/* * fs/proc/kcore.c kernel ELF core dumper * * Modelled on fs/exec.c:aout_core_dump() * Jeremy Fitzhardinge <jeremy@sw.oz.au> * ELF version written by David Howells <David.Howells@nexor.co.uk> * Modified and incorporated into 2.3.x by Tigran Aivazian <tigran@veritas.com> * Support to dump vmalloc'd areas (ELF only), Tigran Aivazian <tigran@veritas.com> * Safe accesses to vmalloc/direct-mapped discontiguous areas, Kanoj Sarcar <kanoj@sgi.com> */ #include <linux/mm.h> #include <linux/proc_fs.h> #include <linux/user.h> #include <linux/capability.h> #include <linux/elf.h> #include <linux/elfcore.h> #include <linux/vmalloc.h> #include <linux/highmem.h> #include <linux/init.h> #include <asm/uaccess.h> #include <asm/io.h> #define CORE_STR "CORE" #ifndef ELF_CORE_EFLAGS #define ELF_CORE_EFLAGS 0 #endif static struct proc_dir_entry *proc_root_kcore; static int open_kcore(struct inode * inode, struct file * filp) { return capable(CAP_SYS_RAWIO) ? 0 : -EPERM; } static ssize_t read_kcore(struct file *, char __user *, size_t, loff_t *); static const struct file_operations proc_kcore_operations = { .read = read_kcore, .open = open_kcore, }; #ifndef kc_vaddr_to_offset #define kc_vaddr_to_offset(v) ((v) - PAGE_OFFSET) #endif #ifndef kc_offset_to_vaddr #define kc_offset_to_vaddr(o) ((o) + PAGE_OFFSET) #endif /* An ELF note in memory */ struct memelfnote { const char *name; int type; unsigned int datasz; void *data; }; static struct kcore_list *kclist; static DEFINE_RWLOCK(kclist_lock); void kclist_add(struct kcore_list *new, void *addr, size_t size) { new->addr = (unsigned long)addr; new->size = size; write_lock(&kclist_lock); new->next = kclist; kclist = new; write_unlock(&kclist_lock); } static size_t get_kcore_size(int *nphdr, size_t *elf_buflen) { size_t try, size; struct kcore_list *m; *nphdr = 1; /* PT_NOTE */ size = 0; for (m=kclist; m; m=m->next) { try = kc_vaddr_to_offset((size_t)m->addr + m->size); if (try > size) size = try; *nphdr = *nphdr + 1; } *elf_buflen = sizeof(struct elfhdr) + (*nphdr + 2)*sizeof(struct elf_phdr) + 3 * ((sizeof(struct elf_note)) + roundup(sizeof(CORE_STR), 4)) + roundup(sizeof(struct elf_prstatus), 4) + roundup(sizeof(struct elf_prpsinfo), 4) + roundup(sizeof(struct task_struct), 4); *elf_buflen = PAGE_ALIGN(*elf_buflen); return size + *elf_buflen; } /*****************************************************************************/ /* * determine size of ELF note */ static int notesize(struct memelfnote *en) { int sz; sz = sizeof(struct elf_note); sz += roundup((strlen(en->name) + 1), 4); sz += roundup(en->datasz, 4); return sz; } /* end notesize() */ /*****************************************************************************/ /* * store a note in the header buffer */ static char *storenote(struct memelfnote *men, char *bufp) { struct elf_note en; #define DUMP_WRITE(addr,nr) do { memcpy(bufp,addr,nr); bufp += nr; } while(0) en.n_namesz = strlen(men->name) + 1; en.n_descsz = men->datasz; en.n_type = men->type; DUMP_WRITE(&en, sizeof(en)); DUMP_WRITE(men->name, en.n_namesz); /* XXX - cast from long long to long to avoid need for libgcc.a */ bufp = (char*) roundup((unsigned long)bufp,4); DUMP_WRITE(men->data, men->datasz); bufp = (char*) roundup((unsigned long)bufp,4); #undef DUMP_WRITE return bufp; } /* end storenote() */ /* * store an ELF coredump header in the supplied buffer * nphdr is the number of elf_phdr to insert */ static void elf_kcore_store_hdr(char *bufp, int nphdr, int dataoff) { struct elf_prstatus prstatus; /* NT_PRSTATUS */ struct elf_prpsinfo prpsinfo; /* NT_PRPSINFO */ struct elf_phdr *nhdr, *phdr; struct elfhdr *elf; struct memelfnote notes[3]; off_t offset = 0; struct kcore_list *m; /* setup ELF header */ elf = (struct elfhdr *) bufp; bufp += sizeof(struct elfhdr); offset += sizeof(struct elfhdr); memcpy(elf->e_ident, ELFMAG, SELFMAG); elf->e_ident[EI_CLASS] = ELF_CLASS; elf->e_ident[EI_DATA] = ELF_DATA; elf->e_ident[EI_VERSION]= EV_CURRENT; elf->e_ident[EI_OSABI] = ELF_OSABI; memset(elf->e_ident+EI_PAD, 0, EI_NIDENT-EI_PAD); elf->e_type = ET_CORE; elf->e_machine = ELF_ARCH; elf->e_version = EV_CURRENT; elf->e_entry = 0; elf->e_phoff = sizeof(struct elfhdr); elf->e_shoff = 0; elf->e_flags = ELF_CORE_EFLAGS; elf->e_ehsize = sizeof(struct elfhdr); elf->e_phentsize= sizeof(struct elf_phdr); elf->e_phnum = nphdr; elf->e_shentsize= 0; elf->e_shnum = 0; elf->e_shstrndx = 0; /* setup ELF PT_NOTE program header */ nhdr = (struct elf_phdr *) bufp; bufp += sizeof(struct elf_phdr); offset += sizeof(struct elf_phdr); nhdr->p_type = PT_NOTE; nhdr->p_offset = 0; nhdr->p_vaddr = 0; nhdr->p_paddr = 0; nhdr->p_filesz = 0; nhdr->p_memsz = 0; nhdr->p_flags = 0; nhdr->p_align = 0; /* setup ELF PT_LOAD program header for every area */ for (m=kclist; m; m=m->next) { phdr = (struct elf_phdr *) bufp; bufp += sizeof(struct elf_phdr); offset += sizeof(struct elf_phdr); phdr->p_type = PT_LOAD; phdr->p_flags = PF_R|PF_W|PF_X; phdr->p_offset = kc_vaddr_to_offset(m->addr) + dataoff; phdr->p_vaddr = (size_t)m->addr; phdr->p_paddr = 0; phdr->p_filesz = phdr->p_memsz = m->size; phdr->p_align = PAGE_SIZE; } /* * Set up the notes in similar form to SVR4 core dumps made * with info from their /proc. */ nhdr->p_offset = offset; /* set up the process status */ notes[0].name = CORE_STR; notes[0].type = NT_PRSTATUS; notes[0].datasz = sizeof(struct elf_prstatus); notes[0].data = &prstatus; memset(&prstatus, 0, sizeof(struct elf_prstatus)); nhdr->p_filesz = notesize(¬es[0]); bufp = storenote(¬es[0], bufp); /* set up the process info */ notes[1].name = CORE_STR; notes[1].type = NT_PRPSINFO; notes[1].datasz = sizeof(struct elf_prpsinfo); notes[1].data = &prpsinfo; memset(&prpsinfo, 0, sizeof(struct elf_prpsinfo)); prpsinfo.pr_state = 0; prpsinfo.pr_sname = 'R'; prpsinfo.pr_zomb = 0; strcpy(prpsinfo.pr_fname, "vmlinux"); strncpy(prpsinfo.pr_psargs, saved_command_line, ELF_PRARGSZ); nhdr->p_filesz += notesize(¬es[1]); bufp = storenote(¬es[1], bufp); /* set up the task structure */ notes[2].name = CORE_STR; notes[2].type = NT_TASKSTRUCT; notes[2].datasz = sizeof(struct task_struct); notes[2].data = current; nhdr->p_filesz += notesize(¬es[2]); bufp = storenote(¬es[2], bufp); } /* end elf_kcore_store_hdr() */ /*****************************************************************************/ /* * read from the ELF header and then kernel memory */ static ssize_t read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) { ssize_t