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authorGravatar Philippe Reynes <philippe.reynes@sagemcom.com>2016-06-29 17:19:44 +0200
committerGravatar Peter Korsgaard <peter@korsgaard.com>2016-06-30 12:13:38 +0200
commit688059ebb23227fb13aad319df6e78686ea6e14a (patch)
tree5a848ce8eaa5b54bdfb89aeb6fc6ab53f0f5ae53
parent4520524ba055706236db9f00dd79f1b2e2e87fde (diff)
downloadbuildroot-688059ebb23227fb13aad319df6e78686ea6e14a.tar.gz
buildroot-688059ebb23227fb13aad319df6e78686ea6e14a.tar.bz2
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>
-rw-r--r--docs/manual/makedev-syntax.txt30
-rw-r--r--package/makedevs/makedevs.c72
-rw-r--r--package/makedevs/makedevs.mk13
-rw-r--r--system/Config.in5
4 files changed, 116 insertions, 4 deletions
diff --git a/docs/manual/makedev-syntax.txt b/docs/manual/makedev-syntax.txt
index e4dffc95aa..d6efb31d42 100644
--- 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 e5ef16413e..cacb144e21 100644
--- 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 fa8e753cbd..130f5bc9cb 100644
--- 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 3018b0a7bd..15d5b55ddf 100644
--- 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"