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Set cache file tstamp to the mtime of most recent policy file tstamp

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Currently the cache file has its mtime set at creation time, but this
can lead to cache issues when a policy file is updated separately from
the cache. This makes it possible for an update to ship a policy file
that is newer than the what the cache file was generated from, but
result in a cache hit because the cache file was local compiled after
the policy file was package into an update (this requires the update
to set the mtime of the file when locally installed to the mtime of
the file in its update archive but this is commonly done, especially
in image based updates).

Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Seth Arnold <seth.arnold@canonical.com>
This commit is contained in:
John Johansen 2015-06-06 01:22:53 -07:00
parent c2bbe64ab1
commit 5d0e6c26b7
4 changed files with 29 additions and 14 deletions
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1
parser/parser.h
View file

@ -333,7 +333,6 @@ extern int abort_on_error;
extern int skip_bad_cache_rebuild;
extern int mru_skip_cache;
extern int debug_cache;
extern struct timespec mru_tstamp;
/* provided by parser_lex.l (cannot be used in tst builds) */
extern FILE *yyin;

5
parser/parser_main.c
View file

@ -77,7 +77,7 @@ int abort_on_error = 0; /* stop processing profiles if error */
int skip_bad_cache_rebuild = 0;
int mru_skip_cache = 1;
int debug_cache = 0;
struct timespec mru_tstamp;
struct timespec cache_tstamp, mru_policy_tstamp;
static char *apparmorfs = NULL;
static char *cacheloc = NULL;
@ -646,7 +646,8 @@ int process_binary(int option, aa_kernel_interface *kernel_interface,
void reset_parser(const char *filename)
{
memset(&mru_tstamp, 0, sizeof(mru_tstamp));
memset(&mru_policy_tstamp, 0, sizeof(mru_policy_tstamp));
memset(&cache_tstamp, 0, sizeof(cache_tstamp));
mru_skip_cache = 1;
free_aliases();
free_symtabs();

25
parser/policy_cache.c
View file

@ -25,6 +25,8 @@
#include <sys/types.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <utime.h>
#include "lib.h"
#include "parser.h"
@ -70,22 +72,27 @@ bool valid_cached_file_version(const char *cachename)
}
void set_mru_tstamp(struct timespec t)
void set_cache_tstamp(struct timespec t)
{
mru_skip_cache = 0;
mru_tstamp = t;
cache_tstamp = t;
}
void update_mru_tstamp(FILE *file, const char *name)
{
struct stat stat_file;
if (fstat(fileno(file), &stat_file) || (mru_tstamp.tv_sec == 0 && mru_tstamp.tv_nsec == 0))
if (fstat(fileno(file), &stat_file))
return;
if (mru_t_cmp(stat_file.st_mtim)) {
if (tstamp_cmp(mru_policy_tstamp, stat_file.st_mtim) < 0)
/* keep track of the most recent policy tstamp */
mru_policy_tstamp = stat_file.st_mtim;
if (tstamp_is_null(cache_tstamp))
return;
if (tstamp_cmp(stat_file.st_mtim, cache_tstamp) > 0) {
if (debug_cache)
pwarn("%s: file '%s' is newer than cache file\n", progname, name);
mru_skip_cache = 1;
}
}
}
char *cache_filename(const char *cachedir, const char *basename)
@ -109,7 +116,7 @@ void valid_read_cache(const char *cachename)
if (stat(cachename, &stat_bin) == 0 &&
stat_bin.st_size > 0) {
if (valid_cached_file_version(cachename))
set_mru_tstamp(stat_bin.st_mtim);
set_cache_tstamp(stat_bin.st_mtim);
else if (!cond_clear_cache)
write_cache = 0;
} else {
@ -159,6 +166,12 @@ void install_cache(const char *cachetmpname, const char *cachename)
/* Only install the generate cache file if it parsed correctly
and did not have write/close errors */
if (cachetmpname) {
struct timeval t;
/* set the mtime of the cache file to the most newest mtime
* of policy files used to generate it
*/
TIMESPEC_TO_TIMEVAL(&t, &mru_policy_tstamp);
utimes(cachetmpname, &t);
if (rename(cachetmpname, cachename) < 0) {
pwarn("Warning failed to write cache: %s\n", cachename);
unlink(cachetmpname);

12
parser/policy_cache.h
View file

@ -19,12 +19,14 @@
#ifndef __AA_POLICY_CACHE_H
#define __AA_POLICY_CACHE_H
extern struct timespec mru_tstamp;
extern struct timespec cache_tstamp, mru_policy_tstamp;
/* returns true if time is more recent than mru_tstamp */
#define mru_t_cmp(a) \
(((a).tv_sec == (mru_tstamp).tv_sec) ? \
(a).tv_nsec > (mru_tstamp).tv_nsec : (a).tv_sec > (mru_tstamp).tv_sec)
#define tstamp_cmp(a, b) \
(((a).tv_sec == (b).tv_sec) ? \
((a).tv_nsec - (b).tv_nsec) : \
((a).tv_sec - (b).tv_sec))
#define tstamp_is_null(a) ((a).tv_sec == 0 && (a).tv_nsec == 0)
extern int show_cache;
extern int skip_cache;
@ -36,7 +38,7 @@ extern int create_cache_dir; /* create the cache dir if missing? */
extern int mru_skip_cache;
extern int debug_cache;
void set_mru_tstamp(struct timespec t);
void set_cache_tstamp(struct timespec t);
void update_mru_tstamp(FILE *file, const char *path);
bool valid_cached_file_version(const char *cachename);
char *cache_filename(const char *cachedir, const char *basename);