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Re: [Xen-devel] [PATCH] readnote: Add bzImage kernel support



# HG changeset patch
# Parent d690c7e896a26c54a5ab85458824059de72d5cba
readnote: Add bzImage kernel support

Add the check of bzImage kernel and make it work
with RHEL 6 big zImage kernel

Signed-off-by: Xuesen Guo <Xuesen.Guo@xxxxxxxxxxxxxxxxxxxxx>
Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

---
Changed since v1:
  * add additional checks of the offset and length
  * not changing st.st_size, use size instead of st.st_size
  
---
Changed since v2:
  * changing decription bzipped kernels to big zImage kernel

diff -r d690c7e896a2 tools/xcutils/readnotes.c
--- a/tools/xcutils/readnotes.c Thu Apr 05 11:06:03 2012 +0100
+++ b/tools/xcutils/readnotes.c Thu Apr 26 16:53:16 2012 +0800
@@ -18,6 +18,48 @@
 
 static xc_interface *xch;
 
+/* According to the implemation of xc_dom_probe_bzimage_kernel()
function */
+/* We add support of bzImage kernel */
+/* Copied from tools/libxc/xc_doom_bzImageloader.c */
+struct setup_header {
+       uint8_t  _pad0[0x1f1];  /* skip uninteresting stuff */
+       uint8_t  setup_sects;
+       uint16_t root_flags;
+       uint32_t syssize;
+       uint16_t ram_size;
+       uint16_t vid_mode;
+       uint16_t root_dev;
+       uint16_t boot_flag;
+       uint16_t jump;
+       uint32_t header;
+#define HDR_MAGIC  "HdrS"
+#define HDR_MAGIC_SZ 4
+       uint16_t version;
+#define VERSION(h,l) (((h)<<8) | (l))
+       uint32_t realmode_swtch;
+       uint16_t start_sys;
+       uint16_t kernel_version;
+       uint8_t  type_of_loader;
+       uint8_t  loadflags;
+       uint16_t setup_move_size;
+       uint32_t code32_start;
+       uint32_t ramdisk_image;
+       uint32_t ramdisk_size;
+       uint32_t bootsect_kludge;
+       uint16_t heap_end_ptr;
+       uint16_t _pad1;
+       uint32_t cmd_line_ptr;
+       uint32_t initrd_addr_max;
+       uint32_t kernel_alignment;
+       uint8_t  relocatable_kernel;
+       uint8_t  _pad2[3];
+       uint32_t cmdline_size;
+       uint32_t hardware_subarch;
+       uint64_t hardware_subarch_data;
+       uint32_t payload_offset;
+       uint32_t payload_length;
+} __attribute__((packed));
+
 static void print_string_note(const char *prefix, struct elf_binary
*elf,
                              const elf_note *note)
 {
@@ -131,6 +173,9 @@ int main(int argc, char **argv)
        const elf_shdr *shdr;
        int notes_found = 0;
 
+       struct setup_header *hdr;
+       uint64_t payload_offset, payload_length;
+
        if (argc != 2)
        {
                fprintf(stderr, "Usage: readnotes <elfimage>\n");
@@ -159,13 +204,45 @@ int main(int argc, char **argv)
                fprintf(stderr, "Unable to map %s: %s\n", f, strerror(errno));
                return 1;
        }
-       size = st.st_size;
+       
+       /* Check the magic of bzImage kernel */
+       hdr = (struct setup_header *)image;
+       if ( memcmp(&hdr->header, HDR_MAGIC, HDR_MAGIC_SZ) == 0 )
+       {
+               if ( hdr->version < VERSION(2,8) )
+               {
+                       printf("%s: boot protocol too old (%04x)", __FUNCTION__,
hdr->version);
+                       return 1;
+               }
 
