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basic: timezone_is_valid: check for magic bytes "TZif"

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Fixes: https://github.com/systemd/systemd/issues/8905
This commit is contained in:
Mike Gilbert 2018-05-10 15:10:48 -04:00
parent 81321f51cf
commit a2932d5116
1 changed files with 27 additions and 4 deletions
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31
src/basic/time-util.c
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@ -21,11 +21,13 @@
#include "fd-util.h"
#include "fileio.h"
#include "fs-util.h"
#include "io-util.h"
#include "log.h"
#include "macro.h"
#include "parse-util.h"
#include "path-util.h"
#include "process-util.h"
#include "stat-util.h"
#include "string-util.h"
#include "strv.h"
#include "time-util.h"
@ -1276,7 +1278,9 @@ int get_timezones(char ***ret) {
bool timezone_is_valid(const char *name) {
bool slash = false;
const char *p, *t;
struct stat st;
_cleanup_close_ int fd = -1;
char buf[4];
int r;
if (isempty(name))
return false;
@ -1305,11 +1309,30 @@ bool timezone_is_valid(const char *name) {
return false;
t = strjoina("/usr/share/zoneinfo/", name);
if (stat(t, &st) < 0)
return false;
if (!S_ISREG(st.st_mode))
fd = open(t, O_RDONLY|O_CLOEXEC);
if (fd < 0) {
log_debug_errno(errno, "Failed to open timezone file '%s': %m", t);
return false;
}
r = fd_verify_regular(fd);
if (r < 0) {
log_debug_errno(r, "Timezone file '%s' is not a regular file: %m", t);
return false;
}
r = loop_read_exact(fd, buf, 4, false);
if (r < 0) {
log_debug_errno(r, "Failed to read from timezone file '%s': %m", t);
return false;
}
/* Magic from tzfile(5) */
if (memcmp(buf, "TZif", 4) != 0) {
log_debug("Timezone file '%s' has wrong magic bytes", t);
return false;
}
return true;
}