to
remember, hard to spell, etc.
So I'm trying not to use it, if I can. Often when people
say 'bpf' they mean 'extended' one and
when they need to refer to old they say 'classic bpf'.
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply [flat|nested] 5+ messages in thread* [PATCH v2 man-pages] bpf.2: new page documenting bpf(2)
@ 2015-03-11 4:28 Alexei Starovoitov
[not found] ` <1426048097-14726-1-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
0 siblings, 1 reply; 5+ messages in thread
From: Alexei Starovoitov @ 2015-03-11 4:28 UTC (permalink / raw)
To: Michael Kerrisk; +Cc: Silvan Jegen, Daniel Borkmann, lkml, linux-man
Signed-off-by: Alexei Starovoitov <ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
---
man2/bpf.2 | 630 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 630 insertions(+)
create mode 100644 man2/bpf.2
diff --git a/man2/bpf.2 b/man2/bpf.2
new file mode 100644
index 0000000..a605489
--- /dev/null
+++ b/man2/bpf.2
@@ -0,0 +1,630 @@
+.\" Copyright (C) 2015 Alexei Starovoitov <ast-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
+.\"
+.\" %%%LICENSE_START(VERBATIM)
+.\" Permission is granted to make and distribute verbatim copies of this
+.\" manual provided the copyright notice and this permission notice are
+.\" preserved on all copies.
+.\"
+.\" Permission is granted to copy and distribute modified versions of this
+.\" manual under the conditions for verbatim copying, provided that the
+.\" entire resulting derived work is distributed under the terms of a
+.\" permission notice identical to this one.
+.\"
+.\" Since the Linux kernel and libraries are constantly changing, this
+.\" manual page may be incorrect or out-of-date. The author(s) assume no
+.\" responsibility for errors or omissions, or for damages resulting from
+.\" the use of the information contained herein. The author(s) may not
+.\" have taken the same level of care in the production of this manual,
+.\" which is licensed free of charge, as they might when working
+.\" professionally.
+.\"
+.\" Formatted or processed versions of this manual, if unaccompanied by
+.\" the source, must acknowledge the copyright and authors of this work.
+.\" %%%LICENSE_END
+.\"
+.TH BPF 2 2015-03-10 "Linux" "Linux Programmer's Manual"
+.SH NAME
+bpf - perform a command on an extended BPF map or program
+.SH SYNOPSIS
+.nf
+.B #include <linux/bpf.h>
+.sp
+.BI "int bpf(int cmd, union bpf_attr *attr, unsigned int size);
+
+.SH DESCRIPTION
+.BR bpf()
+syscall is a multiplexor for a range of different operations on extended BPF
+which can be characterized as "universal in-kernel virtual machine".
+Extended BPF (or eBPF) is similar to the original Berkeley Packet Filter
+(or "classic BPF") used to filter network packets. Both statically analyze
+the programs before loading them into the kernel to ensure that they cannot
+harm the running system.
+.P
+eBPF extends classic BPF in multiple ways including the ability to call
+in-kernel helper functions and access shared data structures like BPF maps.
+The programs can be written in a restricted C that is compiled into
+eBPF bytecode and executed on the in-kernel virtual machine or JITed into
+native code.
+.SS Extended BPF Design/Architecture
+.P
+BPF maps are a generic data structure for storage of different data types.
+A user process can create multiple maps (with key/value-pairs being
+opaque bytes of data) and access them via file descriptor.
+BPF programs can access maps from inside the kernel in parallel.
+It's up to the user process and BPF program to decide what they store
+inside maps.
+.P
+BPF programs are similar to kernel modules. They are loaded by the user
+process and automatically unloaded when the process exits.
+Each BPF program is a set of instructions that is safe to run until
+its completion. The BPF verifier statically determines that the program
+terminates and is safe to execute. During
+verification the program takes hold of maps that it intends to use,
+so selected maps cannot be removed until the program is unloaded. The program
+can be attached to different events. These events can be packets, tracing
+events and other types that may be added in the future. A new event triggers
+execution of the program which may store information about the event in the maps.
