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tar: optional support for restoring selinux context

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function                                             old     new   delta
get_header_tar                                      1690    1976    +286
data_extract_all                                     821     881     +60
.rodata                                           151446  151503     +57
get_header_cpio                                     1044    1077     +33
------------------------------------------------------------------------------
(add/remove: 0/0 grow/shrink: 4/0 up/down: 436/0)             Total: 436 bytes

Signed-off-by: J. Tang <tang@jtang.org>
Signed-off-by: Denys Vlasenko <vda.linux@googlemail.com>
This commit is contained in:
J. Tang 2010-03-19 14:48:51 +01:00 committed by Denys Vlasenko
parent bcda0042e2
commit 77a2c51e79
4 changed files with 108 additions and 3 deletions
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8
archival/Config.in
View File

@ -289,6 +289,14 @@ config FEATURE_TAR_NOPRESERVE_TIME
With this option busybox supports GNU tar -m
(do not preserve time) option.
config FEATURE_TAR_SELINUX
bool "Support for extracting SELinux labels"
default n
depends on TAR && SELINUX
help
With this option busybox supports restoring SELinux labels
when extracting files from tar archives.
config UNCOMPRESS
bool "uncompress"
default n

21
archival/libunarchive/data_extract_all.c
View File

@ -12,6 +12,17 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
int dst_fd;
int res;
#if ENABLE_FEATURE_TAR_SELINUX
char *sctx = archive_handle->tar__next_file_sctx;
if (!sctx)
sctx = archive_handle->tar__global_sctx;
if (sctx) { /* setfscreatecon is 4 syscalls, avoid if possible */
setfscreatecon(sctx);
free(archive_handle->tar__next_file_sctx);
archive_handle->tar__next_file_sctx = NULL;
}
#endif
if (archive_handle->ah_flags & ARCHIVE_CREATE_LEADING_DIRS) {
char *slash = strrchr(file_header->name, '/');
if (slash) {
@ -45,7 +56,7 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
"same age file exists", file_header->name);
}
data_skip(archive_handle);
return;
goto ret;
}
else if ((unlink(file_header->name) == -1) && (errno != EISDIR)) {
bb_perror_msg_and_die("can't remove old file %s",
@ -158,4 +169,12 @@ void FAST_FUNC data_extract_all(archive_handle_t *archive_handle)
utimes(file_header->name, t);
}
}
ret: ;
#if ENABLE_FEATURE_TAR_SELINUX
if (sctx) {
/* reset the context after creating an entry */
setfscreatecon(NULL);
}
#endif
}

78
archival/libunarchive/get_header_tar.c
View File

@ -103,6 +103,63 @@ static unsigned long long getOctal(char *str, int len)
}
#define GET_OCTAL(a) getOctal((a), sizeof(a))
#if ENABLE_FEATURE_TAR_SELINUX
/* Scan a PAX header for SELinux contexts, via "RHT.security.selinux" keyword.
* This is what Red Hat's patched version of tar uses.
*/
# define SELINUX_CONTEXT_KEYWORD "RHT.security.selinux"
static char *get_selinux_sctx_from_pax_hdr(archive_handle_t *archive_handle, unsigned sz)
{
char *buf, *p;
char *result;
p = buf = xmalloc(sz + 1);
/* prevent bb_strtou from running off the buffer */
buf[sz] = '\0';
xread(archive_handle->src_fd, buf, sz);
archive_handle->offset += sz;
result = NULL;
while (sz != 0) {
char *end, *value;
unsigned len;
/* Every record has this format: "LEN NAME=VALUE\n" */
len = bb_strtou(p, &end, 10);
/* expect errno to be EINVAL, because the character
* following the digits should be a space
*/
p += len;
sz -= len;
if ((int)sz < 0
|| len == 0
|| errno != EINVAL
|| *end != ' '
) {
bb_error_msg("malformed extended header, skipped");
// More verbose version:
//bb_error_msg("malformed extended header at %"OFF_FMT"d, skipped",
// archive_handle->offset - (sz + len));
break;
}
/* overwrite the terminating newline with NUL
* (we do not bother to check that it *was* a newline)
*/
p[-1] = '\0';
/* Is it selinux security context? */
value = end + 1;
if (strncmp(value, SELINUX_CONTEXT_KEYWORD"=", sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1) == 0) {
value += sizeof(SELINUX_CONTEXT_KEYWORD"=") - 1;
result = xstrdup(value);
break;
}
}
free(buf);
return result;
}
#endif
void BUG_tar_header_size(void);
char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
{
@ -150,7 +207,7 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
if (sizeof(tar) != 512)
BUG_tar_header_size();
#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS
#if ENABLE_FEATURE_TAR_GNU_EXTENSIONS || ENABLE_FEATURE_TAR_SELINUX
again:
#endif
/* Align header */
@ -392,8 +449,13 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
case 'S': /* Sparse file */
case 'V': /* Volume header */
#endif
#if !ENABLE_FEATURE_TAR_SELINUX
case 'g': /* pax global header */
case 'x': { /* pax extended header */
case 'x': /* pax extended header */
#else
skip_ext_hdr:
#endif
{
off_t sz;
bb_error_msg("warning: skipping header '%c'", tar.typeflag);
sz = (file_header->size + 511) & ~(off_t)511;
@ -404,6 +466,18 @@ char FAST_FUNC get_header_tar(archive_handle_t *archive_handle)
/* return get_header_tar(archive_handle); */
goto again_after_align;
}
#if ENABLE_FEATURE_TAR_SELINUX
case 'g': /* pax global header */
case 'x': { /* pax extended header */
char **pp;
if ((uoff_t)file_header->size > 0xfffff) /* paranoia */
goto skip_ext_hdr;
pp = (tar.typeflag == 'g') ? &archive_handle->tar__global_sctx : &archive_handle->tar__next_file_sctx;
free(*pp);
*pp = get_selinux_sctx_from_pax_hdr(archive_handle, file_header->size);
goto again;
}
#endif
default:
bb_error_msg_and_die("unknown typeflag: 0x%x", tar.typeflag);
}

4
include/unarchive.h
View File

@ -59,6 +59,10 @@ typedef struct archive_handle_t {
char* tar__longname;
char* tar__linkname;
# endif
# if ENABLE_FEATURE_TAR_SELINUX
char* tar__global_sctx;
char* tar__next_file_sctx;
# endif
#endif
#if ENABLE_CPIO || ENABLE_RPM2CPIO || ENABLE_RPM
uoff_t cpio__blocks;