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libtar: backup and restore posix capabilities

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This patch also allows libtar to combine data from multiple extended
tar headers into a single header.

Change-Id: I82d13e89a3622ea665b60062b1904ddbedfa41b3
This commit is contained in:
Ethan Yonker
2017-01-13 13:30:10 -06:00
committed by Dees Troy
parent a083dc68c6
commit 7118774ec9
6 changed files with 174 additions and 116 deletions
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libtar/append.c
+22
View File
@@ -22,6 +22,10 @@
#include <sys/types.h>
#include <stdbool.h>
#include <sys/capability.h>
#include <sys/xattr.h>
#include <linux/xattr.h>
#ifdef STDC_HEADERS
# include <stdlib.h>
# include <string.h>
@@ -154,6 +158,24 @@ tar_append_file(TAR *t, const char *realname, const char *savename)
}
#endif
/* get posix file capabilities */
if (TH_ISREG(t) && t->options & TAR_STORE_POSIX_CAP)
{
if (t->th_buf.has_cap_data)
{
memset(&t->th_buf.cap_data, 0, sizeof(struct vfs_cap_data));
t->th_buf.has_cap_data = 0;
}
if (getxattr(realname, XATTR_NAME_CAPS, &t->th_buf.cap_data, sizeof(struct vfs_cap_data)) >= 0)
{
t->th_buf.has_cap_data = 1;
#if 1 //def DEBUG
print_caps(&t->th_buf.cap_data);
#endif
}
}
/* check if it's a hardlink */
#ifdef DEBUG
puts("tar_append_file(): checking inode cache for hardlink...");
libtar/block.c
+118 -112
View File
@@ -29,6 +29,10 @@
#define E4CRYPT_TAG "TWRP.security.e4crypt="
#define E4CRYPT_TAG_LEN 22
// Used to identify Posix capabilities in extended ('x')
#define CAPABILITIES_TAG "SCHILY.xattr.security.capability="
#define CAPABILITIES_TAG_LEN 33
/* read a header block */
/* FIXME: the return value of this function should match the return value
of tar_block_read(), which is a macro which references a prototype
@@ -128,6 +132,11 @@ th_read(TAR *t)
free(t->th_buf.e4crypt_policy);
}
#endif
if (t->th_buf.has_cap_data)
{
memset(&t->th_buf.cap_data, 0, sizeof(struct vfs_cap_data));
t->th_buf.has_cap_data = 0;
}
memset(&(t->th_buf), 0, sizeof(struct tar_header));
@@ -241,8 +250,8 @@ th_read(TAR *t)
}
}
#ifdef HAVE_SELINUX
if(TH_ISEXTHEADER(t))
// Extended headers (selinux contexts, posix file capabilities, ext4 encryption policies)
while(TH_ISEXTHEADER(t) || TH_ISPOLHEADER(t))
{
sz = th_get_size(t);
@@ -267,7 +276,19 @@ th_read(TAR *t)
buf[T_BLOCKSIZE-1] = 0;
int len = strlen(buf);
char *start = strstr(buf, SELINUX_TAG);
// posix capabilities
char *start = strstr(buf, CAPABILITIES_TAG);
if(start && start+CAPABILITIES_TAG_LEN < buf+len)
{
start += CAPABILITIES_TAG_LEN;
memcpy(&t->th_buf.cap_data, start, sizeof(struct vfs_cap_data));
t->th_buf.has_cap_data = 1;
#ifdef DEBUG
printf(" th_read(): Posix capabilities detected\n");
#endif
} // end posix capabilities
#ifdef HAVE_SELINUX // selinux contexts
start = strstr(buf, SELINUX_TAG);
if(start && start+SELINUX_TAG_LEN < buf+len)
{
start += SELINUX_TAG_LEN;
@@ -280,45 +301,9 @@ th_read(TAR *t)
