FreeBSD/Linux Kernel Cross Reference
sys/kern/kern_vnodedumper.c

     /*-
      * Copyright (c) 2021-2022 Juniper Networks
      *
      * This software was developed by Mitchell Horne <mhorne@FreeBSD.org>
      * under sponsorship from Juniper Networks and Klara Systems.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     *
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     */
    
    #include <sys/param.h>
    #include <sys/systm.h>
    #include <sys/conf.h>
    #include <sys/caprights.h>
    #include <sys/disk.h>
    #include <sys/eventhandler.h>
    #include <sys/fcntl.h>
    #include <sys/file.h>
    #include <sys/kerneldump.h>
    #include <sys/limits.h>
    #include <sys/malloc.h>
    #include <sys/namei.h>
    #include <sys/priv.h>
    #include <sys/proc.h>
    #include <sys/stat.h>
    #include <sys/sysctl.h>
    #include <sys/vnode.h>
    
    #include <machine/vmparam.h>
    
    static dumper_start_t vnode_dumper_start;
    static dumper_t vnode_dump;
    static dumper_hdr_t vnode_write_headers;
    
    static struct sx livedump_sx;
    SX_SYSINIT(livedump, &livedump_sx, "Livedump sx");
    
    /*
     * Invoke a live minidump on the system.
     */
    int
    livedump_start(int fd, int flags, uint8_t compression)
    {
    #if MINIDUMP_PAGE_TRACKING == 1
            struct dumperinfo di, *livedi;
            struct diocskerneldump_arg kda;
            struct vnode *vp;
            struct file *fp;
            void *rl_cookie;
            int error;
    
            error = priv_check(curthread, PRIV_KMEM_READ);
            if (error != 0)
                    return (error);
    
            if (flags != 0)
                    return (EINVAL);
    
            error = getvnode(curthread, fd, &cap_write_rights, &fp);
            if (error != 0)
                    return (error);
            vp = fp->f_vnode;
    
            if ((fp->f_flag & FWRITE) == 0) {
                    error = EBADF;
                    goto drop;
            }
    
            /* Set up a new dumper. */
            bzero(&di, sizeof(di));
            di.dumper_start = vnode_dumper_start;
            di.dumper = vnode_dump;
            di.dumper_hdr = vnode_write_headers;
            di.blocksize = PAGE_SIZE; /* Arbitrary. */
            di.maxiosize = MAXDUMPPGS * PAGE_SIZE;
    
            bzero(&kda, sizeof(kda));
            kda.kda_compression = compression;
            error = dumper_create(&di, "livedump", &kda, &livedi);
            if (error != 0)
                    goto drop;
   
           /* Only allow one livedump to proceed at a time. */
           if (sx_try_xlock(&livedump_sx) == 0) {
                   dumper_destroy(livedi);
                   error = EBUSY;
                   goto drop;
           }
   
           /* To be used by the callback functions. */
           livedi->priv = vp;
   
           /* Lock the entire file range and vnode. */
           rl_cookie = vn_rangelock_wlock(vp, 0, OFF_MAX);
           vn_lock(vp, LK_EXCLUSIVE | LK_RETRY);
   
           EVENTHANDLER_INVOKE(livedumper_start, &error);
           if (error != 0)
                   goto out;
   
           dump_savectx();
           error = minidumpsys(livedi, true);
   
           EVENTHANDLER_INVOKE(livedumper_finish);
   out:
           VOP_UNLOCK(vp);
           vn_rangelock_unlock(vp, rl_cookie);
           sx_xunlock(&livedump_sx);
           dumper_destroy(livedi);
   drop:
           fdrop(fp, curthread);
           return (error);
   #else
           return (EOPNOTSUPP);
   #endif /* MINIDUMP_PAGE_TRACKING == 1 */
   }
   
   int
   vnode_dumper_start(struct dumperinfo *di, void *key, uint32_t keysize)
   {
   
           /* Always begin with an offset of zero. */
           di->dumpoff = 0;
   
           KASSERT(keysize == 0, ("encryption not supported for livedumps"));
           return (0);
   }
   
   /*
    * Callback from dumpsys() to dump a chunk of memory.
    *
    * Parameters:
    *      arg      Opaque private pointer to vnode
    *      virtual  Virtual address (where to read the data from)
    *      offset   Offset from start of core file
    *      length   Data length
    *
    * Return value:
    *      0 on success
    *      errno on error
    */
   int
   vnode_dump(void *arg, void *virtual, off_t offset, size_t length)
   {
           struct vnode *vp;
           int error = 0;
   
           vp = arg;
           MPASS(vp != NULL);
           ASSERT_VOP_LOCKED(vp, __func__);
   
           EVENTHANDLER_INVOKE(livedumper_dump, virtual, offset, length, &error);
           if (error != 0)
                   return (error);
   
           /* Done? */
           if (virtual == NULL)
                   return (0);
   
           error = vn_rdwr(UIO_WRITE, vp, virtual, length, offset, UIO_SYSSPACE,
               IO_NODELOCKED, curthread->td_ucred, NOCRED, NULL, curthread);
           if (error != 0)
                   uprintf("%s: error writing livedump block at offset %jx: %d\n",
                       __func__, (uintmax_t)offset, error);
           return (error);
   }
   
   /*
    * Callback from dumpsys() to write out the dump header, placed at the end.
    */
   int
   vnode_write_headers(struct dumperinfo *di, struct kerneldumpheader *kdh)
   {
           struct vnode *vp;
           int error;
           off_t offset;
   
           vp = di->priv;
           MPASS(vp != NULL);
           ASSERT_VOP_LOCKED(vp, __func__);
   
           /* Compensate for compression/encryption adjustment of dumpoff. */
           offset = roundup2(di->dumpoff, di->blocksize);
   
           /* Write the kernel dump header to the end of the file. */
           error = vn_rdwr(UIO_WRITE, vp, kdh, sizeof(*kdh), offset,
               UIO_SYSSPACE, IO_NODELOCKED, curthread->td_ucred, NOCRED, NULL,
               curthread);
           if (error != 0)
                   uprintf("%s: error writing livedump header: %d\n", __func__,
                       error);
           return (error);
   }

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