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| author | Eric Biggers <ebiggers@google.com> | 2017-09-27 12:50:46 -0700 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2017-10-18 09:12:41 +0100 |
| commit | ab5c69f01313c80df948e4f768efe616258f85f4 (patch) | |
| tree | 4ba32c1aad16a4bf1573a2f6b15d749b04a5eb42 /security/keys | |
| parent | 9d6c8711b6a751a694bcfaf49fb557b82092ee46 (diff) | |
| download | linux-ab5c69f01313c80df948e4f768efe616258f85f4.tar.bz2 | |
KEYS: load key flags and expiry time atomically in proc_keys_show()
In proc_keys_show(), the key semaphore is not held, so the key ->flags
and ->expiry can be changed concurrently. We therefore should read them
atomically just once.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'security/keys')
| -rw-r--r-- | security/keys/proc.c | 24 |
1 files changed, 14 insertions, 10 deletions
diff --git a/security/keys/proc.c b/security/keys/proc.c index 4089ce1f7757..6d1fcbba1e09 100644 --- a/security/keys/proc.c +++ b/security/keys/proc.c @@ -179,7 +179,9 @@ static int proc_keys_show(struct seq_file *m, void *v) struct rb_node *_p = v; struct key *key = rb_entry(_p, struct key, serial_node); struct timespec now; + time_t expiry; unsigned long timo; + unsigned long flags; key_ref_t key_ref, skey_ref; char xbuf[16]; short state; @@ -218,12 +220,13 @@ static int proc_keys_show(struct seq_file *m, void *v) rcu_read_lock(); /* come up with a suitable timeout value */ - if (key->expiry == 0) { + expiry = READ_ONCE(key->expiry); + if (expiry == 0) { memcpy(xbuf, "perm", 5); - } else if (now.tv_sec >= key->expiry) { + } else if (now.tv_sec >= expiry) { memcpy(xbuf, "expd", 5); } else { - timo = key->expiry - now.tv_sec; + timo = expiry - now.tv_sec; if (timo < 60) sprintf(xbuf, "%lus", timo); @@ -239,18 +242,19 @@ static int proc_keys_show(struct seq_file *m, void *v) state = key_read_state(key); -#define showflag(KEY, LETTER, FLAG) \ - (test_bit(FLAG, &(KEY)->flags) ? LETTER : '-') +#define showflag(FLAGS, LETTER, FLAG) \ + ((FLAGS & (1 << FLAG)) ? LETTER : '-') + flags = READ_ONCE(key->flags); seq_printf(m, "%08x %c%c%c%c%c%c%c %5d %4s %08x %5d %5d %-9.9s ", key->serial, state != KEY_IS_UNINSTANTIATED ? 'I' : '-', - showflag(key, 'R', KEY_FLAG_REVOKED), - showflag(key, 'D', KEY_FLAG_DEAD), - showflag(key, 'Q', KEY_FLAG_IN_QUOTA), - showflag(key, 'U', KEY_FLAG_USER_CONSTRUCT), + showflag(flags, 'R', KEY_FLAG_REVOKED), + showflag(flags, 'D', KEY_FLAG_DEAD), + showflag(flags, 'Q', KEY_FLAG_IN_QUOTA), + showflag(flags, 'U', KEY_FLAG_USER_CONSTRUCT), state < 0 ? 'N' : '-', - showflag(key, 'i', KEY_FLAG_INVALIDATED), + showflag(flags, 'i', KEY_FLAG_INVALIDATED), refcount_read(&key->usage), xbuf, key->perm, |