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Merge Make libaalogparse fully reentrant by removing its globals

Browse source 
Tested by using Valgrind's Helgrind and DRD against the reentrancy test that I wrote: they both report no errors with the changes while reporting many errors with the old versions.

Commits "Inline _parse_yacc in libaalogparse" and "Make parse_record take a const char pointer since it never modified str anyways" have a tiny potential to be backwards-incompatible changes: I have justified why they shouldn't be in the commit messages, but it's worth looking over in case I was mistaken and we need to back those out.

Signed-off-by: Ryan Lee <ryan.lee@canonical.com>

MR: https://gitlab.com/apparmor/apparmor/-/merge_requests/1322
Approved-by: John Johansen <john@jjmx.net>
Merged-by: John Johansen <john@jjmx.net>
This commit is contained in:
John Johansen 2024-09-11 07:54:39 +00:00
commit 37cac653d1
8 changed files with 243 additions and 141 deletions
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4
.gitignore vendored
View file

@ -109,6 +109,10 @@ libraries/libapparmor/src/tst_aalogmisc
libraries/libapparmor/src/tst_aalogmisc.log
libraries/libapparmor/src/tst_aalogmisc.o
libraries/libapparmor/src/tst_aalogmisc.trs
libraries/libapparmor/src/tst_aalogparse_reentrancy
libraries/libapparmor/src/tst_aalogparse_reentrancy.log
libraries/libapparmor/src/tst_aalogparse_reentrancy.o
libraries/libapparmor/src/tst_aalogparse_reentrancy.trs
libraries/libapparmor/src/tst_features
libraries/libapparmor/src/tst_features.log
libraries/libapparmor/src/tst_features.o

71
libraries/libapparmor/include/aalogparse.h
View file

@ -26,10 +26,10 @@
#define AA_RECORD_LINK 16
/**
* This is just for convenience now that we have two
* wildly different grammars.
* Enum representing which syntax version the log entry used.
* Support for V1 parsing was completely removed in 2011 and that enum entry
* is only still there for API compatibility reasons.
*/
typedef enum
{
AA_RECORD_SYNTAX_V1,
@ -48,69 +48,6 @@ typedef enum
AA_RECORD_STATUS /* Configuration change */
} aa_record_event_type;
/**
* With the sole exception of active_hat, this is a 1:1
* mapping from the keys that the new syntax uses.
*
* Some examples of the old syntax and how they're mapped with the aa_log_record struct:
*
* "PERMITTING r access to /path (program_name(12345) profile /profile active hat)"
* - operation: access
* - requested_mask: r
* - pid: 12345
* - profile: /profile
* - name: /path
* - info: program_name
* - active_hat: hat
*
* "REJECTING mkdir on /path/to/something (bash(23415) profile /bin/freak-aa-out active /bin/freak-aa-out"
* - operation: mkdir
* - name: /path/to/something
* - info: bash
* - pid: 23415
* - profile: /bin/freak-aa-out
* - active_hat: /bin/freak-aa-out
*
* "REJECTING xattr set on /path/to/something (bash(23415) profile /bin/freak-aa-out active /bin/freak-aa-out)"
* - operation: xattr
* - attribute: set
* - name: /path/to/something
* - info: bash
* - pid: 23415
* - profile: /bin/freak-aa-out
* - active_hat: /bin/freak-aa-out
*
* "PERMITTING attribute (something) change to /else (bash(23415) profile /bin/freak-aa-out active /bin/freak-aa-out)"
* - operation: setattr
* - attribute: something
* - name: /else
* - info: bash
* - pid: 23415
* - profile: /bin/freak-aa-out
* - active_hat: /bin/freak-aa-out
*
* "PERMITTING access to capability 'cap' (bash(23415) profile /bin/freak-aa-out active /bin/freak-aa-out)"
* - operation: capability
* - name: cap
* - info: bash
* - pid: 23415
* - profile: /bin/freak-aa-out
* - active_hat: /bin/freak-aa-out
*
* "LOGPROF-HINT unknown_hat TESTHAT pid=27764 profile=/change_hat_test/test_hat active=/change_hat_test/test_hat"
* - operation: change_hat
* - name: TESTHAT
* - info: unknown_hat
* - pid: 27764
* - profile: /change_hat_test/test_hat
* - active_hat: /change_hat_test/test_hat
*
* "LOGPROF-HINT fork pid=27764 child=38229"
* - operation: clone
* - task: 38229
* - pid: 27764
**/
typedef struct
{
aa_record_syntax_version version;
@ -177,7 +114,7 @@ typedef struct
* @return Parsed data.
*/
aa_log_record *
parse_record(char *str);
parse_record(const char *str);
/**
* Frees all struct data.

