| Message ID | 1415795308-14639-1-git-send-email-ard.biesheuvel@linaro.org |
|---|---|
| State | New |
| Headers | show |
On Wed, 12 Nov 2014 13:28:28 +0100 , Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > Create a new /sys entry '/sys/firmware/fdt' to export the FDT blob > that was passed to the kernel by the bootloader. This allows userland > applications such as kexec to access the raw binary. > > The fact that this node does not reside under /sys/firmware/device-tree > is deliberate: FDT is also used on arm64 UEFI/ACPI systems to > communicate just the UEFI and ACPI entry points, but the FDT is never > unflattened and used to configure the system. > > A CRC32 checksum is calculated over the entire FDT blob, and verified > at late_initcall time. The sysfs entry is instantiated only if the > checksum is valid, i.e., if the FDT blob has not been modified in the > mean time. Otherwise, a warning is printed. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> Looks good to me. Merged, thanks. g. > --- > v4: use pr_warn() instead of WARN() > v3: keep checksum instead of copying the entire blob, and WARN on mismatch > > drivers/of/Kconfig | 1 + > drivers/of/fdt.c | 37 +++++++++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+) > > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig > index 1a13f5b722c5..0348c208343c 100644 > --- a/drivers/of/Kconfig > +++ b/drivers/of/Kconfig > @@ -23,6 +23,7 @@ config OF_FLATTREE > bool > select DTC > select LIBFDT > + select CRC32 > > config OF_EARLY_FLATTREE > bool > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index d1ffca8b34ea..0004871ebccf 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -9,6 +9,7 @@ > * version 2 as published by the Free Software Foundation. > */ > > +#include <linux/crc32.h> > #include <linux/kernel.h> > #include <linux/initrd.h> > #include <linux/memblock.h> > @@ -22,10 +23,20 @@ > #include <linux/libfdt.h> > #include <linux/debugfs.h> > #include <linux/serial_core.h> > +#include <linux/sysfs.h> > > #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ > #include <asm/page.h> > > +static u32 of_fdt_crc32; > + > +static u32 of_fdt_get_crc32(void *fdt) > +{ > + static u32 const OF_FDT_CRC32_SEED = 0x04c11db7; > + > + return crc32_be(OF_FDT_CRC32_SEED, fdt, fdt_totalsize(fdt)); > +} > + > /* > * of_fdt_limit_memory - limit the number of regions in the /memory node > * @limit: maximum entries > @@ -1003,6 +1014,8 @@ bool __init early_init_dt_verify(void *params) > return false; > } > > + of_fdt_crc32 = of_fdt_get_crc32(initial_boot_params); > + > return true; > } > > @@ -1103,4 +1116,28 @@ static int __init of_flat_dt_debugfs_export_fdt(void) > module_init(of_flat_dt_debugfs_export_fdt); > #endif > > +#ifdef CONFIG_SYSFS > +static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj, > + struct bin_attribute *bin_attr, > + char *buf, loff_t off, size_t count) > +{ > + memcpy(buf, initial_boot_params + off, count); > + return count; > +} > + > +static int __init of_fdt_raw_init(void) > +{ > + static struct bin_attribute of_fdt_raw_attr = > + __BIN_ATTR(fdt, S_IRUSR, of_fdt_raw_read, NULL, 0); > + > + if (of_fdt_crc32 != of_fdt_get_crc32(initial_boot_params)) { > + pr_warn("fdt: not creating '/sys/firmware/fdt': CRC check failed"); > + return 0; > + } > + of_fdt_raw_attr.size = fdt_totalsize(initial_boot_params); > + return sysfs_create_bin_file(firmware_kobj, &of_fdt_raw_attr); > +} > +late_initcall(of_fdt_raw_init); > +#endif > + > #endif /* CONFIG_OF_EARLY_FLATTREE */ > -- > 1.8.3.2 > -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