#endif
}
}
}
i = th_read_internal(t);
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
}
#endif
#endif // HAVE_SELINUX
#ifdef HAVE_EXT4_CRYPT
if(TH_ISPOLHEADER(t))
{
sz = th_get_size(t);
if(sz >= T_BLOCKSIZE) // Not supported
{
#ifdef DEBUG
printf(" th_read(): Policy header is too long!\n");
#endif
}
else
{
char buf[T_BLOCKSIZE];
i = tar_block_read(t, buf);
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
// To be sure
buf[T_BLOCKSIZE-1] = 0;
int len = strlen(buf);
char *start = strstr(buf, E4CRYPT_TAG);
start = strstr(buf, E4CRYPT_TAG);
if(start && start+E4CRYPT_TAG_LEN < buf+len)
{
start += E4CRYPT_TAG_LEN;
@@ -331,6 +316,7 @@ th_read(TAR *t)
#endif
}
}
#endif // HAVE_EXT4_CRYPT
}
i = th_read_internal(t);
@@ -341,11 +327,55 @@ th_read(TAR *t)
return -1;
}
}
#endif
return 0;
}
/* write an extended block */
static int
th_write_extended(TAR *t, char* buf, uint64_t sz)
{
char type2;
uint64_t sz2;
int i;
/* save old size and type */
type2 = t->th_buf.typeflag;
sz2 = th_get_size(t);
/* write out initial header block with fake size and type */
t->th_buf.typeflag = TH_EXT_TYPE;
if(sz >= T_BLOCKSIZE) // impossible
{
errno = EINVAL;
return -1;
}
th_set_size(t, sz);
th_finish(t);
i = tar_block_write(t, &(t->th_buf));
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
i = tar_block_write(t, buf);
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
/* reset type and size to original values */
t->th_buf.typeflag = type2;
th_set_size(t, sz2);
memset(buf, 0, T_BLOCKSIZE);
return 0;
}
/* write a header block */
int
@@ -353,7 +383,7 @@ th_write(TAR *t)
{
int i, j;
char type2;
uint64_t sz, sz2;
uint64_t sz, sz2, total_sz = 0;
char *ptr;
char buf[T_BLOCKSIZE];
@@ -464,6 +494,8 @@ th_write(TAR *t)
th_set_size(t, sz2);
}
memset(buf, 0, T_BLOCKSIZE);
ptr = buf;
#ifdef HAVE_SELINUX
if((t->options & TAR_STORE_SELINUX) && t->th_buf.selinux_context != NULL)
{
@@ -471,13 +503,6 @@ th_write(TAR *t)
printf("th_write(): using selinux_context (\"%s\")\n",
t->th_buf.selinux_context);
#endif
/* save old size and type */
type2 = t->th_buf.typeflag;
sz2 = th_get_size(t);
/* write out initial header block with fake size and type */
t->th_buf.typeflag = TH_EXT_TYPE;
/* setup size - EXT header has format "*size of this whole tag as ascii numbers* *space* *content* *newline* */
// size newline
sz = SELINUX_TAG_LEN + strlen(t->th_buf.selinux_context) + 3 + 1;
@@ -485,35 +510,9 @@ th_write(TAR *t)
if(sz >= 100) // another ascci digit for size
++sz;
if(sz >= T_BLOCKSIZE) // impossible
{
errno = EINVAL;
return -1;
}
th_set_size(t, sz);
th_finish(t);
i = tar_block_write(t, &(t->th_buf));
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
memset(buf, 0, T_BLOCKSIZE);
snprintf(buf, T_BLOCKSIZE, "%d "SELINUX_TAG"%s\n", (int)sz, t->th_buf.selinux_context);
i = tar_block_write(t, &buf);
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
/* reset type and size to original values */
t->th_buf.typeflag = type2;
