The Design and Implementation of the Anykernel and Rump Kernels

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B–20 Congratulations, that’s it. Any application you run from the shell in which you set the variables will use the rump TCP/IP stack. If you wish to use another rump TCP/IP server (which has networking configured), simply adjust RUMP_SERVER. Using this method you can for example segregate some ”evil” applications to their own networking stack. B.3.3 Transparent TCP/IP stack restarts Since the TCP/IP stack is running in a separate process from the client, it is possible kill and restart the TCP/IP stack from under the application without having to restart the application. Potential uses for this are to take features available in later releases into use or fixing a security vulnerability. Even though NetBSD kernel code barely ever crashes, it does happen, and this will also protect against that. Since networking stack code does not contain any checkpointing support, killing the hosting process will cause all kernel state to go missing and for example previously used sockets will not be available after restart. Even if checkpointing were added for things like file descriptors, generally speaking checkpointing a TCP connection is not possible. The reaction to this unexpected loss of state largely depends on the application. For example, ssh will not handle this well, but Firefox will generally speaking recover without adverse effects. Before starting the hijacked application you should instruct the rump client library to retry to connect to the server in case the connection is lost. This is done by setting the RUMPHIJACK_RETRYCONNECT environment variable. golem> export RUMPHIJACK_RETRYCONNECT=inftime golem> firefox
B–21 Now we can use Firefox just like we would with the host kernel networking stack. When we want to restart the TCP/IP stack, we can use any method we’d like for killing the TCP/IP server, even kill -9 or just having it panic. The client will detect the severed connection and print out the following diagnostic warnings. rump_sp: connection to kernel lost, trying to reconnect ... rump_sp: still trying to reconnect ... rump_sp: still trying to reconnect ... Once the server has been restarted, the following message will be printed. If the server downtime was long, the client can take up to 10 seconds to retry, so do not be surprised if you do not see it immediately. rump_sp: reconnected! Note that this message only signals that the client has a connection to the server. In case the server has not been configured yet to have an IP address and a gateway, the application will not be able to function regularly. However, when that step is complete, normal service can resume. Any pages that were loading when the TCP/IP server went down will not finish loading. However, this can be ”fixed” simply by reloading the pages. B.4 Emulating makefs The makefs command takes a directory tree and creates a file system image out of it. This groundbreaking utility was developed back when crossbuild capability was added to the NetBSD source tree. Since makefs constructs the file system
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Department of Computer Science and
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9 Preface Meet the new boss Same as
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11 Then there is my dear Xi, who, s
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14 2.3.3 InterruptsandPreemption...
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16 4.1.1 Implementation Effort ....
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18 Appendix C Patches to the 5.99.4
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20 ISA LGPL LRU LWP MD MI MMU NIC O
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23 List of Figures 2.1 Rumpkernelhi
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25 4.14 Time to execute 5M system c
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29 1 Introduction In its classic ro
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31 and application-level drivers. T
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33 We define an anykernel to be an
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35 Our implementation supports rump
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37 The project was done in small in
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39 2 The Anykernel and Rump Kernels
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41 building on top of the entities
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43 Drivers in a rump kernel remain
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45 Figure 2.1: Rump k
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47 in Section 3.2.3. Whenever discu
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49 int rumpns_bpfopen(dev_t, int, i
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51 Figure 2.4:
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53 while the application logic stil
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55 We must solve the lack of a rump
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57 2.3.1 Kernel threads Up until no
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59 void * pool_cache_get_paddr(pool
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61 2.3.4 An Example We present an e
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63 Figure 2.6: Prov
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65 The straightforward use of exist
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68 We identified three obstacles fo
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70 for loadable kernel modules (dis
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72 e.g. the routine for mapping a p
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74 3.2.1 C Symbol Namespaces In the
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76 the double underscore namespace
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78 since the representation might n
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80 The following rumpuser interface
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82 The entry point rump_schedule()
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84 3.3.1 CPU Scheduling Recall from
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86 The fastpath is taken in cases w
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88 Releasing a CPU requires the fol
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90 10 8 seconds 6 4 2 0 1CPU 2CPU n
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92 Hardware interrupt handlers are
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94 Due to the design choice that a
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96 in. Therefore, we should critica
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98 Pager window create+access time
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100 A rump kernel can be configured
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102 Since all pages managed by the
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104 not in control of thread schedu
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106 synchronization part of the alg
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108 /* * Run a cross call to cycle
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110 kernel needs to do is make sure
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112 The kernel with uniprocessor lo
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114 the header file while open() c
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116 The same wrapper works both for
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118 5. Some calling conventions (e.
