Repository: jcalvinowens/asmhttpd Branch: master Commit: 2cc6edacdbf3 Files: 8 Total size: 37.5 KB Directory structure: gitextract_bxrp70mk/ ├── .gitignore ├── LICENSE ├── MACROS ├── Makefile ├── README ├── asmhttpd.asm ├── constants.inc └── syscall.inc ================================================ FILE CONTENTS ================================================ ================================================ FILE: .gitignore ================================================ asmhttpd asmhttpd.o ================================================ FILE: LICENSE ================================================ GNU GENERAL PUBLIC LICENSE Version 2, June 1991 Copyright (C) 1989, 1991 Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. Preamble The licenses for most software are designed to take away your freedom to share and change it. By contrast, the GNU General Public License is intended to guarantee your freedom to share and change free software--to make sure the software is free for all its users. This General Public License applies to most of the Free Software Foundation's software and to any other program whose authors commit to using it. (Some other Free Software Foundation software is covered by the GNU Lesser General Public License instead.) You can apply it to your programs, too. When we speak of free software, we are referring to freedom, not price. Our General Public Licenses are designed to make sure that you have the freedom to distribute copies of free software (and charge for this service if you wish), that you receive source code or can get it if you want it, that you can change the software or use pieces of it in new free programs; and that you know you can do these things. To protect your rights, we need to make restrictions that forbid anyone to deny you these rights or to ask you to surrender the rights. These restrictions translate to certain responsibilities for you if you distribute copies of the software, or if you modify it. For example, if you distribute copies of such a program, whether gratis or for a fee, you must give the recipients all the rights that you have. You must make sure that they, too, receive or can get the source code. And you must show them these terms so they know their rights. We protect your rights with two steps: (1) copyright the software, and (2) offer you this license which gives you legal permission to copy, distribute and/or modify the software. Also, for each author's protection and ours, we want to make certain that everyone understands that there is no warranty for this free software. If the software is modified by someone else and passed on, we want its recipients to know that what they have is not the original, so that any problems introduced by others will not reflect on the original authors' reputations. Finally, any free program is threatened constantly by software patents. We wish to avoid the danger that redistributors of a free program will individually obtain patent licenses, in effect making the program proprietary. To prevent this, we have made it clear that any patent must be licensed for everyone's free use or not licensed at all. The precise terms and conditions for copying, distribution and modification follow. GNU GENERAL PUBLIC LICENSE TERMS AND CONDITIONS FOR COPYING, DISTRIBUTION AND MODIFICATION 0. This License applies to any program or other work which contains a notice placed by the copyright holder saying it may be distributed under the terms of this General Public License. The "Program", below, refers to any such program or work, and a "work based on the Program" means either the Program or any derivative work under copyright law: that is to say, a work containing the Program or a portion of it, either verbatim or with modifications and/or translated into another language. (Hereinafter, translation is included without limitation in the term "modification".) Each licensee is addressed as "you". Activities other than copying, distribution and modification are not covered by this License; they are outside its scope. The act of running the Program is not restricted, and the output from the Program is covered only if its contents constitute a work based on the Program (independent of having been made by running the Program). Whether that is true depends on what the Program does. 1. You may copy and distribute verbatim copies of the Program's source code as you receive it, in any medium, provided that you conspicuously and appropriately publish on each copy an appropriate copyright notice and disclaimer of warranty; keep intact all the notices that refer to this License and to the absence of any