8
libraries/libapparmor/src/Makefile.am
View file

@ -44,7 +44,7 @@ include $(COMMONDIR)/Make.rules
BUILT_SOURCES = grammar.h scanner.h af_protos.h
AM_LFLAGS = -v
AM_YFLAGS = -d -p aalogparse_
AM_YFLAGS = -Wno-yacc -d -p aalogparse_
AM_CPPFLAGS = -D_GNU_SOURCE -I$(top_srcdir)/include/
scanner.h: scanner.l
$(LEX) -v $<
@ -73,6 +73,10 @@ CLEANFILES = libapparmor.pc
tst_aalogmisc_SOURCES = tst_aalogmisc.c
tst_aalogmisc_LDADD = .libs/libapparmor.a
tst_aalogparse_reentrancy_SOURCES = tst_aalogparse_reentrancy.c
tst_aalogparse_reentrancy_LDADD = .libs/libapparmor.a
tst_aalogparse_reentrancy_LDFLAGS = -pthread
tst_features_SOURCES = tst_features.c
tst_features_LDADD = .libs/libapparmor.a
@ -80,7 +84,7 @@ tst_kernel_SOURCES = tst_kernel.c
tst_kernel_LDADD = .libs/libapparmor.a
tst_kernel_LDFLAGS = -pthread
check_PROGRAMS = tst_aalogmisc tst_features tst_kernel
check_PROGRAMS = tst_aalogmisc tst_aalogparse_reentrancy tst_features tst_kernel
TESTS = $(check_PROGRAMS)
.PHONY: check-local

54
libraries/libapparmor/src/grammar.y
View file

@ -15,17 +15,15 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
/* aalogparse_error now requires visibility of the aa_log_record type
* Also include in a %code requires block to add it to the header
*/
%code requires{
#include <aalogparse.h>
}
%{
/* set the following to non-zero to get bison to emit debugging
* information about tokens given and rules matched.
* Also:
* Uncomment the %defines
* parse.error
* parse.trace
*/
#define YYDEBUG 0
#include <string.h>
#include <aalogparse.h>
#include "parser.h"
@ -41,12 +39,10 @@
#define debug_unused_ unused_
#endif
aa_log_record *ret_record;
/* Since we're a library, on any errors we don't want to print out any
* error messages. We should probably add a debug interface that does
* emit messages when asked for. */
void aalogparse_error(unused_ void *scanner, debug_unused_ char const *s)
void aalogparse_error(unused_ void *scanner, aa_log_record *ret_record, debug_unused_ char const *s)
{
#if (YYDEBUG != 0)
printf("ERROR: %s\n", s);
@ -89,9 +85,10 @@ aa_record_event_type lookup_aa_event(unsigned int type)
%define parse.trace
*/
%define api.pure
%define api.pure full
%lex-param{void *scanner}
%parse-param{void *scanner}
%parse-param{aa_log_record *ret_record}
%union
{
@ -284,8 +281,9 @@ audit_user_msg: TOK_KEY_MSG TOK_EQUALS audit_id audit_user_msg_tail
audit_id: TOK_AUDIT TOK_OPEN_PAREN TOK_AUDIT_DIGITS TOK_PERIOD TOK_AUDIT_DIGITS TOK_COLON TOK_AUDIT_DIGITS TOK_CLOSE_PAREN TOK_COLON
{
if (!asprintf(&ret_record->audit_id, "%s.%s:%s", $3, $5, $7))
yyerror(scanner, YY_("Out of memory"));
if (!asprintf(&ret_record->audit_id, "%s.%s:%s", $3, $5, $7)) {
yyerror(scanner, ret_record, YY_("Out of memory"));
}
ret_record->epoch = atol($3);
ret_record->audit_sub_id = atoi($7);
free($3);
@ -477,31 +475,3 @@ protocol: TOK_QUOTED_STRING
}
;
%%
aa_log_record *
_parse_yacc(char *str)
{
/* yydebug = 1; */
YY_BUFFER_STATE lex_buf;
yyscan_t scanner;
ret_record = NULL;
ret_record = malloc(sizeof(aa_log_record));
_init_log_record(ret_record);
if (ret_record == NULL)
return NULL;
#if (YYDEBUG != 0)
yydebug = 1;
#endif
aalogparse_lex_init(&scanner);
lex_buf = aalogparse__scan_string(str, scanner);
/* Ignore return value to return an AA_RECORD_INVALID event */
(void)aalogparse_parse(scanner);
aalogparse__delete_buffer(lex_buf, scanner);
aalogparse_lex_destroy(scanner);
return ret_record;
}

