Re: [PATCH v4 07/11] smack: abstraction layer for 2 common Smack operations
From: Casey Schaufler
Date: Thu Oct 29 2015 - 18:51:32 EST
On 10/14/2015 5:42 AM, Lukasz Pawelczyk wrote:
> This patch adds two new functions that provide an abstraction layer for
> two common internal Smack operations:
>
> smk_find_label_name() - returns a label name (char*) from a struct
> smack_known pointer
> smk_get_label() - either finds or imports a label from a raw label
> name (char*) and returns struct smack_known
> pointer
>
> This patch also simplifies some pieces of code due to addition of those
> 2 functions (e.g. smack_inode_post_setxattr, smk_fill_rule,
> smk_write_revoke_subj).
>
> It is meant as a preparation for namespaces patches. Those 2 functions
> will serve as entry points for namespace operations.
>
> This patch should not change the Smack behaviour in any way.
>
> Signed-off-by: Lukasz Pawelczyk <l.pawelczyk@xxxxxxxxxxx>
> Reviewed-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
Acked-by: Casey Schaufler <casey@xxxxxxxxxxxxxxxx>
> ---
> security/smack/smack.h | 2 +
> security/smack/smack_access.c | 41 ++++++++++++
> security/smack/smack_lsm.c | 78 +++++++++++-----------
> security/smack/smackfs.c | 147 +++++++++++++++++++++++-------------------
> 4 files changed, 166 insertions(+), 102 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index ca8fb7c..091efc2 100644
> --- a/security/smack/smack.h
> +++ b/security/smack/smack.h
> @@ -306,6 +306,8 @@ int smack_has_ns_privilege(struct task_struct *task,
> int smack_has_privilege(struct task_struct *task, int cap);
> int smack_ns_privileged(struct user_namespace *user_ns, int cap);
> int smack_privileged(int cap);
> +char *smk_find_label_name(struct smack_known *skp);
> +struct smack_known *smk_get_label(const char *string, int len, bool import);
>
> /*
> * Shared data.
> diff --git a/security/smack/smack_access.c b/security/smack/smack_access.c
> index 72f848e..131c742 100644
> --- a/security/smack/smack_access.c
> +++ b/security/smack/smack_access.c
> @@ -716,3 +716,44 @@ int smack_privileged(int cap)
> {
> return smack_ns_privileged(&init_user_ns, cap);
> }
> +
> +/**
> + * smk_find_label_name - A helper to get a string value of a label
> + * @skp: a label we want a string value from
> + *
> + * Returns a pointer to a label name or NULL if label name not found.
> + */
> +char *smk_find_label_name(struct smack_known *skp)
> +{
> + return skp->smk_known;
> +}
> +
> +/**
> + * smk_get_label - A helper to get the smack_known value from a string using
> + * either import or find functions if it already exists
> + * @string: a name of a label we look for or want to import
> + * @len: the string size, or zero if it is NULL terminated
> + * @import: whether we should import the label if not found
> + *
> + * Returns a smack_known label that is either imported or found.
> + * NULL if label not found (only when import == false).
> + * Error code otherwise.
> + */
> +struct smack_known *smk_get_label(const char *string, int len, bool import)
> +{
> + struct smack_known *skp;
> + char *cp;
> +
> + if (import) {
> + skp = smk_import_entry(string, len);
> + } else {
> + cp = smk_parse_smack(string, len);
> + if (IS_ERR(cp))
> + return ERR_CAST(cp);
> +
> + skp = smk_find_entry(cp);
> + kfree(cp);
> + }
> +
> + return skp;
> +}
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 198d3d6..7303c37 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -746,31 +746,31 @@ static int smack_set_mnt_opts(struct super_block *sb,
> for (i = 0; i < num_opts; i++) {
> switch (opts->mnt_opts_flags[i]) {
> case FSDEFAULT_MNT:
> - skp = smk_import_entry(opts->mnt_opts[i], 0);