warranty; and give any other recipients of the Program a copy of this License along with the Program. You may charge a fee for the physical act of transferring a copy, and you may at your option offer warranty protection in exchange for a fee. 2. You may modify your copy or copies of the Program or any portion of it, thus forming a work based on the Program, and copy and distribute such modifications or work under the terms of Section 1 above, provided that you also meet all of these conditions: a) You must cause the modified files to carry prominent notices stating that you changed the files and the date of any change. b) You must cause any work that you distribute or publish, that in whole or in part contains or is derived from the Program or any part thereof, to be licensed as a whole at no charge to all third parties under the terms of this License. c) If the modified program normally reads commands interactively when run, you must cause it, when started running for such interactive use in the most ordinary way, to print or display an announcement including an appropriate copyright notice and a notice that there is no warranty (or else, saying that you provide a warranty) and that users may redistribute the program under these conditions, and telling the user how to view a copy of this License. (Exception: if the Program itself is interactive but does not normally print such an announcement, your work based on the Program is not required to print an announcement.) These requirements apply to the modified work as a whole. If identifiable sections of that work are not derived from the Program, and can be reasonably considered independent and separate works in themselves, then this License, and its terms, do not apply to those sections when you distribute them as separate works. But when you distribute the same sections as part of a whole which is a work based on the Program, the distribution of the whole must be on the terms of this License, whose permissions for other licensees extend to the entire whole, and thus to each and every part regardless of who wrote it. Thus, it is not the intent of this section to claim rights or contest your rights to work written entirely by you; rather, the intent is to exercise the right to control the distribution of derivative or collective works based on the Program. In addition, mere aggregation of another work not based on the Program with the Program (or with a work based on the Program) on a volume of a storage or distribution medium does not bring the other work under the scope of this License. 3. You may copy and distribute the Program (or a work based on it, under Section 2) in object code or executable form under the terms of Sections 1 and 2 above provided that you also do one of the following: a) Accompany it with the complete corresponding machine-readable source code, which must be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, b) Accompany it with a written offer, valid for at least three years, to give any third party, for a charge no more than your cost of physically performing source distribution, a complete machine-readable copy of the corresponding source code, to be distributed under the terms of Sections 1 and 2 above on a medium customarily used for software interchange; or, c) Accompany it with the information you received as to the offer to distribute corresponding source code. (This alternative is allowed only for noncommercial distribution and only if you received the program in object code or executable form with such an offer, in accord with Subsection b above.) The source code for a work means the preferred form of the work for making modifications to it. For an executable work, complete source code means all the source code for all modules it contains, plus any associated interface definition files, plus the scripts used to control compilation and installation of the executable. However, as a special exception, the source code distributed need not include anything that is normally distributed (in either source or binary form) with the major components (compiler, kernel, and so on) of the operating system on which the executable runs, unless that component itself accompanies the executable. If distribution of executable or object code is made by offering access to copy from a designated place, then offering equivalent access to copy the source code from the same place counts as distribution of the source code, even though third parties are not compelled to copy the source along with the object code. 4. You may not copy, modify, sublicense, or distribute the Program except as expressly provided under this License. Any attempt otherwise to copy, modify, sublicense or distribute the Program is void, and will automatically terminate your rights under this License. However, parties who have received copies, or rights, from you under this License will not have their licenses terminated so long as such parties remain in full compliance. 