--- v22
+++ v30
@@ -1,328 +1,89 @@
-Add an entry /proc/.../attr/context which displays the full
-process security "context" in compound format:
- lsm1\0value\0lsm2\0value\0...
-This entry is not writable.
+Replace the osid field in the audit_names structure
+with a lsmblob structure. This accomodates the use
+of an lsmblob in security_audit_rule_match() and
+security_inode_getsecid().
-A security module may decide that its policy does not allow
-this information to be displayed. In this case none of the
-information will be displayed.
+Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
+---
+ kernel/audit.h | 2 +-
+ kernel/auditsc.c | 22 ++++++++--------------
+ 2 files changed, 9 insertions(+), 15 deletions(-)
-Reviewed-by: Kees Cook <keescook@chromium.org>
-Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
-Cc: linux-api@vger.kernel.org
----
- Documentation/security/lsm.rst | 28 ++++++++++
- fs/proc/base.c | 1 +
- include/linux/lsm_hooks.h | 6 +++
- security/apparmor/include/procattr.h | 2 +-
- security/apparmor/lsm.c | 8 ++-
- security/apparmor/procattr.c | 22 ++++----
- security/security.c | 79 ++++++++++++++++++++++++++++
- security/selinux/hooks.c | 2 +-
- security/smack/smack_lsm.c | 2 +-
- 9 files changed, 135 insertions(+), 15 deletions(-)
+diff --git a/kernel/audit.h b/kernel/audit.h
+index 527d4c4acb12..a2fca1134519 100644
+--- a/kernel/audit.h
++++ b/kernel/audit.h
+@@ -82,7 +82,7 @@ struct audit_names {
+ kuid_t uid;
+ kgid_t gid;
+ dev_t rdev;
+- u32 osid;
++ struct lsmblob lsmblob;
+ struct audit_cap_data fcap;
+ unsigned int fcap_ver;
+ unsigned char type; /* record type */
+diff --git a/kernel/auditsc.c b/kernel/auditsc.c
+index ded4e8740fa2..0d0351dc0c52 100644
+--- a/kernel/auditsc.c
++++ b/kernel/auditsc.c
+@@ -691,17 +691,16 @@ static int audit_filter_rules(struct task_struct *tsk,
+ * lsmblob, which happens later in
+ * this patch set.
+ */
+- lsmblob_init(&blob, name->osid);
+ result = security_audit_rule_match(
+- &blob,
++ &name->lsmblob,
+ f->type,
+ f->op,
+ &f->lsm_rules);
+ } else if (ctx) {
+ list_for_each_entry(n, &ctx->names_list, list) {
+- lsmblob_init(&blob, n->osid);
+ if (security_audit_rule_match(
+- &blob, f->type, f->op,
++ &n->lsmblob,
++ f->type, f->op,
+ &f->lsm_rules)) {
+ ++result;
+ break;
+@@ -1528,13 +1527,12 @@ static void audit_log_name(struct audit_context *context, struct audit_names *n,
+ from_kgid(&init_user_ns, n->gid),
+ MAJOR(n->rdev),
+ MINOR(n->rdev));
+- if (n->osid != 0) {
+- struct lsmblob blob;
++ if (lsmblob_is_set(&n->lsmblob)) {
+ struct lsmcontext lsmctx;
+
+- lsmblob_init(&blob, n->osid);
+- if (security_secid_to_secctx(&blob, &lsmctx, LSMBLOB_FIRST)) {
+- audit_log_format(ab, " osid=%u", n->osid);
++ if (security_secid_to_secctx(&n->lsmblob, &lsmctx,
++ LSMBLOB_FIRST)) {
++ audit_log_format(ab, " osid=?");
+ if (call_panic)
+ *call_panic = 2;
+ } else {
+@@ -2236,17 +2234,13 @@ static void audit_copy_inode(struct audit_names *name,
+ const struct dentry *dentry,
+ struct inode *inode, unsigned int flags)
+ {
+- struct lsmblob blob;
+-
+ name->ino = inode->i_ino;
+ name->dev = inode->i_sb->s_dev;
+ name->mode = inode->i_mode;
+ name->uid = inode->i_uid;
+ name->gid = inode->i_gid;
+ name->rdev = inode->i_rdev;
+- security_inode_getsecid(inode, &blob);
+- /* scaffolding until osid is updated */
+- name->osid = blob.secid[0];
++ security_inode_getsecid(inode, &name->lsmblob);
+ if (flags & AUDIT_INODE_NOEVAL) {
+ name->fcap_ver = -1;
+ return;
+--
+2.31.1
-diff --git a/Documentation/security/lsm.rst b/Documentation/security/lsm.rst
-index 6a2a2e973080..3a1403b7cf10 100644
---- a/Documentation/security/lsm.rst
-+++ b/Documentation/security/lsm.rst
-@@ -129,3 +129,31 @@ to identify it as the first security module to be registered.
