From patchwork Fri Jul 6 19:32:36 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Omar Sandoval X-Patchwork-Id: 10512433 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork.web.codeaurora.org (Postfix) with ESMTP id 5E5C660325 for ; Fri, 6 Jul 2018 19:33:39 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 4DA5B287AC for ; Fri, 6 Jul 2018 19:33:39 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 41F60287B7; Fri, 6 Jul 2018 19:33:39 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.9 required=2.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID, MAILING_LIST_MULTI, RCVD_IN_DNSWL_HI autolearn=unavailable version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 70DF4287AC for ; Fri, 6 Jul 2018 19:33:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934825AbeGFTd1 (ORCPT ); Fri, 6 Jul 2018 15:33:27 -0400 Received: from mail-pf0-f194.google.com ([209.85.192.194]:39175 "EHLO mail-pf0-f194.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S934767AbeGFTcv (ORCPT ); Fri, 6 Jul 2018 15:32:51 -0400 Received: by mail-pf0-f194.google.com with SMTP id s21-v6so9197857pfm.6 for ; Fri, 06 Jul 2018 12:32:51 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=osandov-com.20150623.gappssmtp.com; s=20150623; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=tkNowSeMKdSY9qW3aM4suoNZ5b8PMWqlFZwaD8C0z5k=; b=fZNJ2jLC05CXKbFQ7MAHURJ3ggkxlfzlBEQNpT+mJBi1w6B8IgLU+1i/VIWuShLKPp aEtT0xukKoQGpKokXM87JtJ/Spkv7zgiCDltLUrXK/JeCiWutp2gQ2yYw10iDyvM8fLt ILAsSseO+HdJ0E4AejQZMqWkkG4vZrtWBw9LXOZ7EThpSRGFvlZiAs2yrUpW9tuqrUMd MPqX280EsVAt9QgZLO6kGHgVqM+/i67YDcsRXxaJ7pF+yZZB89nKCWGSRc1rzpoDRccZ GHhDZ4ohuP4s2kuEabsN+jMphCOguIsj1x8ZTSN6FoFI/daxgS5N8sdEvDKzmb+c/IzR 1ldg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=tkNowSeMKdSY9qW3aM4suoNZ5b8PMWqlFZwaD8C0z5k=; b=OPh5Imaqcv3311jM+D5zPprEr5GsC/fU2JGQvUZgJfqhrxffnIFgV5RBUEIHwrkHOm 9l4LVllVqzT8qOEkpML2IvuRbclQtfkUDdHYhwdu9A0GEi8AB5NPviyR9RVqvDx4jxYn xooCDNaqle7kML54gxb2VdEIwRI1kXaJx3mDtY8NYubX0aacESzDPOfrT8Kk5fUjAVWZ BO4LEYrDNyBvX0xtrN6KQGpyU2jLPNeiFq8+QuCi4PR3A7vJoTQ5cSEorF0+q0INLYY/ AShD0gnWaOn3t28IN6Q6aSnv5w1oSn3ohcOXoB8ytr8XdL/XpX4bSAdJ3LCYFqMdYTR+ 6uFA== X-Gm-Message-State: APt69E3nIaCpns9EMRFUtzv93oUiEYDf/63bN8W8UGwMqkwfRErKOULb CvgUq+gTG736gXuMGcoxXXlqIQ== X-Google-Smtp-Source: AAOMgpefBZS5ahNZ7qi2cDPz2FoTr6TRL6yL1JcOb2t/LJOHgX49LyoxSp9Koa2YPNni6kqjclT21A== X-Received: by 2002:aa7:80cf:: with SMTP id a15-v6mr11729962pfn.19.1530905570425; Fri, 06 Jul 2018 12:32:50 -0700 (PDT) Received: from vader.thefacebook.com ([2620:10d:c090:200::4:984e]) by smtp.gmail.com with ESMTPSA id a11-v6sm12846162pgq.32.2018.07.06.12.32.49 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Fri, 06 Jul 2018 12:32:49 -0700 (PDT) From: Omar Sandoval To: linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, Alexey Dobriyan Cc: Eric Biederman , kernel-team@fb.com Subject: [PATCH 5/7] proc/kcore: clean up ELF header generation Date: Fri, 6 Jul 2018 12:32:36 -0700 Message-Id: <196479b479237502d4d8b0e5a562b52205e5c374.1530904769.git.osandov@fb.com> X-Mailer: git-send-email 2.18.0 In-Reply-To: References: Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP From: Omar Sandoval Currently, the ELF file header, program headers, and note segment are allocated all at once, in some icky code dating back to 2.3. Programs tend to read the file header, then the program headers, then the note segment, all separately, so this is a waste of effort. It's cleaner and more efficient to handle the three separately. Signed-off-by: Omar Sandoval --- fs/proc/kcore.c | 346 +++++++++++++++++++----------------------------- 1 file changed, 139 insertions(+), 207 deletions(-) diff --git a/fs/proc/kcore.c b/fs/proc/kcore.c index b7ff2e2ec350..de225b61f34f 100644 --- a/fs/proc/kcore.c +++ b/fs/proc/kcore.c @@ -49,15 +49,6 @@ static struct proc_dir_entry *proc_root_kcore; #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 LIST_HEAD(kclist_head); static DECLARE_RWSEM(kclist_lock); static atomic_t kcore_need_update = ATOMIC_INIT(1); @@ -73,7 +64,8 @@ kclist_add(struct kcore_list *new, void *addr, size_t size, int type) list_add_tail(&new->list, &kclist_head); } -static size_t get_kcore_size(int *nphdr, size_t *elf_buflen) +static size_t get_kcore_size(int *nphdr, size_t *phdrs_len, size_t *notes_len, + size_t *data_offset) { size_t try, size; struct kcore_list *m; @@ -87,15 +79,15 @@ static size_t get_kcore_size(int *nphdr, size_t *elf_buflen) 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(arch_task_struct_size, 4); - *elf_buflen = PAGE_ALIGN(*elf_buflen); - return size + *elf_buflen; + + *phdrs_len = *nphdr * sizeof(struct elf_phdr); + *notes_len = (3 * (sizeof(struct elf_note) + ALIGN(sizeof(CORE_STR), 4)) + + ALIGN(sizeof(struct elf_prstatus), 4) + + ALIGN(sizeof(struct elf_prpsinfo), 4) + + ALIGN(arch_task_struct_size, 4)); + *data_offset = PAGE_ALIGN(sizeof(struct elfhdr) + *phdrs_len + + *notes_len); + return *data_offset + size; } #ifdef CONFIG_HIGHMEM @@ -241,7 +233,7 @@ static int kcore_update_ram(void) LIST_HEAD(list); LIST_HEAD(garbage); int nphdr; - size_t size; + size_t phdrs_len, notes_len, data_offset; struct kcore_list *tmp, *pos; int ret = 0; @@ -263,7 +255,8 @@ static int kcore_update_ram(void) } list_splice_tail(&list, &kclist_head); - proc_root_kcore->size = get_kcore_size(&nphdr, &size); + proc_root_kcore->size = get_kcore_size(&nphdr, &phdrs_len, ¬es_len, + &data_offset); out: up_write(&kclist_lock); @@ -274,226 +267,166 @@ static int kcore_update_ram(void) return ret; } -/*****************************************************************************/ -/* - * determine size of ELF note - */ -static int notesize(struct memelfnote *en) +static void append_kcore_note(char *notes, size_t *i, const char *name, + unsigned int type, const void *desc, + size_t descsz) { - 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 */ - list_for_each_entry(m, &kclist_head, list) { - 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; - if (m->type == KCORE_RAM || m->type == KCORE_TEXT) - phdr->p_paddr = __pa(m->addr); - else - phdr->p_paddr = (elf_addr_t)-1; - 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"); - strlcpy(prpsinfo.pr_psargs, saved_command_line, sizeof(prpsinfo.pr_psargs)); - - 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 = arch_task_struct_size; - notes[2].data = current; - - nhdr->p_filesz += notesize(¬es[2]); - bufp = storenote(¬es[2], bufp); - -} /* end elf_kcore_store_hdr() */ + struct elf_note *note = (struct elf_note *)¬es[*i]; + + note->n_namesz = strlen(name) + 1; + note->n_descsz = descsz; + note->n_type = type; + *i += sizeof(*note); + memcpy(¬es[*i], name, note->n_namesz); + *i = ALIGN(*i + note->n_namesz, 4); + memcpy(¬es[*i], desc, descsz); + *i = ALIGN(*i + descsz, 4); +} -/*****************************************************************************/ -/* - * 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) { char *buf = file->private_data; - size_t size, tsz; - size_t elf_buflen; + size_t phdrs_offset, notes_offset, data_offset; + size_t phdrs_len, notes_len; + struct kcore_list *m; + size_t tsz; int nphdr; unsigned long start; size_t orig_buflen = buflen; int ret = 0; down_read(&kclist_lock); - size = get_kcore_size(&nphdr, &elf_buflen); - if (buflen == 0 || *fpos >= size) - goto out; + get_kcore_size(&nphdr, &phdrs_len, ¬es_len, &data_offset); + phdrs_offset = sizeof(struct elfhdr); + notes_offset = phdrs_offset + phdrs_len; + + /* ELF file header. */ + if (buflen && *fpos < sizeof(struct