> + skp = smk_get_label(opts->mnt_opts[i], 0, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
> sp->smk_default = skp;
> break;
> case FSFLOOR_MNT:
> - skp = smk_import_entry(opts->mnt_opts[i], 0);
> + skp = smk_get_label(opts->mnt_opts[i], 0, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
> sp->smk_floor = skp;
> break;
> case FSHAT_MNT:
> - skp = smk_import_entry(opts->mnt_opts[i], 0);
> + skp = smk_get_label(opts->mnt_opts[i], 0, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
> sp->smk_hat = skp;
> break;
> case FSROOT_MNT:
> - skp = smk_import_entry(opts->mnt_opts[i], 0);
> + skp = smk_get_label(opts->mnt_opts[i], 0, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
> sp->smk_root = skp;
> break;
> case FSTRANS_MNT:
> - skp = smk_import_entry(opts->mnt_opts[i], 0);
> + skp = smk_get_label(opts->mnt_opts[i], 0, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
> sp->smk_root = skp;
> @@ -1288,7 +1288,7 @@ static int smack_inode_setxattr(struct dentry *dentry, const char *name,
> rc = -EPERM;
>
> if (rc == 0 && check_import) {
> - skp = size ? smk_import_entry(value, size) : NULL;
> + skp = size ? smk_get_label(value, size, true) : NULL;
> if (IS_ERR(skp))
> rc = PTR_ERR(skp);
> else if (skp == NULL || (check_star &&
> @@ -1322,6 +1322,7 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
> const void *value, size_t size, int flags)
> {
> struct smack_known *skp;
> + struct smack_known **skpp = NULL;
> struct inode_smack *isp = d_backing_inode(dentry)->i_security;
>
> if (strcmp(name, XATTR_NAME_SMACKTRANSMUTE) == 0) {
> @@ -1329,27 +1330,21 @@ static void smack_inode_post_setxattr(struct dentry *dentry, const char *name,
> return;
> }
>
> - if (strcmp(name, XATTR_NAME_SMACK) == 0) {
> - skp = smk_import_entry(value, size);
> - if (!IS_ERR(skp))
> - isp->smk_inode = skp;
> - else
> - isp->smk_inode = &smack_known_invalid;
> - } else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0) {
> - skp = smk_import_entry(value, size);
> - if (!IS_ERR(skp))
> - isp->smk_task = skp;
> - else
> - isp->smk_task = &smack_known_invalid;
> - } else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0) {
> - skp = smk_import_entry(value, size);
> + if (strcmp(name, XATTR_NAME_SMACK) == 0)
> + skpp = &isp->smk_inode;
> + else if (strcmp(name, XATTR_NAME_SMACKEXEC) == 0)
> + skpp = &isp->smk_task;
> + else if (strcmp(name, XATTR_NAME_SMACKMMAP) == 0)
> + skpp = &isp->smk_mmap;
> +
> + if (skpp) {
> + skp = smk_get_label(value, size, true);
> +
> if (!IS_ERR(skp))
> - isp->smk_mmap = skp;
> + *skpp = skp;
> else
> - isp->smk_mmap = &smack_known_invalid;
> + *skpp = &smack_known_invalid;
> }
> -
> - return;
> }
>
> /**
> @@ -1443,15 +1438,17 @@ static int smack_inode_getsecurity(const struct inode *inode,
> struct socket *sock;
> struct super_block *sbp;
> struct inode *ip = (struct inode *)inode;
> - struct smack_known *isp;
> - int ilen;
> + struct smack_known *isp = NULL;
> int rc = 0;
>
> - if (strcmp(name, XATTR_SMACK_SUFFIX) == 0) {
> + if (strcmp(name, XATTR_SMACK_SUFFIX) == 0)
> isp = smk_of_inode(inode);
> - ilen = strlen(isp->smk_known);
> - *buffer = isp->smk_known;
> - return ilen;
> +
> + if (isp) {
> + *buffer = smk_find_label_name(isp);
> + if (*buffer == NULL)
> + *buffer = smack_known_huh.smk_known;
> + return strlen(*buffer);
> }
>
> /*
> @@ -1474,10 +1471,11 @@ static int smack_inode_getsecurity(const struct inode *inode,
> else
> return -EOPNOTSUPP;
>
> - ilen = strlen(isp->smk_known);
> if (rc == 0) {
> - *buffer = isp->smk_known;
> - rc = ilen;
> + *buffer = smk_find_label_name(isp);
> + if (*buffer == NULL)
> + *buffer = smack_known_huh.smk_known;
