Task Attribute
~~~~~~~~~~~~~~
-The Smack label of a process can be read from /proc/<pid>/attr/current. A
-process can read its own Smack label from /proc/self/attr/current. A
+The Smack label of a process can be read from ``/proc/<pid>/attr/current``. A
+process can read its own Smack label from ``/proc/self/attr/current``. A
privileged process can change its own Smack label by writing to
-/proc/self/attr/current but not the label of another process.
+``/proc/self/attr/current`` but not the label of another process.
+
+Format of writing is : only the label or the label followed by one of the
+3 trailers: ``\n`` (by common agreement for ``/proc/...`` interfaces),
+``\0`` (because some applications incorrectly include it),
+``\n\0`` (because we think some applications may incorrectly include it).
File Attribute
~~~~~~~~~~~~~~
int smk_curacc(struct smack_known *, u32, struct smk_audit_info *);
int smack_str_from_perm(char *string, int access);
struct smack_known *smack_from_secid(const u32);
+int smk_parse_label_len(const char *string, int len);
char *smk_parse_smack(const char *string, int len);
int smk_netlbl_mls(int, char *, struct netlbl_lsm_secattr *, int);
struct smack_known *smk_import_entry(const char *, int);
+struct smack_known *smk_import_valid_label(const char *label, int label_len,
+ gfp_t gfp);
void smk_insert_entry(struct smack_known *skp);
struct smack_known *smk_find_entry(const char *);
bool smack_privileged(int cap);
}
/**
- * smk_parse_smack - parse smack label from a text string
- * @string: a text string that might contain a Smack label
- * @len: the maximum size, or zero if it is NULL terminated.
+ * smk_parse_label_len - calculate the length of the starting segment
+ * in the string that constitutes a valid smack label
+ * @string: a text string that might contain a Smack label at the beginning
+ * @len: the maximum size to look into, may be zero if string is null-terminated
*
- * Returns a pointer to the clean label or an error code.
+ * Returns the length of the segment (0 < L < SMK_LONGLABEL) or an error code.
*/
-char *smk_parse_smack(const char *string, int len)
+int smk_parse_label_len(const char *string, int len)
{
- char *smack;
int i;
- if (len <= 0)
- len = strlen(string) + 1;
+ if (len <= 0 || len > SMK_LONGLABEL)
+ len = SMK_LONGLABEL;
/*
* Reserve a leading '-' as an indicator that
* including /smack/cipso and /smack/cipso2
*/
if (string[0] == '-')
- return ERR_PTR(-EINVAL);
+ return -EINVAL;
for (i = 0; i < len; i++)
if (string[i] > '~' || string[i] <= ' ' || string[i] == '/' ||
break;
if (i == 0 || i >= SMK_LONGLABEL)
+ return -EINVAL;
+
+ return i;
+}
+
+/**
+ * smk_parse_smack - copy the starting segment in the string
+ * that constitutes a valid smack label
+ * @string: a text string that might contain a Smack label at the beginning
+ * @len: the maximum size to look into, may be zero if string is null-terminated
+ *
+ * Returns a pointer to the copy of the label or an error code.
+ */
+char *smk_parse_smack(const char *string, int len)
+{
+ char *smack;
+ int i = smk_parse_label_len(string, len);
+
+ if (i < 0)
return ERR_PTR(-EINVAL);
smack = kstrndup(string, i, GFP_NOFS);
}
/**
- * smk_import_entry - import a label, return the list entry
- * @string: a text string that might be a Smack label
- * @len: the maximum size, or zero if it is NULL terminated.
+ * smk_import_valid_allocated_label - import a label, return the list entry
+ * @smack: a text string that is a valid Smack label and may be kfree()ed.
+ * It is consumed: either becomes a part of the entry or kfree'ed.
*
- * Returns a pointer to the entry in the label list that
- * matches the passed string, adding it if necessary,
- * or an error code.
+ * Returns: see description of smk_import_entry()
*/
-struct smack_known *smk_import_entry(const char *string, int len)
+static struct smack_known *
+smk_import_allocated_label(char *smack, gfp_t gfp)
{
struct smack_known *skp;
- char *smack;
int rc;
- smack = smk_parse_smack(string, len);
- if (IS_ERR(smack))
- return ERR_CAST(smack);
-
mutex_lock(&smack_known_lock);
skp = smk_find_entry(smack);
if (skp != NULL)
goto freeout;
- skp = kzalloc(sizeof(*skp), GFP_NOFS);
+ skp = kzalloc(sizeof(*skp), gfp);
if (skp == NULL) {
skp = ERR_PTR(-ENOMEM);
goto freeout;
return skp;
}
+/**
+ * smk_import_entry - import a label, return the list entry
+ * @string: a text string that might contain a Smack label at the beginning
+ * @len: the maximum size to look into, may be zero if string is null-terminated
+ *
+ * Returns a pointer to the entry in the label list that
+ * matches the passed string, adding it if necessary,
+ * or an error code.
+ */
+struct smack_known *smk_import_entry(const char *string, int len)
+{
+ char *smack = smk_parse_smack(string, len);
+
+ if (IS_ERR(smack))
+ return ERR_CAST(smack);
+
+ return smk_import_allocated_label(smack, GFP_NOFS);
+}
+
+/**
+ * smk_import_valid_label - import a label, return the list entry
+ * @label a text string that is a valid Smack label, not null-terminated
+ *
+ * Returns: see description of smk_import_entry()
+ */
+struct smack_known *
+smk_import_valid_label(const char *label, int label_len, gfp_t gfp)
+{
+ char *smack = kstrndup(label, label_len, gfp);
+
+ if (!smack)
+ return ERR_PTR(-ENOMEM);
+
+ return smk_import_allocated_label(smack, gfp);
+}
+
/**
* smack_from_secid - find the Smack label associated with a secid
* @secid: an integer that might be associated with a Smack label
* @attr: which attribute to fetch
* @ctx: buffer to receive the result
* @size: available size in, actual size out
- * @flags: unused
+ * @flags: reserved, currently zero
*
* Fill the passed user space @ctx with the details of the requested
* attribute.
