lkml.org 
[lkml]   [2017]   [Dec]   [7]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    Date
    From
    SubjectRe: [PATCH v3 1/4] kaslr: add immovable_mem=nn[KMG]@ss[KMG] to specify extracting memory
    On Thu, Dec 07, 2017 at 12:58:06PM +0800, Baoquan He wrote:
    >On 12/07/17 at 12:16pm, Dou Liyang wrote:
    >> Hi All,
    >>
    >> At 12/07/2017 11:56 AM, Chao Fan wrote:
    >> > On Thu, Dec 07, 2017 at 11:09:24AM +0800, Baoquan He wrote:
    >> > > On 12/07/17 at 10:53am, Chao Fan wrote:
    >> > > > On Wed, Dec 06, 2017 at 05:35:57PM +0800, Baoquan He wrote:
    >> > > > > Hi Chao,
    >> > > > >
    >> > > > > Yes, now the code looks much better than the last version.
    >> > > > >
    >> > > > > On 12/05/17 at 04:51pm, Chao Fan wrote:
    >> > > > > > In current code, kaslr may choose the memory region in movable
    >> > > > > > nodes to extract kernel, which will make the nodes can't be hot-removed.
    >> > > > > > To solve it, we can specify the memory region in immovable node.
    >> > > > > > Create immovable_mem to store the regions in immovable_mem, where should
    >> > > > > > be chosen by kaslr.
    >> > > > > >
    >> > > > > > Multiple regions can be specified, comma delimited.
    >> > > > > > Considering the usage of memory, only support for 4 regions.
    >> > > > > > 4 regions contains 2 nodes at least, enough for kernel to extract.
    >> > > > > >
    >> > > > > > Also change the "handle_mem_memmap" to "handle_mem_filter", since
    >> > > > > > it will not only handle memmap parameter now.
    >> > > > >
    >> > > > > One concern is whether it will fail to do KASLR if only specify
    >> > > >
    >> > > > Sorry, I think I have not understood your point.
    >> > > > So if there is something wrong, please let me know.
    >> > >
    >> > > What I meant is whether we need check 'movable_node' and
    >> > > 'immovable_mem=' being specified together. If only specify 'movable_node',
    >> > > we may need to return and do not do kaslr or do not do physical kaslr
    >> > > since kernel could be located on movable mem region.
    >> >
    >> Indeed.
    >>
    >> If *immovable_mem* is valid only when Kernel supports both
    >> KASLR and Node hotplug(movable_node). we need check them together:
    >>
    >> ...
    >> else if (!strcmp(param, "movable_node")) {
    >> if (!strcmp(param, "immovable_mem"))
    >> parse_immovable_mem_regions(val);
    >> else
    >> //no KASLR or no node hotplug?
    >>
    >> }
    >
    >Yes, I meant this. We can skip kernel physical address randomization,
    >the virtual address can still be randomized.
    >

    Thanks Baoquan and Dou, I will make the new version.