th_set_size(t, sz2);
total_sz += sz;
snprintf(ptr, T_BLOCKSIZE, "%d "SELINUX_TAG"%s\n", (int)sz, t->th_buf.selinux_context);
ptr += sz;
}
#endif
@@ -524,13 +523,6 @@ th_write(TAR *t)
printf("th_write(): using e4crypt_policy %s\n",
t->th_buf.e4crypt_policy);
#endif
/* save old size and type */
type2 = t->th_buf.typeflag;
sz2 = th_get_size(t);
/* write out initial header block with fake size and type */
t->th_buf.typeflag = TH_POL_TYPE;
/* setup size - EXT header has format "*size of this whole tag as ascii numbers* *space* *content* *newline* */
// size newline
sz = E4CRYPT_TAG_LEN + EXT4_KEY_DESCRIPTOR_HEX + 3 + 1;
@@ -538,38 +530,52 @@ th_write(TAR *t)
if(sz >= 100) // another ascci digit for size
++sz;
if(sz >= T_BLOCKSIZE) // impossible
if (total_sz + sz >= T_BLOCKSIZE)
{
errno = EINVAL;
return -1;
if (th_write_extended(t, &buf, total_sz))
return -1;
ptr = buf;
total_sz = sz;
}
else
total_sz += sz;
th_set_size(t, sz);
th_finish(t);
i = tar_block_write(t, &(t->th_buf));
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
memset(buf, 0, T_BLOCKSIZE);
snprintf(buf, T_BLOCKSIZE, "%d "E4CRYPT_TAG"%s\n", (int)sz, t->th_buf.e4crypt_policy);
i = tar_block_write(t, &buf);
if (i != T_BLOCKSIZE)
{
if (i != -1)
errno = EINVAL;
return -1;
}
/* reset type and size to original values */
t->th_buf.typeflag = type2;
th_set_size(t, sz2);
snprintf(ptr, T_BLOCKSIZE, "%d "E4CRYPT_TAG"%s", (int)sz, t->th_buf.e4crypt_policy);
char *nlptr = ptr + sz - 1;
*nlptr = '\n';
ptr += sz;
}
#endif
if((t->options & TAR_STORE_POSIX_CAP) && t->th_buf.has_cap_data)
{
#ifdef DEBUG
printf("th_write(): has a posix capability\n");
#endif
sz = CAPABILITIES_TAG_LEN + sizeof(struct vfs_cap_data) + 3 + 1;
if(sz >= 100) // another ascci digit for size
++sz;
if (total_sz + sz >= T_BLOCKSIZE)
{
if (th_write_extended(t, &buf, total_sz))
return -1;
ptr = buf;
total_sz = sz;
}
else
total_sz += sz;
snprintf(ptr, T_BLOCKSIZE, "%d "CAPABILITIES_TAG, (int)sz);
memcpy(ptr + CAPABILITIES_TAG_LEN + 3, &t->th_buf.cap_data, sizeof(struct vfs_cap_data));
char *nlptr = ptr + sz - 1;
*nlptr = '\n';
ptr += sz;
}
if (total_sz > 0 && th_write_extended(t, &buf, total_sz)) // write any outstanding tar extended header
return -1;
th_finish(t);
#ifdef DEBUG
libtar/extract.c
+14
View File
@@ -20,6 +20,10 @@
#include <errno.h>
#include <utime.h>
#include <sys/capability.h>
#include <sys/xattr.h>
#include <linux/xattr.h>
#ifdef STDC_HEADERS
# include <stdlib.h>
#endif
@@ -166,6 +170,16 @@ tar_extract_file(TAR *t, const char *realname, const char *prefix, const int *pr
}
#endif
if((t->options & TAR_STORE_POSIX_CAP) && t->th_buf.has_cap_data)
{
#if 1 //def DEBUG
printf("tar_extract_file(): restoring posix capabilities to file %s\n", realname);
print_caps(&t->th_buf.cap_data);
#endif
if (setxattr(realname, XATTR_NAME_CAPS, &t->th_buf.cap_data, sizeof(struct vfs_cap_data), 0) < 0)
fprintf(stderr, "tar_extract_file(): failed to restore posix capabilities to file %s !!!\n", realname);
}
