[yocto] [meta-selinux][PATCHv2 6/8] e2fsprogs: Copy xattr block from source file.
Huang, Jie (Jackie)
Jackie.Huang at windriver.com
Thu Aug 20 23:25:14 PDT 2015
> -----Original Message-----
> From: yocto-bounces at yoctoproject.org [mailto:yocto-bounces at yoctoproject.org] On Behalf Of Philip
> Tricca
> Sent: Thursday, June 18, 2015 6:31 AM
> To: yocto at yoctoproject.org
> Subject: [yocto] [meta-selinux][PATCHv2 6/8] e2fsprogs: Copy xattr block from source file.
>
> Signed-off-by: Philip Tricca <flihp at twobit.us>
> ---
> .../e2fsprogs/misc-xattr-create-xattr-block.patch | 341 +++++++++++++++++++++
> .../e2fsprogs/e2fsprogs_1.42.9.bbappend | 1 +
> 2 files changed, 342 insertions(+)
> create mode 100644 recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block.patch
>
> diff --git a/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block.patch b/recipes-
> devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block.patch
> new file mode 100644
> index 0000000..5955b44
> --- /dev/null
> +++ b/recipes-devtools/e2fsprogs/e2fsprogs/misc-xattr-create-xattr-block
> +++ .patch
> @@ -0,0 +1,341 @@
> +To build the xattr disk block we process the output from listxattr and
> +lgetxattr from the source file system object. This data is formated in
> +a disk block according to the format specified in the kernel ext2 file system driver.
> +See the comment block at the beginning of fs/ext2/xattr.c for details.
> +
> +Currently we only process attributes with the 'security.' prefix as our
> +use case is SELinux labels and IMA. Additional prefixes can likely be
> +supported with minimal effort but none have been tested.
> +
> +Once the xattr block has been created it is written to disk. The xattr
> +block is associated with the appropriate file system object through the
> +i_file_acl inode member and the inode is updated on disk.
> +
> +Signed-off-by: Philip Tricca <flihp at twobit.us>
> +
> +Index: e2fsprogs-1.42.9/misc/xattr.c
> +===================================================================
> +--- e2fsprogs-1.42.9.orig/misc/xattr.c
> ++++ e2fsprogs-1.42.9/misc/xattr.c
> +@@ -1,6 +1,23 @@
> + #include "xattr.h"
> +
> ++#include <attr/xattr.h>
> ++#include <ctype.h>
> ++#include <errno.h>
> ++#include <ext2fs/ext2_ext_attr.h>
> ++#include <linux/xattr.h>
> ++#include <stdint.h>
> + #include <stdio.h>
> ++#include <stdlib.h>
> ++#include <string.h>
> ++#include <sys/stat.h>
> ++#include <sys/types.h>
> ++#include <unistd.h>
> ++
> ++#define MIN(X, Y) (((X) < (Y)) ? (X) : (Y)) #define HEADER(ptr)
> ++((struct ext2_ext_attr_header *)(ptr)) #define ENTRY(ptr) ((struct
> ++ext2_ext_attr_entry *)(ptr)) #define FIRST_ENTRY(ptr)
> ++ENTRY(HEADER(ptr) + 1) #define VALUE(hdr, ent) (((char*)hdr) +
> ++(ent->e_value_offs))
> +
> + #ifdef XATTR_DEBUG
> + #define XATTR_STDERR(fmt, args...) fprintf (stderr, fmt, ##args) @@
> +-8,6 +25,28 @@ #define XATTR_STDERR(fmt, args...) do {} while (0)
> +#endif
> +
> ++/* structure for mapping xattr name prefix data */ typedef struct
> ++xattr_prefix {
> ++ int index;
> ++ char *name;
> ++ size_t length;
> ++} xattr_prefix_t;
> ++
> ++xattr_prefix_t xattr_prefixes [] = {
> ++/* Only interested in security prefix. Can support others though.
