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util: properly detect what the last capability is

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This commit is contained in:
Lennart Poettering 2011-10-11 22:30:31 +02:00
parent d2134abdd5
commit 64685e0cea
4 changed files with 38 additions and 12 deletions
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7
src/execute.c
View File

@ -895,12 +895,9 @@ static int do_capability_bounding_set_drop(uint64_t drop) {
}
}
for (i = 0; i <= MAX(63LU, (unsigned long) CAP_LAST_CAP); i++)
for (i = 0; i <= cap_last_cap(); i++)
if (drop & ((uint64_t) 1ULL << (uint64_t) i)) {
if (prctl(PR_CAPBSET_DROP, i) < 0) {
if (errno == EINVAL)
break;
r = -errno;
goto finish;
}
@ -1720,7 +1717,7 @@ void exec_context_dump(ExecContext *c, FILE* f, const char *prefix) {
unsigned long l;
fprintf(f, "%sCapabilityBoundingSet:", prefix);
for (l = 0; l <= (unsigned long) CAP_LAST_CAP; l++)
for (l = 0; l <= cap_last_cap(); l++)
if (!(c->capability_bounding_set_drop & ((uint64_t) 1ULL << (uint64_t) l))) {
char *t;

8
src/nspawn.c
View File

@ -361,7 +361,7 @@ static int drop_capabilities(void) {
unsigned long l;
for (l = 0; l <= MAX(63LU, (unsigned long) CAP_LAST_CAP); l++) {
for (l = 0; l <= cap_last_cap(); l++) {
unsigned i;
for (i = 0; i < ELEMENTSOF(retain); i++)
@ -372,12 +372,6 @@ static int drop_capabilities(void) {
continue;
if (prctl(PR_CAPBSET_DROP, l) < 0) {
/* If this capability is not known, EINVAL
* will be returned, let's ignore this. */
if (errno == EINVAL)
break;
log_error("PR_CAPBSET_DROP failed: %m");
return -errno;
}

33
src/util.c
View File

@ -5703,3 +5703,36 @@ int strdup_or_null(const char *a, char **b) {
*b = c;
return 0;
}
unsigned long cap_last_cap(void) {
static __thread unsigned long saved;
static __thread bool valid = false;
unsigned long p;
if (valid)
return saved;
p = (unsigned long) CAP_LAST_CAP;
if (prctl(PR_CAPBSET_READ, p) < 0) {
/* Hmm, look downwards, until we find one that
* works */
for (p--; p > 0; p --)
if (prctl(PR_CAPBSET_READ, p) >= 0)
break;
} else {
/* Hmm, look upwards, until we find one that doesn't
* work */
for (;; p++)
if (prctl(PR_CAPBSET_READ, p+1) < 0)
break;
}
saved = p;
valid = true;
return p;
}

2
src/util.h
View File

@ -506,4 +506,6 @@ extern char **saved_argv;
bool kexec_loaded(void);
unsigned long cap_last_cap(void);
#endif