> + rc = strlen(*buffer);
> }
>
> return rc;
> @@ -2658,7 +2656,7 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
> if (value == NULL || size > SMK_LONGLABEL || size == 0)
> return -EINVAL;
>
> - skp = smk_import_entry(value, size);
> + skp = smk_get_label(value, size, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
>
> @@ -3528,7 +3526,10 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
> if (strcmp(name, "current") != 0)
> return -EINVAL;
>
> - cp = kstrdup(skp->smk_known, GFP_KERNEL);
> + cp = smk_find_label_name(skp);
> + if (cp == NULL)
> + cp = smack_known_huh.smk_known;
> + cp = kstrdup(cp, GFP_KERNEL);
> if (cp == NULL)
> return -ENOMEM;
>
> @@ -3572,7 +3573,7 @@ static int smack_setprocattr(struct task_struct *p, const struct cred *f_cred,
> if (strcmp(name, "current") != 0)
> return -EINVAL;
>
> - skp = smk_import_entry(value, size);
> + skp = smk_get_label(value, size, true);
> if (IS_ERR(skp))
> return PTR_ERR(skp);
>
> @@ -4311,7 +4312,10 @@ static int smack_key_getsecurity(struct key *key, char **_buffer)
> return 0;
> }
>
> - copy = kstrdup(skp->smk_known, GFP_KERNEL);
> + copy = smk_find_label_name(skp);
> + if (copy == NULL)
> + copy = smack_known_huh.smk_known;
> + copy = kstrdup(copy, GFP_KERNEL);
> if (copy == NULL)
> return -ENOMEM;
> length = strlen(copy) + 1;
> diff --git a/security/smack/smackfs.c b/security/smack/smackfs.c
> index 05e09ee2..e5fb555 100644
> --- a/security/smack/smackfs.c
> +++ b/security/smack/smackfs.c
> @@ -340,36 +340,17 @@ static int smk_fill_rule(const char *subject, const char *object,
> struct smack_parsed_rule *rule, int import,
> int len)
> {
> - const char *cp;
> - struct smack_known *skp;
> -
> - if (import) {
> - rule->smk_subject = smk_import_entry(subject, len);
> - if (IS_ERR(rule->smk_subject))
> - return PTR_ERR(rule->smk_subject);
> -
> - rule->smk_object = smk_import_entry(object, len);
> - if (IS_ERR(rule->smk_object))
> - return PTR_ERR(rule->smk_object);
> - } else {
> - cp = smk_parse_smack(subject, len);
> - if (IS_ERR(cp))
> - return PTR_ERR(cp);
> - skp = smk_find_entry(cp);
> - kfree(cp);
> - if (skp == NULL)
> - return -ENOENT;
> - rule->smk_subject = skp;
> -
> - cp = smk_parse_smack(object, len);
> - if (IS_ERR(cp))
> - return PTR_ERR(cp);
> - skp = smk_find_entry(cp);
> - kfree(cp);
> - if (skp == NULL)
> - return -ENOENT;
> - rule->smk_object = skp;
> - }
> + rule->smk_subject = smk_get_label(subject, len, import);
> + if (IS_ERR(rule->smk_subject))
> + return PTR_ERR(rule->smk_subject);
> + if (rule->smk_subject == NULL)
> + return -ENOENT;
> +
> + rule->smk_object = smk_get_label(object, len, import);
> + if (IS_ERR(rule->smk_object))
> + return PTR_ERR(rule->smk_object);
> + if (rule->smk_object == NULL)
> + return -ENOENT;
>
> rule->smk_access1 = smk_perm_from_str(access1);
> if (access2)
> @@ -592,6 +573,9 @@ static void smk_seq_stop(struct seq_file *s, void *v)
>
> static void smk_rule_show(struct seq_file *s, struct smack_rule *srp, int max)
> {
> + char *sbj;
> + char *obj;
> +
> /*
> * Don't show any rules with label names too long for
> * interface file (/smack/load or /smack/load2)
> @@ -605,9 +589,13 @@ static void smk_rule_show(struct seq_file *s, struct smack_rule *srp, int max)
> if (srp->smk_access == 0)
> return;
>
> - seq_printf(s, "%s %s",
> - srp->smk_subject->smk_known,
> - srp->smk_object->smk_known);
> + sbj = smk_find_label_name(srp->smk_subject);
> + obj = smk_find_label_name(srp->smk_object);
> +
> + if (sbj == NULL || obj == NULL)
> + return;
> +
> + seq_printf(s, "%s %s", sbj, obj);
>
> seq_putc(s, ' ');
>
> @@ -798,6 +786,7 @@ static int cipso_seq_show(struct seq_file *s, void *v)