+Beyond storing data the programs may call into in-kernel helper functions.
+The same program can be attached to multiple events and different programs can
+access the same map:
+.nf
+ tracing tracing tracing packet packet
+ event A event B event C on eth0 on eth1
+ | | | | |
+ | | | | |
+ --> tracing <-- tracing socket socket
+ prog_1 prog_2 prog_3 prog_4
+ | | | |
+ |--- -----| |-------| map_3
+ map_1 map_2
+.fi
+.SS Syscall Arguments
+.B bpf()
+syscall operation is determined by
+.IR cmd
+which can be one of the following:
+.TP
+.B BPF_MAP_CREATE
+Create a map with the given type and attributes and return map FD
+.TP
+.B BPF_MAP_LOOKUP_ELEM
+Lookup element by key in a given map and return its value
+.TP
+.B BPF_MAP_UPDATE_ELEM
+Create or update element (key/value pair) in a given map
+.TP
+.B BPF_MAP_DELETE_ELEM
+Lookup and delete element by key in a given map
+.TP
+.B BPF_MAP_GET_NEXT_KEY
+Lookup element by key in a given map and return key of next element
+.TP
+.B BPF_PROG_LOAD
+Verify and load BPF program
+.TP
+.B attr
+is a pointer to a union of type bpf_attr as defined below.
+.TP
+.B size
+is the size of the union.
+.P
+.nf
+union bpf_attr {
+ struct { /* anonymous struct used by BPF_MAP_CREATE command */
+ __u32 map_type;
+ __u32 key_size; /* size of key in bytes */
+ __u32 value_size; /* size of value in bytes */
+ __u32 max_entries; /* max number of entries in a map */
+ };
+
+ struct { /* anonymous struct used by BPF_MAP_*_ELEM commands */
+ __u32 map_fd;
+ __aligned_u64 key;
+ union {
+ __aligned_u64 value;
+ __aligned_u64 next_key;
+ };
+ __u64 flags;
+ };
+
+ struct { /* anonymous struct used by BPF_PROG_LOAD command */
+ __u32 prog_type;
+ __u32 insn_cnt;
+ __aligned_u64 insns; /* 'const struct bpf_insn *' */
+ __aligned_u64 license; /* 'const char *' */
+ __u32 log_level; /* verbosity level of verifier */
+ __u32 log_size; /* size of user buffer */
+ __aligned_u64 log_buf; /* user supplied 'char *' buffer */
+ };
+} __attribute__((aligned(8)));
+.fi
+.SS BPF maps
+maps are a generic data structure for storage of different types
+and sharing data between kernel and userspace.
+
+Any map type has the following attributes:
+ . type
+ . max number of elements
+ . key size in bytes
+ . value size in bytes
+
+The following wrapper functions demonstrate how this syscall can be used to
+access the maps. The functions use the
+.IR cmd
+argument to invoke different operations.
+.TP
+.B BPF_MAP_CREATE
+.nf
+int bpf_create_map(enum bpf_map_type map_type, int key_size,
+ int value_size, int max_entries)
+{
+ union bpf_attr attr = {
+ .map_type = map_type,
+ .key_size = key_size,
+ .value_size = value_size,
+ .max_entries = max_entries
+ };
+
+ return bpf(BPF_MAP_CREATE, &attr, sizeof(attr));
+}
+.fi
+bpf() syscall creates a map of
+.I map_type
+type and given attributes
+.I key_size, value_size, max_entries.
+On success it returns a process-local file descriptor. On error, \-1 is returned and
+.I errno
+is set to EINVAL or EPERM or ENOMEM.
+
+The attributes
+.I key_size
+and
+.I value_size
+will be used by the verifier during program loading to check that the program
+is calling bpf_map_*_elem() helper functions with a correctly initialized
+.I key
+and that the program doesn't access map element
+.I value
+beyond the specified
+.I value_size.