- The capabilities security module does not use the general security
- blobs, unlike other modules. The reasons are historical and are
- based on overhead, complexity and performance concerns.
-+
-+LSM External Interfaces
-+=======================
-+
-+The LSM infrastructure does not generally provide external interfaces.
-+The individual security modules provide what external interfaces they
-+require.
-+
-+The file ``/sys/kernel/security/lsm`` provides a comma
-+separated list of the active security modules.
-+
-+The file ``/proc/pid/attr/display`` contains the name of the security
-+module for which the ``/proc/pid/attr/current`` interface will
-+apply. This interface can be written to.
-+
-+The infrastructure does provide an interface for the special
-+case where multiple security modules provide a process context.
-+This is provided in compound context format.
-+
-+- `lsm\0value\0lsm\0value\0`
-+
-+The `lsm` and `value` fields are NUL-terminated bytestrings.
-+Each field may contain whitespace or non-printable characters.
-+The NUL bytes are included in the size of a compound context.
-+The context ``Bell\0Secret\0Biba\0Loose\0`` has a size of 23.
-+
-+The file ``/proc/pid/attr/context`` provides the security
-+context of the identified process.
-diff --git a/fs/proc/base.c b/fs/proc/base.c
-index 7432f24f0132..1894ed42a2a6 100644
---- a/fs/proc/base.c
-+++ b/fs/proc/base.c
-@@ -2807,6 +2807,7 @@ static const struct pid_entry attr_dir_stuff[] = {
- ATTR(NULL, "keycreate", 0666),
- ATTR(NULL, "sockcreate", 0666),
- ATTR(NULL, "display", 0666),
-+ ATTR(NULL, "context", 0444),
- #ifdef CONFIG_SECURITY_SMACK
- DIR("smack", 0555,
- proc_smack_attr_dir_inode_ops, proc_smack_attr_dir_ops),
-diff --git a/include/linux/lsm_hooks.h b/include/linux/lsm_hooks.h
-index c2f5adef0ad7..5218aae856e7 100644
---- a/include/linux/lsm_hooks.h
-+++ b/include/linux/lsm_hooks.h
-@@ -1372,6 +1372,12 @@
- * @pages contains the number of pages.
- * Return 0 if permission is granted.
- *
-+ * @getprocattr:
-+ * Provide the named process attribute for display in special files in
-+ * the /proc/.../attr directory. Attribute naming and the data displayed
-+ * is at the discretion of the security modules. The exception is the
-+ * "context" attribute, which will contain the security context of the
-+ * task as a nul terminated text string without trailing whitespace.
