[PATCH V2] kexec: Provide an option to use new kexec system call
Vivek Goyal
vgoyal at redhat.com
Tue Aug 26 07:30:34 PDT 2014
On Mon, Aug 18, 2014 at 11:22:32AM -0400, Vivek Goyal wrote:
> Hi,
>
> This is v2 of the patch. Since v1, I moved syscall implemented check littler
> earlier in the function as per the feedback.
>
> Now a new kexec syscall (kexec_file_load()) has been merged in upstream
> kernel. This system call takes file descriptors of kernel and initramfs
> as input (as opposed to list of segments to be loaded). This new system
> call allows for signature verification of the kernel being loaded.
>
> One use of signature verification of kernel is secureboot systems where
> we want to allow kexec into a kernel only if it is validly signed by
> a key system trusts.
>
> This patch provides and option --kexec-file-syscall (-s), to force use of
> new system call for kexec. Default is to continue to use old syscall.
>
> Currently only bzImage64 on x86_64 can be loaded using this system call.
> As kernel adds support for more arches and for more image types, kexec-tools
> can be modified accordingly.
>
Hi Simon,
Do you have any concerns with this patch? If not, can you please consider
it for merge.
Thanks
Vivek
> Signed-off-by: Vivek Goyal <vgoyal at redhat.com>
> ---
> kexec/arch/x86_64/kexec-bzImage64.c | 86 +++++++++++++++++++++++
> kexec/kexec-syscall.h | 32 ++++++++
> kexec/kexec.c | 132 +++++++++++++++++++++++++++++++++++-
> kexec/kexec.h | 11 ++-
> 4 files changed, 257 insertions(+), 4 deletions(-)
>
> Index: kexec-tools/kexec/kexec.c
> ===================================================================
> --- kexec-tools.orig/kexec/kexec.c 2014-08-13 11:02:21.106631417 -0400
> +++ kexec-tools/kexec/kexec.c 2014-08-18 11:16:28.869392839 -0400
> @@ -51,6 +51,8 @@
> unsigned long long mem_min = 0;
> unsigned long long mem_max = ULONG_MAX;
> static unsigned long kexec_flags = 0;
> +/* Flags for kexec file (fd) based syscall */
> +static unsigned long kexec_file_flags = 0;
> int kexec_debug = 0;
>
> void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int nr_mr)
> @@ -787,6 +789,19 @@ static int my_load(const char *type, int
> return result;
> }
>
> +static int kexec_file_unload(unsigned long kexec_file_flags)
> +{
> + int ret = 0;
> +
> + ret = kexec_file_load(-1, -1, 0, NULL, kexec_file_flags);
> + if (ret != 0) {
> + /* The unload failed, print some debugging information */
> + fprintf(stderr, "kexec_file_load(unload) failed\n: %s\n",
> + strerror(errno));
> + }
> + return ret;
> +}
> +
> static int k_unload (unsigned long kexec_flags)
> {
> int result;
> @@ -925,6 +940,7 @@ void usage(void)
> " (0 means it's not jump back or\n"
> " preserve context)\n"
> " to original kernel.\n"
> + " -s, --kexec-file-syscall Use file based syscall for kexec operation\n"
> " -d, --debug Enable debugging to help spot a failure.\n"
> "\n"
> "Supported kernel file types and options: \n");
> @@ -1072,6 +1088,82 @@ char *concat_cmdline(const char *base, c
> return cmdline;
> }
>
> +/* New file based kexec system call related code */
> +static int do_kexec_file_load(int fileind, int argc, char **argv,
> + unsigned long flags) {
> +
> + char *kernel;
> + int kernel_fd, i;
> + struct kexec_info info;
> + int ret = 0;
> + char *kernel_buf;
