gen_init_cpio: support file checksum archiving

Documentation/driver-api/early-userspace/buffer-format.rst includes the
specification for checksum-enabled cpio archives.  Implement support for
this format in gen_init_cpio via a new '-c' parameter.

Link: https://lkml.kernel.org/r/20220404093429.27570-6-ddiss@suse.de
Signed-off-by: David Disseldorp <ddiss@suse.de>
Suggested-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <christian.brauner@ubuntu.com>
Cc: Martin Wilck <mwilck@suse.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/usr/gen_init_cpio.c b/usr/gen_init_cpio.c
index 9a0f8c3..dc838e2 100644 (file)
--- a/usr/gen_init_cpio.c
+++ b/usr/gen_init_cpio.c
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <stdio.h>
 #include <stdlib.h>
+#include <stdint.h>
+#include <stdbool.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <string.h>
@@ -25,6 +27,7 @@
 static unsigned int offset;
 static unsigned int ino = 721;
 static time_t default_mtime;
+static bool do_csum = false;
 
 struct file_handler {
        const char *type;
@@ -78,7 +81,7 @@ static void cpio_trailer(void)
 
        sprintf(s, "%s%08X%08X%08lX%08lX%08X%08lX"
               "%08X%08X%08X%08X%08X%08X%08X",
-               "070701",               /* magic */
+               do_csum ? "070702" : "070701", /* magic */
                0,                      /* ino */
                0,                      /* mode */
                (long) 0,               /* uid */
@@ -110,7 +113,7 @@ static int cpio_mkslink(const char *name, const char *target,
                name++;
        sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
               "%08X%08X%08X%08X%08X%08X%08X",
-               "070701",               /* magic */
+               do_csum ? "070702" : "070701", /* magic */
                ino++,                  /* ino */
                S_IFLNK | mode,         /* mode */
                (long) uid,             /* uid */
@@ -159,7 +162,7 @@ static int cpio_mkgeneric(const char *name, unsigned int mode,
                name++;
        sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
               "%08X%08X%08X%08X%08X%08X%08X",
-               "070701",               /* magic */
+               do_csum ? "070702" : "070701", /* magic */
                ino++,                  /* ino */
                mode,                   /* mode */
                (long) uid,             /* uid */
@@ -253,7 +256,7 @@ static int cpio_mknod(const char *name, unsigned int mode,
                name++;
        sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
               "%08X%08X%08X%08X%08X%08X%08X",
-               "070701",               /* magic */
+               do_csum ? "070702" : "070701", /* magic */
                ino++,                  /* ino */
                mode,                   /* mode */
                (long) uid,             /* uid */
@@ -293,6 +296,29 @@ static int cpio_mknod_line(const char *line)
        return rc;
 }
 
+static int cpio_mkfile_csum(int fd, unsigned long size, uint32_t *csum)
+{
+       while (size) {
+               unsigned char filebuf[65536];
+               ssize_t this_read;
+               size_t i, this_size = MIN(size, sizeof(filebuf));
+
+               this_read = read(fd, filebuf, this_size);
+               if (this_read <= 0 || this_read > this_size)
+                       return -1;
+
+               for (i = 0; i < this_read; i++)
+                       *csum += filebuf[i];
+
+               size -= this_read;
+       }
+       /* seek back to the start for data segment I/O */
+       if (lseek(fd, 0, SEEK_SET) < 0)
+               return -1;
+
+       return 0;
+}
+
 static int cpio_mkfile(const char *name, const char *location,
                        unsigned int mode, uid_t uid, gid_t gid,
                        unsigned int nlinks)
@@ -305,6 +331,7 @@ static int cpio_mkfile(const char *name, const char *location,
        int rc = -1;
        int namesize;
        unsigned int i;
+       uint32_t csum = 0;
 
        mode |= S_IFREG;
 
@@ -332,6 +359,11 @@ static int cpio_mkfile(const char *name, const char *location,
                goto error;
        }
 
+       if (do_csum && cpio_mkfile_csum(file, buf.st_size, &csum) < 0) {
+               fprintf(stderr, "Failed to checksum file %s\n", location);
+               goto error;
+       }
+
        size = 0;
        for (i = 1; i <= nlinks; i++) {
                /* data goes on last link */
@@ -343,7 +375,7 @@ static int cpio_mkfile(const char *name, const char *location,
                namesize = strlen(name) + 1;
                sprintf(s,"%s%08X%08X%08lX%08lX%08X%08lX"
                       "%08lX%08X%08X%08X%08X%08X%08X",
-                       "070701",               /* magic */
+                       do_csum ? "070702" : "070701", /* magic */
                        ino,                    /* ino */
                        mode,                   /* mode */
                        (long) uid,             /* uid */
@@ -356,7 +388,7 @@ static int cpio_mkfile(const char *name, const char *location,
                        0,                      /* rmajor */
                        0,                      /* rminor */
                        namesize,               /* namesize */
-                       0);                     /* chksum */
+                       size ? csum : 0);       /* chksum */
                push_hdr(s);
                push_string(name);
                push_pad();
@@ -464,7 +496,7 @@ static int cpio_mkfile_line(const char *line)
 static void usage(const char *prog)
 {
        fprintf(stderr, "Usage:\n"
-               "\t%s [-t <timestamp>] <cpio_list>\n"
+               "\t%s [-t <timestamp>] [-c] <cpio_list>\n"
                "\n"
                "<cpio_list> is a file containing newline separated entries that\n"
                "describe the files to be included in the initramfs archive:\n"
@@ -499,7 +531,8 @@ static void usage(const char *prog)
                "\n"
                "<timestamp> is time in seconds since Epoch that will be used\n"
                "as mtime for symlinks, special files and directories. The default\n"
-               "is to use the current time for these entries.\n",
+               "is to use the current time for these entries.\n"
+               "-c: calculate and store 32-bit checksums for file data.\n",
                prog);
 }
 
@@ -541,7 +574,7 @@ int main (int argc, char *argv[])
 
        default_mtime = time(NULL);
        while (1) {
-               int opt = getopt(argc, argv, "t:h");
+               int opt = getopt(argc, argv, "t:ch");
                char *invalid;
 
                if (opt == -1)
@@ -556,6 +589,9 @@ int main (int argc, char *argv[])
                                exit(1);
                        }
                        break;
+               case 'c':
+                       do_csum = true;
+                       break;
                case 'h':
                case '?':
                        usage(argv[0]);