[yocto] [meta-selinux][PATCHv2 6/8] e2fsprogs: Copy xattr block from source file.
Huang, Jie (Jackie)
Jackie.Huang at windriver.com
Sun Aug 23 22:27:08 PDT 2015
> -----Original Message-----
> From: Philip Tricca [mailto:flihp at twobit.us]
> Sent: Monday, August 24, 2015 6:25 AM
> To: Huang, Jie (Jackie)
> Cc: yocto at yoctoproject.org
> Subject: Re: [yocto] [meta-selinux][PATCHv2 6/8] e2fsprogs: Copy xattr block from source file.
>
> Hello Jackie,
>
> On 08/20/2015 11:25 PM, Huang, Jie (Jackie) wrote:
> >> -----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.pa
> >> tch
> >>
> >> 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-bl
> >> +++ ock
> >> +++ .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.
>
> I took a look at this yesterday. Creating a bbappend for linux-libc-headers and adding 'native' to
> BBCLASSEXTEND seems like the most direct fix. Add a new dependency to the e2fsprogs package and I
> think the issue is resolved. I'll send patches to the list and if you're willing to test them I'd appreciate it.
I tested with your patch and it works fine, thanks!
Thanks,
Jackie
>
> Thanks,
> Philip
>
> >> ++ },
> >> ++ { 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
> >>
> >> --
> >> _______________________________________________
> >> yocto mailing list
> >> yocto at yoctoproject.org
> >> https://lists.yoctoproject.org/listinfo/yocto
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