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[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [Xen-devel] [PATCH v8.1 11/27] xsplice: Implement payload loading
From: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Add support for loading xsplice payloads. This is somewhat similar to
the Linux kernel module loader, implementing the following steps:
- Verify the elf file.
- Parse the elf file.
- Allocate a region of memory mapped within a free area of
[xen_virt_end, XEN_VIRT_END].
- Copy allocated sections into the new region. Split them in three
regions - .text, .data, and .rodata. MUST have at least .text.
- Resolve section symbols. All other symbols must be absolute addresses.
(Note that patch titled "xsplice,symbols: Implement symbol name resolution
on address" implements that)
- Perform relocations.
- Secure the the regions (.text,.data,.rodata) with proper permissions.
We capitalize on the vmalloc callback API (see patch titled:
"rm/x86/vmap: Add vmalloc_xen, vfree_xen and vm_init_type") to allocate
a region of memory within the [xen_virt_end, XEN_VIRT_END] for the code.
We also use the "x86/mm: Introduce modify_xen_mappings()"
to change the virtual address page-table permissions.
Signed-off-by: Ross Lagerwall <ross.lagerwall@xxxxxxxxxx>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
Reviewed-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Acked-by: Julien Grall <julien.grall@xxxxxxx>
---
Cc: Stefano Stabellini <sstabellini@xxxxxxxxxx>
Cc: Julien Grall <julien.grall@xxxxxxx>
Cc: Keir Fraser <keir@xxxxxxx>
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
v2: - Change the 'xsplice_patch_func' structure layout/size.
- Add more error checking. Fix memory leak.
- Move elf_resolve and elf_perform relocs in elf file.
- Print the payload address and pages in keyhandler.
v3:
- Make it build under ARM
- Build it without using the return_ macro.
- Add fixes from Ross.
- Add the _return macro back - but only use it during debug builds.
- Remove the macro, prefix arch_ on arch specific calls.
v4:
- Move alloc_payload to arch specific file.
- Use void* instead of uint8_t, use const
- Add copyrights
- Unroll the vmap code to add ASSERT. Change while to not incur
potential long error loop
- Use vmalloc/vfree cb APIs
- Secure .text pages to be RX instead of RWX.
v5:
- Fix allocation of virtual addresses only allowing one page to be allocated.
- Create .text, .data, and .rodata regions with different permissions.
- Make the find_space_t not a typedef to pointer to a function.
- Allocate memory in here.
v6: Drop parentheses on typedefs.
- s/an xSplice/a xSplice/
- Rebase on "vmap: Add vmalloc_cb"
- Rebase on "vmap: Add vmalloc_type and vm_init_type"
- s/uint8_t/void/ on load_addr
- Set xsplice_elf on stack without using memset.
v7:
- Changed the check on delta = elf->hdr->e_shoff + elf->hdr->e_shnum *
elf->hdr->e_shentsize;
The sections can be right at the back of the file (different linker!), so
the failing conditional
for 'if (delta >= elf->len)' is incorrect and should have been '>'.
- Changed dprintk(XENLOG_DEBUG to XENLOG_ERR, then back to DEBUG. Converted
some of the printk to dprintk.
- Rebase on " arm/x86/vmap: Add vmalloc_xen, vfree_xen and vm_init_type"
- Changed some of the printk XENLOG_ERR to XENLOG_DEBUG
- Check the idx in the relocation to make sure it is within bounds and
implemented.
- Use "x86/mm: Introduce modify_xen_mappings()"
- Introduce PRIxElfAddr
- Check for overflow in R_X86_64_PC32
- Return -EOPNOTSUPP if we don't support types in ELF64_R_TYPE
v8:
- Change dprintk and printk XENLOG_DEBUG to XENLOG_ERR
- Convert four of the printks in dprintk.