> + off_t kernel_size;
> +
> + memset(&info, 0, sizeof(info));
> + info.segment = NULL;
> + info.nr_segments = 0;
> + info.entry = NULL;
> + info.backup_start = 0;
> + info.kexec_flags = flags;
> +
> + info.file_mode = 1;
> + info.initrd_fd = -1;
> +
> + if (!is_kexec_file_load_implemented()) {
> + fprintf(stderr, "syscall kexec_file_load not available.\n");
> + return -1;
> + }
> +
> + if (argc - fileind <= 0) {
> + fprintf(stderr, "No kernel specified\n");
> + usage();
> + return -1;
> + }
> +
> + kernel = argv[fileind];
> +
> + kernel_fd = open(kernel, O_RDONLY);
> + if (kernel_fd == -1) {
> + fprintf(stderr, "Failed to open file %s:%s\n", kernel,
> + strerror(errno));
> + return -1;
> + }
> +
> + /* slurp in the input kernel */
> + kernel_buf = slurp_decompress_file(kernel, &kernel_size);
> +
> + for (i = 0; i < file_types; i++) {
> + if (file_type[i].probe(kernel_buf, kernel_size) >= 0)
> + break;
> + }
> +
> + if (i == file_types) {
> + fprintf(stderr, "Cannot determine the file type " "of %s\n",
> + kernel);
> + return -1;
> + }
> +
> + ret = file_type[i].load(argc, argv, kernel_buf, kernel_size, &info);
> + if (ret < 0) {
> + fprintf(stderr, "Cannot load %s\n", kernel);
> + return ret;
> + }
> +
> + /*
> + * If there is no initramfs, set KEXEC_FILE_NO_INITRAMFS flag so that
> + * kernel does not return error with negative initrd_fd.
> + */
> + if (info.initrd_fd == -1)
> + info.kexec_flags |= KEXEC_FILE_NO_INITRAMFS;
> +
> + ret = kexec_file_load(kernel_fd, info.initrd_fd, info.command_line_len,
> + info.command_line, info.kexec_flags);
> + if (ret != 0)
> + fprintf(stderr, "kexec_file_load failed: %s\n",
> + strerror(errno));
> + return ret;
> +}
> +
>
> int main(int argc, char *argv[])
> {
> @@ -1083,6 +1175,7 @@ int main(int argc, char *argv[])
> int do_ifdown = 0;
> int do_unload = 0;
> int do_reuse_initrd = 0;
> + int do_kexec_file_syscall = 0;
> void *entry = 0;
> char *type = 0;
> char *endptr;
> @@ -1095,6 +1188,23 @@ int main(int argc, char *argv[])
> };
> static const char short_options[] = KEXEC_ALL_OPT_STR;
>
> + /*
> + * First check if --use-kexec-file-syscall is set. That changes lot of
> + * things
> + */
> + while ((opt = getopt_long(argc, argv, short_options,
> + options, 0)) != -1) {
> + switch(opt) {
> + case OPT_KEXEC_FILE_SYSCALL:
> + do_kexec_file_syscall = 1;
> + break;
> + }
> + }
> +
> + /* Reset getopt for the next pass. */
> + opterr = 1;
> + optind = 1;
> +
> while ((opt = getopt_long(argc, argv, short_options,
> options, 0)) != -1) {
> switch(opt) {
> @@ -1127,6 +1237,8 @@ int main(int argc, char *argv[])
> do_shutdown = 0;
> do_sync = 0;
> do_unload = 1;
> + if (do_kexec_file_syscall)
> + kexec_file_flags |= KEXEC_FILE_UNLOAD;
> break;
> case OPT_EXEC:
> do_load = 0;
> @@ -1169,7 +1281,10 @@ int main(int argc, char *argv[])
> do_exec = 0;
> do_shutdown = 0;
> do_sync = 0;
> - kexec_flags = KEXEC_ON_CRASH;
> + if (do_kexec_file_syscall)
> + kexec_file_flags |= KEXEC_FILE_ON_CRASH;
> + else
> + kexec_flags = KEXEC_ON_CRASH;
> break;
> case OPT_MEM_MIN:
> mem_min = strtoul(optarg, &endptr, 0);
> @@ -1194,6 +1309,9 @@ int main(int argc, char *argv[])
> case OPT_REUSE_INITRD:
> do_reuse_initrd = 1;
> break;
> + case OPT_KEXEC_FILE_SYSCALL:
> + /* We already parsed it. Nothing to do. */
> + break;
> default:
> break;