+For example, when a map is created with key_size = 8 and the program calls
+.nf
+bpf_map_lookup_elem(map_fd, fp - 4)
+.fi
+the program will be rejected,
+since the in-kernel helper function bpf_map_lookup_elem(map_fd, void *key) expects
+to read 8 bytes from 'key' pointer, but 'fp - 4' starting address will cause
+out of bounds stack access.
+
+Similarly, when a map is created with value_size = 1 and the program calls
+.nf
+value = bpf_map_lookup_elem(...);
+*(u32 *)value = 1;
+.fi
+the program will be rejected, since it accesses the
+.I value
+pointer beyond the specified 1 byte value_size limit.
+
+Currently two
+.I map_type
+are supported:
+.nf
+enum bpf_map_type {
+ BPF_MAP_TYPE_UNSPEC,
+ BPF_MAP_TYPE_HASH,
+ BPF_MAP_TYPE_ARRAY,
+};
+.fi
+.I map_type
+selects one of the available map implementations in the kernel. For all map_types
+programs access maps with the same bpf_map_lookup_elem()/bpf_map_update_elem()
+helper functions.
+.TP
+.B BPF_MAP_LOOKUP_ELEM
+.nf
+int bpf_lookup_elem(int fd, void *key, void *value)
+{
+ union bpf_attr attr = {
+ .map_fd = fd,
+ .key = ptr_to_u64(key),
+ .value = ptr_to_u64(value),
+ };
+
+ return bpf(BPF_MAP_LOOKUP_ELEM, &attr, sizeof(attr));
+}
+.fi
+bpf() syscall looks up an element with a given
+.I key
+in a map
+.I fd.
+If an element is found it returns zero and stores element's value into
+.I value.
+If no element is found it returns \-1 and sets
+.I errno
+to ENOENT.
+.TP
+.B BPF_MAP_UPDATE_ELEM
+.nf
+int bpf_update_elem(int fd, void *key, void *value, __u64 flags)
+{
+ union bpf_attr attr = {
+ .map_fd = fd,
+ .key = ptr_to_u64(key),
+ .value = ptr_to_u64(value),
+ .flags = flags,
+ };
+
+ return bpf(BPF_MAP_UPDATE_ELEM, &attr, sizeof(attr));
+}
+.fi
+The call creates or updates an element with a given
+.I key/value
+in a map
+.I fd
+according to
+.I flags
+which can have one of 3 possible values:
+.nf
+#define BPF_ANY 0 /* create new element or update existing */
+#define BPF_NOEXIST 1 /* create new element if it didn't exist */
+#define BPF_EXIST 2 /* update existing element */
+.fi
+On success it returns zero.
+On error, \-1 is returned and
+.I errno
+is set to EINVAL, EPERM, ENOMEM or E2BIG.
+.B E2BIG
+indicates that the number of elements in the map reached
+.I max_entries
+limit specified at map creation time.
+.B EEXIST
+will be returned from a call to bpf_update_elem(fd, key, value, BPF_NOEXIST) if
+the element with 'key' already exists in the map.
+.B ENOENT
+will be returned from a call to bpf_update_elem(fd, key, value, BPF_EXIST) if
+the element with 'key' doesn't exist in the map.
+.TP
+.B BPF_MAP_DELETE_ELEM
+.nf
+int bpf_delete_elem(int fd, void *key)
+{
+ union bpf_attr attr = {
+ .map_fd = fd,
+ .key = ptr_to_u64(key),
+ };
+
+ return bpf(BPF_MAP_DELETE_ELEM, &attr, sizeof(attr));
+}
+.fi
+The call deletes an element in a map
+.I fd
+with a given
+.I key.
+Returns zero on success. If the element is not found it returns \-1 and sets
+.I errno
+to ENOENT.