---
---
xen/arch/arm/Makefile | 1 +
xen/arch/arm/xsplice.c | 54 ++++++++++
xen/arch/x86/Makefile | 1 +
xen/arch/x86/xsplice.c | 188 +++++++++++++++++++++++++++++++++++
xen/common/xsplice.c | 226 +++++++++++++++++++++++++++++++++++++++++-
xen/common/xsplice_elf.c | 124 ++++++++++++++++++++++-
xen/include/xen/elfstructs.h | 4 +
xen/include/xen/xsplice.h | 29 ++++++
xen/include/xen/xsplice_elf.h | 9 +-
9 files changed, 631 insertions(+), 5 deletions(-)
create mode 100644 xen/arch/arm/xsplice.c
create mode 100644 xen/arch/x86/xsplice.c
diff --git a/xen/arch/arm/Makefile b/xen/arch/arm/Makefile
index 0328b50..eae5cb3 100644
--- a/xen/arch/arm/Makefile
+++ b/xen/arch/arm/Makefile
@@ -40,6 +40,7 @@ obj-y += device.o
obj-y += decode.o
obj-y += processor.o
obj-y += smc.o
+obj-$(CONFIG_XSPLICE) += xsplice.o
#obj-bin-y += ....o
diff --git a/xen/arch/arm/xsplice.c b/xen/arch/arm/xsplice.c
new file mode 100644
index 0000000..4465244
--- /dev/null
+++ b/xen/arch/arm/xsplice.c
@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2016 Citrix Systems R&D Ltd.
+ */
+#include <xen/lib.h>
+#include <xen/errno.h>
+#include <xen/xsplice_elf.h>
+#include <xen/xsplice.h>
+
+int arch_xsplice_verify_elf(const struct xsplice_elf *elf)
+{
+ return -ENOSYS;
+}
+
+int arch_xsplice_perform_rel(struct xsplice_elf *elf,
+ const struct xsplice_elf_sec *base,
+ const struct xsplice_elf_sec *rela)
+{
+ return -ENOSYS;
+}
+
+int arch_xsplice_perform_rela(struct xsplice_elf *elf,
+ const struct xsplice_elf_sec *base,
+ const struct xsplice_elf_sec *rela)
+{
+ return -ENOSYS;
+}
+
+void *arch_xsplice_alloc_payload(unsigned int pages)
+{
+ return NULL;
+}
+
+int arch_xsplice_secure(void *va, unsigned int pages, enum va_type type)
+{
+ return -ENOSYS;
+}
+
+void arch_xsplice_free_payload(void *va)
+{
+}
+
+void arch_xsplice_init(void)
+{
+}
+
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/arch/x86/Makefile b/xen/arch/x86/Makefile
index 729065b..8a6a7d5 100644
--- a/xen/arch/x86/Makefile
+++ b/xen/arch/x86/Makefile
@@ -64,6 +64,7 @@ obj-y += vm_event.o
obj-y += xstate.o
obj-$(crash_debug) += gdbstub.o
+obj-$(CONFIG_XSPLICE) += xsplice.o
x86_emulate.o: x86_emulate/x86_emulate.c x86_emulate/x86_emulate.h
diff --git a/xen/arch/x86/xsplice.c b/xen/arch/x86/xsplice.c
new file mode 100644
index 0000000..3000ecb
--- /dev/null
+++ b/xen/arch/x86/xsplice.c
@@ -0,0 +1,188 @@
+/*
+ * Copyright (C) 2016 Citrix Systems R&D Ltd.
