254 lines
8.0 KiB
C++
254 lines
8.0 KiB
C++
/******************************************************************************
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COPYRIGHT(C) JONAS 'SORTIE' TERMANSEN 2011.
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This file is part of Sortix.
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Sortix is free software: you can redistribute it and/or modify it under the
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terms of the GNU General Public License as published by the Free Software
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Foundation, either version 3 of the License, or (at your option) any later
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version.
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Sortix is distributed in the hope that it will be useful, but WITHOUT ANY
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WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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details.
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You should have received a copy of the GNU General Public License along
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with Sortix. If not, see <http://www.gnu.org/licenses/>.
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elf.cpp
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Constructs processes from ELF files.
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******************************************************************************/
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#include <sortix/kernel/platform.h>
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#include <sortix/mman.h>
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#include <assert.h>
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#include <errno.h>
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#include <string.h>
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#include "elf.h"
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#include <sortix/kernel/memorymanagement.h>
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#include <sortix/kernel/panic.h>
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#include "process.h"
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namespace Sortix
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{
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namespace ELF
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{
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int ToProgramSectionType(int flags)
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{
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switch ( flags & (PF_X | PF_R | PF_W) )
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{
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case 0:
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return SEG_NONE;
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case PF_X:
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case PF_X | PF_R:
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case PF_X | PF_W:
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case PF_X | PF_R | PF_W:
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return SEG_TEXT;
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case PF_R:
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case PF_W:
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case PF_R | PF_W:
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default:
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return SEG_DATA;
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}
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}
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addr_t Construct32(Process* process, const void* file, size_t filelen)
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{
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if ( filelen < sizeof(Header32) ) { return 0; }
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const Header32* header = (const Header32*) file;
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// Check for little endian.
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if ( header->dataencoding != DATA2LSB ) { return 0; }
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if ( header->version != CURRENTVERSION ) { return 0; }
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addr_t entry = header->entry;
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// Find the location of the program headers.
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addr_t phtbloffset = header->programheaderoffset;
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if ( filelen < phtbloffset ) { return 0; }
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addr_t phtblpos = ((addr_t) file) + phtbloffset;
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size_t phsize = header->programheaderentrysize;
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const ProgramHeader32* phtbl = (const ProgramHeader32*) phtblpos;
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// Validate that all program headers are present.
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uint16_t numprogheaders = header->numprogramheaderentries;
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size_t neededfilelen = phtbloffset + numprogheaders * phsize;
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if ( filelen < neededfilelen ) { return 0; }
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// Prepare the process for execution (clean up address space, etc.)
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process->ResetForExecute();
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// Flush the TLB such that no stale information from the last
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// address space is used when creating the new one.
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Memory::Flush();
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// Create all the segments in the final process.
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// TODO: Handle errors on bad/malicious input or out-of-mem!
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for ( uint16_t i = 0; i < numprogheaders; i++ )
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{
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const ProgramHeader32* pht = &(phtbl[i]);
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if ( pht->type != PT_LOAD ) { continue; }
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addr_t virtualaddr = pht->virtualaddr;
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addr_t mapto = Page::AlignDown(virtualaddr);
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addr_t mapbytes = virtualaddr - mapto + pht->memorysize;
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assert(pht->offset % pht->align == virtualaddr % pht->align);
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assert(pht->offset + pht->filesize < filelen);
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assert(pht->filesize <= pht->memorysize);
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ProcessSegment* segment = new ProcessSegment;
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if ( segment == NULL ) { return 0; }
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segment->position = mapto;
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segment->size = Page::AlignUp(mapbytes);
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segment->type = ToProgramSectionType(pht->flags);
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int prot = PROT_FORK | PROT_KREAD | PROT_KWRITE;
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if ( pht->flags & PF_X ) { prot |= PROT_EXEC; }
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if ( pht->flags & PF_R ) { prot |= PROT_READ; }
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if ( pht->flags & PF_W ) { prot |= PROT_WRITE; }
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if ( segment->Intersects(process->segments) )
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{
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delete segment;
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return 0;
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}
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if ( !Memory::MapRange(mapto, mapbytes, prot))
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{
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// TODO: Memory leak of segment?
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return 0;
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}
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// Insert our newly allocated memory into the processes segment
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// list such that it can be reclaimed later.
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if ( process->segments ) { process->segments->prev = segment; }
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segment->next = process->segments;
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process->segments = segment;
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// Copy as much data as possible and memset the rest to 0.