acc = 0; size_t size, tsz; size_t elf_buflen; int nphdr; unsigned long start; read_lock(&kclist_lock); proc_root_kcore->size = size = get_kcore_size(&nphdr, &elf_buflen); if (buflen == 0 || *fpos >= size) { read_unlock(&kclist_lock); return 0; } /* trim buflen to not go beyond EOF */ if (buflen > size - *fpos) buflen = size - *fpos; /* construct an ELF core header if we'll need some of it */ if (*fpos < elf_buflen) { char * elf_buf; tsz = elf_buflen - *fpos; if (buflen < tsz) tsz = buflen; elf_buf = kzalloc(elf_buflen, GFP_ATOMIC); if (!elf_buf) { read_unlock(&kclist_lock); return -ENOMEM; } elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); read_unlock(&kclist_lock); if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { kfree(elf_buf); return -EFAULT; } kfree(elf_buf); buflen -= tsz; *fpos += tsz; buffer += tsz; acc += tsz; /* leave now if filled buffer already */ if (buflen == 0) return acc; } else read_unlock(&kclist_lock); /* * Check to see if our file offset matches with any of * the addresses in the elf_phdr on our list. */ start = kc_offset_to_vaddr(*fpos - elf_buflen); if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; while (buflen) { struct kcore_list *m; read_lock(&kclist_lock); for (m=kclist; m; m=m->next) { if (start >= m->addr && start < (m->addr+m->size)) break; } read_unlock(&kclist_lock); if (m == NULL) { if (clear_user(buffer, tsz)) return -EFAULT; } else if (is_vmalloc_addr((void *)start)) { char * elf_buf; struct vm_struct *m; unsigned long curstart = start; unsigned long cursize = tsz; elf_buf = kzalloc(tsz, GFP_KERNEL); if (!elf_buf) return -ENOMEM; read_lock(&vmlist_lock); for (m=vmlist; m && cursize; m=m->next) { unsigned long vmstart; unsigned long vmsize; unsigned long msize = m->size - PAGE_SIZE; if (((unsigned long)m->addr + msize) < curstart) continue; if ((unsigned long)m->addr > (curstart + cursize)) break; vmstart = (curstart < (unsigned long)m->addr ? (unsigned long)m->addr : curstart); if (((unsigned long)m->addr + msize) > (curstart + cursize)) vmsize = curstart + cursize - vmstart; else vmsize = (unsigned long)m->addr + msize - vmstart; curstart = vmstart + vmsize; cursize -= vmsize; /* don't dump ioremap'd stuff! (TA) */ if (m->flags & VM_IOREMAP) continue; memcpy(elf_buf + (vmstart - start), (char *)vmstart, vmsize); } read_unlock(&vmlist_lock); if (copy_to_user(buffer, elf_buf, tsz)) { kfree(elf_buf); return -EFAULT; } kfree(elf_buf); } else { if (kern_addr_valid(start)) { unsigned long n; n = copy_to_user(buffer, (char *)start, tsz); /* * We cannot distingush between fault on source * and fault on destination. When this happens * we clear too and hope it will trigger the * EFAULT again. */ if (n) { if (clear_user(buffer + tsz - n, n)) return -EFAULT; } } else { if (clear_user(buffer, tsz)) return -EFAULT; } } buflen -= tsz; *fpos += tsz; buffer += tsz; acc += tsz; start += tsz; tsz = (buflen > PAGE_SIZE ? PAGE_SIZE : buflen); } return acc; } static int __init proc_kcore_init(void) { proc_root_kcore = proc_create("kcore", S_IRUSR, NULL, &proc_kcore_operations); if (proc_root_kcore) proc_root_kcore->size = (size_t)high_memory - PAGE_OFFSET + PAGE_SIZE; return 0; } module_init(proc_kcore_init);