makedevs: add capability support

Add the support of capability to makedevs as extended attribute.
Now, it's possible to add a  line "|xattr <capability>" after a
file description to also add a capability to this file. It's
possible to add severals capabilities with severals lines.

[Peter: extend doc, reword Config.in, extend error message,
	use HOST_MAKEDEVS_CFLAGS/LDFLAGS for all flags]
Signed-off-by: Philippe Reynes <philippe.reynes@sagemcom.com>
Signed-off-by: Peter Korsgaard <peter@korsgaard.com>

diff --git a/docs/manual/makedev-syntax.txt b/docs/manual/makedev-syntax.txt
index e4dffc95aaad5f275f0d32475e331b6b36e5efac..d6efb31d4210ca99bff7cd167782520b21df08ce 100644 (file)
--- a/docs/manual/makedev-syntax.txt
+++ b/docs/manual/makedev-syntax.txt
@@ -71,3 +71,33 @@ and then for device files corresponding to the partitions of
 /dev/hda b 640 root root 3 1 1 1 15
 ----
 
+Extended attributes are supported if
++BR2_ROOTFS_DEVICE_TABLE_SUPPORTS_EXTENDED_ATTRIBUTES+ is enabled.
+This is done by adding a line starting with +|xattr+ after
+the line describing the file. Right now, only capability
+is supported as extended attribute.
+
+|=====================
+| \|xattr | capability
+|=====================
+
+- +|xattr+ is a "flag" that indicate an extended attribute
+- +capability+ is a capability to add to the previous file
+
+If you want to add the capability cap_sys_admin to the binary foo,
+you will write :
+
+----
+/usr/bin/foo f 755 root root - - - - -
+|xattr cap_sys_admin+eip
+----
+
+You can add several capabilities to a file by using several +|xattr+ lines.
+If you want to add the capability cap_sys_admin and cap_net_admin to the
+binary foo, you will write :
+
+----
+/usr/bin/foo f 755 root root - - - - -
+|xattr cap_sys_admin+eip
+|xattr cap_net_admin+eip
+----

diff --git a/package/makedevs/makedevs.c b/package/makedevs/makedevs.c
index e5ef16413e65a124a79dce323d2af6272975f670..cacb144e2147ab75ccda5ef1f44e76a285a9e124 100644 (file)
--- a/package/makedevs/makedevs.c
+++ b/package/makedevs/makedevs.c
@@ -35,6 +35,9 @@
 #include <sys/sysmacros.h>     /* major() and minor() */
 #endif
 #include <ftw.h>
+#ifdef EXTENDED_ATTRIBUTES
+#include <sys/capability.h>
+#endif /* EXTENDED_ATTRIBUTES */
 
 const char *bb_applet_name;
 uid_t recursive_uid;
@@ -349,6 +352,49 @@ char *concat_path_file(const char *path, const char *filename)
        return outbuf;
 }
 
+#ifdef EXTENDED_ATTRIBUTES
+int bb_set_xattr(const char *fpath, const char *xattr)
+{
+       cap_t cap, cap_file, cap_new;
+       char *cap_file_text, *cap_new_text;
+       ssize_t length;
+
+       cap = cap_from_text(xattr);
+       if (cap == NULL)
+               bb_perror_msg_and_die("cap_from_text failed for %s", xattr);
+
+       cap_file = cap_get_file(fpath);
+       if (cap_file == NULL) {
+               /* if no capability was set before, we initialize cap_file */
+               if (errno != ENODATA)
+                       bb_perror_msg_and_die("cap_get_file failed on %s", fpath);
+
+               cap_file = cap_init();
+               if (!cap_file)
+                       bb_perror_msg_and_die("cap_init failed");
+       }
+
+       if ((cap_file_text = cap_to_text(cap_file, &length)) == NULL)
+               bb_perror_msg_and_die("cap_to_name failed on %s", fpath);
+
+       bb_xasprintf(&cap_new_text, "%s %s", cap_file_text, xattr);
+
+       if ((cap_new = cap_from_text(cap_new_text)) == NULL)
+               bb_perror_msg_and_die("cap_from_text failed on %s", cap_new_text);
+
+       if (cap_set_file(fpath, cap_new) == -1)
+               bb_perror_msg_and_die("cap_set_file failed for %s (xattr = %s)", fpath, xattr);
+
+       cap_free(cap);
+       cap_free(cap_file);
+       cap_free(cap_file_text);
+       cap_free(cap_new);
+       cap_free(cap_new_text);
+
+       return 0;
+}
+#endif /* EXTENDED_ATTRIBUTES */
+
 void bb_show_usage(void)
 {
        fprintf(stderr, "%s: [-d device_table] rootdir\n\n", bb_applet_name);
@@ -413,6 +459,7 @@ int main(int argc, char **argv)
        int opt;
        FILE *table = stdin;
        char *rootdir = NULL;
+       char *full_name = NULL;
        char *line = NULL;
        int linenum = 0;
        int ret = EXIT_SUCCESS;
@@ -454,15 +501,30 @@ int main(int argc, char **argv)
                unsigned int count = 0;
                unsigned int increment = 0;
                unsigned int start = 0;
+               char xattr[255];
                char name[4096];
                char user[41];
                char group[41];
-               char *full_name;
                uid_t uid;
                gid_t gid;
 
                linenum++;
 