+.TP
+.B BPF_MAP_GET_NEXT_KEY
+.nf
+int bpf_get_next_key(int fd, void *key, void *next_key)
+{
+ union bpf_attr attr = {
+ .map_fd = fd,
+ .key = ptr_to_u64(key),
+ .next_key = ptr_to_u64(next_key),
+ };
+
+ return bpf(BPF_MAP_GET_NEXT_KEY, &attr, sizeof(attr));
+}
+.fi
+The call looks up an element by
+.I key
+in a given map
+.I fd
+and sets the
+.I next_key
+pointer to the key of the next element.
+If
+.I key
+is not found, it returns zero and sets the
+.I next_key
+pointer to the key of the first element.
+If
+.I key
+is the last element, it returns \-1 and sets
+.I errno
+to ENOENT. Other possible
+.I errno
+values are ENOMEM, EFAULT, EPERM and EINVAL.
+This method can be used to iterate over all elements in the map.
+.TP
+.B close(map_fd)
+will delete the map
+.I map_fd.
+When the user space program that created maps exits all maps will
+be deleted automatically.
+
+.P
+.SS BPF programs
+
+.TP
+.B BPF_PROG_LOAD
+This
+.IR cmd
+is used to load extended BPF program into the kernel.
+
+.nf
+char bpf_log_buf[LOG_BUF_SIZE];
+
+int bpf_prog_load(enum bpf_prog_type prog_type,
+ const struct bpf_insn *insns, int insn_cnt,
+ const char *license)
+{
+ union bpf_attr attr = {
+ .prog_type = prog_type,
+ .insns = ptr_to_u64(insns),
+ .insn_cnt = insn_cnt,
+ .license = ptr_to_u64(license),
+ .log_buf = ptr_to_u64(bpf_log_buf),
+ .log_size = LOG_BUF_SIZE,
+ .log_level = 1,
+ };
+
+ return bpf(BPF_PROG_LOAD, &attr, sizeof(attr));
+}
+.fi
+.B prog_type
+is one of the available program types:
+.nf
+enum bpf_prog_type {
+ BPF_PROG_TYPE_UNSPEC,
+ BPF_PROG_TYPE_SOCKET_FILTER,
+ BPF_PROG_TYPE_SCHED_CLS,
+};
+.fi
+By picking
+.I prog_type
+the program author selects a set of helper functions callable from
+the program and the corresponding format of
+.I struct bpf_context
+(which is the data blob passed into the program as the first argument).
+For example, the programs loaded with
+.I prog_type
+= BPF_PROG_TYPE_SOCKET_FILTER may call bpf_map_lookup_elem() helper,
+whereas some future types may not.
+The set of functions available to the programs under a given type may increase
+in the future.
+
+Currently the set of functions for
+.B BPF_PROG_TYPE_SOCKET_FILTER
+is:
+.nf
+bpf_map_lookup_elem(map_fd, void *key) // lookup key in a map_fd
+bpf_map_update_elem(map_fd, void *key, void *value) // update key/value
+bpf_map_delete_elem(map_fd, void *key) // delete key in a map_fd
+.fi
+
+and bpf_context is a pointer to 'struct sk_buff'. Programs cannot
+access fields of 'sk_buff' directly.
+
+More program types may be added in the future. Like
+.B BPF_PROG_TYPE_KPROBE
+and bpf_context for it may be defined as a pointer to 'struct pt_regs'.
+
+.B insns
+array of "struct bpf_insn" instructions.
+
+.B insn_cnt
+number of instructions in the program.
+
+.B license
+license string, which must be GPL compatible to call helper functions
+marked gpl_only.
+
+.B log_buf
+user supplied buffer that the in-kernel verifier is using to store the
+verification log. This log is a multi-line string that can be checked by
+the program author in order to understand how the verifier came to
+the conclusion that the BPF program is unsafe.
+The format of the output can change at any time as the verifier evolves.
+
+.B log_size
+size of user buffer. If the size of the buffer is not large enough to store all
+verifier messages, \-1 is returned and
+.I errno
+is set to ENOSPC.