33
libraries/libapparmor/src/libaalogparse.c
View file

@ -34,13 +34,42 @@
#include <aalogparse.h>
#include "parser.h"
#include "grammar.h"
#include "scanner.h"
/* This is mostly just a wrapper around the code in grammar.y */
aa_log_record *parse_record(char *str)
aa_log_record *parse_record(const char *str)
{
YY_BUFFER_STATE lex_buf;
yyscan_t scanner;
aa_log_record *ret_record;
if (str == NULL)
return NULL;
return _parse_yacc(str);
ret_record = malloc(sizeof(aa_log_record));
_init_log_record(ret_record);
if (ret_record == NULL)
return NULL;
struct string_buf string_buf = {.buf = NULL, .buf_len = 0, .buf_alloc = 0};
#if (YYDEBUG != 0)
/* Warning: this is still a global even in reentrant parsers */
aalogparse_debug = 1;
#endif
aalogparse_lex_init_extra(&string_buf, &scanner);
lex_buf = aalogparse__scan_string(str, scanner);
/* Ignore return value to return an AA_RECORD_INVALID event */
(void)aalogparse_parse(scanner, ret_record);
aalogparse__delete_buffer(lex_buf, scanner);
aalogparse_lex_destroy(scanner);
/* free(NULL) is a no-op */
free(string_buf.buf);
return ret_record;
}
void free_record(aa_log_record *record)

8
libraries/libapparmor/src/parser.h
View file

@ -19,8 +19,14 @@
#ifndef __AA_LOG_PARSER_H__
#define __AA_LOG_PARSER_H__
// Internal-only type
struct string_buf {
char *buf;
unsigned int buf_len;
unsigned int buf_alloc;
};
extern void _init_log_record(aa_log_record *record);
extern aa_log_record *_parse_yacc(char *str);
extern char *hex_to_string(char *str);
extern char *ipproto_to_string(unsigned int proto);