#ifdef LIBTAR_FILE_HASH
pn = th_get_pathname(t);
pathname_len = strlen(pn) + 1;
libtar/libtar.h
+9 -2
View File
@@ -15,6 +15,7 @@
#include <sys/types.h>
#include <sys/stat.h>
#include <linux/capability.h>
#include "tar.h"
#include "libtar_listhash.h"
@@ -43,7 +44,7 @@ extern "C"
/* extended metadata for next file - used to store selinux_context */
#define TH_EXT_TYPE 'x'
#define TH_POL_TYPE 'p'
#define TH_POL_TYPE_DO_NOT_USE 'p'
/* our version of the tar header structure */
struct tar_header
@@ -73,6 +74,8 @@ struct tar_header
#ifdef HAVE_EXT4_CRYPT
char *e4crypt_policy;
#endif
int has_cap_data;
struct vfs_cap_data cap_data;
};
@@ -118,6 +121,7 @@ TAR;
#define TAR_STORE_SELINUX 128 /* store selinux context */
#define TAR_USE_NUMERIC_ID 256 /* favor numeric owner over names */
#define TAR_STORE_EXT4_POL 512 /* store ext4 crypto policy */
#define TAR_STORE_POSIX_CAP 1024 /* store posix file capabilities */
/* this is obsolete - it's here for backwards-compatibility only */
#define TAR_IGNORE_MAGIC 0
@@ -214,7 +218,7 @@ int th_write(TAR *t);
#define TH_ISLONGNAME(t) ((t)->th_buf.typeflag == GNU_LONGNAME_TYPE)
#define TH_ISLONGLINK(t) ((t)->th_buf.typeflag == GNU_LONGLINK_TYPE)
#define TH_ISEXTHEADER(t) ((t)->th_buf.typeflag == TH_EXT_TYPE)
#define TH_ISPOLHEADER(t) ((t)->th_buf.typeflag == TH_POL_TYPE)
#define TH_ISPOLHEADER(t) ((t)->th_buf.typeflag == TH_POL_TYPE_DO_NOT_USE)
/* decode tar header info */
#define th_get_crc(t) oct_to_int((t)->th_buf.chksum, sizeof((t)->th_buf.chksum))
@@ -323,6 +327,9 @@ void int_to_oct(int64_t num, char *oct, size_t octlen);
/* integer to string-octal conversion, or binary as necessary */
void int_to_oct_ex(int64_t num, char *oct, size_t octlen);
/* prints posix file capabilities */
void print_caps(struct vfs_cap_data *cap_data);
/***** wrapper.c **********************************************************/
libtar/util.c
+9
View File
@@ -15,6 +15,7 @@
#include <stdio.h>
#include <sys/param.h>
#include <errno.h>
#include <linux/capability.h>
#ifdef STDC_HEADERS
# include <string.h>
@@ -210,3 +211,11 @@ int_to_oct_ex(int64_t num, char *oct, size_t octlen)
}
int_to_oct(num, oct, octlen);
}
void print_caps(struct vfs_cap_data *cap_data) {
printf(" magic_etc=%u \n", cap_data->magic_etc);
printf(" data[0].permitted=%u \n", cap_data->data[0].permitted);
printf(" data[0].inheritable=%u \n", cap_data->data[0].inheritable);
printf(" data[1].permitted=%u \n", cap_data->data[1].permitted);
printf(" data[1].inheritable=%u \n", cap_data->data[1].inheritable);
}
twrpTar.cpp
+2 -2
View File
@@ -55,9 +55,9 @@ extern "C" {
#ifdef TW_INCLUDE_FBE
#include "crypto/ext4crypt/ext4crypt_tar.h"
#define TWTAR_FLAGS TAR_GNU | TAR_STORE_SELINUX | TAR_STORE_EXT4_POL
#define TWTAR_FLAGS TAR_GNU | TAR_STORE_SELINUX | TAR_STORE_POSIX_CAP |TAR_STORE_EXT4_POL
#else
#define TWTAR_FLAGS TAR_GNU | TAR_STORE_SELINUX
#define TWTAR_FLAGS TAR_GNU | TAR_STORE_SELINUX | TAR_STORE_POSIX_CAP
#endif
using namespace std;