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120 int rump_pub_lwproc_rfork(int a
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122 By convention, file system devi
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124 ule directory tree from /stand
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126 After these steps have been per
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128 Host Dynamic Linker Using the h
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130 for (i = 0; i < SYS_NSYSENT; i+
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132 into a rump kernel and the driv
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134 sys/arch/x86/include/cpu.h: #de
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136 3.8.4 Rump Component Init Routi
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138 RUMP_COMPONENT(RUMP_COMPONENT_N
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140 We have three distinct cases we
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142 # ifconfig tap0 create # ifconf
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144 Unprivileged use of host’s ne
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146 DOMAIN_DEFINE(sockindomain); co
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148 issue another write before the
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150 using an interface called USBDI
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152 The kernel device configuration
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154 # $NetBSD: UMASS.ioconf,v 1.4 2
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156 USB Host Controller Hub0 (root)
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158 Figure 3.30: File s
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160 in-kernel mount: /dev/sd0e /m/u
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162 structure being created by rump
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164 3.12.1 Client-Kernel Locators B
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166 A tmpfs server listening on INA
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168 Request Arguments Response Desc
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170 Host syscall rump syscall 1. op
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172 A client’s initial connection
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174 their system calls to a rump ke
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176 stdin/stdout, the new file desc
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178 Supporting fork() Recall, the f
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180 As with fork, most of the kerne
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182 Anecdotal analysis For several
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184
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186 SLOC 8000 7000 6000 5000 4000 3
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188 Total commits to the kernel 9,6
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190 120 build time (minutes) 100 80
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192 4.2.2 makefs For a source tree
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194 not include later debugging [76
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196 the necessary tools such as mak
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198 proach of supplying alternate c
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200 are not out-of-the-box compatib
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202 golem> mount -t msdos -o rump /
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204 Full OS By a full OS we mean a
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206 • Rapid prototyping: One of t
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208 4.5.3 Testing: Case Studies We
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210 static void scsitest_request(st
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212 waits for the timeout and check
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214 • We noticed that even in sup
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216 which were discovered during wr
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218 version swap no swap NetBSD 5.1
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220 It needs to be stressed that Ta
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222 Network clusters Bootstrapping
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224 8 7 Standard components Self-co
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226 Rump kernel calls, as expected,
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228 Traditional FFS We measure the
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230 80 70 60 seconds 50 40 30 20 10
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232 The results are presented in Fi
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234 behavior is required by the act
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236
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238 Rialto [29] is an operating sys
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240 One argument for partitioned op
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242 View OS The View OS [37] approa
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244 OSKit Instead of making system
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246 discussing the type incompatibi
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248 difference to the abovementione
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250 At runtime, a rump kernel can a
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252 For testing and development we
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254
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256 Art of Virtualization. In: Proc
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258 [30] Adam Dunkels. 2001. Design
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260 [47] Galen C. Hunt and James R.
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262 [67] Steven McCanne and Van Jac
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264 [87] NetBSD Project. URL http:/
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266 of the 6th Workshop on Programm
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268
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A-2 RUMP.DHCPCLIENT(1) NetBSD Gener
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A-4 RUMP.HALT(1) NetBSD General Com
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A-6 RUMP_SERVER(1) NetBSD General C
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A-8 RUMP_SERVER(1) NetBSD General C
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A-10 SHMIF_DUMPBUS(1) NetBSD Genera
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A-12 P2K(3) NetBSD Library Function
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A-14 P2K(3) NetBSD Library Function
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A-16 RUMP(3) NetBSD Library Functio
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A-18 RUMP(3) NetBSD Library Functio
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A-20 RUMP_ETFS(3) NetBSD Library Fu
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Page 324 and 325: B-2 TCP connections use standard TC
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Page 332 and 333: B-10 golem> export RUMP_SERVER=unix
Page 334 and 335: B-12 golem> rump.dd if=/dev/rcgd0d
Page 336 and 337: B-14 demogorgon# cgdconfig cgd0 /de
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Page 340 and 341: B-18 golem> rump.ifconfig virt0 cre
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Page 356 and 357: C-2 This is a quick fix for making
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The Design and Implementation of the Anykernel and Rump Kernels

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