52
libraries/libapparmor/src/scanner.l
View file

@ -19,6 +19,7 @@
%option nounput
%option noyy_top_state
%option reentrant
%option extra-type="struct string_buf*"
%option prefix="aalogparse_"
%option bison-bridge
%option header-file="scanner.h"
@ -34,40 +35,37 @@
#define YY_NO_INPUT
unsigned int string_buf_alloc = 0;
unsigned int string_buf_len = 0;
char *string_buf = NULL;
void string_buf_reset()
void string_buf_reset(struct string_buf* char_buf)
{
/* rewind buffer to zero, possibly doing initial allocation too */
string_buf_len = 0;
if (string_buf == NULL) {
string_buf_alloc = 128;
string_buf = malloc(string_buf_alloc);
assert(string_buf != NULL);
char_buf->buf_len = 0;
if (char_buf->buf == NULL) {
char_buf->buf_alloc = 128;
char_buf->buf = malloc(char_buf->buf_alloc);
assert(char_buf->buf != NULL);
}
/* always start with a valid but empty string */
string_buf[0] = '\0';
char_buf->buf[0] = '\0';
}
void string_buf_append(unsigned int length, char *text)
void string_buf_append(struct string_buf* char_buf, unsigned int length, char *text)
{
unsigned int current_length = string_buf_len;
unsigned int current_length = char_buf->buf_len;
/* handle calling ..._append before ..._reset */
if (string_buf == NULL) string_buf_reset();
if (char_buf->buf == NULL) string_buf_reset(char_buf);
string_buf_len += length;
char_buf->buf_len += length;
/* expand allocation if this append would exceed the allocation */
while (string_buf_len >= string_buf_alloc) {
string_buf_alloc *= 2;
string_buf = realloc(string_buf, string_buf_alloc);
assert(string_buf != NULL);
while (char_buf->buf_len >= char_buf->buf_alloc) {
// TODO: overflow?
char_buf->buf_alloc *= 2;
char_buf->buf = realloc(char_buf->buf, char_buf->buf_alloc);
assert(char_buf->buf != NULL);
}
/* copy and unconditionally terminate */
memcpy(string_buf+current_length, text, length);
string_buf[string_buf_len] = '\0';
memcpy(char_buf->buf+current_length, text, length);
char_buf->buf[char_buf->buf_len] = '\0';
}
%}
@ -232,7 +230,7 @@ yy_flex_debug = 0;
{open_paren} { return(TOK_OPEN_PAREN); }
{close_paren} { BEGIN(INITIAL); return(TOK_CLOSE_PAREN); }
{ws} { }
\" { string_buf_reset(); BEGIN(quoted_string); }
\" { string_buf_reset(yyextra); BEGIN(quoted_string); }
{ID}+ {
yylval->t_str = strdup(yytext);
BEGIN(INITIAL);
@ -241,20 +239,20 @@ yy_flex_debug = 0;
{equals} { return(TOK_EQUALS); }
}
\" { string_buf_reset(); BEGIN(quoted_string); }
\" { string_buf_reset(yyextra); BEGIN(quoted_string); }
<quoted_string>\" { /* End of the quoted string */
BEGIN(INITIAL);
yylval->t_str = strdup(string_buf);
yylval->t_str = strdup(yyextra->buf);
return(TOK_QUOTED_STRING);
}
<quoted_string>\\(.|\n) { string_buf_append(1, &yytext[1]); }
<quoted_string>\\(.|\n) { string_buf_append(yyextra, 1, &yytext[1]); }
<quoted_string>[^\\\n\"]+ { string_buf_append(yyleng, yytext); }
<quoted_string>[^\\\n\"]+ { string_buf_append(yyextra, yyleng, yytext); }
<safe_string>{
\" { string_buf_reset(); BEGIN(quoted_string); }
\" { string_buf_reset(yyextra); BEGIN(quoted_string); }
{hexstring} { yylval->t_str = hex_to_string(yytext); BEGIN(INITIAL); return(TOK_HEXSTRING);}
{equals} { return(TOK_EQUALS); }
. { /* eek, error! try another state */ BEGIN(INITIAL); yyless(0); }