+ */
+
+#include <xen/errno.h>
+#include <xen/lib.h>
+#include <xen/mm.h>
+#include <xen/pfn.h>
+#include <xen/vmap.h>
+#include <xen/xsplice_elf.h>
+#include <xen/xsplice.h>
+
+int arch_xsplice_verify_elf(const struct xsplice_elf *elf)
+{
+
+ const Elf_Ehdr *hdr = elf->hdr;
+
+ if ( hdr->e_machine != EM_X86_64 )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Unsupported ELF Machine type!\n",
+ elf->name);
+ return -EOPNOTSUPP;
+ }
+
+ return 0;
+}
+
+int arch_xsplice_perform_rel(struct xsplice_elf *elf,
+ const struct xsplice_elf_sec *base,
+ const struct xsplice_elf_sec *rela)
+{
+ dprintk(XENLOG_ERR, XSPLICE "%s: SHT_REL relocation unsupported\n",
+ elf->name);
+ return -EOPNOTSUPP;
+}
+
+int arch_xsplice_perform_rela(struct xsplice_elf *elf,
+ const struct xsplice_elf_sec *base,
+ const struct xsplice_elf_sec *rela)
+{
+ const Elf_RelA *r;
+ unsigned int symndx, i;
+ uint64_t val;
+ uint8_t *dest;
+
+ if ( !rela->sec->sh_entsize || !rela->sec->sh_size ||
+ rela->sec->sh_entsize != sizeof(Elf_RelA) )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Section relative header is
corrupted!\n",
+ elf->name);
+ return -EINVAL;
+ }
+
+ for ( i = 0; i < (rela->sec->sh_size / rela->sec->sh_entsize); i++ )
+ {
+ r = rela->data + i * rela->sec->sh_entsize;
+ if ( (unsigned long)r > (unsigned long)(elf->hdr + elf->len) )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Relative entry %u in %s is past
end!\n",
+ elf->name, i, rela->name);
+ return -EINVAL;
+ }
+
+ symndx = ELF64_R_SYM(r->r_info);
+ if ( symndx > elf->nsym )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Relative symbol wants symbol@%u
which is past end!\n",
+ elf->name, symndx);
+ return -EINVAL;
+ }
+
+ dest = base->load_addr + r->r_offset;
+ val = r->r_addend + elf->sym[symndx].sym->st_value;
+
+ switch ( ELF64_R_TYPE(r->r_info) )
+ {
+ case R_X86_64_NONE:
+ break;
+
+ case R_X86_64_64:
+ *(uint64_t *)dest = val;
+ break;
+
+ case R_X86_64_PLT32:
+ /*
+ * Xen uses -fpic which normally uses PLT relocations
+ * except that it sets visibility to hidden which means
+ * that they are not used. However, when gcc cannot
+ * inline memcpy it emits memcpy with default visibility
+ * which then creates a PLT relocation. It can just be
+ * treated the same as R_X86_64_PC32.
+ */
+ /* Fall through */
+ case R_X86_64_PC32:
+ val -= (uint64_t)dest;
+ *(uint32_t *)dest = val;
+ if ( (s64)val != *(s32 *)dest )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Overflow in relocation %u in
%s for %s!\n",
+ elf->name, i, rela->name, base->name);
+ return -EOVERFLOW;
+ }
+ break;
+
+ default:
+ dprintk(XENLOG_ERR, XSPLICE "%s: Unhandled relocation %lu\n",
+ elf->name, ELF64_R_TYPE(r->r_info));
+ return -EOPNOTSUPP;
+ }
+ }
+
+ return 0;
+}
+
+/*
+ * The function prepares a xSplice payload by allocating space which
+ * then can be used for loading the allocated sections, resolving symbols,
+ * performing relocations, etc.
+ */
+void *arch_xsplice_alloc_payload(unsigned int pages)
+{
+ unsigned int i;
+ void *p;
+
+ ASSERT(pages);
+
+ p = vmalloc_xen(pages * PAGE_SIZE);
+ WARN_ON(!p);
+ if ( p )
+ {
+ /* By default they are PAGE_HYPERVISOR aka PAGE_HYPERVISOR_RWX.*/
+ for ( i = 0; i < pages; i++ )
+ clear_page(p + (i * PAGE_SIZE) );
+ }
+ return p;
+}
+
+/*
+ * Once the resolving symbols, performing relocations, etc is complete
+ * we secure the memory by putting in the proper page table attributes
+ * for the desired type.
