| Message ID | 1472596811-9596-6-git-send-email-zohar@linux.vnet.ibm.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
Hi, Mimi On 08/30/16 at 06:40pm, Mimi Zohar wrote: > From: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> > > This patch uses the kexec buffer passing mechanism to pass the > serialized IMA binary_runtime_measurements to the next kernel. > > Changelog v2: > - Fix build issue by defining a stub ima_add_kexec_buffer and stub > struct kimage when CONFIG_IMA=n and CONFIG_IMA_KEXEC=n. (Fenguang Wu) > - removed kexec_add_handover_buffer() checksum argument. > - added skip_checksum member to kexec_buf > - only register reboot notifier once > > Changelog v1: > - updated to call IMA functions (Mimi) > - move code from ima_template.c to ima_kexec.c (Mimi) > > Signed-off-by: Thiago Jung Bauermann <bauerman@linux.vnet.ibm.com> > Signed-off-by: Mimi Zohar <zohar@linux.vnet.ibm.com> > --- > include/linux/ima.h | 12 ++++++ > kernel/kexec_file.c | 4 ++ > security/integrity/ima/ima_kexec.c | 88 ++++++++++++++++++++++++++++++++++++++ > 3 files changed, 104 insertions(+) > > diff --git a/include/linux/ima.h b/include/linux/ima.h > index 0eb7c2e..7f6952f 100644 > --- a/include/linux/ima.h > +++ b/include/linux/ima.h > @@ -11,6 +11,7 @@ > #define _LINUX_IMA_H > > #include <linux/fs.h> > +#include <linux/kexec.h> > struct linux_binprm; > > #ifdef CONFIG_IMA > @@ -23,6 +24,10 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size, > enum kernel_read_file_id id); > extern void ima_post_path_mknod(struct dentry *dentry); > > +#ifdef CONFIG_IMA_KEXEC > +extern void ima_add_kexec_buffer(struct kimage *image); > +#endif > + > #else > static inline int ima_bprm_check(struct linux_binprm *bprm) > { > @@ -62,6 +67,13 @@ static inline void ima_post_path_mknod(struct dentry *dentry) > > #endif /* CONFIG_IMA */ > > +#ifndef CONFIG_IMA_KEXEC > +struct kimage; > + > +static inline void ima_add_kexec_buffer(struct kimage *image) > +{} > +#endif > + > #ifdef CONFIG_IMA_APPRAISE > extern void ima_inode_post_setattr(struct dentry *dentry); > extern int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, > diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c > index 0e90d14..9585861 100644 > --- a/kernel/kexec_file.c > +++ b/kernel/kexec_file.c > @@ -19,6 +19,7 @@ > #include <linux/mutex.h> > #include <linux/list.h> > #include <linux/fs.h> > +#include <linux/ima.h> > #include <crypto/hash.h> > #include <crypto/sha.h> > #include <linux/syscalls.h> > @@ -200,6 +201,9 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, > return ret; > image->kernel_buf_len = size; > > + /* IMA needs to pass the measurement list to the next kernel. */ > + ima_add_kexec_buffer(image); > + > /* Call arch image probe handlers */ > ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, > image->kernel_buf_len); > diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c > index e77ca9d..0e4d0db 100644 > --- a/security/integrity/ima/ima_kexec.c > +++ b/security/integrity/ima/ima_kexec.c > @@ -23,6 +23,11 @@ > > #include "ima.h" > > +#ifdef CONFIG_IMA_KEXEC > +/* Physical address of the measurement buffer in the next kernel. */ > +static unsigned long kexec_buffer_load_addr; > +static size_t kexec_segment_size; > + > static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, > unsigned long segment_size) > { > @@ -75,6 +80,89 @@ out: > } > > /* > + * Called during kexec execute so that IMA can save the measurement list. > + */ > +static int ima_update_kexec_buffer(struct notifier_block *self, > + unsigned long action, void *data) > +{ > + void *kexec_buffer = NULL; > + size_t kexec_buffer_size; > + int ret; > + > + if (!kexec_in_progress) > + return NOTIFY_OK; > + > + kexec_buffer_size = ima_get_binary_runtime_size(); > + if (kexec_buffer_size > > + (kexec_segment_size - sizeof(struct ima_kexec_hdr))) { > + pr_err("Binary measurement list grew too large.