154
libraries/libapparmor/src/tst_aalogparse_reentrancy.c Normal file
View file

@ -0,0 +1,154 @@
#include <pthread.h>
#include <string.h>
#include <aalogparse.h>
#include "private.h"
const char* log_line = "[23342.075380] audit: type=1400 audit(1725487203.971:1831): apparmor=\"DENIED\" operation=\"open\" class=\"file\" profile=\"snap-update-ns.firmware-updater\" name=\"/proc/202964/maps\" pid=202964 comm=\"5\" requested_mask=\"r\" denied_mask=\"r\" fsuid=1000 ouid=0";
const char* log_line_2 = "[ 4074.372559] audit: type=1400 audit(1725553393.143:793): apparmor=\"DENIED\" operation=\"capable\" class=\"cap\" profile=\"/usr/lib/snapd/snap-confine\" pid=19034 comm=\"snap-confine\" capability=12 capname=\"net_admin\"";
static int pthread_barrier_ok(int barrier_result) {
return barrier_result == 0 || barrier_result == PTHREAD_BARRIER_SERIAL_THREAD;
}
static int nullcmp_and_strcmp(const void *s1, const void *s2)
{
/* Return 0 if both pointers are NULL & non-zero if only one is NULL */
if (!s1 || !s2)
return s1 != s2;
return strcmp(s1, s2);
}
int aa_log_record_eq(aa_log_record *record1, aa_log_record *record2) {
int are_eq = 1;
are_eq &= (record1->version == record2->version);
are_eq &= (record1->event == record2->event);
are_eq &= (record1->pid == record2->pid);
are_eq &= (record1->peer_pid == record2->peer_pid);
are_eq &= (record1->task == record2->task);
are_eq &= (record1->magic_token == record2->magic_token);
are_eq &= (record1->epoch == record2->epoch);
are_eq &= (record1->audit_sub_id == record2->audit_sub_id);
are_eq &= (record1->bitmask == record2->bitmask);
are_eq &= (nullcmp_and_strcmp(record1->audit_id, record2->audit_id) == 0);
are_eq &= (nullcmp_and_strcmp(record1->operation, record2->operation) == 0);
are_eq &= (nullcmp_and_strcmp(record1->denied_mask, record2->denied_mask) == 0);
are_eq &= (nullcmp_and_strcmp(record1->requested_mask, record2->requested_mask) == 0);
are_eq &= (record1->fsuid == record2->fsuid);
are_eq &= (record1->ouid == record2->ouid);
are_eq &= (nullcmp_and_strcmp(record1->profile, record2->profile) == 0);
are_eq &= (nullcmp_and_strcmp(record1->peer_profile, record2->peer_profile) == 0);
are_eq &= (nullcmp_and_strcmp(record1->comm, record2->comm) == 0);
are_eq &= (nullcmp_and_strcmp(record1->name, record2->name) == 0);
are_eq &= (nullcmp_and_strcmp(record1->name2, record2->name2) == 0);
are_eq &= (nullcmp_and_strcmp(record1->namespace, record2->namespace) == 0);
are_eq &= (nullcmp_and_strcmp(record1->attribute, record2->attribute) == 0);
are_eq &= (record1->parent == record2->parent);
are_eq &= (nullcmp_and_strcmp(record1->info, record2->info) == 0);
are_eq &= (nullcmp_and_strcmp(record1->peer_info, record2->peer_info) == 0);
are_eq &= (record1->error_code == record2->error_code);
are_eq &= (nullcmp_and_strcmp(record1->active_hat, record2->active_hat) == 0);
are_eq &= (nullcmp_and_strcmp(record1->net_family, record2->net_family) == 0);
are_eq &= (nullcmp_and_strcmp(record1->net_protocol, record2->net_protocol) == 0);
are_eq &= (nullcmp_and_strcmp(record1->net_sock_type, record2->net_sock_type) == 0);
are_eq &= (nullcmp_and_strcmp(record1->net_local_addr, record2->net_local_addr) == 0);
are_eq &= (record1->net_local_port == record2->net_local_port);
are_eq &= (nullcmp_and_strcmp(record1->net_foreign_addr, record2->net_foreign_addr) == 0);
are_eq &= (record1->net_foreign_port == record2->net_foreign_port);
are_eq &= (nullcmp_and_strcmp(record1->execpath, record2->execpath) == 0);