5. You are not required to accept this License, since you have not signed it. However, nothing else grants you permission to modify or distribute the Program or its derivative works. These actions are prohibited by law if you do not accept this License. Therefore, by modifying or distributing the Program (or any work based on the Program), you indicate your acceptance of this License to do so, and all its terms and conditions for copying, distributing or modifying the Program or works based on it. 6. Each time you redistribute the Program (or any work based on the Program), the recipient automatically receives a license from the original licensor to copy, distribute or modify the Program subject to these terms and conditions. You may not impose any further restrictions on the recipients' exercise of the rights granted herein. You are not responsible for enforcing compliance by third parties to this License. 7. If, as a consequence of a court judgment or allegation of patent infringement or for any other reason (not limited to patent issues), conditions are imposed on you (whether by court order, agreement or otherwise) that contradict the conditions of this License, they do not excuse you from the conditions of this License. If you cannot distribute so as to satisfy simultaneously your obligations under this License and any other pertinent obligations, then as a consequence you may not distribute the Program at all. For example, if a patent license would not permit royalty-free redistribution of the Program by all those who receive copies directly or indirectly through you, then the only way you could satisfy both it and this License would be to refrain entirely from distribution of the Program. If any portion of this section is held invalid or unenforceable under any particular circumstance, the balance of the section is intended to apply and the section as a whole is intended to apply in other circumstances. It is not the purpose of this section to induce you to infringe any patents or other property right claims or to contest validity of any such claims; this section has the sole purpose of protecting the integrity of the free software distribution system, which is implemented by public license practices. Many people have made generous contributions to the wide range of software distributed through that system in reliance on consistent application of that system; it is up to the author/donor to decide if he or she is willing to distribute software through any other system and a licensee cannot impose that choice. This section is intended to make thoroughly clear what is believed to be a consequence of the rest of this License. 8. If the distribution and/or use of the Program is restricted in certain countries either by patents or by copyrighted interfaces, the original copyright holder who places the Program under this License may add an explicit geographical distribution limitation excluding those countries, so that distribution is permitted only in or among countries not thus excluded. In such case, this License incorporates the limitation as if written in the body of this License. 9. The Free Software Foundation may publish revised and/or new versions of the General Public License from time to time. Such new versions will be similar in spirit to the present version, but may differ in detail to address new problems or concerns. Each version is given a distinguishing version number. If the Program specifies a version number of this License which applies to it and "any later version", you have the option of following the terms and conditions either of that version or of any later version published by the Free Software Foundation. If the Program does not specify a version number of this License, you may choose any version ever published by the Free Software Foundation. 