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uint8_t* memdest = (uint8_t*) virtualaddr;
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uint8_t* memsource = (uint8_t*) ( ((addr_t)file) + pht->offset);
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memcpy(memdest, memsource, pht->filesize);
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memset(memdest + pht->filesize, 0, pht->memorysize - pht->filesize);
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}
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return entry;
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}
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addr_t Construct64(Process* process, const void* file, size_t filelen)
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{
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#ifndef PLATFORM_X64
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(void) process;
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(void) file;
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(void) filelen;
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errno = ENOEXEC;
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return 0;
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#else
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if ( filelen < sizeof(Header64) ) { return 0; }
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const Header64* header = (const Header64*) file;
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// Check for little endian.
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if ( header->dataencoding != DATA2LSB ) { return 0; }
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if ( header->version != CURRENTVERSION ) { return 0; }
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addr_t entry = header->entry;
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// Find the location of the program headers.
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addr_t phtbloffset = header->programheaderoffset;
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if ( filelen < phtbloffset ) { return 0; }
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addr_t phtblpos = ((addr_t) file) + phtbloffset;
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size_t phsize = header->programheaderentrysize;
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const ProgramHeader64* phtbl = (const ProgramHeader64*) phtblpos;
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// Validate that all program headers are present.
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uint16_t numprogheaders = header->numprogramheaderentries;
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size_t neededfilelen = phtbloffset + numprogheaders * phsize;
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if ( filelen < neededfilelen ) { return 0; }
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// Prepare the process for execution (clean up address space, etc.)
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process->ResetForExecute();
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// Flush the TLB such that no stale information from the last
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// address space is used when creating the new one.
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Memory::Flush();
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// Create all the segments in the final process.
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// TODO: Handle errors on bad/malicious input or out-of-mem!
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for ( uint16_t i = 0; i < numprogheaders; i++ )
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{
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const ProgramHeader64* pht = &(phtbl[i]);
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if ( pht->type != PT_LOAD ) { continue; }
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addr_t virtualaddr = pht->virtualaddr;
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addr_t mapto = Page::AlignDown(virtualaddr);
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addr_t mapbytes = virtualaddr - mapto + pht->memorysize;
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assert(pht->offset % pht->align == virtualaddr % pht->align);
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assert(pht->offset + pht->filesize < filelen);
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assert(pht->filesize <= pht->memorysize);
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ProcessSegment* segment = new ProcessSegment;
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if ( segment == NULL ) { return 0; }
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segment->position = mapto;
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segment->size = Page::AlignUp(mapbytes);
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segment->type = ToProgramSectionType(pht->flags);
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int prot = PROT_FORK | PROT_KREAD | PROT_KWRITE;
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if ( pht->flags & PF_X ) { prot |= PROT_EXEC; }
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if ( pht->flags & PF_R ) { prot |= PROT_READ; }
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if ( pht->flags & PF_W ) { prot |= PROT_WRITE; }
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if ( segment->Intersects(process->segments) )
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{
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delete segment;
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return 0;
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}
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if ( !Memory::MapRange(mapto, mapbytes, prot))
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{
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// TODO: Memory leak of segment?
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return 0;
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}
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// Insert our newly allocated memory into the processes segment
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// list such that it can be reclaimed later.
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if ( process->segments ) { process->segments->prev = segment; }
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segment->next = process->segments;
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process->segments = segment;
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// Copy as much data as possible and memset the rest to 0.
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uint8_t* memdest = (uint8_t*) virtualaddr;
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uint8_t* memsource = (uint8_t*) ( ((addr_t)file) + pht->offset);
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memcpy(memdest, memsource, pht->filesize);
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memset(memdest + pht->filesize, 0, pht->memorysize - pht->filesize);
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}
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return entry;
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#endif
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}
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addr_t Construct(Process* process, const void* file, size_t filelen)
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{
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if ( filelen < sizeof(Header) ) { errno = ENOEXEC; return 0; }
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const Header* header = (const Header*) file;
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if ( !(header->magic[0] == 0x7F && header->magic[1] == 'E' &&
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header->magic[2] == 'L' && header->magic[3] == 'F' ) )
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{
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errno = ENOEXEC;
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return 0;
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}
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switch ( header->fileclass )
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{
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case CLASS32:
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return Construct32(process, file, filelen);
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case CLASS64:
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return Construct64(process, file, filelen);
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default:
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return 0;
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}
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}
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}
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}
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