On Wed, Nov 12, 2014 at 6:28 AM, Ard Biesheuvel <ard.biesheuvel@linaro.org> wrote: > Create a new /sys entry '/sys/firmware/fdt' to export the FDT blob > that was passed to the kernel by the bootloader. This allows userland > applications such as kexec to access the raw binary. > > The fact that this node does not reside under /sys/firmware/device-tree > is deliberate: FDT is also used on arm64 UEFI/ACPI systems to > communicate just the UEFI and ACPI entry points, but the FDT is never > unflattened and used to configure the system. > > A CRC32 checksum is calculated over the entire FDT blob, and verified > at late_initcall time. The sysfs entry is instantiated only if the > checksum is valid, i.e., if the FDT blob has not been modified in the > mean time. Otherwise, a warning is printed. > > Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> > --- > v4: use pr_warn() instead of WARN() > v3: keep checksum instead of copying the entire blob, and WARN on mismatch > > drivers/of/Kconfig | 1 + > drivers/of/fdt.c | 37 +++++++++++++++++++++++++++++++++++++ > 2 files changed, 38 insertions(+) > > diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig > index 1a13f5b722c5..0348c208343c 100644 > --- a/drivers/of/Kconfig > +++ b/drivers/of/Kconfig > @@ -23,6 +23,7 @@ config OF_FLATTREE > bool > select DTC > select LIBFDT > + select CRC32 > > config OF_EARLY_FLATTREE > bool > diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c > index d1ffca8b34ea..0004871ebccf 100644 > --- a/drivers/of/fdt.c > +++ b/drivers/of/fdt.c > @@ -9,6 +9,7 @@ > * version 2 as published by the Free Software Foundation. > */ > > +#include <linux/crc32.h> > #include <linux/kernel.h> > #include <linux/initrd.h> > #include <linux/memblock.h> > @@ -22,10 +23,20 @@ > #include <linux/libfdt.h> > #include <linux/debugfs.h> > #include <linux/serial_core.h> > +#include <linux/sysfs.h> > > #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ > #include <asm/page.h> > > +static u32 of_fdt_crc32; > + > +static u32 of_fdt_get_crc32(void *fdt) > +{ > + static u32 const OF_FDT_CRC32_SEED = 0x04c11db7; Where did this value come from? A comment would be useful. > + > + return crc32_be(OF_FDT_CRC32_SEED, fdt, fdt_totalsize(fdt)); > +} > + > /* > * of_fdt_limit_memory - limit the number of regions in the /memory node > * @limit: maximum entries > @@ -1003,6 +1014,8 @@ bool __init early_init_dt_verify(void *params) > return false; > } > > + of_fdt_crc32 = of_fdt_get_crc32(initial_boot_params); > + > return true; > } > > @@ -1103,4 +1116,28 @@ static int __init of_flat_dt_debugfs_export_fdt(void) > module_init(of_flat_dt_debugfs_export_fdt); > #endif > > +#ifdef CONFIG_SYSFS > +static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj, > + struct bin_attribute *bin_attr, > + char *buf, loff_t off, size_t count) > +{ > + memcpy(buf, initial_boot_params + off, count); > + return count; > +} > + > +static int __init of_fdt_raw_init(void) > +{ > + static struct bin_attribute of_fdt_raw_attr = > + __BIN_ATTR(fdt, S_IRUSR, of_fdt_raw_read, NULL, 0); > + > + if (of_fdt_crc32 != of_fdt_get_crc32(initial_boot_params)) { > + pr_warn("fdt: not creating '/sys/firmware/fdt': CRC check failed"); > + return 0; > + } > + of_fdt_raw_attr.size = fdt_totalsize(initial_boot_params); > + return sysfs_create_bin_file(firmware_kobj, &of_fdt_raw_attr); > +} > +late_initcall(of_fdt_raw_init); > +#endif > + > #endif /* CONFIG_OF_EARLY_FLATTREE */ You have a mixture of things inside and outside of CONFIG_OF_EARLY_FLATTREE which in theory could cause warnings. However looking more closely at this, it is fine for now. Instead I think we need to get rid of CONFIG_OF_EARLY_FLATTREE (or merge with OF_FLATTREE) . Every platform selects it except Sparc. Rob