+ */
+int arch_xsplice_secure(void *va, unsigned int pages, enum va_type type)
+{
+ unsigned long start = (unsigned long)va;
+ int flag;
+
+ ASSERT(va);
+ ASSERT(pages);
+
+ if ( type == XSPLICE_VA_RX ) /* PAGE_HYPERVISOR_RX */
+ flag = _PAGE_PRESENT;
+ else if ( type == XSPLICE_VA_RW ) /* PAGE_HYPERVISOR_RW */
+ flag = _PAGE_RW | _PAGE_NX | _PAGE_PRESENT;
+ else /* PAGE_HYPERVISOR_RO */
+ flag = _PAGE_NX | _PAGE_PRESENT;
+
+ /* The ones we are allowed to modify are: _PAGE_NX|_PAGE_RW|_PAGE_PRESENT
*/
+ modify_xen_mappings(start, start + pages * PAGE_SIZE, flag);
+
+ return 0;
+}
+
+void arch_xsplice_free_payload(void *va)
+{
+ vfree_xen(va);
+}
+
+void arch_xsplice_init(void)
+{
+ void *start, *end;
+
+ start = (void *)xen_virt_end;
+ end = (void *)(XEN_VIRT_END - NR_CPUS * PAGE_SIZE);
+
+ BUG_ON(end <= start);
+
+ vm_init_type(VMAP_XEN, start, end);
+}
+/*
+ * Local variables:
+ * mode: C
+ * c-file-style: "BSD"
+ * c-basic-offset: 4
+ * tab-width: 4
+ * indent-tabs-mode: nil
+ * End:
+ */
diff --git a/xen/common/xsplice.c b/xen/common/xsplice.c
index 04151e9..809b067 100644
--- a/xen/common/xsplice.c
+++ b/xen/common/xsplice.c
@@ -13,6 +13,7 @@
#include <xen/smp.h>
#include <xen/spinlock.h>
#include <xen/vmap.h>
+#include <xen/xsplice_elf.h>
#include <xen/xsplice.h>
#include <asm/event.h>
@@ -29,6 +30,13 @@ struct payload {
uint32_t state; /* One of the XSPLICE_STATE_*. */
int32_t rc; /* 0 or -XEN_EXX. */
struct list_head list; /* Linked to 'payload_list'. */
+ void *text_addr; /* Virtual address of .text. */
+ size_t text_size; /* .. and its size. */
+ void *rw_addr; /* Virtual address of .data. */
+ size_t rw_size; /* .. and its size (if any). */
+ void *ro_addr; /* Virtual address of .rodata. */
+ size_t ro_size; /* .. and its size (if any). */
+ size_t pages; /* Total pages for [text,rw,ro]_addr
*/
char name[XEN_XSPLICE_NAME_SIZE]; /* Name of it. */
};
@@ -86,19 +94,215 @@ static struct payload *find_payload(const char *name)
return found;
}
+/*
+ * Functions related to XEN_SYSCTL_XSPLICE_UPLOAD (see xsplice_upload), and
+ * freeing payload (XEN_SYSCTL_XSPLICE_ACTION:XSPLICE_ACTION_UNLOAD).
+ */
+
+static void free_payload_data(struct payload *payload)
+{
+ /* Set to zero until "move_payload". */
+ if ( !payload->text_addr )
+ return;
+
+ arch_xsplice_free_payload(payload->text_addr);
+
+ payload->text_addr = NULL;
+ payload->ro_addr = NULL;
+ payload->rw_addr = NULL;
+ payload->pages = 0;
+}
+
+/*
+* calc_section computes the size (taking into account section alignment).
+*
+* It also modifies sh_entsize with the offset of from the start of
+* virtual address space. This is used in move_payload to figure out the
+* destination location.
+*/
+static void calc_section(struct xsplice_elf_sec *sec, size_t *size)
+{
+ Elf_Shdr *s = sec->sec;
+ size_t align_size;
+
+ align_size = ROUNDUP(*size, s->sh_addralign);
+ s->sh_entsize = align_size;
+
+ *size = s->sh_size + align_size;
+}
+
+static int move_payload(struct payload *payload, struct xsplice_elf *elf)
+{
+ uint8_t *buf;
+ unsigned int i;
+ size_t size = 0;
+
+ /* Compute text regions. */
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ if ( (elf->sec[i].sec->sh_flags & (SHF_ALLOC|SHF_EXECINSTR)) ==
+ (SHF_ALLOC|SHF_EXECINSTR) )
+ calc_section(&elf->sec[i], &payload->text_size);
+ }
+
+ /* Compute rw data. */
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
+ !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
+ (elf->sec[i].sec->sh_flags & SHF_WRITE) )
+ calc_section(&elf->sec[i], &payload->rw_size);
+ }
+
+ /* Compute ro data. */
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ if ( (elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
+ !(elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
+ !(elf->sec[i].sec->sh_flags & SHF_WRITE) )
+ calc_section(&elf->sec[i], &payload->ro_size);
+ }
+
+ /* Do not accept wx. */
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ if ( !(elf->sec[i].sec->sh_flags & SHF_ALLOC) &&
+ (elf->sec[i].sec->sh_flags & SHF_EXECINSTR) &&
+ (elf->sec[i].sec->sh_flags & SHF_WRITE) )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: No WX sections!\n", elf->name);
+ return -EINVAL;
+ }
+ }
+
+ /*
+ * Total of all three regions - RX, RW, and RO. We have to have
+ * keep them in seperate pages so we PAGE_ALIGN the RX and RW to have
+ * them on seperate pages. The last one will by default fall on its
+ * own page.