    Thanks,
    Chao Fan

    >> ...
    >>
    >> > I think both are OK and have reasons, and I tend to not return.
    >> > Because if there is a parameter can solve the problem, but not specified.
    >> > It's a problem of user-level.
    >> > How do you think?
    >> >
    >>
    >> Seems we should clarify the scope of 'immovable_mem=' and document it.
    >>
    >> Thanks,
    >> dou
    >>
    >> > Thanks,
    >> > Chao Fan
    >> >
    >> > >
    >> > > Otherwise it will do physical kaslr anyway, memory hotplug will be
    >> > > impacted later.
    >> > >
    >> > > >
    >> > > > I don't think if only specify "movable_node" will fail KASLR.
    >> > > > Since in this patchset(3/4), only disable kernel mirror. KASLR in
    >> > > > current upstream code didn't parse "movable_node".
    >> > > >
    >> > > > > "movable_node". Surely in this case it won't fail system, just hotplug
    >> > > > > memory might be impacted if kernel is located on that, will FJ mind
    >> > > >
    >> > > > Yes, it's the reason why I make this patchset.
    >> > > > In my personal understanding, "movable_node" is a beginning why I make
    >> > > > this patchset, but not the whole reason.
    >> > > > Only "movable_node" specified might cause hotplug memory can't be
    >> > > > removed if kernel is located on that, so we need the help of
    >> > > > "immovable_mem=". "movable_node" help hotplug memory can be removed, and
    >> > > > "immovable_mem=" works for the same target, but just in kaslr.
    >> > > > So up to now, there is not a very tight coupling between "movable_node"
    >> > > > and "immovable_mem=". The independence of "immovable_mem=" is that,
    >> > > > help kaslr selects the right regions, avoid the memory in hotpluggable
    >> > > > NUMA nodes, which causes the memory can't removed. It's a independent
    >> > > > reason why we need a parameter like "immovable_mem=".
    >> > > > So I think we should also handle it if only specify "immovable_mem="
    >> > > > without "movable_node".
    >> > > >
    >> > > > Thanks,
    >> > > > Chao Fan
    >> > > >
    >> > > > > this? And what if only specify 'immovable_mem=' but without 'movable_node'?
    >> > > > >
    >> > > > > Thanks
    >> > > > > Baoquan
    >> > > > >
    >> > > > > >
    >> > > > > > Signed-off-by: Chao Fan <fanc.fnst@cn.fujitsu.com>
    >> > > > > > ---
    >> > > > > > arch/x86/boot/compressed/kaslr.c | 80 ++++++++++++++++++++++++++++++++++++++--
    >> > > > > > 1 file changed, 77 insertions(+), 3 deletions(-)
    >> > > > > >
    >> > > > > > diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
    >> > > > > > index a63fbc25ce84..0bbbaf5f6370 100644
    >> > > > > > --- a/arch/x86/boot/compressed/kaslr.c
    >> > > > > > +++ b/arch/x86/boot/compressed/kaslr.c
    >> > > > > > @@ -108,6 +108,15 @@ enum mem_avoid_index {
    >> > > > > > static struct mem_vector mem_avoid[MEM_AVOID_MAX];
    >> > > > > > +/* Only supporting at most 4 immovable memory regions with kaslr */
    >> > > > > > +#define MAX_IMMOVABLE_MEM 4
    >> > > > > > +
    >> > > > > > +/* Store the memory regions in immovable node */
    >> > > > > > +static struct mem_vector immovable_mem[MAX_IMMOVABLE_MEM];
    >> > > > > > +
    >> > > > > > +/* The immovable regions user specify, not more than 4 */
    >> > > > > > +static int num_immovable_region;
    >> > > > > > +
    >> > > > > > static bool mem_overlaps(struct mem_vector *one, struct mem_vector *two)
    >> > > > > > {
    >> > > > > > /* Item one is entirely before item two. */
    >> > > > > > @@ -168,6 +177,38 @@ parse_memmap(char *p, unsigned long long *start, unsigned long long *size)
    >> > > > > > return -EINVAL;
    >> > > > > > }
    >> > > > > > +static int parse_immovable_mem(char *p,
    >> > > > > > + unsigned long long *start,
    >> > > > > > + unsigned long long *size)
    >> > > > > > +{
    >> > > > > > + char *oldp;
    >> > > > > > +
