diff options
| -rw-r--r-- | Documentation/security/Smack.txt | 11 | ||||
| -rw-r--r-- | security/smack/smackfs.c | 249 |
2 files changed, 181 insertions, 79 deletions
diff --git a/Documentation/security/Smack.txt b/Documentation/security/Smack.txt index 8a177e4b6e21..7a2d30c132e3 100644 --- a/Documentation/security/Smack.txt +++ b/Documentation/security/Smack.txt @@ -117,6 +117,17 @@ access2 ambient This contains the Smack label applied to unlabeled network packets. +change-rule + This interface allows modification of existing access control rules. + The format accepted on write is: + "%s %s %s %s" + where the first string is the subject label, the second the + object label, the third the access to allow and the fourth the + access to deny. The access strings may contain only the characters + "rwxat-". If a rule for a given subject and object exists it will be + modified by enabling the permissions in the third string and disabling + those in the fourth string. If there is no such rule it will be + created using the access specified in the third and the fourth strings. cipso This interface allows a specific CIPSO header to be assigned to a Smack label. The format accepted on write is: diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c index 337e32c551da..2479a41a7dff 100644 --- a/security/smack/smackfs.c +++ b/security/smack/smackfs.c @@ -50,12 +50,12 @@ enum smk_inos { SMK_ACCESS2 = 16, /* make an access check with long labels */ SMK_CIPSO2 = 17, /* load long label -> CIPSO mapping */ SMK_REVOKE_SUBJ = 18, /* set rules with subject label to '-' */ + SMK_CHANGE_RULE = 19, /* change or add rules (long labels) */ }; /* * List locks */ -static DEFINE_MUTEX(smack_list_lock); static DEFINE_MUTEX(smack_cipso_lock); static DEFINE_MUTEX(smack_ambient_lock); static DEFINE_MUTEX(smk_netlbladdr_lock); @@ -110,6 +110,13 @@ struct smack_master_list { LIST_HEAD(smack_rule_list); +struct smack_parsed_rule { + char *smk_subject; + char *smk_object; + int smk_access1; + int smk_access2; +}; + static int smk_cipso_doi_value = SMACK_CIPSO_DOI_DEFAULT; const char *smack_cipso_option = SMACK_CIPSO_OPTION; @@ -167,25 +174,28 @@ static void smk_netlabel_audit_set(struct netlbl_audit *nap) #define SMK_NETLBLADDRMIN 9 /** - * smk_set_access - add a rule to the rule list - * @srp: the new rule to add + * smk_set_access - add a rule to the rule list or replace an old rule + * @srp: the rule to add or replace * @rule_list: the list of rules * @rule_lock: the rule list lock + * @global: if non-zero, indicates a global rule * * Looks through the current subject/object/access list for * the subject/object pair and replaces the access that was * there. If the pair isn't found add it with the specified * access. * - * Returns 1 if a rule was found to exist already, 0 if it is new * Returns 0 if nothing goes wrong or -ENOMEM if it fails * during the allocation of the new pair to add. */ -static int smk_set_access(struct smack_rule *srp, struct list_head *rule_list, - struct mutex *rule_lock) +static int smk_set_access(struct smack_parsed_rule *srp, + struct list_head *rule_list, + struct mutex *rule_lock, int global) { struct smack_rule *sp; + struct smack_master_list *smlp; int found = 0; + int rc = 0; mutex_lock(rule_lock); @@ -197,23 +207,89 @@ static int smk_set_access(struct smack_rule *srp, struct list_head *rule_list, if (sp->smk_object == srp->smk_object && sp->smk_subject == srp->smk_subject) { found = 1; - sp->smk_access = srp->smk_access; + sp->smk_access |= srp->smk_access1; + sp->smk_access &= ~srp->smk_access2; break; } } - if (found == 0) - list_add_rcu(&srp->list, rule_list); + if (found == 0) { + sp = kzalloc(sizeof(*sp), GFP_KERNEL); + if (sp == NULL) { + rc = -ENOMEM; + goto out; + } + + sp->smk_subject = srp->smk_subject; + sp->smk_object = srp->smk_object; + sp->smk_access = srp->smk_access1 & ~srp->smk_access2; + + list_add_rcu(&sp->list, rule_list); + /* + * If this is a global as opposed to self and a new rule + * it needs to get added for reporting. + */ + if (global) { + smlp = kzalloc(sizeof(*smlp), GFP_KERNEL); + if (smlp != NULL) { + smlp->smk_rule = sp; + list_add_rcu(&smlp->list, &smack_rule_list); + } else + rc = -ENOMEM; + } + } + +out: mutex_unlock(rule_lock); + return