> list_entry_rcu(list, struct smack_known, list);
> struct netlbl_lsm_catmap *cmp = skp->smk_netlabel.attr.mls.cat;
> char sep = '/';
> + char *cp;
> int i;
>
> /*
> @@ -811,7 +800,11 @@ static int cipso_seq_show(struct seq_file *s, void *v)
> if (strlen(skp->smk_known) >= SMK_LABELLEN)
> return 0;
>
> - seq_printf(s, "%s %3d", skp->smk_known, skp->smk_netlabel.attr.mls.lvl);
> + cp = smk_find_label_name(skp);
> + if (cp == NULL)
> + return 0;
> +
> + seq_printf(s, "%s %3d", cp, skp->smk_netlabel.attr.mls.lvl);
>
> for (i = netlbl_catmap_walk(cmp, 0); i >= 0;
> i = netlbl_catmap_walk(cmp, i + 1)) {
> @@ -900,7 +893,7 @@ static ssize_t smk_set_cipso(struct file *file, const char __user *buf,
> */
> mutex_lock(&smack_cipso_lock);
>
> - skp = smk_import_entry(rule, 0);
> + skp = smk_get_label(rule, 0, true);
> if (IS_ERR(skp)) {
> rc = PTR_ERR(skp);
> goto out;
> @@ -989,9 +982,14 @@ static int cipso2_seq_show(struct seq_file *s, void *v)
> list_entry_rcu(list, struct smack_known, list);
> struct netlbl_lsm_catmap *cmp = skp->smk_netlabel.attr.mls.cat;
> char sep = '/';
> + char *cp;
> int i;
>
> - seq_printf(s, "%s %3d", skp->smk_known, skp->smk_netlabel.attr.mls.lvl);
> + cp = smk_find_label_name(skp);
> + if (cp == NULL)
> + return 0;
> +
> + seq_printf(s, "%s %3d", cp, skp->smk_netlabel.attr.mls.lvl);
>
> for (i = netlbl_catmap_walk(cmp, 0); i >= 0;
> i = netlbl_catmap_walk(cmp, i + 1)) {
> @@ -1072,8 +1070,12 @@ static int net4addr_seq_show(struct seq_file *s, void *v)
> list_entry_rcu(list, struct smk_net4addr, list);
> char *kp = SMACK_CIPSO_OPTION;
>
> - if (skp->smk_label != NULL)
> - kp = skp->smk_label->smk_known;
> + if (skp->smk_label != NULL) {
> + kp = smk_find_label_name(skp->smk_label);
> + if (kp == NULL)
> + kp = smack_known_huh.smk_known;
> + }
> +
> seq_printf(s, "%pI4/%d %s\n", &skp->smk_host.s_addr,
> skp->smk_masks, kp);
>
> @@ -1224,7 +1226,7 @@ static ssize_t smk_write_net4addr(struct file *file, const char __user *buf,
> * If smack begins with '-', it is an option, don't import it
> */
> if (smack[0] != '-') {
> - skp = smk_import_entry(smack, 0);
> + skp = smk_get_label(smack, 0, true);
> if (IS_ERR(skp)) {
> rc = PTR_ERR(skp);
> goto free_out;
> @@ -1343,10 +1345,16 @@ static int net6addr_seq_show(struct seq_file *s, void *v)
> struct list_head *list = v;
> struct smk_net6addr *skp =
> list_entry(list, struct smk_net6addr, list);
> + char *kp;
>
> - if (skp->smk_label != NULL)
> - seq_printf(s, "%pI6/%d %s\n", &skp->smk_host, skp->smk_masks,
> - skp->smk_label->smk_known);
> + if (skp->smk_label != NULL) {
> + kp = smk_find_label_name(skp->smk_label);
> + if (kp == NULL)
> + kp = smack_known_huh.smk_known;
> +
> + seq_printf(s, "%pI6/%d %s\n", &skp->smk_host,
> + skp->smk_masks, kp);
> + }
>
> return 0;
> }
> @@ -1500,7 +1508,7 @@ static ssize_t smk_write_net6addr(struct file *file, const char __user *buf,
> * If smack begins with '-', it is an option, don't import it
> */
> if (smack[0] != '-') {
> - skp = smk_import_entry(smack, 0);
> + skp = smk_get_label(smack, 0, true);
> if (IS_ERR(skp)) {
> rc = PTR_ERR(skp);
> goto free_out;
> @@ -1820,6 +1828,7 @@ static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
> size_t cn, loff_t *ppos)
> {
> ssize_t rc;
> + char *cp;
> int asize;
>
> if (*ppos != 0)
> @@ -1830,12 +1839,14 @@ static ssize_t smk_read_ambient(struct file *filp, char __user *buf,
> */
> mutex_lock(&smack_ambient_lock);
>
> - asize = strlen(smack_net_ambient->smk_known) + 1;
> + cp = smk_find_label_name(smack_net_ambient);
> + if (cp == NULL)
> + cp = smack_known_huh.smk_known;
> +
> + asize = strlen(cp) + 1;