10. If you wish to incorporate parts of the Program into other free programs whose distribution conditions are different, write to the author to ask for permission. For software which is copyrighted by the Free Software Foundation, write to the Free Software Foundation; we sometimes make exceptions for this. Our decision will be guided by the two goals of preserving the free status of all derivatives of our free software and of promoting the sharing and reuse of software generally. NO WARRANTY 11. BECAUSE THE PROGRAM IS LICENSED FREE OF CHARGE, THERE IS NO WARRANTY FOR THE PROGRAM, TO THE EXTENT PERMITTED BY APPLICABLE LAW. EXCEPT WHEN OTHERWISE STATED IN WRITING THE COPYRIGHT HOLDERS AND/OR OTHER PARTIES PROVIDE THE PROGRAM "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. THE ENTIRE RISK AS TO THE QUALITY AND PERFORMANCE OF THE PROGRAM IS WITH YOU. SHOULD THE PROGRAM PROVE DEFECTIVE, YOU ASSUME THE COST OF ALL NECESSARY SERVICING, REPAIR OR CORRECTION. 12. IN NO EVENT UNLESS REQUIRED BY APPLICABLE LAW OR AGREED TO IN WRITING WILL ANY COPYRIGHT HOLDER, OR ANY OTHER PARTY WHO MAY MODIFY AND/OR REDISTRIBUTE THE PROGRAM AS PERMITTED ABOVE, BE LIABLE TO YOU FOR DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY OTHER PROGRAMS), EVEN IF SUCH HOLDER OR OTHER PARTY HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGES. END OF TERMS AND CONDITIONS How to Apply These Terms to Your New Programs If you develop a new program, and you want it to be of the greatest possible use to the public, the best way to achieve this is to make it free software which everyone can redistribute and change under these terms. To do so, attach the following notices to the program. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the "copyright" line and a pointer to where the full notice is found. Copyright (C) This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. Also add information on how to contact you by electronic and paper mail. If the program is interactive, make it output a short notice like this when it starts in an interactive mode: Gnomovision version 69, Copyright (C) year name of author Gnomovision comes with ABSOLUTELY NO WARRANTY; for details type `show w'. This is free software, and you are welcome to redistribute it under certain conditions; type `show c' for details. The hypothetical commands `show w' and `show c' should show the appropriate parts of the General Public License. Of course, the commands you use may be called something other than `show w' and `show c'; they could even be mouse-clicks or menu items--whatever suits your program. You should also get your employer (if you work as a programmer) or your school, if any, to sign a "copyright disclaimer" for the program, if necessary. Here is a sample; alter the names: Yoyodyne, Inc., hereby disclaims all copyright interest in the program `Gnomovision' (which makes passes at compilers) written by James Hacker. , 1 April 1989 Ty Coon, President of Vice This General Public License does not permit incorporating your program into proprietary programs. If your program is a subroutine library, you may consider it more useful to permit linking proprietary applications with the library. If this is what you want to do, use the GNU Lesser General Public License instead of this License. ================================================ FILE: MACROS ================================================ The syscall() macro should be invoked as follows: syscall(#,arg1,arg2,arg3,arg4,arg5,arg6) Error checking is built into the macro. You _MUST_ define an error-handler. If the syscall() macro is invoked without an error handler defined, the assembler will throw an error. You define error handlers like this: ech(label_for_your_error_code) ; do shit ech(other_label_for_stuff) The error checking consists of: or rax,rax js @ERROR_HANDLER So, the FLAGS are set based on the error return of the syscall, which is nice. The arguments are loaded with 32-bit 'mov' by default. You can change that in the following ways: +arg : Load arg with a 64-bit 'mov' ^arg : Load arg with a 32-bit 'mov' (redundant in this usage) ^^arg : Load arg with a 16-bit 'mov' ^^^arg : Load arg with an 8-bit 'mov' [arg] : Load arg with 'lea' (eg, "lea rdi,[arg]") +[arg] : Dereference arg and load (eg, "mov rdi,[arg]") ^[arg] ^^[arg] ^^^[arg] [+arg] : Discard brackets and load with 'mov' (eg, "mov rdi,arg") [^arg] (This functionality is stupid) [^^arg] [^^^arg] NULL : Make the argument NULL (Always 64-bit, eg "xor rdi,rdi") Note that the syscall number ("#" in the example) is also expanded in this fashion -- In our thread-based model, each thread calls mmap() to grab it's own memory, and sets %rbp the base of that memory. The tmalloc(symbol,$bytes) macro "reserves" space in that memory. It defines 'symbol' to be [rbp+bytes]. So, for example: tmalloc(crap,8) tmalloc(shit,16) tmalloc(moreshit,32) crap is "rbp" shit is "rbp+8" moreshit is "rbp+24" ================================================ FILE: Makefile ================================================ asmhttpd: asmhttpd.o ld $^ -o $@ %.o: %.asm nasm -f elf64 -O0 -o $@ $< clean: rm -f *.o asmhttpd ================================================ FILE: README ================================================ asmhttpd - The tiniest webserver ever written HOW TO BUILD: ------------- Just run "make". You will need NASM on your system. HOW TO RUN: ----------- ./asmhttpd /path/to/your/webroot sudo ./asmhttpd /path/to/your/webroot If run as root, it will listen on port 80. Otherwise, it will use port 8080. HOW TINY IS IT? --------------- The entire text and data fit on a single 4K page: {0}[calvin ~] cat /proc/$(pgrep -n asmhttpd)/maps 00401000-00402000 r-xp 00001000 00:16 2483272 asmhttpd Each client allocates an additional 4K page and a thread while connected. The code is written in a monolithic "branching tree" style with no functions, and uses registers for all local variables. RAM is only used for buffering the HTTP request, and for building structures necessary for system calls. Because there is no stack, and the targets of all branch instructions are constants, traditional buffer overflow exploits are impossible. ================================================ FILE: asmhttpd.asm ================================================ ; vim: syntax=nasm ; ; asmhttpd: A minimalist HTTP webserver for Linux, written in x86_64 assembly. ; ; Copyright (C) 2012 Calvin Owens ; ; This program is free software; you can redistribute it and/or modify ; it under the terms of the GNU General Public License as published by ; the Free Software Foundation; either version 2 of the License, or ; (at your option) any later version. ; ; This program is distributed in the hope that it will be useful, ; but WITHOUT ANY WARRANTY; without even the implied warranty of ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the ; GNU General Public License for more details. [bits 64] global _start %include "constants.inc" ; Flags for system calls, etc. %include "syscall.inc" ; syscall() definition %assign thread_memory_offset 0 ; This is rewritten each time tmalloc() is called %macro reserve_thread_memory 2 %define %1 rbp+%[thread_memory_offset] %define len%1 %2 %assign thread_memory_offset thread_memory_offset+%[%2] %endmacro %define tmalloc(a,b) reserve_thread_memory a,b %define GLOBAL_REQUEST_TIMEOUT 5 %define GLOBAL_MAX_HTTP_REQLEN 1024 %define THREAD_MEM_SIZE 4096 %define CLIENT_TIMEOUT_MS 60000 %define NAME_MAX 254 segment .text SEGMENT_BEGIN: Setsock_ARGUMENT: dd 0x00000001 ; Turn option ON Sighand_SIGPIPE: dq 0x0000000000000001 ; SIG_IGN is 1 dq 0x0000000000000000 SocketAddress: dw 0x0002 ; AF_INET is 2 (AF_INET6 is 0xa) dw 0x5000 ; TCP Port we want to bind to (:80) (Net byte ordering) dd 0x00000000 ; Address to bind to (0.0.0.0 or ::) dd 0x00000000 dd 0x00000000 dd 0x00000000 dd 0x00000000 SocketAddressNotRoot: dw 0x0002 ; AF_INET is 2 (AF_INET6 is 0xa) dw 0x901F ; TCP Port we want to bind to (:8080) (Net byte ordering) dd 0x00000000 ; Address to bind to (0.0.0.0 or ::) dd 0x00000000 dd 0x00000000 dd 0x00000000 dd 0x00000000 DecAsciiConvTable: db 0x30,0x31,0x21,0x32,0x33,0x21,0x34,0x21,0x35,0x36,0x21,0x37,0x38,0x21,0x39,0x21 Response200: db "HTTP/1.1 200 OK",0x0d,0x0a %define lenResponse200 17 Header12: db "Content-Length: " %define lenHeader12 16 Error400: db "HTTP/1.1 400 Bad Request",0x0d,0x0a,0x0d,0x0a %define lenError400 28 Error403: db "HTTP/1.1 403 Forbidden",0x0d,0x0a,0x0d,0x0a %define lenError403 26 Error404: db "HTTP/1.1 404 Not Found",0x0d,0x0a,0x0d,0x0a %define lenError404 26 Error408: db "HTTP/1.1 408 Request Timeout",0x0d,0x0a,0x0d,0x0a %define lenError408 32 Error411: db "HTTP/1.1 411 Length Required",0x0d,0x0a,0x0d,0x0a %define lenError411 32 Error413: db "HTTP/1.1 413 Request Entity Too Large",0x0d,0x0a,0x0d,0x0a %define lenError413 41 Error414: db "HTTP/1.1 414 Request URI Too Long",0x0d,0x0a,0x0d,0x0a %define lenError414 37 Error500: db "HTTP/1.1 500 Internal Server Error",0x0d,0x0a,0x0d,0x0a %define lenError500 38 Error501: db "HTTP/1.1 501 Not Implemented",0x0d,0x0a,0x0d,0x0a %define lenError501 32 Error599: db "HTTP/1.1 599 System Call Not Implemented",0x0d,0x0a,0x0d,0x0a db "Your kernel is probably missing openat2(): Upgrade to >= 5.6",0x0a %define lenError599 105 HelpMessage: db "Usage: ./asmhttpd ",0x0a %define lenHelpMessage 28 ech(____die) ; Who shall catch the catchers? DieClientDisconnected: syscall(sys_close,+rbx) syscall(sys_munmap,+rbp,THREAD_MEM_SIZE) syscall(sys_exit,-1) DieError403: lea rcx,[Error403] mov edx,lenError403 jmp __die DieError404: lea rcx,[Error404] mov edx,lenError404 jmp __die DieError414: lea rcx,[Error414] mov edx,lenError414 jmp __die DieError500: lea rcx,[Error500] mov edx,lenError500 jmp __die