--- v29
+++ v8
@@ -1,270 +1,31 @@
Add an entry /proc/.../attr/context which displays the full
-process security "context" in compound format:
+process security "context" in compound format:'
lsm1\0value\0lsm2\0value\0...
This entry is not writable.
-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>
+---
+ fs/proc/base.c | 1 +
+ security/security.c | 27 +++++++++++++++++++++++++++
+ 2 files changed, 28 insertions(+)
-Reviewed-by: Kees Cook <keescook@chromium.org>
-Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
-Cc: linux-api@vger.kernel.org
-Cc: linux-doc@vger.kernel.org
----
- Documentation/ABI/testing/procfs-attr-context | 14 ++++
- Documentation/security/lsm.rst | 14 ++++
- 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 +-
- 10 files changed, 135 insertions(+), 15 deletions(-)
- create mode 100644 Documentation/ABI/testing/procfs-attr-context
-
-diff --git a/Documentation/ABI/testing/procfs-attr-context b/Documentation/ABI/testing/procfs-attr-context
-new file mode 100644
-index 000000000000..40da1c397c30
---- /dev/null
-+++ b/Documentation/ABI/testing/procfs-attr-context
-@@ -0,0 +1,14 @@
-+What: /proc/*/attr/context
-+Contact: linux-security-module@vger.kernel.org,
-+Description: The current security information used by all Linux
-+ security module (LSMs) that are active on the system.
-+ The details of permissions required to read from
-+ this interface and hence obtain the security state
-+ of the task identified is dependent on the LSMs that
-+ are active on the system.
-+ A process cannot write to this interface.
-+ The data provided by this interface will have the form:
-+ lsm_name\0lsm_data\0[lsm_name\0lsm_data\0]...
-+ where lsm_name is the name of the LSM and the following
-+ lsm_data is the process data for that LSM.
-+Users: LSM user-space
-diff --git a/Documentation/security/lsm.rst b/Documentation/security/lsm.rst
-index b77b4a540391..070225ae6ceb 100644
---- a/Documentation/security/lsm.rst
-+++ b/Documentation/security/lsm.rst
-@@ -143,3 +143,17 @@ separated list of the active security modules.
- The file ``/proc/pid/attr/interface_lsm`` 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 65da9d2f3060..b87977f0488b 100644
+index 7bf70e041315..79600df5f7a2 100644
--- a/fs/proc/base.c
+++ b/fs/proc/base.c
-@@ -2824,6 +2824,7 @@ static const struct pid_entry attr_dir_stuff[] = {
+@@ -2619,6 +2619,7 @@ static const struct pid_entry attr_dir_stuff[] = {
ATTR(NULL, "keycreate", 0666),
ATTR(NULL, "sockcreate", 0666),
- ATTR(NULL, "interface_lsm", 0666),
-+ ATTR(NULL, "context", 0444),
+ ATTR(NULL, "display", 0666),
++ ATTR(NULL, "context", 0666),
#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 d2c4bc94d47f..f6ffe8b069e2 100644
---- a/include/linux/lsm_hooks.h
-+++ b/include/linux/lsm_hooks.h
-@@ -1397,6 +1397,12 @@
- * @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 4237536106aa..65a004597e53 100644
---- a/security/apparmor/lsm.c
-+++ b/security/apparmor/lsm.c
-@@ -602,6 +602,7 @@ 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));
-@@ -609,11 +610,14 @@ 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 96b1d9c37d49..798e887b18fe 100644
+index 8cb91f33c166..d151ac4a398b 100644
--- a/security/security.c
+++ b/security/security.c
-@@ -802,6 +802,57 @@ static int lsm_superblock_alloc(struct super_block *sb)
- return 0;
- }
-
-+/**
-+ * 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:
-@@ -2235,6 +2286,10 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
+@@ -2082,6 +2082,10 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
char **value)
{
struct security_hook_list *hp;
@@ -272,18 +33,18 @@
+ char *cp;
+ int rc = 0;
+ int finallen = 0;
- int ilsm = lsm_task_ilsm(current);
+ int display = lsm_task_display(current);
int slot = 0;
-@@ -2262,6 +2317,30 @@ int security_getprocattr(struct task_struct *p, const char *lsm, char *name,
+@@ -2099,6 +2103,29 @@ 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)
++ rc = hp->hook.getprocattr(p, "current", &cp);
++ if (rc == -EINVAL || rc == -ENOPROTOOPT)
+ continue;
+ if (rc < 0) {
+ kfree(final);
@@ -291,7 +52,6 @@
+ }
+ rc = append_ctx(&final, &finallen, hp->lsmid->lsm,
+ cp, rc);
-+ kfree(cp);
+ if (rc < 0) {
+ kfree(final);
+ return rc;
@@ -306,32 +66,6 @@
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 c3e5fcedae0b..ec045d9e240a 100644
---- a/security/selinux/hooks.c
-+++ b/security/selinux/hooks.c
-@@ -6462,7 +6462,7 @@ 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 711fb49b4d5f..bd46921b9d28 100644
---- a/security/smack/smack_lsm.c
-+++ b/security/smack/smack_lsm.c
-@@ -3477,7 +3477,7 @@ 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);
--
-2.31.1
+2.20.1