are_eq &= (nullcmp_and_strcmp(record1->dbus_bus, record2->dbus_bus) == 0);
are_eq &= (nullcmp_and_strcmp(record1->dbus_path, record2->dbus_path) == 0);
are_eq &= (nullcmp_and_strcmp(record1->dbus_interface, record2->dbus_interface) == 0);
are_eq &= (nullcmp_and_strcmp(record1->dbus_member, record2->dbus_member) == 0);
are_eq &= (nullcmp_and_strcmp(record1->signal, record2->signal) == 0);
are_eq &= (nullcmp_and_strcmp(record1->peer, record2->peer) == 0);
are_eq &= (nullcmp_and_strcmp(record1->fs_type, record2->fs_type) == 0);
are_eq &= (nullcmp_and_strcmp(record1->flags, record2->flags) == 0);
are_eq &= (nullcmp_and_strcmp(record1->src_name, record2->src_name) == 0);
are_eq &= (nullcmp_and_strcmp(record1->class, record2->class) == 0);
are_eq &= (nullcmp_and_strcmp(record1->net_addr, record2->net_addr) == 0);
are_eq &= (nullcmp_and_strcmp(record1->peer_addr, record2->peer_addr) == 0);
return are_eq;
}
typedef struct {
const char* log;
pthread_barrier_t *barrier;
} pthread_parse_args;
void* pthread_parse_log(void* args) {
pthread_parse_args *args_real = (pthread_parse_args *) args;
int barrier_wait_result = pthread_barrier_wait(args_real->barrier);
/* Return NULL and fail test if barrier wait fails */
if (!pthread_barrier_ok(barrier_wait_result)) {
return NULL;
}
aa_log_record *record = parse_record(args_real->log);
return (void*) record;
}
#define NUM_THREADS 16
int main(void) {
pthread_t thread_ids[NUM_THREADS];
pthread_barrier_t barrier;
int barrier_wait_result;
aa_log_record* parsed_logs[NUM_THREADS];
int rc = 0;
/* Set up arguments to be passed to threads */
pthread_parse_args args = {.log=log_line, .barrier=&barrier};
pthread_parse_args args2 = {.log=log_line_2, .barrier=&barrier};
MY_TEST(NUM_THREADS > 2, "Test requires more than 2 threads");
/* Use barrier to synchronize the start of log parsing among all the threads
* This increases the likelihood of tickling race conditions, if there are any
*/
MY_TEST(pthread_barrier_init(&barrier, NULL, NUM_THREADS+1) == 0,
"Could not init pthread barrier");
for (int i=0; i<NUM_THREADS; i++) {
if (i%2 == 0) {
pthread_create(&thread_ids[i], NULL, pthread_parse_log, (void *) &args);
} else {
pthread_create(&thread_ids[i], NULL, pthread_parse_log, (void *) &args2);
}
}
/* Final barrier_wait to set off the thread race */
barrier_wait_result = pthread_barrier_wait(&barrier);
MY_TEST(pthread_barrier_ok(barrier_wait_result), "Could not wait on pthread barrier");
/* Wait for threads to finish parsing the logs */
for (int i=0; i<NUM_THREADS; i++) {
MY_TEST(pthread_join(thread_ids[i], (void*) &parsed_logs[i]) == 0, "Could not join thread");
}
/* Check that all logs parsed and are equal */
for (int i=0; i<NUM_THREADS; i++) {
MY_TEST(parsed_logs[i] != NULL, "Log failed to parse");
MY_TEST(parsed_logs[i]->version == AA_RECORD_SYNTAX_V2, "Log should have parsed as v2 form");
MY_TEST(parsed_logs[i]->event == AA_RECORD_DENIED, "Log should have parsed as denied");
/* Also check i==0 and i==1 as a sanity check for aa_log_record_eq */
if (i%2 == 0) {
MY_TEST(aa_log_record_eq(parsed_logs[0], parsed_logs[i]), "Log 0 != Log even");
} else {
MY_TEST(aa_log_record_eq(parsed_logs[1], parsed_logs[i]), "Log 1 != Log odd");
}
}
MY_TEST(!aa_log_record_eq(parsed_logs[0], parsed_logs[1]), "Log 0 and log 1 shouldn't be equal");
/* Clean up */
MY_TEST(pthread_barrier_destroy(&barrier) == 0, "Could not destroy pthread barrier");
for (int i=0; i<NUM_THREADS; i++) {
free_record(parsed_logs[i]);
}
return rc;
}