-       usize = xc_dom_check_gzip(xch, image, st.st_size);
+               /* upcast to 64 bits to avoid overflow */
+               /* setup_sects is u8 and so cannot overflow */
+               payload_offset = (hdr->setup_sects + 1) * 512;
+               payload_offset += hdr->payload_offset;
+               payload_length = hdr->payload_length;
+               
+               if ( payload_offset >= st.st_size )
+               {
+                       printf("%s: payload offset overflow", __FUNCTION__);
+                       return 1;
+               }
+               if ( (payload_offset + payload_length) > st.st_size )
+               {
+                       printf("%s: payload length overflow", __FUNCTION__);
+                       return 1;
+               }
+
+               image = image + payload_offset;
+               size = payload_length;
+       } else {
+               size = st.st_size;
+       }
+
+       usize = xc_dom_check_gzip(xch, image, size);
        if (usize)
        {
                tmp = malloc(usize);
-               xc_dom_do_gunzip(xch, image, st.st_size, tmp, usize);
+               xc_dom_do_gunzip(xch, image, size, tmp, usize);
                image = tmp;
                size = usize;
        }


On Thu, 2012-04-26 at 17:51 +0800, Xuesen Guo wrote:
> I fixed the confusion, shall I need to resend this patch?
> ------------------------------------------------------------------------
> readnote: Add bzImage kernel support
> 
> Add the check of bzImage kernel and make it work
> with RHEL 6 big zImage kernel
> 
> Signed-off-by: Xuesen Guo <Xuesen.Guo@xxxxxxxxxxxxxxxxxxxxx>
> Acked-by: Ian Campbell <ian.campbell@xxxxxxxxxx>
> 
> ---
> Changed since v1:
>   * add additional checks of the offset and length
>   * not changing st.st_size, use size instead of st.st_size
>   
> ---
> Changed since v2:
>   * changing decription bzipped kernels to big zImage kernel
> 
> 
> Thanks!
> Xuesen 
> 
> On Thu, 2012-04-26 at 10:20 +0100, Ian Campbell wrote: 
> > On Thu, 2012-04-26 at 10:13 +0100, Jan Beulich wrote:
> > > >>> On 26.04.12 at 10:54, Xuesen Guo <Xuesen.Guo@xxxxxxxxxxxxxxxxxxxxx> 
> > > >>> wrote:
> > > > Add the check of bzImage kernel and make it work
> > > > with RHEL 6 bzipped kernels
> > > 
> > > I fail to see the relation of the term "bzipped" above to the actual 
> > > patch.
> > 
> > Oh yes, this is a common misconception (which I failed to notice in my
> > review).
> > 
> > The "bz" in bzImage does not refer to the bzip compression algorithm.
> > Rather it refers to "big zImage". It's a historical thing because the
> > original zImage compressor was restricted to <1M (or something) of RAM
> > at decompression time and bzImage was introduced to cope with more and
> > therefore worked for larger kernels. Obviously 1M is very limiting to in
> > practice everyone uses bzImage today...
> > 
> > Now of course today, just to add to the confusion, bzImage can support
> > multiple compression algorithms, including the original z, but also
> > bzip2, lzma and xz.
> > 
> > Ian
> > 
> > > 
> > > Jan
> > > 
> > > > Signed-off-by: Xuesen Guo <Xuesen.Guo@xxxxxxxxxxxxxxxxxxxxx>
> > > > 
> > > > ---
> > > > Changed since v1:
> > > >   * add additional checks of the offset and length
> > > >   * not changing st.st_size, use size instead of st.st_size
> > > > 
> > > > diff -r d690c7e896a2 -r 27a6422ac06d tools/xcutils/readnotes.c
> > > > --- a/tools/xcutils/readnotes.c Thu Apr 05 11:06:03 2012 +0100
> > > > +++ b/tools/xcutils/readnotes.c Thu Apr 26 16:53:17 2012 +0800
> > > > @@ -18,6 +18,48 @@
> > > >  
> > > >  static xc_interface *xch;
> > > >  
> > > > +/* According to the implemation of xc_dom_probe_bzimage_kernel() 
> > > > function 
> > > > */
> > > > +/* We add support of bzImage kernel */
> > > > +/* Copied from tools/libxc/xc_doom_bzImageloader.c */
> > > > +struct setup_header {
> > > > +       uint8_t  _pad0[0x1f1];  /* skip uninteresting stuff */
> > > > +       uint8_t  setup_sects;
> > > > +       uint16_t root_flags;
> > > > +       uint32_t syssize;
> > > > +       uint16_t ram_size;
