diff options
| -rw-r--r-- | arch/x86/kernel/machine_kexec_64.c | 45 | ||||
| -rw-r--r-- | include/linux/kexec.h | 53 | ||||
| -rw-r--r-- | include/uapi/linux/kexec.h | 11 | ||||
| -rw-r--r-- | kernel/kexec.c | 483 |
4 files changed, 587 insertions, 5 deletions
diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c index 679cef0..c8875b5 100644 --- a/arch/x86/kernel/machine_kexec_64.c +++ b/arch/x86/kernel/machine_kexec_64.c @@ -22,6 +22,10 @@ #include <asm/mmu_context.h> #include <asm/debugreg.h> +static struct kexec_file_ops *kexec_file_loaders[] = { + NULL, +}; + static void free_transition_pgtable(struct kimage *image) { free_page((unsigned long)image->arch.pud); @@ -283,3 +287,44 @@ void arch_crash_save_vmcoreinfo(void) (unsigned long)&_text - __START_KERNEL); } +/* arch-dependent functionality related to kexec file-based syscall */ + +int arch_kexec_kernel_image_probe(struct kimage *image, void *buf, + unsigned long buf_len) +{ + int i, ret = -ENOEXEC; + struct kexec_file_ops *fops; + + for (i = 0; i < ARRAY_SIZE(kexec_file_loaders); i++) { + fops = kexec_file_loaders[i]; + if (!fops || !fops->probe) + continue; + + ret = fops->probe(buf, buf_len); + if (!ret) { + image->fops = fops; + return ret; + } + } + + return ret; +} + +void *arch_kexec_kernel_image_load(struct kimage *image) +{ + if (!image->fops || !image->fops->load) + return ERR_PTR(-ENOEXEC); + + return image->fops->load(image, image->kernel_buf, + image->kernel_buf_len, image->initrd_buf, + image->initrd_buf_len, image->cmdline_buf, + image->cmdline_buf_len); +} + +int arch_kimage_file_post_load_cleanup(struct kimage *image) +{ + if (!image->fops || !image->fops->cleanup) + return 0; + + return image->fops->cleanup(image); +} diff --git a/include/linux/kexec.h b/include/linux/kexec.h index 66d56ac..8e80901 100644 --- a/include/linux/kexec.h +++ b/include/linux/kexec.h @@ -121,13 +121,57 @@ struct kimage { #define KEXEC_TYPE_DEFAULT 0 #define KEXEC_TYPE_CRASH 1 unsigned int preserve_context : 1; + /* If set, we are using file mode kexec syscall */ + unsigned int file_mode:1; #ifdef ARCH_HAS_KIMAGE_ARCH struct kimage_arch arch; #endif + + /* Additional fields for file based kexec syscall */ + void *kernel_buf; + unsigned long kernel_buf_len; + + void *initrd_buf; + unsigned long initrd_buf_len; + + char *cmdline_buf; + unsigned long cmdline_buf_len; + + /* File operations provided by image loader */ + struct kexec_file_ops *fops; + + /* Image loader handling the kernel can store a pointer here */ + void *image_loader_data; }; +/* + * Keeps track of buffer parameters as provided by caller for requesting + * memory placement of buffer. + */ +struct kexec_buf { + struct kimage *image; + char *buffer; + unsigned long bufsz; + unsigned long memsz; + unsigned long buf_align; + unsigned long buf_min; + unsigned long buf_max; + bool top_down; /* allocate from top of memory hole */ +}; +typedef int (kexec_probe_t)(const char *kernel_buf, unsigned long kernel_size); +typedef void *(kexec_load_t)(struct kimage *image, char *kernel_buf, + unsigned long kernel_len, char *initrd, + unsigned long initrd_len, char *cmdline, + unsigned long cmdline_len); +typedef int (kexec_cleanup_t)(struct kimage *image); + +struct kexec_file_ops { + kexec_probe_t *probe; + kexec_load_t *load; + kexec_cleanup_t *cleanup; +}; /* kexec interface functions */ extern void machine_kexec(struct kimage *image); @@ -138,6 +182,11 @@ extern asmlinkage long sys_kexec_load(unsigned long entry, struct kexec_segment __user *segments, unsigned long flags); extern int kernel_kexec(void); +extern int kexec_add_buffer(struct kimage *image, char *buffer, + unsigned long