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tar: improve compatibility 

- check magic field for 'ustar' on read
- harden get_octal to report errors on non-octal characters
  (e.g. GNU base256 encoding), fixes #10757
- fix mtime and size octal fields to not have zero terminator
cute-signatures
Timo Teräs 2021-08-23 14:15:12 +03:00
parent 33c1de8ea1
commit da7264733d
1 changed files with 30 additions and 20 deletions
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50
src/tar.c
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@ -33,21 +33,24 @@ struct tar_header {
char padding[12]; /* 500-511 */ char padding[12]; /* 500-511 */
}; };
#define TAR_BLOB(s) APK_BLOB_PTR_LEN(s, strnlen(s, sizeof(s))) #define TAR_BLOB(s) APK_BLOB_PTR_LEN(s, strnlen(s, sizeof(s)))
#define GET_OCTAL(s) get_octal(s, sizeof(s)) #define GET_OCTAL(s,r) get_octal(s, sizeof(s), r)
#define PUT_OCTAL(s,v) put_octal(s, sizeof(s), v) #define PUT_OCTAL(s,v,hz) put_octal(s, sizeof(s), v, hz)
static unsigned int get_octal(char *s, size_t l) static unsigned int get_octal(char *s, size_t l, int *r)
{ {
apk_blob_t b = APK_BLOB_PTR_LEN(s, l); apk_blob_t b = APK_BLOB_PTR_LEN(s, l);
return apk_blob_pull_uint(&b, 8); unsigned int val = apk_blob_pull_uint(&b, 8);
while (b.len >= 1 && b.ptr[0] == 0) b.ptr++, b.len--;
if (b.len != 0) *r = -APKE_V2PKG_FORMAT;
return val;
} }
static void put_octal(char *s, size_t l, size_t value) static void put_octal(char *s, size_t l, size_t value, int has_zero)
{ {
char *ptr = &s[l - 1]; char *ptr = &s[l - 1];
*(ptr--) = '\0'; if (has_zero) *(ptr--) = '\0';
while (value != 0 && ptr >= s) { while (value != 0 && ptr >= s) {
*(ptr--) = '0' + (value % 8); *(ptr--) = '0' + (value % 8);
value /= 8; value /= 8;
@ -131,20 +134,27 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
end++; end++;
continue; continue;
} }
if (memcmp(buf.magic, "ustar", 5) != 0) {
r = -APKE_V2PKG_FORMAT;
goto err;
}
r = 0;
entry = (struct apk_file_info){ entry = (struct apk_file_info){
.size = GET_OCTAL(buf.size), .size = GET_OCTAL(buf.size, &r),
.uid = apk_id_cache_resolve_uid(idc, TAR_BLOB(buf.uname), GET_OCTAL(buf.uid)), .uid = apk_id_cache_resolve_uid(idc, TAR_BLOB(buf.uname), GET_OCTAL(buf.uid, &r)),
.gid = apk_id_cache_resolve_gid(idc, TAR_BLOB(buf.gname), GET_OCTAL(buf.gid)), .gid = apk_id_cache_resolve_gid(idc, TAR_BLOB(buf.gname), GET_OCTAL(buf.gid, &r)),
.mode = GET_OCTAL(buf.mode) & 07777, .mode = GET_OCTAL(buf.mode, &r) & 07777,
.mtime = GET_OCTAL(buf.mtime), .mtime = GET_OCTAL(buf.mtime, &r),
.name = entry.name, .name = entry.name,
.uname = buf.uname, .uname = buf.uname,
.gname = buf.gname, .gname = buf.gname,
.device = makedev(GET_OCTAL(buf.devmajor), .device = makedev(GET_OCTAL(buf.devmajor, &r),
GET_OCTAL(buf.devminor)), GET_OCTAL(buf.devminor, &r)),
.xattrs = entry.xattrs, .xattrs = entry.xattrs,
}; };
if (r != 0) goto err;
if (buf.prefix[0] && buf.typeflag != 'x' && buf.typeflag != 'g') { if (buf.prefix[0] && buf.typeflag != 'x' && buf.typeflag != 'g') {
snprintf(filename, sizeof filename, "%.*s/%.*s", snprintf(filename, sizeof filename, "%.*s/%.*s",
(int) sizeof buf.prefix, buf.prefix, (int) sizeof buf.prefix, buf.prefix,
@ -271,11 +281,11 @@ int apk_tar_write_entry(struct apk_ostream *os, const struct apk_file_info *ae,
strlcpy(buf.uname, ae->uname ?: "root", sizeof buf.uname); strlcpy(buf.uname, ae->uname ?: "root", sizeof buf.uname);
strlcpy(buf.gname, ae->gname ?: "root", sizeof buf.gname); strlcpy(buf.gname, ae->gname ?: "root", sizeof buf.gname);
PUT_OCTAL(buf.size, ae->size); PUT_OCTAL(buf.size, ae->size, 0);
PUT_OCTAL(buf.uid, ae->uid); PUT_OCTAL(buf.uid, ae->uid, 1);
PUT_OCTAL(buf.gid, ae->gid); PUT_OCTAL(buf.gid, ae->gid, 1);
PUT_OCTAL(buf.mode, ae->mode & 07777); PUT_OCTAL(buf.mode, ae->mode & 07777, 1);
PUT_OCTAL(buf.mtime, ae->mtime ?: apk_get_build_time()); PUT_OCTAL(buf.mtime, ae->mtime ?: apk_get_build_time(), 0);
/* Checksum */ /* Checksum */
strcpy(buf.magic, "ustar "); strcpy(buf.magic, "ustar ");
@ -283,7 +293,7 @@ int apk_tar_write_entry(struct apk_ostream *os, const struct apk_file_info *ae,
src = (const unsigned char *) &buf; src = (const unsigned char *) &buf;
for (i = chksum = 0; i < sizeof(buf); i++) for (i = chksum = 0; i < sizeof(buf); i++)
chksum += src[i]; chksum += src[i];
put_octal(buf.chksum, sizeof(buf.chksum)-1, chksum); put_octal(buf.chksum, sizeof(buf.chksum)-1, chksum, 1);
} }
if (apk_ostream_write(os, &buf, sizeof(buf)) < 0) if (apk_ostream_write(os, &buf, sizeof(buf)) < 0)