+ */
+ size = PAGE_ALIGN(payload->text_size) + PAGE_ALIGN(payload->rw_size) +
+ payload->ro_size;
+
+ size = PFN_UP(size);
+ buf = arch_xsplice_alloc_payload(size);
+ if ( !buf )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Could not allocate memory for
payload!\n",
+ elf->name);
+ return -ENOMEM;
+ }
+ payload->pages = size;
+ payload->text_addr = buf;
+ payload->rw_addr = payload->text_addr + PAGE_ALIGN(payload->text_size);
+ payload->ro_addr = payload->rw_addr + PAGE_ALIGN(payload->rw_size);
+
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ if ( elf->sec[i].sec->sh_flags & SHF_ALLOC )
+ {
+ if ( (elf->sec[i].sec->sh_flags & SHF_EXECINSTR) )
+ buf = payload->text_addr;
+ else if ( (elf->sec[i].sec->sh_flags & SHF_WRITE) )
+ buf = payload->rw_addr;
+ else
+ buf = payload->ro_addr;
+
+ elf->sec[i].load_addr = buf + elf->sec[i].sec->sh_entsize;
+
+ /* Don't copy NOBITS - such as BSS. */
+ if ( elf->sec[i].sec->sh_type != SHT_NOBITS )
+ {
+ memcpy(elf->sec[i].load_addr, elf->sec[i].data,
+ elf->sec[i].sec->sh_size);
+ dprintk(XENLOG_DEBUG, XSPLICE "%s: Loaded %s at 0x%p\n",
+ elf->name, elf->sec[i].name, elf->sec[i].load_addr);
+ }
+ }
+ }
+
+ return 0;
+}
+
+static int secure_payload(struct payload *payload, struct xsplice_elf *elf)
+{
+ int rc;
+ unsigned int text_pages, rw_pages, ro_pages;
+
+ text_pages = PFN_UP(payload->text_size);
+ ASSERT(text_pages);
+
+ rc = arch_xsplice_secure(payload->text_addr, text_pages, XSPLICE_VA_RX);
+ if ( rc )
+ return rc;
+
+ rw_pages = PFN_UP(payload->rw_size);
+ if ( rw_pages )
+ {
+ rc = arch_xsplice_secure(payload->rw_addr, rw_pages, XSPLICE_VA_RW);
+ if ( rc )
+ return rc;
+ }
+
+ ro_pages = PFN_UP(payload->ro_size);
+ if ( ro_pages )
+ {
+ rc = arch_xsplice_secure(payload->ro_addr, ro_pages, XSPLICE_VA_RO);
+ }
+
+ ASSERT(ro_pages + rw_pages + text_pages == payload->pages);
+
+ return rc;
+}
+
static void free_payload(struct payload *data)
{
ASSERT(spin_is_locked(&payload_lock));
list_del(&data->list);
payload_cnt--;
payload_version++;
+ free_payload_data(data);
xfree(data);
}
+static int load_payload_data(struct payload *payload, void *raw, size_t len)
+{
+ struct xsplice_elf elf = { .name = payload->name, .len = len };
+ int rc = 0;
+
+ rc = xsplice_elf_load(&elf, raw);
+ if ( rc )
+ goto out;
+
+ rc = move_payload(payload, &elf);
+ if ( rc )
+ goto out;
+
+ rc = xsplice_elf_resolve_symbols(&elf);
+ if ( rc )
+ goto out;
+
+ rc = xsplice_elf_perform_relocs(&elf);