> }
> @@ -1238,10 +1356,18 @@ int main(int argc, char *argv[])
> }
>
> if (do_unload) {
> - result = k_unload(kexec_flags);
> + if (do_kexec_file_syscall)
> + result = kexec_file_unload(kexec_file_flags);
> + else
> + result = k_unload(kexec_flags);
> }
> if (do_load && (result == 0)) {
> - result = my_load(type, fileind, argc, argv, kexec_flags, entry);
> + if (do_kexec_file_syscall)
> + result = do_kexec_file_load(fileind, argc, argv,
> + kexec_file_flags);
> + else
> + result = my_load(type, fileind, argc, argv,
> + kexec_flags, entry);
> }
> /* Don't shutdown unless there is something to reboot to! */
> if ((result == 0) && (do_shutdown || do_exec) && !kexec_loaded()) {
> Index: kexec-tools/kexec/kexec.h
> ===================================================================
> --- kexec-tools.orig/kexec/kexec.h 2014-08-13 11:02:21.106631417 -0400
> +++ kexec-tools/kexec/kexec.h 2014-08-13 11:02:32.393697149 -0400
> @@ -156,6 +156,13 @@ struct kexec_info {
> unsigned long kexec_flags;
> unsigned long backup_src_start;
> unsigned long backup_src_size;
> + /* Set to 1 if we are using kexec file syscall */
> + unsigned long file_mode :1;
> +
> + /* Filled by kernel image processing code */
> + int initrd_fd;
> + char *command_line;
> + int command_line_len;
> };
>
> struct arch_map_entry {
> @@ -207,6 +214,7 @@ extern int file_types;
> #define OPT_UNLOAD 'u'
> #define OPT_TYPE 't'
> #define OPT_PANIC 'p'
> +#define OPT_KEXEC_FILE_SYSCALL 's'
> #define OPT_MEM_MIN 256
> #define OPT_MEM_MAX 257
> #define OPT_REUSE_INITRD 258
> @@ -230,9 +238,10 @@ extern int file_types;
> { "mem-min", 1, 0, OPT_MEM_MIN }, \
> { "mem-max", 1, 0, OPT_MEM_MAX }, \
> { "reuseinitrd", 0, 0, OPT_REUSE_INITRD }, \
> + { "kexec-file-syscall", 0, 0, OPT_KEXEC_FILE_SYSCALL }, \
> { "debug", 0, 0, OPT_DEBUG }, \
>
> -#define KEXEC_OPT_STR "h?vdfxluet:p"
> +#define KEXEC_OPT_STR "h?vdfxluet:ps"
>
> extern void dbgprint_mem_range(const char *prefix, struct memory_range *mr, int nr_mr);
> extern void die(const char *fmt, ...)
> Index: kexec-tools/kexec/arch/x86_64/kexec-bzImage64.c
> ===================================================================
> --- kexec-tools.orig/kexec/arch/x86_64/kexec-bzImage64.c 2014-08-13 11:02:21.106631417 -0400
> +++ kexec-tools/kexec/arch/x86_64/kexec-bzImage64.c 2014-08-13 11:02:32.393697149 -0400
> @@ -235,6 +235,89 @@ static int do_bzImage64_load(struct kexe
> return 0;
> }
>
> +/* This assumes file is being loaded using file based kexec syscall */
> +int bzImage64_load_file(int argc, char **argv, struct kexec_info *info)
> +{
> + int ret = 0;
> + char *command_line = NULL, *tmp_cmdline = NULL;
> + const char *ramdisk = NULL, *append = NULL;
> + int entry_16bit = 0, entry_32bit = 0;
> + int opt;
> + int command_line_len;
> +
> + /* See options.h -- add any more there, too. */
> + static const struct option options[] = {
> + KEXEC_ARCH_OPTIONS
> + { "command-line", 1, 0, OPT_APPEND },
> + { "append", 1, 0, OPT_APPEND },
> + { "reuse-cmdline", 0, 0, OPT_REUSE_CMDLINE },
> + { "initrd", 1, 0, OPT_RAMDISK },
> + { "ramdisk", 1, 0, OPT_RAMDISK },
> + { "real-mode", 0, 0, OPT_REAL_MODE },
> + { "entry-32bit", 0, 0, OPT_ENTRY_32BIT },
> + { 0, 0, 0, 0 },
> + };
> + static const char short_options[] = KEXEC_ARCH_OPT_STR "d";
> +