> ++ {
> ++ .index = EXT2_XATTR_INDEX_USER,
> ++ .name = XATTR_USER_PREFIX,
> ++ .length = XATTR_USER_PREFIX_LEN,
> ++ },
> ++*/
> ++ {
> ++ .index = EXT2_XATTR_INDEX_SECURITY,
> ++ .name = XATTR_SECURITY_PREFIX,
> ++ .length = XATTR_SECURITY_PREFIX_LEN,
Hi Philip,
This cause build errors on some host OS when building e2fsprogs-native:
| /build/yp/y_x64_150821/tmp/work/x86_64-linux/e2fsprogs-native/1.42.9-r0/e2fsprogs-1.42.9/debugfs/../misc/xattr.c:62:11: error: 'XATTR_SECURITY_PREFIX' undeclared here (not in a function)
| .name = XATTR_SECURITY_PREFIX,
| ^
| /build/yp/y_x64_150821/tmp/work/x86_64-linux/e2fsprogs-native/1.42.9-r0/e2fsprogs-1.42.9/debugfs/../misc/xattr.c:63:13: error: 'XATTR_SECURITY_PREFIX_LEN' undeclared here (not in a function)
| .length = XATTR_SECURITY_PREFIX_LEN,
| ^
I did some investigate and found that your patch needs the header linux/xattr.h,
which is provided by linux-libc-headers, but for -native package, there is no linux-libc-headers-native,
so it search the one from host OS, but the problem is, there is no XATTR_SECURITY_PREFIX definition
in the linux/xattr.h on some host OS like: SUSE 11.x, centos 6, etc.
I'm not sure if your patch is really needed by the e2fsprogs-native, if not, I think we can make this
patch only apply for target package. If yes, you may need to make it avoid the dependency on host's
header or you may have a better idea about this.
Thanks,
Jackie
> ++ },
> ++ { 0 },
> ++};
> +
> + /* Free remaining resources after all files have been processed. */
> +void @@ -16,6 +55,211 @@ xattr_cleanup ()
> + XATTR_STDERR ("Cleaning up resources from xattrs.\n"); }
> +
> ++/* Get value for named xattr from file at path.
> ++ * Returns pointer to allocated block for value and length in length param.
> ++ * If no value, return NULL pointer and length of 0.
> ++ * On error return NULL pointer and length set to -1.
> ++ */
> ++static char*
> ++xattr_get_value (const char *path, const char *name, ssize_t *length)
> ++{
> ++ char *value = NULL;
> ++
> ++ *length = lgetxattr (path, name, NULL, 0);
> ++ if (*length == -1) {
> ++ com_err (__func__, errno, "lgetattr");
> ++ goto out;
> ++ }
> ++ if (*length == 0) {
> ++ fprintf (stderr, "xattr %s has value length 0\n", name);
> ++ goto out;
> ++ }
> ++ value = calloc (1, *length);
> ++ if (value == NULL) {
> ++ com_err (__func__, errno, "calloc");
> ++ goto out;
> ++ }
> ++ *length = lgetxattr (path, name, value, *length);
> ++ if (*length == -1) {
> ++ com_err (__func__, errno, "lgetattr");
> ++ goto value_err;
> ++ }
> ++out:
> ++ return value;
> ++
> ++value_err:
> ++ if (value)
> ++ free (value);
> ++ return NULL;
> ++}
> ++
> ++/* Get all attribute names for file at path. Return pointer to
> ++allocated memory
> ++ * block holding all names and the length through parameter size.
> ++ * If no xattrs: return NULL and set size to 0
> ++ * If error: return NULL and set size to -1 */ static char*
> ++xattr_get_names (const char *path, ssize_t *size) {
> ++ char *names = NULL;
> ++
> ++ *size = llistxattr (path, NULL, 0);
> ++ if (*size == -1) {
> ++ com_err (__func__, errno, "llistxattr");
> ++ goto out;
> ++ }
> ++ if (*size == 0) {
> ++ /* no xattrs */
> ++ goto out;
> ++ }
> ++ names = calloc (1, *size);
> ++ if (names == NULL) {
> ++ com_err (__func__, errno, "calloc");
> ++ goto out;
> ++ }
> ++ *size = llistxattr (path, names, *size);
> ++ if (*size == -1) {
> ++ com_err (__func__, errno, "llistxattr");
> ++ goto cleanup;
> ++ }
> ++ if (*size == 0) {
> ++ fprintf (stdout, "Conflicting data, no xattrs for file: %s\n", path);
> ++ goto cleanup;
> ++ }
> ++out:
> ++ return names;
> ++
> ++cleanup:
> ++ if (names)
> ++ free (names);
> ++ return NULL;
> ++}
> ++
> ++/* return pointer to next string in xattr name block, don't go beyond
> ++length */ static inline char* next_name (char *name, size_t length) {
> ++ int i = 0;
> ++
> ++ for (i = 0; i < length; ++i)
> ++ if (name [i] == '\0') {
> ++ ++i;
> ++ break;
> ++ }
> ++
> ++ return name + i;
> ++}
> ++
> ++/* Find entry in xattr_table with matching prefix. */ static const
> ++xattr_prefix_t* xattr_find_prefix (char *name, size_t length) {
> ++ int i = 0;
> ++
> ++ XATTR_STDERR ("find_attr_data: searching for prefix from xattr name: %s\n", name);
> ++ for (i = 0; xattr_prefixes[i].index != 0; ++i) {
> ++ if (!strncmp (name, xattr_prefixes[i].name, MIN (length, xattr_prefixes[i].length))) {
> ++ XATTR_STDERR ("found match in table with index: %d\n",
> xattr_prefixes[i].index);
> ++ return &xattr_prefixes[i];
> ++ }
> ++ }
> ++ return NULL;
> ++}
> ++
> ++/* Query file at path for attributes. build up structure the file
> ++system
> ++ * expects of an extended attribute disk block (header parameter).