+ if ( rc )
+ goto out;
+
+ rc = secure_payload(payload, &elf);
+
+ out:
+ if ( rc )
+ free_payload_data(payload);
+
+ /* Free our temporary data structure. */
+ xsplice_elf_free(&elf);
+
+ return rc;
+}
+
static int xsplice_upload(xen_sysctl_xsplice_upload_t *upload)
{
struct payload *data = NULL, *found;
char n[XEN_XSPLICE_NAME_SIZE];
+ void *raw_data = NULL;
int rc;
rc = verify_payload(upload, n);
@@ -126,9 +330,20 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t
*upload)
goto out;
}
- rc = 0;
+ rc = -ENOMEM;
+ raw_data = vmalloc(upload->size);
+ if ( !raw_data )
+ goto out;
+
+ rc = -EFAULT;
+ if ( __copy_from_guest(raw_data, upload->payload, upload->size) )
+ goto out;
memcpy(data->name, n, strlen(n));
+ rc = load_payload_data(data, raw_data, upload->size);
+ if ( rc )
+ goto out;
+
data->state = XSPLICE_STATE_CHECKED;
INIT_LIST_HEAD(&data->list);
@@ -139,6 +354,8 @@ static int xsplice_upload(xen_sysctl_xsplice_upload_t
*upload)
out:
spin_unlock(&payload_lock);
+ vfree(raw_data);
+
if ( rc )
xfree(data);
@@ -380,8 +597,9 @@ static void xsplice_printall(unsigned char key)
}
list_for_each_entry ( data, &payload_list, list )
- printk(" name=%s state=%s(%d)\n", data->name,
- state2str(data->state), data->state);
+ printk(" name=%s state=%s(%d) %p (.data=%p, .rodata=%p) using %zu
pages.\n",
+ data->name, state2str(data->state), data->state,
data->text_addr,
+ data->rw_addr, data->ro_addr, data->pages);
spin_unlock(&payload_lock);
}
@@ -389,6 +607,8 @@ static void xsplice_printall(unsigned char key)
static int __init xsplice_init(void)
{
register_keyhandler('x', xsplice_printall, "print xsplicing info", 1);
+
+ arch_xsplice_init();
return 0;
}
__initcall(xsplice_init);
diff --git a/xen/common/xsplice_elf.c b/xen/common/xsplice_elf.c
index 0d96b78..f59f011 100644
--- a/xen/common/xsplice_elf.c
+++ b/xen/common/xsplice_elf.c
@@ -101,7 +101,7 @@ static int elf_resolve_sections(struct xsplice_elf *elf,
const void *data)
}
elf->symtab = &sec[i];
-
+ elf->symtab_idx = i;
/*
* elf->symtab->sec->sh_link would point to the right section
* but we hadn't finished parsing all the sections.
@@ -249,9 +249,127 @@ static int elf_get_sym(struct xsplice_elf *elf, const
void *data)
return 0;
}
+int xsplice_elf_resolve_symbols(struct xsplice_elf *elf)
+{
+ unsigned int i;
+ int rc = 0;
+
+ /*
+ * The first entry of an ELF symbol table is the "undefined symbol index".
+ * aka reserved so we skip it.