rc; +} + +/** + * smk_perm_from_str - parse smack accesses from a text string + * @string: a text string that contains a Smack accesses code + * + * Returns an integer with respective bits set for specified accesses. + */ +static int smk_perm_from_str(const char *string) +{ + int perm = 0; + const char *cp; - return found; + for (cp = string; ; cp++) + switch (*cp) { + case '-': + break; + case 'r': + case 'R': + perm |= MAY_READ; + break; + case 'w': + case 'W': + perm |= MAY_WRITE; + break; + case 'x': + case 'X': + perm |= MAY_EXEC; + break; + case 'a': + case 'A': + perm |= MAY_APPEND; + break; + case 't': + case 'T': + perm |= MAY_TRANSMUTE; + break; + default: + return perm; + } } /** * smk_fill_rule - Fill Smack rule from strings * @subject: subject label string * @object: object label string - * @access: access string + * @access1: access string + * @access2: string with permissions to be removed * @rule: Smack rule * @import: if non-zero, import labels * @len: label length limit @@ -221,8 +297,9 @@ static int smk_set_access(struct smack_rule *srp, struct list_head *rule_list, * Returns 0 on success, -1 on failure */ static int smk_fill_rule(const char *subject, const char *object, - const char *access, struct smack_rule *rule, - int import, int len) + const char *access1, const char *access2, + struct smack_parsed_rule *rule, int import, + int len) { const char *cp; struct smack_known *skp; @@ -255,36 +332,11 @@ static int smk_fill_rule(const char *subject, const char *object, rule->smk_object = skp->smk_known; } - rule->smk_access = 0; - - for (cp = access; *cp != '\0'; cp++) { - switch (*cp) { - case '-': - break; - case 'r': - case 'R': - rule->smk_access |= MAY_READ; - break; - case 'w': - case 'W': - rule->smk_access |= MAY_WRITE; - break; - case 'x': - case 'X': - rule->smk_access |= MAY_EXEC; - break; - case 'a': - case 'A': - rule->smk_access |= MAY_APPEND; - break; - case 't': - case 'T': - rule->smk_access |= MAY_TRANSMUTE; - break; - default: - return 0; - } - } + rule->smk_access1 = smk_perm_from_str(access1); + if (access2) + rule->smk_access2 = smk_perm_from_str(access2); + else + rule->smk_access2 = ~rule->smk_access1; return 0; } @@ -297,30 +349,33 @@ static int smk_fill_rule(const char *subject, const char *object, * * Returns 0 on success, -1 on errors. */ -static int smk_parse_rule(const char *data, struct smack_rule *rule, int import) +static int smk_parse_rule(const char *data, struct smack_parsed_rule *rule, + int import) { int rc; rc = smk_fill_rule(data, data + SMK_LABELLEN, - data + SMK_LABELLEN + SMK_LABELLEN, rule, import, - SMK_LABELLEN); + data + SMK_LABELLEN + SMK_LABELLEN, NULL, rule, + import, SMK_LABELLEN); return rc; } /** * smk_parse_long_rule - parse Smack rule from rule string * @data: string to be parsed, null terminated - * @rule: Smack rule + * @rule: Will be filled with Smack parsed rule * @import: if non-zero, import labels + * @change: if non-zero, data is from /smack/change-rule * * Returns 0 on success, -1 on failure */ -static int smk_parse_long_rule(const char *data, struct smack_rule *rule, - int import) +static int smk_parse_long_rule(const char *data, struct smack_parsed_rule *rule, + int import, int change) { char *subject; char *object; - char *access; + char *access1; + char *access2; int datalen; int rc = -1; @@ -334,14 +389,27 @@ static int smk_parse_long_rule(const char *data, struct smack_rule *rule, object = kzalloc(datalen, GFP_KERNEL); if (object == NULL) goto free_out_s; - access = kzalloc(datalen, GFP_KERNEL); - if (access == NULL) + access1 = kzalloc(datalen, GFP_KERNEL); + if (access1 == NULL) goto free_out_o; + access2 = kzalloc(datalen, GFP_KERNEL); + if (access2 == NULL) + goto free_out_a; + + if (change) { + if (sscanf(data, "%s %s %s %s", + subject, object, access1, access2) == 4) + rc = smk_fill_rule(subject, object, access1, access2, + rule, import, 0); + } else { + if (sscanf(data, "%s %s %s", subject, object, access1) == 3) + rc = smk_fill_rule(subject, object, access1, NULL, + rule, import, 0); + } - if (sscanf(data, "%s %s %s", subject, object, access) == 3) - rc = smk_fill_rule(subject, object, access, rule, import, 0); - - kfree(access); + kfree(access2); +free_out_a: + kfree(access1); free_out_o: kfree(object); free_out_s: @@ -351,6 +419,7 @@ free_out_s: #define SMK_FIXED24_FMT 0 /* Fixed 24byte label format */ #define SMK_LONG_FMT 1 /* Variable long label format */ +#define SMK_CHANGE_FMT 2 /* Rule modification format */ /** * smk_write_rules_list - write() for any /smack rule file * @file: file pointer, not actually used @@ -359,22 +428,24 @@ free_out_s: * @ppos: where to start - must be 0 * @rule_list: the list of rules to write to * @rule_lock: lock for the rule list - * @format: /smack/load or /smack/load2 format. + * @format: /smack/load or /smack/load2 or /smack/change-rule format. * * Get one smack access rule from above. * The format for SMK_LONG_FMT is: * "subject<whitespace>object<whitespace>access[<whitespace>...]" * The format for SMK_FIXED24_FMT is exactly: * "subject object rwxat" + * The format for SMK_CHANGE_FMT is: + * "subject<whitespace>object<whitespace> + * acc_enable<whitespace>acc_disable[<whitespace>...]" */ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf, size_t count, loff_t *ppos, struct list_head *rule_list, struct mutex *rule_lock, int format) { - struct smack_master_list *smlp; struct smack_known *skp; - struct smack_rule *rule; + struct smack_parsed_rule *rule; char *data; int datalen; int rc = -EINVAL; @@ -417,7 +488,11 @@ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf, * Be sure the data string is terminated. */ data[count] = '\0'; - if (smk_parse_long_rule(data, rule, 1)) + if (smk_parse_long_rule(data, rule, 1, 0)) + goto out_free_rule; + } else if (format == SMK_CHANGE_FMT) { + data[count] = '\0'; + if (smk_parse_long_rule(data, rule, 1, 1)) goto out_free_rule; } else { /* @@ -437,22 +512,9 @@ static ssize_t smk_write_rules_list(struct file *file, const char __user *buf, rule_lock = &skp->smk_rules_lock; } - rc = count; - /* - * If this is a global as opposed to self and a new rule - * it needs to get added for reporting. - * smk_set_access returns true if there was already a rule - * for the subject/object pair, and false if it was new. - */ - if (!smk_set_access(rule, rule_list, rule_lock)) { - if (load) { - smlp = kzalloc(sizeof(*smlp), GFP_KERNEL); - if (smlp != NULL) { - smlp->smk_rule = rule; - list_add_rcu(&smlp->list, &smack_rule_list); - } else - rc = -ENOMEM; - } + rc = smk_set_access(rule, rule_list, rule_lock, load); + if (rc == 0) { + rc = count; goto out; } @@ -1774,7 +1836,7 @@ static const struct file_operations smk_load_self_ops = { static ssize_t smk_user_access(struct file *file, const char __user *buf, size_t count, loff_t *ppos, int format) { - struct smack_rule rule; + struct smack_parsed_rule rule; char *data; char *cod; int res; @@ -1796,14 +1858,14 @@ static ssize_t smk_user_access(struct file *file, const char __user *buf, return -ENOMEM; memcpy(cod, data, count); cod[count] = '\0'; - res = smk_parse_long_rule(cod, &rule, 0); + res = smk_parse_long_rule(cod, &rule, 0, 0); kfree(cod); } if (res) return -EINVAL; - res = smk_access(rule.smk_subject, rule.smk_object, rule.smk_access, + res = smk_access(rule.smk_subject, rule.smk_object, rule.smk_access1, NULL); data[0] = res == 0 ? '1' : '0'; data[1] = '\0'; @@ -2075,6 +2137,33 @@ static int smk_init_sysfs(void) } /** + * smk_write_change_rule - write() for /smack/change-rule + * @file: file pointer + * @buf: data from user space + * @count: bytes sent + * @ppos: where to start - must be 0 + */ +static ssize_t smk_write_change_rule(struct file *file, const char __user *buf, + size_t count, loff_t *ppos) +{ + /* + * Must have privilege. + */ + if (!capable(CAP_MAC_ADMIN)) + return -EPERM; + + return smk_write_rules_list(file, buf, count, ppos, NULL, NULL, + SMK_CHANGE_FMT); +} + +static const struct file_operations smk_change_rule_ops = { + .write = smk_write_change_rule, + .read = simple_transaction_read, + .release = simple_transaction_release, + .llseek = generic_file_llseek, +}; + +/** * smk_fill_super - fill the /smackfs superblock * @sb: the empty superblock * @data: unused @@ -2123,6 +2212,8 @@ static int smk_fill_super(struct super_block *sb, void *data, int silent) [SMK_REVOKE_SUBJ] = { "revoke-subject", &smk_revoke_subj_ops, S_IRUGO|S_IWUSR}, + [SMK_CHANGE_RULE] = { + "change-rule", &smk_change_rule_ops, S_IRUGO|S_IWUSR}, /* last one */ {""} }; |