bufsz, unsigned long memsz, + unsigned long buf_align, unsigned long buf_min, + unsigned long buf_max, bool top_down, + unsigned long *load_addr); extern struct page *kimage_alloc_control_pages(struct kimage *image, unsigned int order); extern void crash_kexec(struct pt_regs *); @@ -188,6 +237,10 @@ extern int kexec_load_disabled; #define KEXEC_FLAGS (KEXEC_ON_CRASH | KEXEC_PRESERVE_CONTEXT) #endif +/* List of defined/legal kexec file flags */ +#define KEXEC_FILE_FLAGS (KEXEC_FILE_UNLOAD | KEXEC_FILE_ON_CRASH | \ + KEXEC_FILE_NO_INITRAMFS) + #define VMCOREINFO_BYTES (4096) #define VMCOREINFO_NOTE_NAME "VMCOREINFO" #define VMCOREINFO_NOTE_NAME_BYTES ALIGN(sizeof(VMCOREINFO_NOTE_NAME), 4) diff --git a/include/uapi/linux/kexec.h b/include/uapi/linux/kexec.h index d6629d4..6925f5b 100644 --- a/include/uapi/linux/kexec.h +++ b/include/uapi/linux/kexec.h @@ -13,6 +13,17 @@ #define KEXEC_PRESERVE_CONTEXT 0x00000002 #define KEXEC_ARCH_MASK 0xffff0000 +/* + * Kexec file load interface flags. + * KEXEC_FILE_UNLOAD : Unload already loaded kexec/kdump image. + * KEXEC_FILE_ON_CRASH : Load/unload operation belongs to kdump image. + * KEXEC_FILE_NO_INITRAMFS : No initramfs is being loaded. Ignore the initrd + * fd field. + */ +#define KEXEC_FILE_UNLOAD 0x00000001 +#define KEXEC_FILE_ON_CRASH 0x00000002 +#define KEXEC_FILE_NO_INITRAMFS 0x00000004 + /* These values match the ELF architecture values. * Unless there is a good reason that should continue to be the case. */ diff --git a/kernel/kexec.c b/kernel/kexec.c index ec4386c..9b46219 100644 --- a/kernel/kexec.c +++ b/kernel/kexec.c @@ -6,6 +6,8 @@ * Version 2. See the file COPYING for more details. */ +#define pr_fmt(fmt) "kexec: " fmt + #include <linux/capability.h> #include <linux/mm.h> #include <linux/file.h> @@ -327,6 +329,221 @@ out_free_image: return ret; } +static int copy_file_from_fd(int fd, void **buf, unsigned long *buf_len) +{ + struct fd f = fdget(fd); + int ret; + struct kstat stat; + loff_t pos; + ssize_t bytes = 0; + + if (!f.file) + return -EBADF; + + ret = vfs_getattr(&f.file->f_path, &stat); + if (ret) + goto out; + + if (stat.size > INT_MAX) { + ret = -EFBIG; + goto out; + } + + /* Don't hand 0 to vmalloc, it whines. */ + if (stat.size == 0) { + ret = -EINVAL; + goto out; + } + + *buf = vmalloc(stat.size); + if (!*buf) { + ret = -ENOMEM; + goto out; + } + + pos = 0; + while (pos < stat.size) { + bytes = kernel_read(f.file, pos, (char *)(*buf) + pos, + stat.size - pos); + if (bytes < 0) { + vfree(*buf); + ret = bytes; + goto out; + } + + if (bytes == 0) + break; + pos += bytes; + } + + if (pos != stat.size) { + ret = -EBADF; + vfree(*buf); + goto out; + } + + *buf_len = pos; +out: + fdput(f); + return ret; +} + +/* Architectures can provide this probe function */ +int __weak arch_kexec_kernel_image_probe(struct kimage *image, void *buf, + unsigned long buf_len) +{ + return -ENOEXEC; +} + +void * __weak arch_kexec_kernel_image_load(struct kimage *image) +{ + return ERR_PTR(-ENOEXEC); +} + +void __weak arch_kimage_file_post_load_cleanup(struct kimage *image) +{ +} + +/* + * Free up memory used by kernel, initrd, and comand line. This is temporary + * memory allocation which is not needed any more after these buffers have + * been loaded into separate segments and have been copied elsewhere. + */ +static void kimage_file_post_load_cleanup(struct kimage *image) +{ + vfree(image->kernel_buf); + image->kernel_buf = NULL; + + vfree(image->initrd_buf); + image->initrd_buf = NULL; + + kfree(image->cmdline_buf); + image->cmdline_buf = NULL; + + /* See if architecture has anything to cleanup post load */ + arch_kimage_file_post_load_cleanup(image); +} + +/* + * In