+ */
+ ASSERT(elf->sym);
+
+ for ( i = 1; i < elf->nsym; i++ )
+ {
+ uint16_t idx = elf->sym[i].sym->st_shndx;
+
+ rc = 0;
+ switch ( idx )
+ {
+ case SHN_COMMON:
+ dprintk(XENLOG_ERR, XSPLICE "%s: Unexpected common symbol: %s\n",
+ elf->name, elf->sym[i].name);
+ rc = -EINVAL;
+ break;
+
+ case SHN_UNDEF:
+ dprintk(XENLOG_ERR, XSPLICE "%s: Unknown symbol: %s\n",
+ elf->name, elf->sym[i].name);
+ rc = -ENOENT;
+ break;
+
+ case SHN_ABS:
+ dprintk(XENLOG_DEBUG, XSPLICE "%s: Absolute symbol: %s =>
%#"PRIxElfAddr"\n",
+ elf->name, elf->sym[i].name, elf->sym[i].sym->st_value);
+ break;
+
+ default:
+ /* SHN_COMMON and SHN_ABS are above. */
+ if ( idx > SHN_LORESERVE )
+ rc = -EOPNOTSUPP;
+ /* SHN_UNDEF (0) above. */
+ else if ( idx > elf->hdr->e_shnum && idx < SHN_LORESERVE )
+ rc = -EINVAL;
+
+ if ( rc )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Unknown type=%#"PRIx16"\n",
+ elf->name, idx);
+ break;
+ }
+
+ if ( !(elf->sec[idx].sec->sh_flags & SHF_ALLOC) )
+ break;
+
+ elf->sym[i].sym->st_value += (unsigned
long)elf->sec[idx].load_addr;
+ if ( elf->sym[i].name )
+ dprintk(XENLOG_DEBUG, XSPLICE "%s: Symbol resolved: %s =>
%#"PRIxElfAddr"(%s)\n",
+ elf->name, elf->sym[i].name,
+ elf->sym[i].sym->st_value, elf->sec[idx].name);
+ }
+
+ if ( rc )
+ break;
+ }
+
+ return rc;
+}
+
+int xsplice_elf_perform_relocs(struct xsplice_elf *elf)
+{
+ struct xsplice_elf_sec *rela, *base;
+ unsigned int i;
+ int rc = 0;
+
+ /*
+ * The first entry of an ELF symbol table is the "undefined symbol index".
+ * aka reserved so we skip it.
+ */
+ ASSERT(elf->sym);
+
+ for ( i = 1; i < elf->hdr->e_shnum; i++ )
+ {
+ rela = &elf->sec[i];
+
+ if ( (rela->sec->sh_type != SHT_RELA) &&
+ (rela->sec->sh_type != SHT_REL) )
+ continue;
+
+ /* Is it a valid relocation section? */
+ if ( rela->sec->sh_info >= elf->hdr->e_shnum )
+ continue;
+
+ base = &elf->sec[rela->sec->sh_info];
+
+ /* Don't relocate non-allocated sections. */
+ if ( !(base->sec->sh_flags & SHF_ALLOC) )
+ continue;
+
+ if ( rela->sec->sh_link != elf->symtab_idx )
+ {
+ dprintk(XENLOG_ERR, XSPLICE "%s: Relative link of %s is incorrect
(%d, expected=%d)\n",
+ elf->name, rela->name, rela->sec->sh_link,
elf->symtab_idx);
+ rc = -EINVAL;
+ break;
+ }
+
+ if ( rela->sec->sh_type == SHT_RELA )
+ rc = arch_xsplice_perform_rela(elf, base, rela);
+ else /* SHT_REL */
+ rc = arch_xsplice_perform_rel(elf, base, rela);
+
+ if ( rc )
+ break;
+ }
+
+ return rc;
+}
+
static int xsplice_header_check(const struct xsplice_elf *elf)
{
const Elf_Ehdr *hdr = elf->hdr;
+ int rc;
if ( sizeof(*elf->hdr) > elf->len )
{
@@ -276,6 +394,10 @@ static int xsplice_header_check(const struct xsplice_elf
*elf)
return -EOPNOTSUPP;
}
+ rc = arch_xsplice_verify_elf(elf);
+ if ( rc )
+ return rc;
+
if ( elf->hdr->e_shstrndx == SHN_UNDEF )
{
dprintk(XENLOG_ERR, XSPLICE "%s: Section name idx is undefined!?\n",
diff --git a/xen/include/xen/elfstructs.h b/xen/include/xen/elfstructs.h
index 85f35ed..be55985 100644
--- a/xen/include/xen/elfstructs.h
+++ b/xen/include/xen/elfstructs.h
@@ -472,6 +472,8 @@ typedef struct {
#endif
#if defined(ELFSIZE) && (ELFSIZE == 32)