* Sets the Smack value of the task. Only setting self
* is permitted and only with privilege
*
- * Returns the length of the smack label or an error code
+ * Returns zero on success or an error code
*/
-static int do_setattr(u64 attr, void *value, size_t size)
+static int do_setattr(unsigned int attr, void *value, size_t size)
{
struct task_smack *tsp = smack_cred(current_cred());
struct cred *new;
struct smack_known *skp;
- char *labelstr;
- int rc = 0;
-
- if (!smack_privileged(CAP_MAC_ADMIN) && list_empty(&tsp->smk_relabel))
- return -EPERM;
+ int label_len;
+ /*
+ * let unprivileged user validate input, check permissions later
+ */
if (value == NULL || size == 0 || size >= SMK_LONGLABEL)
return -EINVAL;
- if (attr != LSM_ATTR_CURRENT)
- return -EOPNOTSUPP;
-
- labelstr = smk_parse_smack(value, size);
- if (IS_ERR(labelstr))
- return PTR_ERR(labelstr);
+ label_len = smk_parse_label_len(value, size);
+ if (label_len < 0 || label_len != size)
+ return -EINVAL;
/*
* No process is ever allowed the web ("@") label
* and the star ("*") label.
*/
- if (labelstr[1] == '\0' /* '@', '*' */) {
- const char c = labelstr[0];
+ if (label_len == 1 /* '@', '*' */) {
+ const char c = *(const char *)value;
if (c == *smack_known_web.smk_known ||
- c == *smack_known_star.smk_known) {
- rc = -EPERM;
- goto free_labelstr;
- }
+ c == *smack_known_star.smk_known)
+ return -EPERM;
}
if (!smack_privileged(CAP_MAC_ADMIN)) {
const struct smack_known_list_elem *sklep;
- list_for_each_entry(sklep, &tsp->smk_relabel, list)
- if (strcmp(sklep->smk_label->smk_known, labelstr) == 0)
- goto free_labelstr;
- rc = -EPERM;
- }
+ list_for_each_entry(sklep, &tsp->smk_relabel, list) {
+ const char *cp = sklep->smk_label->smk_known;
-free_labelstr:
- kfree(labelstr);
- if (rc)
+ if (strlen(cp) == label_len &&
+ strncmp(cp, value, label_len) == 0)
+ goto in_relabel;
+ }
return -EPERM;
+in_relabel:
+ ;
+ }
- skp = smk_import_entry(value, size);
+ skp = smk_import_valid_label(value, label_len, GFP_KERNEL);
if (IS_ERR(skp))
return PTR_ERR(skp);
smk_destroy_label_list(&tsp->smk_relabel);
commit_creds(new);
- return size;
+ return 0;
}
/**
* @attr: which attribute to set
* @ctx: buffer containing the data
* @size: size of @ctx
- * @flags: unused
+ * @flags: reserved, must be zero
*
* Fill the passed user space @ctx with the details of the requested
* attribute.
static int smack_setselfattr(unsigned int attr, struct lsm_ctx *ctx,
u32 size, u32 flags)
{
- int rc;
+ if (attr != LSM_ATTR_CURRENT)
+ return -EOPNOTSUPP;
- rc = do_setattr(attr, ctx->ctx, ctx->ctx_len);
- if (rc > 0)
- return 0;
- return rc;
+ if (ctx->flags)
+ return -EINVAL;
+ /*
+ * string must have \0 terminator, included in ctx->ctx
+ * (see description of struct lsm_ctx)
+ */
+ if (ctx->ctx_len == 0)
+ return -EINVAL;
+
+ if (ctx->ctx[ctx->ctx_len - 1] != '\0')
+ return -EINVAL;
+ /*
+ * other do_setattr() caller, smack_setprocattr(),
+ * does not count \0 into size, so
+ * decreasing length by 1 to accommodate the divergence.
+ */
+ return do_setattr(attr, ctx->ctx, ctx->ctx_len - 1);
}
/**
* Sets the Smack value of the task. Only setting self
* is permitted and only with privilege
*
- * Returns the length of the smack label or an error code
+ * Returns the size of the input value or an error code
*/
static int smack_setprocattr(const char *name, void *value, size_t size)
{
- int attr = lsm_name_to_attr(name);
+ size_t realsize = size;
+ unsigned int attr = lsm_name_to_attr(name);
- if (attr != LSM_ATTR_UNDEF)
- return do_setattr(attr, value, size);
- return -EINVAL;
+ switch (attr) {
+ case LSM_ATTR_UNDEF: return -EINVAL;
+ default: return -EOPNOTSUPP;
+ case LSM_ATTR_CURRENT:
+ ;
+ }
+
+ /*
+ * The value for the "current" attribute is the label
+ * followed by one of the 4 trailers: none, \0, \n, \n\0
+ *
+ * I.e. following inputs are accepted as 3-characters long label "foo":
+ *
+ * "foo" (3 characters)
+ * "foo\0" (4 characters)
+ * "foo\n" (4 characters)
+ * "foo\n\0" (5 characters)
+ */
+
+ if (realsize && (((const char *)value)[realsize - 1] == '\0'))
+ --realsize;
+
+ if (realsize && (((const char *)value)[realsize - 1] == '\n'))
+ --realsize;
+
+ return do_setattr(attr, value, realsize) ? : size;
}
/**
projects / thirdparty / linux.git / commitdiff