> + while ((opt = getopt_long(argc, argv, short_options, options, 0)) != -1) {
> + switch (opt) {
> + default:
> + /* Ignore core options */
> + if (opt < OPT_ARCH_MAX)
> + break;
> + case OPT_APPEND:
> + append = optarg;
> + break;
> + case OPT_REUSE_CMDLINE:
> + tmp_cmdline = get_command_line();
> + break;
> + case OPT_RAMDISK:
> + ramdisk = optarg;
> + break;
> + case OPT_REAL_MODE:
> + entry_16bit = 1;
> + break;
> + case OPT_ENTRY_32BIT:
> + entry_32bit = 1;
> + break;
> + }
> + }
> + command_line = concat_cmdline(tmp_cmdline, append);
> + if (tmp_cmdline)
> + free(tmp_cmdline);
> + command_line_len = 0;
> + if (command_line) {
> + command_line_len = strlen(command_line) + 1;
> + } else {
> + command_line = strdup("\0");
> + command_line_len = 1;
> + }
> +
> + if (entry_16bit || entry_32bit) {
> + fprintf(stderr, "Kexec2 syscall does not support 16bit"
> + " or 32bit entry yet\n");
> + ret = -1;
> + goto out;
> + }
> +
> + if (ramdisk) {
> + info->initrd_fd = open(ramdisk, O_RDONLY);
> + if (info->initrd_fd == -1) {
> + fprintf(stderr, "Could not open initrd file %s:%s\n",
> + ramdisk, strerror(errno));
> + ret = -1;
> + goto out;
> + }
> + }
> +
> + info->command_line = command_line;
> + info->command_line_len = command_line_len;
> + return ret;
> +out:
> + free(command_line);
> + return ret;
> +}
> +
> int bzImage64_load(int argc, char **argv, const char *buf, off_t len,
> struct kexec_info *info)
> {
> @@ -247,6 +330,9 @@ int bzImage64_load(int argc, char **argv
> int opt;
> int result;
>
> + if (info->file_mode)
> + return bzImage64_load_file(argc, argv, info);
> +
> /* See options.h -- add any more there, too. */
> static const struct option options[] = {
> KEXEC_ARCH_OPTIONS
> Index: kexec-tools/kexec/kexec-syscall.h
> ===================================================================
> --- kexec-tools.orig/kexec/kexec-syscall.h 2014-08-13 11:02:21.106631417 -0400
> +++ kexec-tools/kexec/kexec-syscall.h 2014-08-13 11:02:32.393697149 -0400
> @@ -53,6 +53,19 @@
> #endif
> #endif /*ifndef __NR_kexec_load*/
>
> +#ifndef __NR_kexec_file_load
> +
> +#ifdef __x86_64__
> +#define __NR_kexec_file_load 320
> +#endif
> +
> +#ifndef __NR_kexec_file_load
> +/* system call not available for the arch */
> +#define __NR_kexec_file_load 0xffffffff /* system call not available */
> +#endif
> +
> +#endif /*ifndef __NR_kexec_file_load*/
> +
> struct kexec_segment;
>
> static inline long kexec_load(void *entry, unsigned long nr_segments,
> @@ -61,10 +74,29 @@ static inline long kexec_load(void *entr
> return (long) syscall(__NR_kexec_load, entry, nr_segments, segments, flags);
> }
>
> +static inline int is_kexec_file_load_implemented(void) {
> + if (__NR_kexec_file_load != 0xffffffff)
> + return 1;
> + return 0;
> +}
> +
> +static inline long kexec_file_load(int kernel_fd, int initrd_fd,
> + unsigned long cmdline_len, const char *cmdline_ptr,
> + unsigned long flags)
> +{
> + return (long) syscall(__NR_kexec_file_load, kernel_fd, initrd_fd,
> + cmdline_len, cmdline_ptr, flags);
> +}
> +
> #define KEXEC_ON_CRASH 0x00000001
> #define KEXEC_PRESERVE_CONTEXT 0x00000002
> #define KEXEC_ARCH_MASK 0xffff0000
>
> +/* Flags for kexec file based system call */
> +#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.
> */
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