DieError408: lea rcx,[Error408] mov edx,lenError408 jmp __die DieError400: lea rcx,[Error400] mov edx,lenError400 jmp __die DieError599: lea rcx,[Error599] mov edx,lenError599 jmp __die PrintHelpMessageAndDie: syscall(sys_write,2,[HelpMessage],lenHelpMessage) jmp ____die __die: syscall(sys_write,+rbx,+rcx,+rdx) syscall(sys_close,+rbx) syscall(sys_munmap,+rbp,THREAD_MEM_SIZE) ____die: syscall(sys_exit,-1); HandleInitSysError: HandleServeSysError: mov rbx,rax syscall(sys_exit,+rbx) HandleGeneralSysErrorAfterOpen: syscall(sys_close,+r13) HandleGeneralSysError: cmp eax,-EPERM je DieError403 ; Permission Denied cmp eax,-ENOENT je DieError404 ; File not found cmp eax,-EACCES je DieError403 ; Permission denied cmp eax,-ENAMETOOLONG je DieError414 ; URI too long (although, is it?) cmp eax,-EPIPE je DieClientDisconnected cmp eax,-ENOSYS je DieError599 jmp DieError500 _start: ech(HandleInitSysError) ; Parse command line arguments. At the start of the program, [rsp] contains a ; qword that tells us how many arguments we got, and [rsp+8] is the beginning of ; a list of pointers to the NUL-terminated argument strings. ; Make sure we have 2 arguments: ; 0: [rsp+8*1] Executable name (we ignore this) ; 1: [rsp+8*2] Webroot mov r11,[rsp] cmp r11,2 jne PrintHelpMessageAndDie syscall(sys_open,+[rsp+8*2],O_DIRECTORY,NULL) mov r15,rax ; Save webroot file descriptor ; Ignore SIGPIPE syscall(sys_rt_sigact,13,[Sighand_SIGPIPE],NULL,8) ; Create and set SO_REUSEADDR on the socket syscall(sys_socket,2,1,NULL) mov rbx,rax syscall(sys_setsockopt,+rbx,SOL_SOCKET,SO_REUSEADDR,[Setsock_ARGUMENT],4) syscall(sys_getuid) test rax,rax jnz .NotRoot ; Bind, and drop privs (nobody) syscall(sys_bind,+rbx,[SocketAddress],24) syscall(sys_setgid,65535) syscall(sys_setuid) jmp .OverNotRoot .NotRoot: syscall(sys_bind,+rbx,[SocketAddressNotRoot],24) .OverNotRoot: syscall(sys_listen,+rbx,1024) ; Now, we can unmap everything but our single page, including the stack! ; If you use L5 pagetables, change the shift by 47 to 56 lea rdi,[SEGMENT_BEGIN] shr rdi,12 inc rdi shl rdi,12 ; Unmap everything after .text mov rsi,1 shl rsi,47 sub rsi,rdi sub rsi,4096 ; Highest page is off-limits syscall(sys_munmap) ; Unmap everything before .text mov rsi,rdi shr rsi,12 dec rsi shl rsi,12 dec rsi xor rdi,rdi syscall(sys_munmap) ServeHTTP: ech(HandleServeSysError) mov r8,rbx ; file descriptor for listening socket mov r9,CLONE_FS|CLONE_THREAD|CLONE_SIGHAND|CLONE_VM|CLONE_FILES mov r10d,sys_accept mov r12d,sys_clone xor rsi,rsi xor rdx,rdx .AcceptNextRequest: syscall(+r10,+r8) mov rbx,rax syscall(+r12,+r9) jnz .AcceptNextRequest ;; (rbx contains client connection file descriptor) HandleConnection: ech(HandleGeneralSysError) syscall(sys_mmap,NULL,THREAD_MEM_SIZE,PROT_READ|PROT_WRITE,MAP_PRIVATE|MAP_ANONYMOUS|MAP_POPULATE,NULL,NULL) mov rbp,rax ; Store offset for tmalloc() macro tmalloc(PollStruct,8) ; Build a struct pollfd in memory mov [PollStruct],rbx mov dword [PollStruct+4],POLLIN tmalloc(ClientRequest,GLOBAL_MAX_HTTP_REQLEN) ; Load offset and counter for receieve loop lea r9,[ClientRequest] mov r10d,GLOBAL_MAX_HTTP_REQLEN ReceiveRequest: syscall(sys_poll,[+PollStruct],1,CLIENT_TIMEOUT_MS) jz DieError408 syscall(sys_read,+rbx,+r9,+r10) jz DieClientDisconnected ; Did we get enough data to be valid? mov ecx,GLOBAL_MAX_HTTP_REQLEN sub rcx,r10 add rcx,rax cmp rcx,18 jge GotEnough ; Need to wait for more, adjust offsets and block again add r9,rax sub r10,rax jmp ReceiveRequest GotEnough: mov esi,0x0a0d0a0d lea rdi,[r9+rax-4] lea r8,[ClientRequest] .FindTerminator: cmp esi,dword [rdi] je short .FoundTerminator dec rdi ; If we haven't reached the beginning... cmp rdi,r8 ; ...then keep looking jne short .FindTerminator add r9,rax ; Adjust offset and counter sub r10,rax jz DieError414 ; If zero, send 412 REQUEST URI TOO LARGE jmp ReceiveRequest ; Go back up and wait for more data .FoundTerminator: lea r14,[r9+rax] ; Store last byte received from client ; Skip past the METHOD specification, find the start of the URI: mov eax,0x20 lea rdi,[ClientRequest] mov ecx,20 repne scasb jne DieError400 ; Go thou and fuck with me no more mov r13,rdi ; NULL-terminate the filename mov ecx,GLOBAL_MAX_HTTP_REQLEN repne scasb jne DieError400 ; This should never happen mov byte [rdi-1],0x00 lea r12,[rdi-1] ; Store addr of last byte of URI lea r8,[rbp+thread_memory_offset] ; Load scratch address, to store offsets of escaped %xx literals xor r10,r10 ; Zero index registers xor r9,r9 mov eax,0x25 ; '%' in ASCII mov rcx,r12 ; Counter for 'repne scasb'... sub rcx,r13 ; ...subtract from end to get length cmp rcx,3 ; If there are less than 3 characters... jl