On 12 November 2014 17:08, Rob Herring <robherring2@gmail.com> wrote: > On Wed, Nov 12, 2014 at 6:28 AM, Ard Biesheuvel > <ard.biesheuvel@linaro.org> wrote: >> Create a new /sys entry '/sys/firmware/fdt' to export the FDT blob >> that was passed to the kernel by the bootloader. This allows userland >> applications such as kexec to access the raw binary. >> >> The fact that this node does not reside under /sys/firmware/device-tree >> is deliberate: FDT is also used on arm64 UEFI/ACPI systems to >> communicate just the UEFI and ACPI entry points, but the FDT is never >> unflattened and used to configure the system. >> >> A CRC32 checksum is calculated over the entire FDT blob, and verified >> at late_initcall time. The sysfs entry is instantiated only if the >> checksum is valid, i.e., if the FDT blob has not been modified in the >> mean time. Otherwise, a warning is printed. >> >> Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> >> --- >> v4: use pr_warn() instead of WARN() >> v3: keep checksum instead of copying the entire blob, and WARN on mismatch >> >> drivers/of/Kconfig | 1 + >> drivers/of/fdt.c | 37 +++++++++++++++++++++++++++++++++++++ >> 2 files changed, 38 insertions(+) >> >> diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig >> index 1a13f5b722c5..0348c208343c 100644 >> --- a/drivers/of/Kconfig >> +++ b/drivers/of/Kconfig >> @@ -23,6 +23,7 @@ config OF_FLATTREE >> bool >> select DTC >> select LIBFDT >> + select CRC32 >> >> config OF_EARLY_FLATTREE >> bool >> diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c >> index d1ffca8b34ea..0004871ebccf 100644 >> --- a/drivers/of/fdt.c >> +++ b/drivers/of/fdt.c >> @@ -9,6 +9,7 @@ >> * version 2 as published by the Free Software Foundation. >> */ >> >> +#include <linux/crc32.h> >> #include <linux/kernel.h> >> #include <linux/initrd.h> >> #include <linux/memblock.h> >> @@ -22,10 +23,20 @@ >> #include <linux/libfdt.h> >> #include <linux/debugfs.h> >> #include <linux/serial_core.h> >> +#include <linux/sysfs.h> >> >> #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ >> #include <asm/page.h> >> >> +static u32 of_fdt_crc32; >> + >> +static u32 of_fdt_get_crc32(void *fdt) >> +{ >> + static u32 const OF_FDT_CRC32_SEED = 0x04c11db7; > > Where did this value come from? A comment would be useful. > Oops, it appears I was a bit sloppy here. I misread 'seed' in the crc32 header as poly, but actually the implementation refers to this polynomial directly as CRCPOLY_BE and the seed should be 0 here (or in the verify case, the original crc, in which case the return value should be 0) >> + >> + return crc32_be(OF_FDT_CRC32_SEED, fdt, fdt_totalsize(fdt)); >> +} >> + >> /* >> * of_fdt_limit_memory - limit the number of regions in the /memory node >> * @limit: maximum entries >> @@ -1003,6 +1014,8 @@ bool __init early_init_dt_verify(void *params) >> return false; >> } >> >> + of_fdt_crc32 = of_fdt_get_crc32(initial_boot_params); >> + >> return true; >> } >> >> @@ -1103,4 +1116,28 @@ static int __init of_flat_dt_debugfs_export_fdt(void) >> module_init(of_flat_dt_debugfs_export_fdt); >> #endif >> >> +#ifdef CONFIG_SYSFS >> +static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj, >> + struct bin_attribute *bin_attr, >> + char *buf, loff_t off, size_t count) >> +{ >> + memcpy(buf, initial_boot_params + off, count); >> + return count; >> +} >> + >> +static int __init of_fdt_raw_init(void) >> +{ >> + static struct bin_attribute of_fdt_raw_attr = >> + __BIN_ATTR(fdt, S_IRUSR, of_fdt_raw_read, NULL, 0); >> + >> + if (of_fdt_crc32 != of_fdt_get_crc32(initial_boot_params)) { >> + pr_warn("fdt: not creating '/sys/firmware/fdt': CRC check failed"); >> + return 0; >> + } >> + of_fdt_raw_attr.size = fdt_totalsize(initial_boot_params); >> + return sysfs_create_bin_file(firmware_kobj, &of_fdt_raw_attr); >> +} >> +late_initcall(of_fdt_raw_init); >> +#endif >> + >> #endif /* CONFIG_OF_EARLY_FLATTREE */ > > You have a mixture of things inside and outside of > CONFIG_OF_EARLY_FLATTREE which in theory could cause warnings. However > looking more closely at this, it is fine for now. Instead I think we > need to get rid of CONFIG_OF_EARLY_FLATTREE (or merge with > OF_FLATTREE) . Every platform selects it except Sparc. > Well, the crc will only be computed if early_init_dt_verify() was called, so it seems putting the initcall() here is not entirely inappropriate. @Grant; I will respin based on the version you posted in this thread, and fix the crc bit. -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
diff --git a/drivers/of/Kconfig b/drivers/of/Kconfig index 1a13f5b722c5..0348c208343c 100644 --- a/drivers/of/Kconfig +++ b/drivers/of/Kconfig @@ -23,6 +23,7 @@ config OF_FLATTREE bool select DTC select LIBFDT + select CRC32 config OF_EARLY_FLATTREE bool diff --git a/drivers/of/fdt.c b/drivers/of/fdt.c index d1ffca8b34ea..0004871ebccf 100644 --- a/drivers/of/fdt.c +++ b/drivers/of/fdt.c @@ -9,6 +9,7 @@ * version 2 as published by the Free Software Foundation. */ +#include <linux/crc32.h> #include <linux/kernel.h> #include <linux/initrd.h> #include <linux/memblock.h> @@ -22,10 +23,20 @@ #include <linux/libfdt.h> #include <linux/debugfs.h> #include <linux/serial_core.h> +#include <linux/sysfs.h> #include <asm/setup.h> /* for COMMAND_LINE_SIZE */ #include <asm/page.h> +static u32 of_fdt_crc32; + +static u32 of_fdt_get_crc32(void *fdt) +{ + static u32 const OF_FDT_CRC32_SEED = 0x04c11db7; + + return crc32_be(OF_FDT_CRC32_SEED, fdt, fdt_totalsize(fdt)); +} + /* * of_fdt_limit_memory - limit the number of regions in the /memory node * @limit: maximum entries @@ -1003,6 +1014,8 @@ bool __init early_init_dt_verify(void *params) return false; } + of_fdt_crc32 = of_fdt_get_crc32(initial_boot_params); + return true; } @@ -1103,4 +1116,28 @@ static int __init of_flat_dt_debugfs_export_fdt(void) module_init(of_flat_dt_debugfs_export_fdt); #endif +#ifdef CONFIG_SYSFS +static ssize_t of_fdt_raw_read(struct file *filp, struct kobject *kobj, + struct bin_attribute *bin_attr, + char *buf, loff_t off, size_t count) +{ + memcpy(buf, initial_boot_params + off, count); + return count; +} + +static int __init of_fdt_raw_init(void) +{ + static struct bin_attribute of_fdt_raw_attr = + __BIN_ATTR(fdt, S_IRUSR, of_fdt_raw_read, NULL, 0); + + if (of_fdt_crc32 != of_fdt_get_crc32(initial_boot_params)) { + pr_warn("fdt: not creating '/sys/firmware/fdt': CRC check failed"); + return 0; + } + of_fdt_raw_attr.size = fdt_totalsize(initial_boot_params); + return sysfs_create_bin_file(firmware_kobj, &of_fdt_raw_attr); +} +late_initcall(of_fdt_raw_init); +#endif + #endif /* CONFIG_OF_EARLY_FLATTREE */
Create a new /sys entry '/sys/firmware/fdt' to export the FDT blob that was passed to the kernel by the bootloader. This allows userland applications such as kexec to access the raw binary. The fact that this node does not reside under /sys/firmware/device-tree is deliberate: FDT is also used on arm64 UEFI/ACPI systems to communicate just the UEFI and ACPI entry points, but the FDT is never unflattened and used to configure the system. A CRC32 checksum is calculated over the entire FDT blob, and verified at late_initcall time. The sysfs entry is instantiated only if the checksum is valid, i.e., if the FDT blob has not been modified in the mean time. Otherwise, a warning is printed. Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org> --- v4: use pr_warn() instead of WARN() v3: keep checksum instead of copying the entire blob, and WARN on mismatch drivers/of/Kconfig | 1 + drivers/of/fdt.c | 37 +++++++++++++++++++++++++++++++++++++ 2 files changed, 38 insertions(+)