diff options
| -rw-r--r-- | Documentation/security/Smack.txt | 6 | ||||
| -rw-r--r-- | security/smack/smack.h | 25 | ||||
| -rw-r--r-- | security/smack/smack_access.c | 41 | ||||
| -rw-r--r-- | security/smack/smackfs.c | 163 |
4 files changed, 163 insertions, 72 deletions
diff --git a/Documentation/security/Smack.txt b/Documentation/security/Smack.txt index abc82f85215b..de5e1aeca7fb 100644 --- a/Documentation/security/Smack.txt +++ b/Documentation/security/Smack.txt @@ -206,11 +206,11 @@ netlabel label. The format accepted on write is: "%d.%d.%d.%d label" or "%d.%d.%d.%d/%d label". onlycap - This contains the label processes must have for CAP_MAC_ADMIN + This contains labels processes must have for CAP_MAC_ADMIN and CAP_MAC_OVERRIDE to be effective. If this file is empty these capabilities are effective at for processes with any - label. The value is set by writing the desired label to the - file or cleared by writing "-" to the file. + label. The values are set by writing the desired labels, separated + by spaces, to the file or cleared by writing "-" to the file. ptrace This is used to define the current ptrace policy 0 - default: this is the policy that relies on Smack access rules. diff --git a/security/smack/smack.h b/security/smack/smack.h index b8c1a869d85e..244e035e5a99 100644 --- a/security/smack/smack.h +++ b/security/smack/smack.h @@ -138,6 +138,11 @@ struct smk_port_label { struct smack_known *smk_out; /* outgoing label */ }; +struct smack_onlycap { + struct list_head list; + struct smack_known *smk_label; +}; + /* * Mount options */ @@ -249,6 +254,7 @@ int smk_netlbl_mls(int, char *, struct netlbl_lsm_secattr *, int); struct smack_known *smk_import_entry(const char *, int); void smk_insert_entry(struct smack_known *skp); struct smack_known *smk_find_entry(const char *); +int smack_privileged(int cap); /* * Shared data. @@ -257,7 +263,6 @@ extern int smack_enabled; extern int smack_cipso_direct; extern int smack_cipso_mapped; extern struct smack_known *smack_net_ambient; -extern struct smack_known *smack_onlycap; extern struct smack_known *smack_syslog_label; #ifdef CONFIG_SECURITY_SMACK_BRINGUP extern struct smack_known *smack_unconfined; @@ -276,6 +281,9 @@ extern struct mutex smack_known_lock; extern struct list_head smack_known_list; extern struct list_head smk_netlbladdr_list; +extern struct mutex smack_onlycap_lock; +extern struct list_head smack_onlycap_list; + #define SMACK_HASH_SLOTS 16 extern struct hlist_head smack_known_hash[SMACK_HASH_SLOTS]; @@ -332,21 +340,6 @@ static inline struct smack_known *smk_of_current(void) } /* - * Is the task privileged and allowed to be privileged - * by the onlycap rule. - */ -static inline int smack_privileged(int cap) -{ - struct smack_known *skp = smk_of_current(); - - if (!capable(cap)) - return 0; - if (smack_onlycap == NULL || smack_onlycap == skp) - return 1; - return 0; -} - -/* * logging functions */ #define SMACK_AUDIT_DENIED 0x1 diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c index 408e20be1ad7..00f6b38bffbd 100644 --- a/security/smack/smack_access.c +++ b/security/smack/smack_access.c @@ -617,3 +617,44 @@ struct smack_known *smack_from_secid(const u32 secid) rcu_read_unlock(); return &smack_known_invalid; } + +/* + * Unless a process is running with one of these labels + * even having CAP_MAC_OVERRIDE isn't enough to grant + * privilege to violate MAC policy. If no labels are + * designated (the empty list case) capabilities apply to + * everyone. + */ +LIST_HEAD(smack_onlycap_list); +DEFINE_MUTEX(smack_onlycap_lock); + +/* + * Is the task privileged and allowed to be privileged + * by the onlycap rule. + * + * Returns 1 if the task is allowed to be privileged, 0 if it's not. + */ +int smack_privileged(int cap) +{ + struct smack_known *skp = smk_of_current(); + struct smack_onlycap *sop; + + if (!capable(cap)) + return 0; + + rcu_read_lock(); + if (list_empty(&smack_onlycap_list)) { + rcu_read_unlock(); + return 1; + } + + list_for_each_entry_rcu(sop, &smack_onlycap_list, list) { + if (sop->smk_label == skp) { + rcu_read_unlock(); + return 1; + } + } + rcu_read_unlock(); + + return 0; +} diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index e40dc48737ff..f1c22a891b1a 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -87,16 +87,6 @@ int smack_cipso_direct = SMACK_CIPSO_DIRECT_DEFAULT; */ int smack_cipso_mapped = SMACK_CIPSO_MAPPED_DEFAULT; -/* - * Unless a process is running with this label even - * having CAP_MAC_OVERRIDE isn't enough to grant - * privilege to violate MAC policy. If no label is - * designated (the NULL case) capabilities apply to - * everyone. It is expected that the hat (^) label - * will be used if any label is used. - */ -struct smack_known *smack_onlycap; - #ifdef CONFIG_SECURITY_SMACK_BRINGUP /* * Allow one label to be unconfined. This is for @@ -1636,34 +1626,79 @@ static const struct file_operations smk_ambient_ops = { .llseek = default_llseek, }; -/** - * smk_read_onlycap - read() for smackfs/onlycap - * @filp: file pointer, not actually used - * @buf: where to put the result - * @cn: maximum to send along - * @ppos: where to start - * - * Returns number of bytes read or error code, as appropriate +/* + * Seq_file operations for /smack/onlycap */ -static ssize_t smk_read_onlycap(struct file *filp, char __user *buf, - size_t cn, loff_t *ppos) +static void *onlycap_seq_start(struct seq_file *s, loff_t *pos) { - char *smack = ""; - ssize_t rc = -EINVAL; - int asize; + return smk_seq_start(s, pos, &smack_onlycap_list); +} - if (*ppos != 0) - return 0; +static void *onlycap_seq_next(struct seq_file *s, void *v, loff_t *pos) +{ + return smk_seq_next(s, v, pos, &smack_onlycap_list); +} - if (smack_onlycap != NULL) - smack = smack_onlycap->smk_known; +static int onlycap_seq_show(struct seq_file *s, void *v) +{ + struct list_head *list = v; + struct smack_onlycap *sop = + list_entry_rcu(list, struct smack_onlycap, list); - asize = strlen(smack) + 1; + seq_puts(s, sop->smk_label->smk_known); + seq_putc(s, ' '); - if (cn >= asize) - rc = simple_read_from_buffer(buf, cn, ppos, smack, asize); + return 0; +} - return rc; +static const struct seq_operations onlycap_seq_ops = { + .start = onlycap_seq_start, + .next = onlycap_seq_next, + .show = onlycap_seq_show, + .stop = smk_seq_stop, +}; + +static int smk_open_onlycap(struct inode *inode, struct file *file) +{ + return seq_open(file, &onlycap_seq_ops); +} + +/** + * smk_list_swap_rcu - swap public list with a private one in RCU-safe way + * The caller must hold appropriate mutex to prevent concurrent modifications + * to the public list. + * Private list is assumed to be not accessible to other threads yet. + * + * @public: public list + * @private: private list + */ +static void smk_list_swap_rcu(struct list_head *public, + struct list_head *private) +{ + struct list_head *first, *last; + + if (list_empty(public)) { + list_splice_init_rcu(private, public, synchronize_rcu); + } else { + /* Remember public list before replacing it */ + first = public->next; + last = public->prev; + + /* Publish private list in place of public in RCU-safe way */ + private->prev->next = public; + private->next->prev = public; + rcu_assign_pointer(public->next, private->next); + public->prev = private->prev; + + synchronize_rcu(); + + /* When all readers are done with the old public list, + * attach it in place of private */ + private->next = first; + private->prev = last; + first->prev = private; + last->next = private; + } } /** @@ -1679,28 +1714,47 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { char *data; - struct smack_known *skp = smk_of_task(current->cred->security); + char *data_parse; + char *tok; + struct smack_known *skp; + struct smack_onlycap *sop; + struct smack_onlycap *sop2; + LIST_HEAD(list_tmp); int rc = count; if (!smack_privileged(CAP_MAC_ADMIN)) return -EPERM; - /* - * This can be done using smk_access() but is done - * explicitly for clarity. The smk_access() implementation - * would use smk_access(smack_onlycap, MAY_WRITE) - */ - if (smack_onlycap != NULL && smack_onlycap != skp) - return -EPERM; - data = kzalloc(count + 1, GFP_KERNEL); if (data == NULL) return -ENOMEM; if (copy_from_user(data, buf, count) != 0) { - rc = -EFAULT; - goto freeout; + kfree(data); + return -EFAULT; + } + + data_parse = data; + while ((tok = strsep(&data_parse, " ")) != NULL) { + if (!*tok) + continue; + + skp = smk_import_entry(tok, 0); + if (IS_ERR(skp)) { + rc = PTR_ERR(skp); + break; + } + + sop = kzalloc(sizeof(*sop), GFP_KERNEL); + if (sop == NULL) { + rc = -ENOMEM; + break; + } + + sop->smk_label = skp; + list_add_rcu(&sop->list, &list_tmp); } + kfree(data); /* * Clear the smack_onlycap on invalid label errors. This means @@ -1710,26 +1764,29 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf, * so "-usecapabilities" will also work. * * But do so only on invalid label, not on system errors. + * The invalid label must be first to count as clearing attempt. */ - skp = smk_import_entry(data, count); - if (PTR_ERR(skp) == -EINVAL) - skp = NULL; - else if (IS_ERR(skp)) { - rc = PTR_ERR(skp); - goto freeout; + if (rc == -EINVAL && list_empty(&list_tmp)) + rc = count; + + if (rc >= 0) { + mutex_lock(&smack_onlycap_lock); + smk_list_swap_rcu(&smack_onlycap_list, &list_tmp); + mutex_unlock(&smack_onlycap_lock); } - smack_onlycap = skp; + list_for_each_entry_safe(sop, sop2, &list_tmp, list) + kfree(sop); -freeout: - kfree(data); return rc; } static const struct file_operations smk_onlycap_ops = { - .read = smk_read_onlycap, + .open = smk_open_onlycap, + .read = seq_read, .write = smk_write_onlycap, - .llseek = default_llseek, + .llseek = seq_lseek, + .release = seq_release, }; #ifdef CONFIG_SECURITY_SMACK_BRINGUP |