elfhdr)) { + struct elfhdr ehdr = { + .e_ident = { + [EI_MAG0] = ELFMAG0, + [EI_MAG1] = ELFMAG1, + [EI_MAG2] = ELFMAG2, + [EI_MAG3] = ELFMAG3, + [EI_CLASS] = ELF_CLASS, + [EI_DATA] = ELF_DATA, + [EI_VERSION] = EV_CURRENT, + [EI_OSABI] = ELF_OSABI, + }, + .e_type = ET_CORE, + .e_machine = ELF_ARCH, + .e_version = EV_CURRENT, + .e_phoff = sizeof(struct elfhdr), + .e_flags = ELF_CORE_EFLAGS, + .e_ehsize = sizeof(struct elfhdr), + .e_phentsize = sizeof(struct elf_phdr), + .e_phnum = nphdr, + }; + + tsz = min_t(size_t, buflen, sizeof(struct elfhdr) - *fpos); + if (copy_to_user(buffer, (char *)&ehdr + *fpos, tsz)) { + ret = -EFAULT; + goto out; + } - /* trim buflen to not go beyond EOF */ - if (buflen > size - *fpos) - buflen = size - *fpos; + buffer += tsz; + buflen -= tsz; + *fpos += tsz; + } - /* construct an ELF core header if we'll need some of it */ - if (*fpos < elf_buflen) { - char * elf_buf; + /* ELF program headers. */ + if (buflen && *fpos < phdrs_offset + phdrs_len) { + struct elf_phdr *phdrs, *phdr; - tsz = elf_buflen - *fpos; - if (buflen < tsz) - tsz = buflen; - elf_buf = kzalloc(elf_buflen, GFP_KERNEL); - if (!elf_buf) { + phdrs = kzalloc(phdrs_len, GFP_KERNEL); + if (!phdrs) { ret = -ENOMEM; goto out; } - elf_kcore_store_hdr(elf_buf, nphdr, elf_buflen); - if (copy_to_user(buffer, elf_buf + *fpos, tsz)) { - kfree(elf_buf); + + phdrs[0].p_type = PT_NOTE; + phdrs[0].p_offset = notes_offset; + phdrs[0].p_filesz = notes_len; + + phdr = &phdrs[1]; + list_for_each_entry(m, &kclist_head, list) { + phdr->p_type = PT_LOAD; + phdr->p_flags = PF_R | PF_W | PF_X; + phdr->p_offset = kc_vaddr_to_offset(m->addr) + data_offset; + phdr->p_vaddr = (size_t)m->addr; + if (m->type == KCORE_RAM || m->type == KCORE_TEXT) + phdr->p_paddr = __pa(m->addr); + else + phdr->p_paddr = (elf_addr_t)-1; + phdr->p_filesz = phdr->p_memsz = m->size; + phdr->p_align = PAGE_SIZE; + phdr++; + } + + tsz = min_t(size_t, buflen, phdrs_offset + phdrs_len - *fpos); + if (copy_to_user(buffer, (char *)phdrs + *fpos - phdrs_offset, + tsz)) { + kfree(phdrs); ret = -EFAULT; goto out; } - kfree(elf_buf); + kfree(phdrs); + + buffer += tsz; buflen -= tsz; *fpos += tsz; - buffer += tsz; + } + + /* ELF note segment. */ + if (buflen && *fpos < notes_offset + notes_len) { + struct elf_prstatus prstatus = {0}; + struct elf_prpsinfo prpsinfo = { + .pr_sname = 'R', + .pr_fname = "vmlinux", + }; + char *notes; + size_t i = 0; + + strlcpy(prpsinfo.pr_psargs, saved_command_line, + sizeof(prpsinfo.pr_psargs)); + + notes = kzalloc(notes_len, GFP_KERNEL); + if (!notes) { + ret = -ENOMEM; + goto out; + } + + append_kcore_note(notes, &i, CORE_STR, NT_PRSTATUS, &prstatus, + sizeof(prstatus)); + append_kcore_note(notes, &i, CORE_STR, NT_PRPSINFO, &prpsinfo, + sizeof(prpsinfo)); + append_kcore_note(notes, &i, CORE_STR, NT_TASKSTRUCT, current, + arch_task_struct_size); - /* leave now if filled buffer already */ - if (buflen == 0) + tsz = min_t(size_t, buflen, notes_offset + notes_len - *fpos); + if (copy_to_user(buffer, notes + *fpos - notes_offset, tsz)) { + kfree(notes); + ret = -EFAULT; goto out; + } + kfree(notes); + + buffer += tsz; + buflen -= tsz; + *fpos += tsz; } /* * 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); + start = kc_offset_to_vaddr(*fpos - data_offset); if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen) tsz = buflen; - - while (buflen) { - struct kcore_list *m; + while (buflen) { list_for_each_entry(m, &kclist_head, list) { if (start >= m->addr && start < (m->addr+m->size)) break; @@ -555,7 +488,6 @@ read_kcore(struct file *file, char __user *buffer, size_t buflen, loff_t *fpos) return orig_buflen - buflen; } - static int open_kcore(struct inode *inode, struct file *filp) { if (!capable(CAP_SYS_RAWIO))