    >> > > > > > + if (!p)
    >> > > > > > + return -EINVAL;
    >> > > > > > +
    >> > > > > > + oldp = p;
    >> > > > > > + *size = memparse(p, &p);
    >> > > > > > + if (p == oldp)
    >> > > > > > + return -EINVAL;
    >> > > > > > +
    >> > > > > > + /* We support nn[KMG]@ss[KMG] and nn[KMG]. */
    >> > > > > > + switch (*p) {
    >> > > > > > + case '@':
    >> > > > > > + *start = memparse(p + 1, &p);
    >> > > > > > + return 0;
    >> > > > > > + default:
    >> > > > > > + /*
    >> > > > > > + * If w/o offset, only size specified, immovable_mem=nn[KMG]
    >> > > > > > + * has the same behaviour as immovable_mem=nn[KMG]@0. It means
    >> > > > > > + * the region starts from 0.
    >> > > > > > + */
    >> > > > > > + *start = 0;
    >> > > > > > + return 0;
    >> > > > > > + }
    >> > > > > > +
    >> > > > > > + return -EINVAL;
    >> > > > > > +}
    >> > > > > > +
    >> > > > > > static void mem_avoid_memmap(char *str)
    >> > > > > > {
    >> > > > > > static int i;
    >> > > > > > @@ -207,7 +248,37 @@ static void mem_avoid_memmap(char *str)
    >> > > > > > memmap_too_large = true;
    >> > > > > > }
    >> > > > > > -static int handle_mem_memmap(void)
    >> > > > > > +#ifdef CONFIG_MEMORY_HOTPLUG
    >> > > > > > +static void parse_immovable_mem_regions(char *str)
    >> > > > > > +{
    >> > > > > > + static int i;
    >> > > > > > +
    >> > > > > > + while (str && (i < MAX_IMMOVABLE_MEM)) {
    >> > > > > > + int rc;
    >> > > > > > + unsigned long long start, size;
    >> > > > > > + char *k = strchr(str, ',');
    >> > > > > > +
    >> > > > > > + if (k)
    >> > > > > > + *k++ = 0;
    >> > > > > > +
    >> > > > > > + rc = parse_immovable_mem(str, &start, &size);
    >> > > > > > + if (rc < 0)
    >> > > > > > + break;
    >> > > > > > + str = k;
    >> > > > > > +
    >> > > > > > + immovable_mem[i].start = start;
    >> > > > > > + immovable_mem[i].size = size;
    >> > > > > > + i++;
    >> > > > > > + }
    >> > > > > > + num_immovable_region = i;
    >> > > > > > +}
    >> > > > > > +#else
    >> > > > > > +static inline void parse_immovable_mem_regions(char *str)
    >> > > > > > +{
    >> > > > > > +}
    >> > > > > > +#endif
    >> > > > > > +
    >> > > > > > +static int handle_mem_filter(void)
    >> > > > > > {
    >> > > > > > char *args = (char *)get_cmd_line_ptr();
    >> > > > > > size_t len = strlen((char *)args);
    >> > > > > > @@ -215,7 +286,8 @@ static int handle_mem_memmap(void)
    >> > > > > > char *param, *val;
    >> > > > > > u64 mem_size;
    >> > > > > > - if (!strstr(args, "memmap=") && !strstr(args, "mem="))
    >> > > > > > + if (!strstr(args, "memmap=") && !strstr(args, "mem=") &&
    >> > > > > > + !strstr(args, "immovable_mem="))
    >> > > > > > return 0;
    >> > > > > > tmp_cmdline = malloc(len + 1);
    >> > > > > > @@ -240,6 +312,8 @@ static int handle_mem_memmap(void)
    >> > > > > > if (!strcmp(param, "memmap")) {
    >> > > > > > mem_avoid_memmap(val);
    >> > > > > > + } else if (!strcmp(param, "immovable_mem")) {
    >> > > > > > + parse_immovable_mem_regions(val);
    >> > > > > > } else if (!strcmp(param, "mem")) {
    >> > > > > > char *p = val;
    >> > > > > > @@ -379,7 +453,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
    >> > > > > > /* We don't need to set a mapping for setup_data. */
    >> > > > > > /* Mark the memmap regions we need to avoid */
    >> > > > > > - handle_mem_memmap();
    >> > > > > > + handle_mem_filter();
    >> > > > > > #ifdef CONFIG_X86_VERBOSE_BOOTUP
    >> > > > > > /* Make sure video RAM can be used. */
    >> > > > > > --
    >> > > > > > 2.14.3
    >> > > > > >
    >> > > > > >
    >> > > > > >
    >> > > > >
    >> > > > >
    >> > > >
    >> > > >
    >> > >
    >> > >
    >> >
    >>
    >>
    >
    >


    \
     
     \ /
      Last update: 2017-12-07 06:33    [W:2.501 / U:0.072 seconds]
    ©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site