>
> if (cn >= asize)
> - rc = simple_read_from_buffer(buf, cn, ppos,
> - smack_net_ambient->smk_known,
> - asize);
> + rc = simple_read_from_buffer(buf, cn, ppos, cp, asize);
> else
> rc = -EINVAL;
>
> @@ -1873,7 +1884,7 @@ static ssize_t smk_write_ambient(struct file *file, const char __user *buf,
> goto out;
> }
>
> - skp = smk_import_entry(data, count);
> + skp = smk_get_label(data, count, true);
> if (IS_ERR(skp)) {
> rc = PTR_ERR(skp);
> goto out;
> @@ -1913,11 +1924,16 @@ static void *onlycap_seq_next(struct seq_file *s, void *v, loff_t *pos)
>
> static int onlycap_seq_show(struct seq_file *s, void *v)
> {
> + char *smack;
> struct list_head *list = v;
> struct smack_onlycap *sop =
> list_entry_rcu(list, struct smack_onlycap, list);
>
> - seq_puts(s, sop->smk_label->smk_known);
> + smack = smk_find_label_name(sop->smk_label);
> + if (smack == NULL)
> + smack = smack_known_huh.smk_known;
> +
> + seq_puts(s, smack);
> seq_putc(s, ' ');
>
> return 0;
> @@ -2011,7 +2027,7 @@ static ssize_t smk_write_onlycap(struct file *file, const char __user *buf,
> if (!*tok)
> continue;
>
> - skp = smk_import_entry(tok, 0);
> + skp = smk_get_label(tok, 0, true);
> if (IS_ERR(skp)) {
> rc = PTR_ERR(skp);
> break;
> @@ -2081,8 +2097,11 @@ static ssize_t smk_read_unconfined(struct file *filp, char __user *buf,
> if (*ppos != 0)
> return 0;
>
> - if (smack_unconfined != NULL)
> - smack = smack_unconfined->smk_known;
> + if (smack_unconfined != NULL) {
> + smack = smk_find_label_name(smack_unconfined);
> + if (smack == NULL)
> + smack = smack_known_huh.smk_known;
> + }
>
> asize = strlen(smack) + 1;
>
> @@ -2129,7 +2148,7 @@ static ssize_t smk_write_unconfined(struct file *file, const char __user *buf,
> *
> * But do so only on invalid label, not on system errors.
> */
> - skp = smk_import_entry(data, count);
> + skp = smk_get_label(data, count, true);
> if (PTR_ERR(skp) == -EINVAL)
> skp = NULL;
> else if (IS_ERR(skp)) {
> @@ -2526,7 +2545,6 @@ static ssize_t smk_write_revoke_subj(struct file *file, const char __user *buf,
> size_t count, loff_t *ppos)
> {
> char *data;
> - const char *cp;
> struct smack_known *skp;
> struct smack_rule *sp;
> struct list_head *rule_list;
> @@ -2551,15 +2569,13 @@ static ssize_t smk_write_revoke_subj(struct file *file, const char __user *buf,
> goto out_data;
> }
>
> - cp = smk_parse_smack(data, count);
> - if (IS_ERR(cp)) {
> - rc = PTR_ERR(cp);
> + skp = smk_get_label(data, count, false);
> + if (IS_ERR(skp)) {
> + rc = PTR_ERR(skp);
> goto out_data;
> }
> -
> - skp = smk_find_entry(cp);
> if (skp == NULL)
> - goto out_cp;
> + goto out_data;
>
> rule_list = &skp->smk_rules;
> rule_lock = &skp->smk_rules_lock;
> @@ -2571,8 +2587,6 @@ static ssize_t smk_write_revoke_subj(struct file *file, const char __user *buf,
>
> mutex_unlock(rule_lock);
>
> -out_cp:
> - kfree(cp);
> out_data:
> kfree(data);
>
> @@ -2641,8 +2655,11 @@ static ssize_t smk_read_syslog(struct file *filp, char __user *buf,
> if (*ppos != 0)
> return 0;
>
> - if (smack_syslog_label != NULL)
> - smack = smack_syslog_label->smk_known;
> + if (smack_syslog_label != NULL) {
> + smack = smk_find_label_name(smack_syslog_label);
> + if (smack == NULL)
> + smack = smack_known_huh.smk_known;
> + }
>
> asize = strlen(smack) + 1;
>
> @@ -2689,7 +2706,7 @@ static ssize_t smk_write_syslog(struct file *file, const char __user *buf,
> *
> * But do so only on invalid label, not on system errors.
> */
> - skp = smk_import_entry(data, count);
> + skp = smk_get_label(data, count, true);
> if (PTR_ERR(skp) == -EINVAL)
> skp = NULL;
> else if (IS_ERR(skp)) {
--
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