\n"); > + goto out; > + } > + > + ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, > + kexec_segment_size); > + if (!kexec_buffer) { > + pr_err("Not enough memory for the kexec measurement buffer.\n"); > + goto out; > + } > + ret = kexec_update_segment(kexec_buffer, kexec_buffer_size, > + kexec_buffer_load_addr, kexec_segment_size); > + if (ret) > + pr_err("Error updating kexec buffer: %d\n", ret); > +out: > + return NOTIFY_OK; > +} > + > +struct notifier_block update_buffer_nb = { > + .notifier_call = ima_update_kexec_buffer, > +}; > + > +/* > + * Called during kexec_file_load so that IMA can add a segment to the kexec > + * image for the measurement list for the next kernel. > + */ > +void ima_add_kexec_buffer(struct kimage *image) > +{ > + static int registered = 0; > + struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE, > + .buf_min = 0, .buf_max = ULONG_MAX, > + .top_down = true, .skip_checksum = true }; > + int ret; > + > + if (!kexec_can_hand_over_buffer()) > + return; > + > + kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + PAGE_SIZE, > + PAGE_SIZE); > + > + if (kexec_segment_size >= (ULONG_MAX - sizeof(long))) { > + pr_err("Binary measurement list too large.\n"); > + return; > + } Now we added a limitation that total segment size can not be larger than half of totalram. see kernel/kexec_core.c sanity_check_segment_list() So can it fail early here if kexec_segment_size is over half of total ram? > + > + /* Ask not to checksum the segment, we will update it later. */ > + kbuf.buffer = NULL; > + kbuf.bufsz = 0; > + kbuf.memsz = kexec_segment_size; > + ret = kexec_add_handover_buffer(&kbuf); > + if (ret) { > + pr_err("Error passing over kexec measurement buffer.\n"); > + return; > + } > + kexec_buffer_load_addr = kbuf.mem; > + > + pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n", > + kexec_buffer_load_addr); > + > + if (registered) > + return; > + > + register_reboot_notifier(&update_buffer_nb); > + registered = 1; > +} > +#endif /* IMA_KEXEC */ > + > +/* > * Restore the measurement list from the previous kernel. > */ > void ima_load_kexec_buffer(void) > -- > 2.1.0 > Thanks Dave -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
Hi Dave, On Thu, 2016-09-01 at 09:57 +0800, Dave Young wrote: > On 08/30/16 at 06:40pm, Mimi Zohar wrote: > > + * Called during kexec_file_load so that IMA can add a segment to the kexec > > + * image for the measurement list for the next kernel. > > + */ > > +void ima_add_kexec_buffer(struct kimage *image) > > +{ > > + static int registered = 0; > > + struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE, > > + .buf_min = 0, .buf_max = ULONG_MAX, > > + .top_down = true, .skip_checksum = true }; > > + int ret; > > + > > + if (!kexec_can_hand_over_buffer()) > > + return; > > + > > + kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + PAGE_SIZE, > > + PAGE_SIZE); > > + > > + if (kexec_segment_size >= (ULONG_MAX - sizeof(long))) { > > + pr_err("Binary measurement list too large.\n"); > > + return; > > + } > > Now we added a limitation that total segment size can not be larger than > half of totalram. see kernel/kexec_core.c sanity_check_segment_list() > > So can it fail early here if kexec_segment_size is over half of total > ram? Sure, I'll include this change in the next post. Mimi -- To unsubscribe from this list: send the line "unsubscribe linux-security-module" 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/include/linux/ima.h b/include/linux/ima.h index 0eb7c2e..7f6952f 100644 --- a/include/linux/ima.h +++ b/include/linux/ima.h @@ -11,6 +11,7 @@ #define _LINUX_IMA_H #include <linux/fs.h> +#include <linux/kexec.h> struct linux_binprm; #ifdef CONFIG_IMA @@ -23,6 +24,10 @@ extern int ima_post_read_file(struct file *file, void *buf, loff_t size, enum kernel_read_file_id id); extern void ima_post_path_mknod(struct dentry *dentry); +#ifdef CONFIG_IMA_KEXEC +extern void ima_add_kexec_buffer(struct kimage *image); +#endif + #else