+
+.B log_level
+verbosity level of the verifier. A value of zero means that the verifier will
+not provide a log.
+
+.TP
+.B close(prog_fd)
+will unload the BPF program.
+.P
+The maps are accessible from programs and used to exchange data between
+programs and between them and user space.
+Programs process various events (like kprobe, packets) and
+store their data into maps. User space fetches data from the maps.
+Either the same or a different map may be used by user space as a configuration
+space to alter program behavior on the fly.
+.SS Events
+.P
+Once a program is loaded, it can be attached to an event. Various kernel
+subsystems have different ways to do so. For example:
+
+.nf
+setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, sizeof(prog_fd));
+.fi
+will attach the program
+.I prog_fd
+to socket
+.I sock
+which was received from a prior call to socket().
+
+In the future
+.nf
+ioctl(event_fd, PERF_EVENT_IOC_SET_BPF, prog_fd);
+.fi
+may attach the program
+.I prog_fd
+to perf event
+.I event_fd
+which was received by prior call to perf_event_open().
+
+.SH EXAMPLES
+.nf
+/* bpf+sockets example:
+ * 1. create array map of 256 elements
+ * 2. load program that counts number of packets received
+ * r0 = skb->data[ETH_HLEN + offsetof(struct iphdr, protocol)]
+ * map[r0]++
+ * 3. attach prog_fd to raw socket via setsockopt()
+ * 4. print number of received TCP/UDP packets every second
+ */
+int main(int ac, char **av)
+{
+ int sock, map_fd, prog_fd, key;
+ long long value = 0, tcp_cnt, udp_cnt;
+
+ map_fd = bpf_create_map(BPF_MAP_TYPE_ARRAY, sizeof(key), sizeof(value), 256);
+ if (map_fd < 0) {
+ printf("failed to create map '%s'\\n", strerror(errno));
+ /* likely not run as root */
+ return 1;
+ }
+
+ struct bpf_insn prog[] = {
+ BPF_MOV64_REG(BPF_REG_6, BPF_REG_1), /* r6 = r1 */
+ BPF_LD_ABS(BPF_B, ETH_HLEN + offsetof(struct iphdr, protocol)), /* r0 = ip->proto */
+ BPF_STX_MEM(BPF_W, BPF_REG_10, BPF_REG_0, -4), /* *(u32 *)(fp - 4) = r0 */
+ BPF_MOV64_REG(BPF_REG_2, BPF_REG_10), /* r2 = fp */
+ BPF_ALU64_IMM(BPF_ADD, BPF_REG_2, -4), /* r2 = r2 - 4 */
+ BPF_LD_MAP_FD(BPF_REG_1, map_fd), /* r1 = map_fd */
+ BPF_CALL_FUNC(BPF_FUNC_map_lookup_elem), /* r0 = map_lookup(r1, r2) */
+ BPF_JMP_IMM(BPF_JEQ, BPF_REG_0, 0, 2), /* if (r0 == 0) goto pc+2 */
+ BPF_MOV64_IMM(BPF_REG_1, 1), /* r1 = 1 */
+ BPF_XADD(BPF_DW, BPF_REG_0, BPF_REG_1, 0, 0), /* lock *(u64 *)r0 += r1 */
+ BPF_MOV64_IMM(BPF_REG_0, 0), /* r0 = 0 */
+ BPF_EXIT_INSN(), /* return r0 */
+ };
+
+ prog_fd = bpf_prog_load(BPF_PROG_TYPE_SOCKET_FILTER, prog, sizeof(prog), "GPL");
+
+ sock = open_raw_sock("lo");
+
+ assert(setsockopt(sock, SOL_SOCKET, SO_ATTACH_BPF, &prog_fd, sizeof(prog_fd)) == 0);
+
+ for (;;) {
+ key = IPPROTO_TCP;
+ assert(bpf_lookup_elem(map_fd, &key, &tcp_cnt) == 0);
+ key = IPPROTO_UDP
+ assert(bpf_lookup_elem(map_fd, &key, &udp_cnt) == 0);
+ printf("TCP %lld UDP %lld packets\n", tcp_cnt, udp_cnt);
+ sleep(1);
+ }
+
+ return 0;
+}
+.fi
+.SH RETURN VALUE
+For a successful call, the return value depends on the operation:
+.TP
+.B BPF_MAP_CREATE
+The new file descriptor associated with the BPF map.
