From: Philippe Reynes Date: Wed, 29 Jun 2016 15:19:44 +0000 (+0200) Subject: makedevs: add capability support X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=688059ebb23227fb13aad319df6e78686ea6e14a;p=buildroot.git makedevs: add capability support Add the support of capability to makedevs as extended attribute. Now, it's possible to add a line "|xattr " 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 Signed-off-by: Peter Korsgaard --- 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 /* major() and minor() */ #endif #include +#ifdef EXTENDED_ATTRIBUTES +#include +#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"