static inline int ima_bprm_check(struct linux_binprm *bprm) { @@ -62,6 +67,13 @@ static inline void ima_post_path_mknod(struct dentry *dentry) #endif /* CONFIG_IMA */ +#ifndef CONFIG_IMA_KEXEC +struct kimage; + +static inline void ima_add_kexec_buffer(struct kimage *image) +{} +#endif + #ifdef CONFIG_IMA_APPRAISE extern void ima_inode_post_setattr(struct dentry *dentry); extern int ima_inode_setxattr(struct dentry *dentry, const char *xattr_name, diff --git a/kernel/kexec_file.c b/kernel/kexec_file.c index 0e90d14..9585861 100644 --- a/kernel/kexec_file.c +++ b/kernel/kexec_file.c @@ -19,6 +19,7 @@ #include <linux/mutex.h> #include <linux/list.h> #include <linux/fs.h> +#include <linux/ima.h> #include <crypto/hash.h> #include <crypto/sha.h> #include <linux/syscalls.h> @@ -200,6 +201,9 @@ kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, return ret; image->kernel_buf_len = size; + /* IMA needs to pass the measurement list to the next kernel. */ + ima_add_kexec_buffer(image); + /* Call arch image probe handlers */ ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, image->kernel_buf_len); diff --git a/security/integrity/ima/ima_kexec.c b/security/integrity/ima/ima_kexec.c index e77ca9d..0e4d0db 100644 --- a/security/integrity/ima/ima_kexec.c +++ b/security/integrity/ima/ima_kexec.c @@ -23,6 +23,11 @@ #include "ima.h" +#ifdef CONFIG_IMA_KEXEC +/* Physical address of the measurement buffer in the next kernel. */ +static unsigned long kexec_buffer_load_addr; +static size_t kexec_segment_size; + static int ima_dump_measurement_list(unsigned long *buffer_size, void **buffer, unsigned long segment_size) { @@ -75,6 +80,89 @@ out: } /* + * Called during kexec execute so that IMA can save the measurement list. + */ +static int ima_update_kexec_buffer(struct notifier_block *self, + unsigned long action, void *data) +{ + void *kexec_buffer = NULL; + size_t kexec_buffer_size; + int ret; + + if (!kexec_in_progress) + return NOTIFY_OK; + + kexec_buffer_size = ima_get_binary_runtime_size(); + if (kexec_buffer_size > + (kexec_segment_size - sizeof(struct ima_kexec_hdr))) { + pr_err("Binary measurement list grew too large.\n"); + goto out; + } + + ima_dump_measurement_list(&kexec_buffer_size, &kexec_buffer, + kexec_segment_size); + if (!kexec_buffer) { + pr_err("Not enough memory for the kexec measurement buffer.\n"); + goto out; + } + ret = kexec_update_segment(kexec_buffer, kexec_buffer_size, + kexec_buffer_load_addr, kexec_segment_size); + if (ret) + pr_err("Error updating kexec buffer: %d\n", ret); +out: + return NOTIFY_OK; +} + +struct notifier_block update_buffer_nb = { + .notifier_call = ima_update_kexec_buffer, +}; + +/* + * Called during kexec_file_load so that IMA can add a segment to the kexec + * image for the measurement list for the next kernel. + */ +void ima_add_kexec_buffer(struct kimage *image) +{ + static int registered = 0; + struct kexec_buf kbuf = { .image = image, .buf_align = PAGE_SIZE, + .buf_min = 0, .buf_max = ULONG_MAX, + .top_down = true, .skip_checksum = true }; + int ret; + + if (!kexec_can_hand_over_buffer()) + return; + + kexec_segment_size = ALIGN(ima_get_binary_runtime_size() + PAGE_SIZE, + PAGE_SIZE); + + if (kexec_segment_size >= (ULONG_MAX - sizeof(long))) { + pr_err("Binary measurement list too large.\n"); + return; + } + + /* Ask not to checksum the segment, we will update it later. */ + kbuf.buffer = NULL; + kbuf.bufsz = 0; + kbuf.memsz = kexec_segment_size; + ret = kexec_add_handover_buffer(&kbuf); + if (ret) { + pr_err("Error passing over kexec measurement buffer.\n"); + return; + } + kexec_buffer_load_addr = kbuf.mem; + + pr_debug("kexec measurement buffer for the loaded kernel at 0x%lx.\n", + kexec_buffer_load_addr); + + if (registered) + return; + + register_reboot_notifier(&update_buffer_nb); + registered = 1; +} +#endif /* IMA_KEXEC */ + +/* * Restore the measurement list from the previous kernel. */ void ima_load_kexec_buffer(void)