+               if (1 == sscanf(line, "|xattr %254s", xattr)) {
+#ifdef EXTENDED_ATTRIBUTES
+                       if (!full_name)
+                               bb_error_msg_and_die("line %d should be after a file\n", linenum);
+
+                       if (bb_set_xattr(full_name, xattr) < 0)
+                               bb_error_msg_and_die("can't set cap %s on file %s\n", xattr, full_name);
+#else
+                       bb_error_msg_and_die("line %d not supported: '%s'\nDid you forget to enable "
+                                            "BR2_ROOTFS_DEVICE_TABLE_SUPPORTS_EXTENDED_ATTRIBUTES?\n",
+                                            linenum, line);
+#endif /* EXTENDED_ATTRIBUTES */
+                       continue;
+               }
+
                if ((2 > sscanf(line, "%4095s %c %o %40s %40s %u %u %u %u %u", name,
                                                &type, &mode, user, group, &major,
                                                &minor, &start, &increment, &count)) ||
@@ -487,6 +549,13 @@ int main(int argc, char **argv)
                } else {
                        uid = getuid();
                }
+
+               /*
+                * free previous full name
+                * we don't de-allocate full_name at the end of the parsing,
+                * because we may need it if the next line is an xattr.
+                */
+               free(full_name);
                full_name = concat_path_file(rootdir, name);
 
                if (type == 'd') {
@@ -585,7 +654,6 @@ int main(int argc, char **argv)
                }
 loop:
                free(line);
-               free(full_name);
        }
        fclose(table);
 

diff --git a/package/makedevs/makedevs.mk b/package/makedevs/makedevs.mk
index fa8e753cbdaccbdf6e5713013b5f98caf2a3f406..130f5bc9cbeef16e759e37bbe1653b7060980ad0 100644 (file)
--- a/package/makedevs/makedevs.mk
+++ b/package/makedevs/makedevs.mk
@@ -11,6 +11,15 @@ HOST_MAKEDEVS_SOURCE =
 MAKEDEVS_VERSION = buildroot-$(BR2_VERSION)
 MAKEDEVS_LICENSE = GPLv2
 
+HOST_MAKEDEVS_CFLAGS = $(HOST_CFLAGS)
+HOST_MAKEDEVS_LDFLAGS = $(HOST_LDFLAGS)
+
+ifeq ($(BR2_ROOTFS_DEVICE_TABLE_SUPPORTS_EXTENDED_ATTRIBUTES),y)
+HOST_MAKEDEVS_DEPENDENCIES += host-libcap
+HOST_MAKEDEVS_CFLAGS += -DEXTENDED_ATTRIBUTES
+HOST_MAKEDEVS_LDFLAGS += -lcap
+endif
+
 define MAKEDEVS_BUILD_CMDS
        $(TARGET_CC) $(TARGET_CFLAGS) $(TARGET_LDFLAGS) \
                package/makedevs/makedevs.c -o $(@D)/makedevs
@@ -21,8 +30,8 @@ define MAKEDEVS_INSTALL_TARGET_CMDS
 endef
 
 define HOST_MAKEDEVS_BUILD_CMDS
-       $(HOSTCC) $(HOST_CFLAGS) $(HOST_LDFLAGS) \
-               package/makedevs/makedevs.c -o $(@D)/makedevs
+       $(HOSTCC) $(HOST_MAKEDEVS_CFLAGS) package/makedevs/makedevs.c \
+               -o $(@D)/makedevs $(HOST_MAKEDEVS_LDFLAGS)
 endef
 
 define HOST_MAKEDEVS_INSTALL_CMDS

diff --git a/system/Config.in b/system/Config.in
index 3018b0a7bdde570bd3d76d24bb1bd6dd16085224..15d5b55ddfb8de6d1666e4c50e9a772149b73349 100644 (file)
--- a/system/Config.in
+++ b/system/Config.in
@@ -162,6 +162,11 @@ config BR2_ROOTFS_STATIC_DEVICE_TABLE
          See package/makedevs/README for details on the usage and
          syntax of these files.
 
+config BR2_ROOTFS_DEVICE_TABLE_SUPPORTS_EXTENDED_ATTRIBUTES
+       bool "support extended attributes in device tables"
+       help
+         Support extended attributes handling in device tables
+
 choice
        prompt "Root FS skeleton"