linux-kernel - [PATCH 2.6.28-rc2] gen_init_cpio expands shell variables in file names

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [thread-next>] [day] [month] [year] [list]

Message-ID: <CFEB29247FA6A94796A15592E348E7B90D2706EE30@exchange07.timesys.com>
Date:	Wed, 29 Oct 2008 09:54:17 -0400
From:	"Sally, Gene" <Gene.Sally@...esys.com>
To:	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: [PATCH 2.6.28-rc2] gen_init_cpio expands shell variables in file
 names

Hi,

This patch modifies gen_init_cpio so that lines that specify files can contain what looks like a shell variable that's expanded during processing.

For example:

file /sbin/kinit ${RFS_BASE}/usr/src/klibc/kinit/kinit 0755 0 0

given RFS_BASE is "/some/directory" in the environment

would be expanded to

file /sbin/kinit /some/directory/usr/src/klibc/kinit/kinit 0755 0 0

If several environment variables appear in a line, they are all expanded with processing happening from left to right.  Undefined variables expand to a null string.  Syntax errors stop processing, letting the existing error handling show the user offending line.

This patch helps embedded folks who frequently create several RFS directories and then switch between them as they're tuning an initramfs.  Having just been such an embedded folk, this seems the most efficient solution.

I didn't see a maintainer for this area (forgive me if I overlooked) so I don't know who I should CC for this patch.

Regards,
gene

--- a/usr/gen_init_cpio.c
+++ b/usr/gen_init_cpio.c
@@ -370,6 +370,30 @@ error:
        return rc;
 }

+static char *cpio_replace_env(char *new_location)
+{
+       char expanded[PATH_MAX + 1];
+       char env_var[PATH_MAX + 1];
+       char *start;
+       char *end;
+
+       for (start = NULL; (start = strstr(new_location, "${")); ) {
+               end = strchr(start, '}');
+               if (start < end) {
+                       *env_var = *expanded = '\0';
+                       strncat(env_var, start + 2, end - start - 2);
+                       strncat(expanded, new_location, start - new_location);
+                       strncat(expanded, getenv(env_var), PATH_MAX);
+                       strncat(expanded, end + 1, PATH_MAX);
+                       strncpy(new_location, expanded, PATH_MAX);
+               } else
+                       break;
+       }
+
+       return new_location;
+}
+
+
 static int cpio_mkfile_line(const char *line)
 {
        char name[PATH_MAX + 1];
@@ -415,7 +439,8 @@ static int cpio_mkfile_line(const char *line)
        } else {
                dname = name;
        }
-       rc = cpio_mkfile(dname, location, mode, uid, gid, nlinks);
+       rc = cpio_mkfile(dname, cpio_replace_env(location),
+                        mode, uid, gid, nlinks);
  fail:
        if (dname_len) free(dname);
        return rc;
@@ -439,6 +464,7 @@ void usage(const char *prog)
                "\n"
                "<name>       name of the file/dir/nod/etc in the archive\n"
                "<location>   location of the file in the current filesystem\n"
+               "             expands shell variables quoted with ${}\n"
                "<target>     link target\n"
                "<mode>       mode/permissions of the file\n"
                "<uid>        user id (0=root)\n"

Signed-off-by: gene.sally@...esys.com


--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/