+.TP
+.B BPF_PROG_LOAD
+The new file descriptor associated with the BPF program.
+.TP
+All other commands
+Zero.
+.PP
+On error, \-1 is returned, and
+.I errno
+is set appropriately.
+.SH ERRORS
+.TP
+.B EPERM
+bpf() syscall was made without sufficient privilege
+(without the
+.B CAP_SYS_ADMIN
+capability).
+.TP
+.B ENOMEM
+Cannot allocate sufficient memory.
+.TP
+.B EBADF
+.I fd
+is not an open file descriptor
+.TP
+.B EFAULT
+One of the pointers (
+.I key
+or
+.I value
+or
+.I log_buf
+or
+.I insns
+) is outside the accessible address space.
+.TP
+.B EINVAL
+The value specified in
+.I cmd
+is not recognized by this kernel.
+.TP
+.B EINVAL
+For
+.BR BPF_MAP_CREATE ,
+either
+.I map_type
+or attributes are invalid.
+.TP
+.B EINVAL
+For
+.BR BPF_MAP_*_ELEM
+commands,
+some of the fields of "union bpf_attr" that are not used by this command
+are not set to zero.
+.TP
+.B EINVAL
+For
+.BR BPF_PROG_LOAD,
+indicates an attempt to load an invalid program. BPF programs can be deemed
+invalid due to unrecognized instructions, the use of reserved fields, jumps
+out of range, infinite loops or calls of unknown functions.
+.TP
+.BR EACCES
+For
+.BR BPF_PROG_LOAD,
+even though all program instructions are valid, the program has been
+rejected because it was deemed unsafe. This may be because it may have
+accessed a disallowed memory region or an uninitialized stack/register or
+because the function contraints don't match the actual types or because
+there was a misaligned memory access.
+In such case it is recommended to call bpf() again with
+.I log_level = 1
+and examine
+.I log_buf
+for the specific reason provided by the verifier.
+.TP
+.BR ENOENT
+For
+.B BPF_MAP_LOOKUP_ELEM
+or
+.B BPF_MAP_DELETE_ELEM,
+indicates that the element with the given
+.I key
+was not found.
+.TP
+.BR E2BIG
+program is too large or
+a map reached
+.I max_entries
+limit (max number of elements).
+.SH NOTES
+These commands may be used only by a privileged process (one having the
+.B CAP_SYS_ADMIN
+capability).
+.SH SEE ALSO
+Both classic and extended BPF are explained in Documentation/networking/filter.txt
--
1.7.9.5
--
To unsubscribe from this list: send the line "unsubscribe linux-man" in
the body of a message to majordomo-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
^ permalink raw reply related [flat|nested] 5+ messages in thread
end of thread, other threads:[~2015-03-12 15:51 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2015-03-12 15:20 [PATCH v2 man-pages] bpf.2: new page documenting bpf(2) Alexei Starovoitov
[not found] ` <CAMEtUuxZrmqUvgBX5zNbEdExqPaNw0LUhFyGP=N9erVqeKwhSQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-12 15:50 ` walter harms
[not found] ` <5501B5BC.2010806-fPG8STNUNVg@public.gmane.org>
2015-03-12 15:51 ` Alexei Starovoitov
-- strict thread matches above, loose matches on Subject: below --
2015-03-11 4:28 Alexei Starovoitov
[not found] ` <1426048097-14726-1-git-send-email-ast-uqk4Ao+rVK5Wk0Htik3J/w@public.gmane.org>
2015-03-12 10:09 ` walter harms
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).