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pam_zfs_key: mlock(2) and munlock(2) can fail 

Since both syscalls can fail, add error handling, including EAGAIN.

Reviewed-by: Felix Dörre <felix@dogcraft.de>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Attila Fülöp <attila@fueloep.org>
Closes #12665
This commit is contained in:
Attila Fülöp 2021-10-21 06:06:55 +02:00 committed by Brian Behlendorf
parent ee7c30b350
commit 50292e2545
1 changed files with 41 additions and 5 deletions
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46
contrib/pam_zfs_key/pam_zfs_key.c
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@ -54,7 +54,7 @@ pam_syslog(pam_handle_t *pamh, int loglevel, const char *fmt, ...)
#endif
#include <string.h>
#include <unistd.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/file.h>
@ -69,11 +69,38 @@ static libzfs_handle_t *g_zfs;
static void destroy_pw(pam_handle_t *pamh, void *data, int errcode);
typedef int (*mlock_func_t) (const void *, size_t);
typedef struct {
size_t len;
char *value;
} pw_password_t;
/*
* Try to mlock or munlock addr while handling EAGAIN by retrying ten times
* and sleeping 10 milliseconds in between for a total of 0.1 seconds.
* lock_func must point to either mlock(2) or munlock(2).
*/
static int
try_lock(mlock_func_t lock_func, const void *addr, size_t len)
{
int err;
int retries = 10;
useconds_t sleep_dur = 10 * 1000;
if ((err = (*lock_func)(addr, len)) != EAGAIN) {
return (err);
}
for (int i = retries; i > 0; --i) {
(void) usleep(sleep_dur);
if ((err = (*lock_func)(addr, len)) != EAGAIN) {
break;
}
}
return (err);
}
static pw_password_t *
alloc_pw_size(size_t len)
{
@ -91,7 +118,11 @@ alloc_pw_size(size_t len)
free(pw);
return (NULL);
}
mlock(pw->value, pw->len);
if (try_lock(mlock, pw->value, pw->len) != 0) {
free(pw->value);
free(pw);
return NULL;
}
return (pw);
}
@ -112,7 +143,11 @@ alloc_pw_string(const char *source)
free(pw);
return (NULL);
}
mlock(pw->value, pw->len);
if (try_lock(mlock, pw->value, pw->len) != 0) {
free(pw->value);
free(pw);
return NULL;
}
memcpy(pw->value, source, pw->len);
return (pw);
}
@ -121,8 +156,9 @@ static void
pw_free(pw_password_t *pw)
{
bzero(pw->value, pw->len);
munlock(pw->value, pw->len);
free(pw->value);
if (try_lock(munlock, pw->value, pw->len) == 0) {
free(pw->value);
}
free(pw);
}