+#define PRIxElfAddr "08x"
+
#define Elf_Ehdr Elf32_Ehdr
#define Elf_Phdr Elf32_Phdr
#define Elf_Shdr Elf32_Shdr
@@ -497,6 +499,8 @@ typedef struct {
#define AuxInfo Aux32Info
#elif defined(ELFSIZE) && (ELFSIZE == 64)
+#define PRIxElfAddr "lx"
+
#define Elf_Ehdr Elf64_Ehdr
#define Elf_Phdr Elf64_Phdr
#define Elf_Shdr Elf64_Shdr
diff --git a/xen/include/xen/xsplice.h b/xen/include/xen/xsplice.h
index cd805a8..83e4f31 100644
--- a/xen/include/xen/xsplice.h
+++ b/xen/include/xen/xsplice.h
@@ -6,6 +6,9 @@
#ifndef __XEN_XSPLICE_H__
#define __XEN_XSPLICE_H__
+struct xsplice_elf;
+struct xsplice_elf_sec;
+struct xsplice_elf_sym;
struct xen_sysctl_xsplice_op;
#ifdef CONFIG_XSPLICE
@@ -15,6 +18,32 @@ struct xen_sysctl_xsplice_op;
int xsplice_op(struct xen_sysctl_xsplice_op *);
+/* Arch hooks. */
+int arch_xsplice_verify_elf(const struct xsplice_elf *elf);
+int arch_xsplice_perform_rel(struct xsplice_elf *elf,
+ const struct xsplice_elf_sec *base,
+ const struct xsplice_elf_sec *rela);
+int arch_xsplice_perform_rela(struct xsplice_elf *elf,
+ const struct xsplice_elf_sec *base,
+ const struct xsplice_elf_sec *rela);
+enum va_type {
+ XSPLICE_VA_RX, /* .text */
+ XSPLICE_VA_RW, /* .data */
+ XSPLICE_VA_RO, /* .rodata */
+};
+
+#include <xen/mm.h>
+void *arch_xsplice_alloc_payload(unsigned int pages);
+
+/*
+ * Function to secure the allocate pages (from arch_xsplice_alloc_payload)
+ * with the right page permissions.
+ */
+int arch_xsplice_secure(void *va, unsigned int pages, enum va_type types);
+
+void arch_xsplice_free_payload(void *va);
+
+void arch_xsplice_init(void);
#else
#include <xen/errno.h> /* For -ENOSYS */
diff --git a/xen/include/xen/xsplice_elf.h b/xen/include/xen/xsplice_elf.h
index 89acb77..6892f59 100644
--- a/xen/include/xen/xsplice_elf.h
+++ b/xen/include/xen/xsplice_elf.h
@@ -15,6 +15,8 @@ struct xsplice_elf_sec {
elf_resolve_section_names. */
const void *data; /* Pointer to the section (done by
elf_resolve_sections). */
+ void *load_addr; /* A pointer to the allocated
destination.
+ Done by load_payload_data. */
};
struct xsplice_elf_sym {
@@ -29,8 +31,10 @@ struct xsplice_elf {
struct xsplice_elf_sec *sec; /* Array of sections, allocated by
us. */
struct xsplice_elf_sym *sym; /* Array of symbols , allocated by
us. */
unsigned int nsym;
- const struct xsplice_elf_sec *symtab;/* Pointer to .symtab section - aka
to sec[x]. */
+ const struct xsplice_elf_sec *symtab;/* Pointer to .symtab section - aka to
+ sec[symtab_idx]. */
const struct xsplice_elf_sec *strtab;/* Pointer to .strtab section - aka
to sec[y]. */
+ unsigned int symtab_idx;
};
const struct xsplice_elf_sec *xsplice_elf_sec_by_name(const struct xsplice_elf
*elf,
@@ -38,6 +42,9 @@ const struct xsplice_elf_sec *xsplice_elf_sec_by_name(const
struct xsplice_elf *
int xsplice_elf_load(struct xsplice_elf *elf, const void *data);
void xsplice_elf_free(struct xsplice_elf *elf);
+int xsplice_elf_resolve_symbols(struct xsplice_elf *elf);
+int xsplice_elf_perform_relocs(struct xsplice_elf *elf);
+
#endif /* __XEN_XSPLICE_ELF_H__ */
/*
--
2.5.0
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