> > > > +       uint16_t vid_mode;
> > > > +       uint16_t root_dev;
> > > > +       uint16_t boot_flag;
> > > > +       uint16_t jump;
> > > > +       uint32_t header;
> > > > +#define HDR_MAGIC  "HdrS"
> > > > +#define HDR_MAGIC_SZ 4
> > > > +       uint16_t version;
> > > > +#define VERSION(h,l) (((h)<<8) | (l))
> > > > +       uint32_t realmode_swtch;
> > > > +       uint16_t start_sys;
> > > > +       uint16_t kernel_version;
> > > > +       uint8_t  type_of_loader;
> > > > +       uint8_t  loadflags;
> > > > +       uint16_t setup_move_size;
> > > > +       uint32_t code32_start;
> > > > +       uint32_t ramdisk_image;
> > > > +       uint32_t ramdisk_size;
> > > > +       uint32_t bootsect_kludge;
> > > > +       uint16_t heap_end_ptr;
> > > > +       uint16_t _pad1;
> > > > +       uint32_t cmd_line_ptr;
> > > > +       uint32_t initrd_addr_max;
> > > > +       uint32_t kernel_alignment;
> > > > +       uint8_t  relocatable_kernel;
> > > > +       uint8_t  _pad2[3];
> > > > +       uint32_t cmdline_size;
> > > > +       uint32_t hardware_subarch;
> > > > +       uint64_t hardware_subarch_data;
> > > > +       uint32_t payload_offset;
> > > > +       uint32_t payload_length;
> > > > +} __attribute__((packed));
> > > > +
> > > >  static void print_string_note(const char *prefix, struct elf_binary 
> > > > *elf,
> > > >                               const elf_note *note)
> > > >  {
> > > > @@ -131,6 +173,9 @@ int main(int argc, char **argv)
> > > >         const elf_shdr *shdr;
> > > >         int notes_found = 0;
> > > >  
> > > > +       struct setup_header *hdr;
> > > > +       uint64_t payload_offset, payload_length;
> > > > +
> > > >         if (argc != 2)
> > > >         {
> > > >                 fprintf(stderr, "Usage: readnotes <elfimage>\n");
> > > > @@ -159,13 +204,45 @@ int main(int argc, char **argv)
> > > >                 fprintf(stderr, "Unable to map %s: %s\n", f, 
> > > > strerror(errno));
> > > >                 return 1;
> > > >         }
> > > > -       size = st.st_size;
> > > > +       
> > > > +       /* Check the magic of bzImage kernel */
> > > > +       hdr = (struct setup_header *)image;
> > > > +       if ( memcmp(&hdr->header, HDR_MAGIC, HDR_MAGIC_SZ) == 0 )
> > > > +       {
> > > > +               if ( hdr->version < VERSION(2,8) )
> > > > +               {
> > > > +                       printf("%s: boot protocol too old (%04x)", 
> > > > __FUNCTION__, hdr->version);
> > > > +                       return 1;
> > > > +               }
> > > >  
> > > > -       usize = xc_dom_check_gzip(xch, image, st.st_size);
> > > > +               /* upcast to 64 bits to avoid overflow */
> > > > +               /* setup_sects is u8 and so cannot overflow */
> > > > +               payload_offset = (hdr->setup_sects + 1) * 512;
> > > > +               payload_offset += hdr->payload_offset;
> > > > +               payload_length = hdr->payload_length;
> > > > +               
> > > > +               if ( payload_offset >= st.st_size )
> > > > +               {
> > > > +                       printf("%s: payload offset overflow", 
> > > > __FUNCTION__);
> > > > +                       return 1;
> > > > +               }
> > > > +               if ( (payload_offset + payload_length) > st.st_size )
> > > > +               {
> > > > +                       printf("%s: payload length overflow", 
> > > > __FUNCTION__);
> > > > +                       return 1;
> > > > +               }
> > > > +
> > > > +               image = image + payload_offset;
> > > > +               size = payload_length;
> > > > +       } else {
> > > > +               size = st.st_size;
> > > > +       }
> > > > +
> > > > +       usize = xc_dom_check_gzip(xch, image, size);
> > > >         if (usize)
> > > >         {
> > > >                 tmp = malloc(usize);
> > > > -               xc_dom_do_gunzip(xch, image, st.st_size, tmp, usize);
> > > > +               xc_dom_do_gunzip(xch, image, size, tmp, usize);
> > > >                 image = tmp;
> > > >                 size = usize;
> > > >         }
> > > > 
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