- * @ismaclabel:
- * Check if the extended attribute specified by @name
- * represents a MAC label. Returns 1 if name is a MAC
-diff --git a/security/apparmor/include/procattr.h b/security/apparmor/include/procattr.h
-index 31689437e0e1..03dbfdb2f2c0 100644
---- a/security/apparmor/include/procattr.h
-+++ b/security/apparmor/include/procattr.h
-@@ -11,7 +11,7 @@
- #ifndef __AA_PROCATTR_H
- #define __AA_PROCATTR_H
-
--int aa_getprocattr(struct aa_label *label, char **string);
-+int aa_getprocattr(struct aa_label *label, char **string, bool newline);
- int aa_setprocattr_changehat(char *args, size_t size, int flags);
-
- #endif /* __AA_PROCATTR_H */
-diff --git a/security/apparmor/lsm.c b/security/apparmor/lsm.c
-index 31a6f11890f1..7ce570b0f491 100644
---- a/security/apparmor/lsm.c
-+++ b/security/apparmor/lsm.c
-@@ -593,6 +593,7 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
- const struct cred *cred = get_task_cred(task);
- struct aa_task_ctx *ctx = task_ctx(current);
- struct aa_label *label = NULL;
-+ bool newline = true;
-
- if (strcmp(name, "current") == 0)
- label = aa_get_newest_label(cred_label(cred));
-@@ -600,11 +601,14 @@ static int apparmor_getprocattr(struct task_struct *task, char *name,
- label = aa_get_newest_label(ctx->previous);
- else if (strcmp(name, "exec") == 0 && ctx->onexec)
- label = aa_get_newest_label(ctx->onexec);
-- else
-+ else if (strcmp(name, "context") == 0) {
-+ label = aa_get_newest_label(cred_label(cred));
-+ newline = false;
-+ } else
- error = -EINVAL;
-
- if (label)
-- error = aa_getprocattr(label, value);
-+ error = aa_getprocattr(label, value, newline);
-
- aa_put_label(label);
- put_cred(cred);
-diff --git a/security/apparmor/procattr.c b/security/apparmor/procattr.c
-index c929bf4a3df1..be3b083d9b74 100644
---- a/security/apparmor/procattr.c
-+++ b/security/apparmor/procattr.c
-@@ -20,6 +20,7 @@
- * aa_getprocattr - Return the profile information for @profile
- * @profile: the profile to print profile info about (NOT NULL)
- * @string: Returns - string containing the profile info (NOT NULL)
-+ * @newline: Should a newline be added to @string.
- *
- * Returns: length of @string on success else error on failure
- *
-@@ -30,20 +31,21 @@
- *
- * Returns: size of string placed in @string else error code on failure
- */
--int aa_getprocattr(struct aa_label *label, char **string)
-+int aa_getprocattr(struct aa_label *label, char **string, bool newline)
- {
- struct aa_ns *ns = labels_ns(label);
- struct aa_ns *current_ns = aa_get_current_ns();
-+ int flags = FLAG_VIEW_SUBNS | FLAG_HIDDEN_UNCONFINED;
- int len;
-
- if (!aa_ns_visible(current_ns, ns, true)) {
- aa_put_ns(current_ns);
- return -EACCES;
- }
-+ if (newline)
-+ flags |= FLAG_SHOW_MODE;
-
-- len = aa_label_snxprint(NULL, 0, current_ns, label,
-- FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
-- FLAG_HIDDEN_UNCONFINED);
-+ len = aa_label_snxprint(NULL, 0, current_ns, label, flags);
- AA_BUG(len < 0);
-
- *string = kmalloc(len + 2, GFP_KERNEL);
-@@ -52,19 +54,19 @@ int aa_getprocattr(struct aa_label *label, char **string)
- return -ENOMEM;
- }
-
-- len = aa_label_snxprint(*string, len + 2, current_ns, label,
-- FLAG_SHOW_MODE | FLAG_VIEW_SUBNS |
-- FLAG_HIDDEN_UNCONFINED);
-+ len = aa_label_snxprint(*string, len + 2, current_ns, label, flags);
- if (len < 0) {
- aa_put_ns(current_ns);
- return len;
- }
-
-- (*string)[len] = '\n';
-- (*string)[len + 1] = 0;
-+ if (newline) {
-+ (*string)[len] = '\n';
-+ (*string)[++len] = 0;
-+ }
-
- aa_put_ns(current_ns);
-- return len + 1;
-+ return len;
- }
-
- /**
-diff --git a/security/security.c b/security/security.c
-index 1a78f7bb808b..e59a75e776cc 100644
---- a/security/security.c
-+++ b/security/security.c
-@@ -757,6 +757,57 @@ static void __init lsm_early_task(struct task_struct *task)
- panic("%s: Early task alloc failed.\n", __func__);
- }
-
-+/**
-+ * append_ctx - append a lsm/context pair to a compound context
-+ * @ctx: the existing compound context
-+ * @ctxlen: size of the old context, including terminating nul byte
-+ * @lsm: new lsm name, nul terminated
-+ * @new: new context, possibly nul terminated
-+ * @newlen: maximum size of @new
-+ *
-+ * replace @ctx with a new compound context, appending @newlsm and @new
-+ * to @ctx. On exit the new data replaces the old, which is freed.