ExpandDone ; ...there can't be anything to unescape mov rdi,r13 ; Beginning of URI ExpandChar: repne scasb ; Search for a '%' character jne ExpandOut ; ...if we didn't find one, we're done cmp rcx,1 ; If there are less than 2 characters left... jle ExpandOut ; ...don't try to unescape movzx rdx,word [rdi] ; Pull the ASCII-encoded hex byte into dx ror dl,4 ; You are not expected to understand this ror dx,4 ror dl,4 and dh,0x44 shr dh,2 add dl,dh shl dh,3 or dl,dh mov [rdi-1],dl ; Overwrite the '%' character with the newly-unescaped byte mov word [rdi],r10w ; Write NULL's over the just-unescaped ASCII-encoded hex mov [r8+r9*8],rdi ; Add the address to our list of unescaped literals inc r9 ; Increment the counter jmp short ExpandChar ; ...and do it again ExpandOut: or r9,r9 ; If r9 is zero... jz ExpandDone ; ...then there was nothing to un-escape - jump over copying mov [r8+r9*8],rdi ; Store the offset of the last byte of the URI xor rax,rax ; Zero out rax (index register for the loop) mov rdi,[r8] ; Get the offset of the first un-escaped literal mov rsi,rdi ; rsi holds the destination DoCopying: add rsi,2 ; Jump over unescaped xx mov rcx,[r8+rax*8+8] ; Load the offset of the next escapee sub rcx,rsi ; Subtract where we are now to get how far to copy rep movsb ; Boom inc rax ; Increment the idex register cmp rax,r9 ; If we're not done... jne DoCopying ; ...do it again mov rcx,r9 ; Use the number of %xx's we unescaped as a counter xor dx,dx ; Zero dx so we can write NULL words mov [rdi],dx ; NUL terminate the (now shorter) string ExpandDone: tmalloc(OpenAtStruct,24) mov qword [OpenAtStruct],0 mov qword [OpenAtStruct+8],0 mov qword [OpenAtStruct+16],RESOLVE_IN_ROOT syscall(sys_openat2,+r15,+r13,[OpenAtStruct],lenOpenAtStruct) mov r13,rax ; Save file descriptor ech(HandleGeneralSysErrorAfterOpen) ; Now if we crash we have to close the file to ; avoid leaking file descriptors tmalloc(StatStruct,144) syscall(sys_fstat,+r13,[StatStruct]) ; Make sure we have a regular file or a symlink mov r12w,[StatStruct+24] ; Get the file mode shr r12w,14 cmp r12w,2 jne DieError403 mov r12,[StatStruct+48] ; Get the file size out of the struct from stat() lea rsp,[rbp+thread_memory_offset] ; Get scratch space, store it in rsp for awhile ; Convert the filesize to ASCII mov rax,r12 ; The file's length to convert (as an unsigned quadword) mov ecx,16 ; Counter for the conversion loop lea rsi,[DecAsciiConvTable] ; Address of table for ASCII conversion mov r8,0x199999999999999a ; Multiplicative inverse of 10d (0xa) xor r9,r9 ; Zero out registers for the ASCII string xor r10,r10 DivisionLoop: shld r9,r10,8 ; Shift the most significant byte of r10 into r9 shl r10,8 ; (shld only shifts in, not out, so we have to discard the byte) mul r8 ; Execute the division shr rax,60 ; Shift the most significant byte of the remainder to the least movzx rax,byte [rsi+rax]; Load the value from our conversion table or r10,rax ; Store the new value in r10 mov rax,rdx ; Restore the working quotient for the next iteration loop DivisionLoop ; ...and do it again mov [rsp],r10 ; Store the ASCII decimal value in memory mov [rsp+8],r9 mov eax,0x30 ; Skip over the leading zeros (they break stupid browsers...) mov ecx,16 mov rdi,rsp repe scasb mov r11,[rdi-1] ; Move the significant values back to the beginning of [rsp] mov [rsp],r11 mov r11,[rdi-1+8] mov [rsp+8],r11 lea rsp,[rsp+rcx+1] ; Skip past the ASCII number mov rdi,rsp ; Copy to the scratch area... mov rsi,Response200 ; ...from the canned HTTP 200 response mov ecx,lenResponse200 ; Size rep movsb ; Boom mov rsi,Header12 ; Copy the "Content-Length: " header mov ecx,lenHeader12 ; Size rep movsb ; Boom lea rsi,[rbp+thread_memory_offset] ; Load rsi with the address of the ASCII-expressed file size mov rcx,rsp ; Get the address of the start of the send buffer sub rcx,rsi ; Subtract the offset of the size from the offset of the buffer (strlen(num)) rep movsb ; ...and copy the difference in bytes to the header field mov dword [rdi], 0x0a0d0a0d ; Terminate the HTTP response lea rdx,[rdi+4] ; Address from which to send response plus 4... sub rdx,rsp ; ...and subtract the end to get the length syscall(sys_sendto,+rbx,[+rsp],+rdx,MSG_MORE,NULL,NULL) keep_sending: syscall(sys_sendfile,+rbx,+r13,NULL,+r12) sub r12,rax jnz keep_sending ; Close file descriptor and socket syscall(sys_close,+r13) syscall(sys_close,+rbx) ; Deallocate thread-local memory and exit syscall(sys_munmap,+rbp,THREAD_MEM_SIZE) syscall(sys_exit,NULL) ud2 ; SIGILL ================================================ FILE: constants.inc ================================================ ;; syscalls %define sys_accept 43 %define sys_bind 49 %define sys_chdir 80 %define sys_chroot 161 %define sys_clone 56 %define sys_close 3 %define sys_exit 60 %define sys_fstat 5 %define sys_getuid 102 %define sys_listen 50 %define sys_mmap 9 %define sys_munmap 11 %define sys_open 2 %define sys_openat2 437 %define sys_poll 7 %define sys_read 0 %define sys_rt_sigact 13 %define sys_sendfile 40 %define sys_sendto 44 %define sys_setgid 106 %define sys_setsockopt 54 %define sys_setuid 105 %define sys_socket 41 %define sys_write 1 ;; errno %define EPERM 1; /* Operation not permitted */ %define ENOENT 2; /* No such file or directory */ %define EACCES 13; /* Permission denied */ %define EPIPE 32; /* Broken pipe */ %define ENAMETOOLONG 36; /* File name too long */ %define ENOSYS 38; /* Invalid system call number */ ;; For clone() %define CLONE_VM 0x00000100; /* Set if VM shared between processes. */ %define CLONE_FS 0x00000200; /* Set if fs info shared between processes. */ %define CLONE_FILES 0x00000400; /* Set if open files shared between processes. */ %define CLONE_SIGHAND 0x00000800; /* Set if signal handlers shared. */ %define CLONE_THREAD 0x00010000; /* Set to add to same thread group. */ ;; For mmap() %define PROT_READ 0x1; /* Page can be read. */ %define PROT_WRITE 0x2; /* Page can be written. */ %define MAP_PRIVATE 0x02; /* Changes are private. */ %define MAP_ANONYMOUS 0x20; /* Don't use a file. */ %define MAP_POPULATE 0x08000; /* Populate (prefault) pagetables. */ ;; For poll() %define POLLIN 0x1; /* There is data to read */ ;; For sendto() %define MSG_MORE 0x8000; /* TCP_CORK behavior */ ;; For setsockopt() %define SOL_SOCKET 1; %define SO_REUSEADDR 2; ;; For open() %define O_DIRECTORY 0x10000; ;; For openat2() %define RESOLVE_IN_ROOT 0x10; ================================================ FILE: syscall.inc ================================================ ; See the MACROS file for a description of how this monstrosity works ;; r64,r32,r16,r8,arg %macro load_syscall_argument 0-* %if %0 == 4 ; Empty Argument %elif %0 == 5 %defstr ___arg_str %[%5] %substr ___arg_c ___arg_str 1 %if ___arg_c == '[' %substr ___arg_c2 ___arg_str 2 %if ___arg_c2 == "+" %substr ___arg_n ___arg_str 3,-2 %deftok ___arg_n_t %[___arg_n] mov %1,___arg_n_t %undef ___arg_n_t %undef ___arg_n %else lea %1,%5 %endif %undef ___arg_c2 %elif ___arg_c == '+' %substr ___arg_n ___arg_str 2,-1 %deftok ___arg_n_t %[___arg_n] mov %1,___arg_n_t %undef ___arg_n_t %undef ___arg_n %elif ___arg_c == '^' %define ___forced_imm_bit_len 32 %substr ___arg_c2 ___arg_str 1,2 %if ___arg_c2 == "^^" %define ___forced_imm_bit_len 16 %substr ___arg_c3 ___arg_str 1,3 %if ___arg_c3 == "^^^" %define ___forced_imm_bit_len 8 %endif %undef ___arg_c3 %endif %undef ___arg_c2 %if ___forced_imm_bit_len == 32 %substr ___arg_n ___arg_str 2,-1 %deftok ___arg_n_t %[___arg_n] %substr ___arg_n_c ___arg_n 1,1 %if ___arg_n_c != '[' %warning "^thing is redundant in SYSCALL: thing is interpreted as 32bit by default" %endif mov %2,___arg_n_t %undef ___arg_n_t %undef ___arg_n %elif ___forced_imm_bit_len == 16 %substr ___arg_n ___arg_str 3,-1 %deftok ___arg_n_t %[___arg_n] mov %3,___arg_n_t %undef ___arg_n_t %undef ___arg_n %elif ___forced_imm_bit_len == 8 %substr ___arg_n ___arg_str 4,-1 %deftok ___arg_n_t %[___arg_n] mov %4,___arg_n_t %undef ___arg_n_t %undef ___arg_n %endif %undef ___forced_imm_bit_len %elif ___arg_str == 'NULL' xor %1,%1 %else mov %2,%5 %endif %undef ___arg_c %undef ___arg_str %else %fatal "You fucked up the SYSCALL-load-arguments macro!" %endif %endmacro %macro macro_do_syscall 1-7 load_syscall_argument rax,eax,ax,al,%1 %if %0 >= 2 load_syscall_argument rdi,edi,di,dil,%2 %endif %if %0 >= 3 load_syscall_argument rsi,esi,si,sil,%3 %endif %if %0 >= 4 load_syscall_argument rdx,edx,dx,dl,%4 %endif %if %0 >= 5 load_syscall_argument r10,r10d,r10w,r10b,%5 %endif %if %0 >= 6 load_syscall_argument r8,r8d,r8w,r8b,%6 %endif %if %0 >= 7 load_syscall_argument r9,r9d,r9w,r9b,%7 %endif syscall ; Invoke loadall286+ %ifdef __syserror_handler or rax,rax ; Set flags based on the return value js __syserror_handler %else %fatal "__syserror_handler is not defined!" %endif %endmacro ;; Yo dawg, I heard you liked macros... %define syscall(a,b,c,d,e,f,g) macro_do_syscall a,b,c,d,e,f,g %define syscall(a,b,c,d,e,f) macro_do_syscall a,b,c,d,e,f %define syscall(a,b,c,d,e) macro_do_syscall a,b,c,d,e %define syscall(a,b,c,d) macro_do_syscall a,b,c,d %define syscall(a,b,c) macro_do_syscall a,b,c %define syscall(a,b) macro_do_syscall a,b %define syscall(a) macro_do_syscall a %macro change_syscall_error_handler 1 %define __syserror_handler %1 %endmacro %define ech(a) change_syscall_error_handler a