file mode list of segments is prepared by kernel. Copy relevant + * data from user space, do error checking, prepare segment list + */ +static int +kimage_file_prepare_segments(struct kimage *image, int kernel_fd, int initrd_fd, + const char __user *cmdline_ptr, + unsigned long cmdline_len, unsigned flags) +{ + int ret = 0; + void *ldata; + + ret = copy_file_from_fd(kernel_fd, &image->kernel_buf, + &image->kernel_buf_len); + if (ret) + return ret; + + /* Call arch image probe handlers */ + ret = arch_kexec_kernel_image_probe(image, image->kernel_buf, + image->kernel_buf_len); + + if (ret) + goto out; + + /* It is possible that there no initramfs is being loaded */ + if (!(flags & KEXEC_FILE_NO_INITRAMFS)) { + ret = copy_file_from_fd(initrd_fd, &image->initrd_buf, + &image->initrd_buf_len); + if (ret) + goto out; + } + + if (cmdline_len) { + image->cmdline_buf = kzalloc(cmdline_len, GFP_KERNEL); + if (!image->cmdline_buf) { + ret = -ENOMEM; + goto out; + } + + ret = copy_from_user(image->cmdline_buf, cmdline_ptr, + cmdline_len); + if (ret) { + ret = -EFAULT; + goto out; + } + + image->cmdline_buf_len = cmdline_len; + + /* command line should be a string with last byte null */ + if (image->cmdline_buf[cmdline_len - 1] != '\0') { + ret = -EINVAL; + goto out; + } + } + + /* Call arch image load handlers */ + ldata = arch_kexec_kernel_image_load(image); + + if (IS_ERR(ldata)) { + ret = PTR_ERR(ldata); + goto out; + } + + image->image_loader_data = ldata; +out: + /* In case of error, free up all allocated memory in this function */ + if (ret) + kimage_file_post_load_cleanup(image); + return ret; +} + +static int +kimage_file_alloc_init(struct kimage **rimage, int kernel_fd, + int initrd_fd, const char __user *cmdline_ptr, + unsigned long cmdline_len, unsigned long flags) +{ + int ret; + struct kimage *image; + + image = do_kimage_alloc_init(); + if (!image) + return -ENOMEM; + + image->file_mode = 1; + + ret = kimage_file_prepare_segments(image, kernel_fd, initrd_fd, + cmdline_ptr, cmdline_len, flags); + if (ret) + goto out_free_image; + + ret = sanity_check_segment_list(image); + if (ret) + goto out_free_post_load_bufs; + + ret = -ENOMEM; + image->control_code_page = kimage_alloc_control_pages(image, + get_order(KEXEC_CONTROL_PAGE_SIZE)); + if (!image->control_code_page) { + pr_err("Could not allocate control_code_buffer\n"); + goto out_free_post_load_bufs; + } + + image->swap_page = kimage_alloc_control_pages(image, 0); + if (!image->swap_page) { + pr_err(KERN_ERR "Could not allocate swap buffer\n"); + goto out_free_control_pages; + } + + *rimage = image; + return 0; +out_free_control_pages: + kimage_free_page_list(&image->control_pages); +out_free_post_load_bufs: + kimage_file_post_load_cleanup(image); + kfree(image->image_loader_data); +out_free_image: + kfree(image); + return ret; +} + static int kimage_is_destination_range(struct kimage *image, unsigned long start, unsigned long end) @@ -644,6 +861,16 @@ static void kimage_free(struct kimage *image) /* Free the kexec control pages... */ kimage_free_page_list(&image->control_pages); + + kfree(image->image_loader_data); + + /* + * Free up any temporary buffers allocated. This might hit if + * error occurred much later after buffer allocation. + */ + if (image->file_mode) + kimage_file_post_load_cleanup(image); + kfree(image); } @@ -772,10 +999,14 @@ static int kimage_load_normal_segment(struct kimage *image, unsigned long maddr; size_t ubytes, mbytes; int result; - unsigned char __user *buf; + unsigned char __user *buf = NULL; + unsigned char *kbuf = NULL; result = 0; - buf = segment->buf; + if (image->file_mode) + kbuf = segment->kbuf; + else + buf = segment->buf; ubytes = segment->bufsz; mbytes = segment->memsz; maddr = segment->mem; @@ -807,7 +1038,11 @@ static int kimage_load_normal_segment(struct kimage *image, PAGE_SIZE - (maddr & ~PAGE_MASK)); uchunk = min(ubytes, mchunk); - result = copy_from_user(ptr, buf, uchunk); + /* For file based kexec, source pages are in kernel memory */ + if (image->file_mode) + memcpy(ptr, kbuf, uchunk); + else + result = copy_from_user(ptr, buf, uchunk); kunmap(page); if (result) { result = -EFAULT; @@ -815,7 +1050,10 @@ static int kimage_load_normal_segment(struct kimage *image, } ubytes -= uchunk; maddr += mchunk; - buf += mchunk; + if (image->file_mode) + kbuf += mchunk; + else + buf += mchunk; mbytes -= mchunk; } out: @@ -1062,7 +1300,72 @@ SYSCALL_DEFINE5(kexec_file_load, int, kernel_fd, int, initrd_fd, unsigned long, cmdline_len, const char __user *, cmdline_ptr, unsigned long, flags) { - return -ENOSYS; + int ret = 0, i; + struct kimage **dest_image, *image; + + /* We only trust the superuser with rebooting the system. */ + if (!capable(CAP_SYS_BOOT) || kexec_load_disabled) + return -EPERM; + + /* Make sure we have a legal set of flags */ + if (flags != (flags & KEXEC_FILE_FLAGS)) + return -EINVAL; + + image = NULL; + + if (!mutex_trylock(&kexec_mutex)) + return -EBUSY; + + dest_image = &kexec_image; + if (flags & KEXEC_FILE_ON_CRASH) + dest_image = &kexec_crash_image; + + if (flags & KEXEC_FILE_UNLOAD) + goto exchange; + + /* + * In case of crash, new kernel gets loaded in reserved region. It is + * same memory where old crash kernel might be loaded. Free any + * current crash dump kernel before we corrupt it. + */ + if (flags & KEXEC_FILE_ON_CRASH) + kimage_free(xchg(&kexec_crash_image, NULL)); + + ret = kimage_file_alloc_init(&image, kernel_fd, initrd_fd, cmdline_ptr, + cmdline_len, flags); + if (ret) + goto out; + + ret = machine_kexec_prepare(image); + if (ret) + goto out; + + for (i = 0; i < image->nr_segments; i++) { + struct kexec_segment *ksegment; + + ksegment = &image->segment[i]; + pr_debug("Loading segment %d: buf=0x%p bufsz=0x%zx mem=0x%lx memsz=0x%zx\n", + i, ksegment->buf, ksegment->bufsz, ksegment->mem, + ksegment->memsz); + + ret = kimage_load_segment(image, &image->segment[i]); + if (ret) + goto out; + } + + kimage_terminate(image); + + /* + * Free up any temporary buffers allocated which are not needed + * after image has been loaded + */ + kimage_file_post_load_cleanup(image); +exchange: + image = xchg(dest_image, image); +out: + mutex_unlock(&kexec_mutex); + kimage_free(image); + return ret; } void crash_kexec(struct pt_regs *regs) @@ -1620,6 +1923,176 @@ static int __init crash_save_vmcoreinfo_init(void) subsys_initcall(crash_save_vmcoreinfo_init); +static int __kexec_add_segment(struct kimage *image, char *buf, + unsigned long bufsz, unsigned long mem, + unsigned long memsz) +{ + struct kexec_segment *ksegment; + + ksegment = &image->segment[image->nr_segments]; + ksegment->kbuf = buf; + ksegment->bufsz = bufsz; + ksegment->mem = mem; + ksegment->memsz = memsz; + image->nr_segments++; + + return 0; +} + +static int locate_mem_hole_top_down(unsigned long start, unsigned long end, + struct kexec_buf *kbuf) +{ + struct kimage *image = kbuf->image; + unsigned long temp_start, temp_end; + + temp_end = min(end, kbuf->buf_max); + temp_start = temp_end - kbuf->memsz; + + do { + /* align down start */ + temp_start = temp_start & (~(kbuf->buf_align - 1)); + + if (temp_start < start || temp_start < kbuf->buf_min) + return 0; + + temp_end = temp_start + kbuf->memsz - 1; + + /* + * Make sure this does not conflict with any of existing + * segments + */ + if (kimage_is_destination_range(image, temp_start, temp_end)) { + temp_start = temp_start - PAGE_SIZE; + continue; + } + + /* We found a suitable memory range */ + break; + } while (1); + + /* If we are here, we found a suitable memory range */ + __kexec_add_segment(image, kbuf->buffer, kbuf->bufsz, temp_start, + kbuf->memsz); + + /* Success, stop navigating through remaining System RAM ranges */ + return 1; +} + +static int locate_mem_hole_bottom_up(unsigned long start, unsigned long end, + struct kexec_buf *kbuf) +{ + struct kimage *image = kbuf->image; + unsigned long temp_start, temp_end; + + temp_start = max(start, kbuf->buf_min); + + do { + temp_start = ALIGN(temp_start, kbuf->buf_align); + temp_end = temp_start + kbuf->memsz - 1; + + if (temp_end > end || temp_end > kbuf->buf_max) + return 0; + /* + * Make sure this does not conflict with any of existing + * segments + */ + if (kimage_is_destination_range(image, temp_start, temp_end)) { + temp_start = temp_start + PAGE_SIZE; + continue; + } + + /* We found a suitable memory range */ + break; + } while (1); + + /* If we are here, we found a suitable memory range */ + __kexec_add_segment(image, kbuf->buffer, kbuf->bufsz, temp_start, + kbuf->memsz); + + /* Success, stop navigating through remaining System RAM ranges */ + return 1; +} + +static int locate_mem_hole_callback(u64 start, u64 end, void *arg) +{ + struct kexec_buf *kbuf = (struct kexec_buf *)arg; + unsigned long sz = end - start + 1; + + /* Returning 0 will take to next memory range */ + if (sz < kbuf->memsz) + return 0; + + if (end < kbuf->buf_min || start > kbuf->buf_max) + return 0; + + /* + * Allocate memory top down with-in ram range. Otherwise bottom up + * allocation. + */ + if (kbuf->top_down) + return locate_mem_hole_top_down(start, end, kbuf); + return locate_mem_hole_bottom_up(start, end, kbuf); +} + +/* + * Helper function for placing a buffer in a kexec segment. This assumes + * that kexec_mutex is held. + */ +int kexec_add_buffer(struct kimage *image, char *buffer, unsigned long bufsz, + unsigned long memsz, unsigned long buf_align, + unsigned long buf_min, unsigned long buf_max, + bool top_down, unsigned long *load_addr) +{ + + struct kexec_segment *ksegment; + struct kexec_buf buf, *kbuf; + int ret; + + /* Currently adding segment this way is allowed only in file mode */ + if (!image->file_mode) + return -EINVAL; + + if (image->nr_segments >= KEXEC_SEGMENT_MAX) + return -EINVAL; + + /* + * Make sure we are not trying to add buffer after allocating + * control pages. All segments need to be placed first before + * any control pages are allocated. As control page allocation + * logic goes through list of segments to make sure there are + * no destination overlaps. + */ + if (!list_empty(&image->control_pages)) { + WARN_ON(1); + return -EINVAL; + } + + memset(&buf, 0, sizeof(struct kexec_buf)); + kbuf = &buf; + kbuf->image = image; + kbuf->buffer = buffer; + kbuf->bufsz = bufsz; + + kbuf->memsz = ALIGN(memsz, PAGE_SIZE); + kbuf->buf_align = max(buf_align, PAGE_SIZE); + kbuf->buf_min = buf_min; + kbuf->buf_max = buf_max; + kbuf->top_down = top_down; + + /* Walk the RAM ranges and allocate a suitable range for the buffer */ + ret = walk_system_ram_res(0, -1, kbuf, locate_mem_hole_callback); + if (ret != 1) { + /* A suitable memory range could not be found for buffer */ + return -EADDRNOTAVAIL; + } + + /* Found a suitable memory range */ + ksegment = &image->segment[image->nr_segments - 1]; + *load_addr = ksegment->mem; + return 0; +} + + /* * Move into place and start executing a preloaded standalone * executable. If nothing was preloaded return an error. |
