Messages in this thread Patch in this message | | | Date | Sun, 21 Oct 2007 04:25:43 +0200 | Subject | [PATCH] Smackv8: Safe lockless {cipso,load} read operation | From | "Ahmed S. Darwish" <> |
| |
Hi,
Utilizing Al's concers about using smack_cipso_count without locking, here's a patch that remove smack_cipso_count and uses simple list traversing in read() without any counting mechanism.
CC: Al Viro <viro@ftp.linux.org.uk> Signed-off-by: Ahmed S. Darwish <darwish.07@gmail.com>
---
Please apply over omit-non-cipso-lables-in-cipso-seq-start.patch Using smack_{list,cipso}_count in the read context was useless anyway cause we were just traversing the list.
diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index b061cd0..c38d0d0 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -63,16 +63,17 @@ int smack_cipso_direct = SMACK_CIPSO_DIRECT_DEFAULT; static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT; static int smack_list_count; -static int smack_cipso_count; struct smk_list_entry *smack_list; +#define SEQ_READ_FINISHED 1 + /* * Seq_file read operations for /smack/load */ static void *load_seq_start(struct seq_file *s, loff_t *pos) { - if (*pos >= smack_list_count) + if (*pos == SEQ_READ_FINISHED) return NULL; return smack_list; @@ -80,8 +81,13 @@ static void *load_seq_start(struct seq_file *s, loff_t *pos) static void *load_seq_next(struct seq_file *s, void *v, loff_t *pos) { - (*pos)++; - return ((struct smk_list_entry *) v)->smk_next; + struct smk_list_entry *skp = ((struct smk_list_entry *) v)->smk_next; + + if (skp) + return skp; + + *pos = SEQ_READ_FINISHED; + return NULL; } static int load_seq_show(struct seq_file *s, void *v) @@ -306,7 +312,7 @@ static void *cipso_seq_start(struct seq_file *s, loff_t *pos) { struct smack_known *skp = smack_known; - if (*pos >= smack_cipso_count) + if (*pos == SEQ_READ_FINISHED) return NULL; while (skp && !skp->smk_cipso) @@ -319,12 +325,14 @@ static void *cipso_seq_next(struct seq_file *s, void *v, loff_t *pos) { struct smack_known *skp = ((struct smack_known *) v)->smk_next; - (*pos)++; - while (skp && !skp->smk_cipso) skp = skp->smk_next; - return skp; + if (skp) + return skp; + + *pos = SEQ_READ_FINISHED; + return NULL; } /* @@ -488,7 +496,6 @@ static ssize_t smk_write_cipso(struct file *file, const char __user *buf, rc = -ENOMEM; break; } - ++smack_cipso_count; } else scp = NULL; -- Ahmed S. Darwish HomePage: http://darwish.07.googlepages.com Blog: http://darwish-07.blogspot.com - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |