From de91cfb1641ad37c56d8cc6360dd818198dd58e6 Mon Sep 17 00:00:00 2001 From: jhb Date: Thu, 9 Apr 2015 19:03:11 +0000 Subject: MFC 279929: Allow the EFI loader to work with large kernels and/or modules (for example, a large mfsroot). Note that for EFI the kernel and modules (as well as other metadata files such as splash screens or memory disk images) are loaded into a statically-sized staging area. When the EFI loader exits it copies this staging area down to the location the kernel expects to run at. - Add bounds checking to the copy routines to fail attempts to access memory outside of the staging area. Previously loading a combined kernel + modules larger than the staging size (32MB) would overflow the staging area trashing whatever memory was afterwards. Under Intel's OVMF firmware for qemu this resulted in fatal faults in the firmware itself. Now the attempt will fail with ENOMEM. - Allow the staging area size to be configured at compile time via an EFI_STAGING_SIZE variable in src.conf or on the command line. It accepts the size of the staging area in MB. The default size remains 32MB. --- sys/boot/amd64/efi/Makefile | 4 ++++ sys/boot/amd64/efi/copy.c | 23 +++++++++++++++++++++-- 2 files changed, 25 insertions(+), 2 deletions(-) (limited to 'sys') diff --git a/sys/boot/amd64/efi/Makefile b/sys/boot/amd64/efi/Makefile index f4138c9..686eb4e 100644 --- a/sys/boot/amd64/efi/Makefile +++ b/sys/boot/amd64/efi/Makefile @@ -44,6 +44,10 @@ LIBFICL= ${.OBJDIR}/../../ficl/libficl.a # Include bcache code. HAVE_BCACHE= yes +.if defined(EFI_STAGING_SIZE) +CFLAGS+= -DEFI_STAGING_SIZE=${EFI_STAGING_SIZE} +.endif + # Always add MI sources .PATH: ${.CURDIR}/../../common .include "${.CURDIR}/../../common/Makefile.inc" diff --git a/sys/boot/amd64/efi/copy.c b/sys/boot/amd64/efi/copy.c index c6cc349..c3cb475 100644 --- a/sys/boot/amd64/efi/copy.c +++ b/sys/boot/amd64/efi/copy.c @@ -37,9 +37,13 @@ __FBSDID("$FreeBSD$"); #include #include -#define STAGE_PAGES 8192 /* 32MB */ +#ifndef EFI_STAGING_SIZE +#define EFI_STAGING_SIZE 32 +#endif -EFI_PHYSICAL_ADDRESS staging; +#define STAGE_PAGES ((EFI_STAGING_SIZE) * 1024 * 1024 / 4096) + +EFI_PHYSICAL_ADDRESS staging, staging_end; int stage_offset_set = 0; ssize_t stage_offset; @@ -55,6 +59,7 @@ x86_efi_copy_init(void) (unsigned long)(status & EFI_ERROR_MASK)); return (status); } + staging_end = staging + STAGE_PAGES * 4096; return (0); } @@ -68,6 +73,11 @@ x86_efi_copyin(const void *src, vm_offset_t dest, const size_t len) stage_offset_set = 1; } + /* XXX: Callers do not check for failure. */ + if (dest + stage_offset + len > staging_end) { + errno = ENOMEM; + return (-1); + } bcopy(src, (void *)(dest + stage_offset), len); return (len); } @@ -76,6 +86,11 @@ ssize_t x86_efi_copyout(const vm_offset_t src, void *dest, const size_t len) { + /* XXX: Callers do not check for failure. */ + if (src + stage_offset + len > staging_end) { + errno = ENOMEM; + return (-1); + } bcopy((void *)(src + stage_offset), dest, len); return (len); } @@ -85,6 +100,10 @@ ssize_t x86_efi_readin(const int fd, vm_offset_t dest, const size_t len) { + if (dest + stage_offset + len > staging_end) { + errno = ENOMEM; + return (-1); + } return (read(fd, (void *)(dest + stage_offset), len)); } -- cgit v1.1