> ++ *
> ++ * The main loop walks through the xattr names one at a time. It gets
> ++the value
> ++ * for each named xattr and copies the data into the xattr block
> ++pointed to by
> ++ * the header parameter. To do this the loop also tracks the location
> ++of the
> ++ * associated entry and value. Values start at the end of the buffer
> ++and grow
> ++ * back towards the header while the entries start immediately after
> ++the header
> ++ * and grow towards the end of the block.
> ++ *
> ++ * See the comment block at the beginning of the xattr.c file in the
> ++ext2 file
> ++ * system code in the kernel: fs/ext2/xattr.c
> ++ * Assume the xattr block pointed to by header parameter is initialized to 0s.
> ++ */
> ++static int
> ++xattr_build_block (const char *path,
> ++ struct ext2_ext_attr_header **header,
> ++ size_t header_length)
> ++{
> ++ struct ext2_ext_attr_entry *entry = NULL;
> ++ char *names = NULL, *value = NULL, *name_curr = NULL;
> ++ ssize_t names_length = 0, value_length = 0;
> ++ size_t name_length = 0, value_index = 0, len_rem = 0;
> ++ const xattr_prefix_t *prefix = NULL;
> ++ int ret = 0;
> ++
> ++ XATTR_STDERR ("xattr_build_block for file: %s\n", path);
> ++ *header = NULL;
> ++ names = xattr_get_names (path, &names_length);
> ++ if (names == NULL) {
> ++ // no xattrs for file @ path or error
> ++ ret = names_length;
> ++ goto out;
> ++ }
> ++ *header = calloc (1, header_length);
> ++ if (*header == NULL) {
> ++ com_err (__func__, errno, "calloc");
> ++ goto out;
> ++ }
> ++ (*header)->h_magic = EXT2_EXT_ATTR_MAGIC;
> ++ (*header)->h_blocks = 1;
> ++ /* Values start at end of buffer. NOTE: It must be moved before a value can
> ++ * be stored.
> ++ */
> ++ value_index = header_length;
> ++ for (name_curr = names, entry = FIRST_ENTRY(*header), len_rem = names_length;
> ++ name_curr < names + names_length;
> ++ len_rem = names_length - (name_curr - names),
> ++ name_curr = next_name (name_curr, len_rem),
> ++ entry = EXT2_EXT_ATTR_NEXT(entry))
> ++ {
> ++ XATTR_STDERR ("xattr_build_block: processing xattr with name %s\n", name_curr);
> ++ name_length = strnlen (name_curr, len_rem);
> ++ prefix = xattr_find_prefix (name_curr, name_length);
> ++ if (!prefix) {
> ++ fprintf (stderr, "Don't currently handle xattr: %s\n", name_curr);
> ++ continue;
> ++ }
> ++ value = xattr_get_value (path, name_curr, &value_length);
> ++ if (value == NULL) {
> ++ // no xattr value or error
> ++ fprintf (stderr, "failed to get value, skipping\n");
> ++ goto next;
> ++ }
> ++ /* setup offsets and lengths for name and value */
> ++ entry->e_name_len = name_length - prefix->length;
> ++ entry->e_name_index = prefix->index;
> ++ /* Can't know these till we know the length of the value. */
> ++ entry->e_value_offs = value_index -= EXT2_EXT_ATTR_SIZE(value_length);
> ++ entry->e_value_size = value_length;
> ++ /* Check to be sure entry name and value don't overlap before copy. */
> ++ if (EXT2_EXT_ATTR_NAME(entry) + entry->e_name_len > VALUE(*header, entry)) {
> ++ fprintf (stderr, "xattr entry name and value overlap! Too much xattr data.");
> ++ ret = -1;
> ++ goto out;
> ++ }
> ++ /* copy name and value data then calculate the hash */
> ++ memcpy (EXT2_EXT_ATTR_NAME(entry),
> ++ name_curr + prefix->length,
> ++ entry->e_name_len);
> ++ memcpy (VALUE(*header, entry), value, entry->e_value_size);
> ++ entry->e_hash = ext2fs_ext_attr_hash_entry (entry, VALUE(*header,
> ++entry));
> ++next:
> ++ if (value)
> ++ free (value);
> ++ }
> ++ XATTR_STDERR ("xattr_build_block: done building xattr buffer\n");
> ++out:
> ++ if (names)
> ++ free (names);
> ++ return ret;
> ++}
> ++
> + /* This is the entry point to the xattr module. This function copies
> +the xattrs
> + * from the file at 'path' to the file system object at 'ino'.