-+ * @ctxlen is set to the new size, which includes a trailing nul byte.
-+ *
-+ * Returns 0 on success, -ENOMEM if no memory is available.
-+ */
-+static int append_ctx(char **ctx, int *ctxlen, const char *lsm, char *new,
-+ int newlen)
-+{
-+ char *final;
-+ size_t llen;
-+ size_t nlen;
-+ size_t flen;
-+
-+ llen = strlen(lsm) + 1;
-+ /*
-+ * A security module may or may not provide a trailing nul on
-+ * when returning a security context. There is no definition
-+ * of which it should be, and there are modules that do it
-+ * each way.
-+ */
-+ nlen = strnlen(new, newlen);
-+
-+ flen = *ctxlen + llen + nlen + 1;
-+ final = kzalloc(flen, GFP_KERNEL);
-+
-+ if (final == NULL)
-+ return -ENOMEM;
-+
-+ if (*ctxlen)
-+ memcpy(final, *ctx, *ctxlen);
-+
-+ memcpy(final + *ctxlen, lsm, llen);
-+ memcpy(final + *ctxlen + llen, new, nlen);
-+
-+ kfree(*ctx);
-+
-+ *ctx = final;
-+ *ctxlen = flen;
-+
-+ return 0;
-+}
-+
- /*
- * The default value of the LSM hook is defined in linux/lsm_hook_defs.h and
- * can be accessed with:
-@@ -2142,6 +2193,10 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
- char **value)
- {
- struct security_hook_list *hp;
-+ char *final = NULL;
-+ char *cp;
-+ int rc = 0;
-+ int finallen = 0;
- int display = lsm_task_display(current);
- int slot = 0;
-
-@@ -2169,6 +2224,30 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
- return -ENOMEM;
- }
-
-+ if (!strcmp(name, "context")) {
-+ hlist_for_each_entry(hp, &security_hook_heads.getprocattr,
-+ list) {
-+ rc = hp->hook.getprocattr(p, "context", &cp);
-+ if (rc == -EINVAL)
-+ continue;
-+ if (rc < 0) {
-+ kfree(final);
-+ return rc;
-+ }
-+ rc = append_ctx(&final, &finallen, hp->lsmid->lsm,
-+ cp, rc);
-+ kfree(cp);
-+ if (rc < 0) {
-+ kfree(final);
-+ return rc;
-+ }
-+ }
-+ if (final == NULL)
-+ return -EINVAL;
-+ *value = final;
-+ return finallen;
-+ }
-+
- hlist_for_each_entry(hp, &security_hook_heads.getprocattr, list) {
- if (lsm != NULL && strcmp(lsm, hp->lsmid->lsm))
- continue;
-diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
-index cb124671c15a..97568224e7d1 100644
---- a/security/selinux/hooks.c
-+++ b/security/selinux/hooks.c
-@@ -6292,7 +6292,7 @@ static int selinux_getprocattr(struct task_struct *p,
- goto bad;
- }
-
-- if (!strcmp(name, "current"))
-+ if (!strcmp(name, "current") || !strcmp(name, "context"))
- sid = __tsec->sid;
- else if (!strcmp(name, "prev"))
- sid = __tsec->osid;
-diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
-index 913d41b4b96a..b4bb0f3676cf 100644
---- a/security/smack/smack_lsm.c
-+++ b/security/smack/smack_lsm.c
-@@ -3478,7 +3478,7 @@ static int smack_getprocattr(struct task_struct *p, char *name, char **value)
- char *cp;
- int slen;
-
-- if (strcmp(name, "current") != 0)
-+ if (strcmp(name, "current") != 0 && strcmp(name, "context") != 0)
- return -EINVAL;
-
- cp = kstrdup(skp->smk_known, GFP_KERNEL);
---
-2.24.1
-