> + *
> +@@ -28,7 +272,56 @@ errcode_t
> + set_inode_xattr (ext2_filsys fs, ext2_ino_t ino, const char *path) {
> + errcode_t ret = 0;
> ++ char *buf = NULL;
> ++ struct ext2_inode inode = { 0 };
> ++ blk_t block = 0;
> ++ struct ext2_ext_attr_header *header = NULL;
> ++ uint32_t newcount = 0;
> +
> + XATTR_STDERR ("Copying xattrs from %s to inode 0x%x.\n", path, ino);
> ++ /* Populate the xattr block for the file at path */
> ++ if (ret = xattr_build_block (path, &header, fs->blocksize)) {
> ++ goto out;
> ++ }
> ++ if (header == NULL) {
> ++ XATTR_STDERR ("set_inode_xattrs: no xattrs for %s\n", path);
> ++ goto out;
> ++ }
> ++ if (ret = ext2fs_read_inode (fs, ino, &inode)) {
> ++ com_err(__func__, ret, "ext2fs_read_inode");
> ++ goto out;
> ++ }
> ++ if (ret = ext2fs_alloc_block (fs, 0, NULL, &block)) {
> ++ com_err(__func__, ret, "ext2fs_alloc_block: returned %d", ret);
> ++ goto out;
> ++ }
> ++ ext2fs_mark_block_bitmap2 (fs->block_map, block);
> ++ XATTR_STDERR ("writing xattr block 0x%x to disk:\n", block);
> ++ if (ret = ext2fs_write_ext_attr (fs, block, header)) {
> ++ com_err(__func__, ret, "ext2fs_write_ext_attr: returned %d", ret);
> ++ goto out;
> ++ }
> ++ /* point inode for current file to xattr block, update block count and
> ++ * write inode to disk
> ++ */
> ++ inode.i_file_acl = block;
> ++ if (ret = ext2fs_adjust_ea_refcount2(fs,
> ++ block,
> ++ (char*)header,
> ++ 1,
> ++ &newcount))
> ++ {
> ++ com_err(__func__, ret, "ext2fs_adjust_ea_refcount");
> ++ goto out;
> ++ }
> ++ if (ret = ext2fs_iblk_add_blocks (fs, &inode, 1)) {
> ++ com_err(__func__, ret, "ext2fs_iblk_add_blocks failed");
> ++ goto out;
> ++ }
> ++ if (ret = ext2fs_write_inode (fs, ino, &inode))
> ++ com_err(__func__, ret, "ext2fs_write_inode: returned %d", ret);
> ++out:
> ++ if (header)
> ++ free (header);
> + return ret;
> + }
> diff --git a/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend b/recipes-
> devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
> index a4576b1..edc94d8 100644
> --- a/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
> +++ b/recipes-devtools/e2fsprogs/e2fsprogs_1.42.9.bbappend
> @@ -4,4 +4,5 @@ SRC_URI += " \
> file://misc-xattr-add-xattr-module-stub.patch \
> file://mke2fs.c-create_inode.c-copy-xattrs.patch \
> file://lib-ext2fs-ext2_ext_attr.h-add-xattr-index.patch \
> + file://misc-xattr-create-xattr-block.patch \
> "
> --
> 2.1.4
>
> --
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