[AppArmor 37/44] AppArmor: Main Part

jjohansen
2007-06-26T23:24:12Z

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The underlying functions by which the AppArmor LSM hooks are implemented.

Signed-off-by: John Johansen <jjohansen@suse.de>
Signed-off-by: Andreas Gruenbacher <agruen@suse.de>

---
security/apparmor/main.c | 1255 +++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 1255 insertions(+)

--- /dev/null
+++ b/security/apparmor/main.c
@@ -0,0 +1,1255 @@
+/*
+ * Copyright (C) 2002-2007 Novell/SUSE
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation, version 2 of the
+ * License.
+ *
+ * AppArmor Core
+ */
+
+#include <linux/security.h>
+#include <linux/namei.h>
+#include <linux/audit.h>
+#include <linux/mount.h>
+#include <linux/ptrace.h>
+
+#include "apparmor.h"
+
+#include "inline.h"
+
+/*
+ * Table of capability names: we generate it from capabilities.h.
+ */
+static const char *capability_names[] = {
+#include "capability_names.h"
+};
+
+/* NULL complain profile
+ *
+ * Used when in complain mode, to emit Permitting messages for non-existant
+ * profiles and hats. This is necessary because of selective mode, in which
+ * case we need a complain null_profile and enforce null_profile
+ *
+ * The null_complain_profile cannot be statically allocated, because it
+ * can be associated to files which keep their reference even if apparmor is
+ * unloaded
+ */
+struct aa_profile *null_complain_profile;
+
+/**
+ * aa_file_denied - check for @mask access on a file
+ * @profile: profile to check against
+ * @name: pathname of file
+ * @mask: permission mask requested for file
+ *
+ * Return %0 on success, or else the permissions in @mask that the
+ * profile denies.
+ */
+static int aa_file_denied(struct aa_profile *profile, const char *name,
+ int mask)
+{
+ return (mask & ~aa_match(profile->file_rules, name));
+}
+
+/**
+ * aa_link_denied - check for permission to link a file
+ * @profile: profile to check against
+ * @link: pathname of link being created
+ * @target: pathname of target to be linked to
+ * @request_mask: the permissions subset valid only if link succeeds
+ * Return %0 on success, or else the permissions that the profile denies.
+ */
+static int aa_link_denied(struct aa_profile *profile, const char *link,
+ const char *target, int *request_mask)
+{
+ int l_mode, t_mode, denied_mask;
+
+ l_mode = aa_match(profile->file_rules, link);
+ t_mode = aa_match(profile->file_rules, target);
+
+ /* Ignore valid-profile-transition flags. */
+ l_mode &= ~AA_CHANGE_PROFILE;
+ t_mode &= ~AA_CHANGE_PROFILE;
+
+ *request_mask = l_mode | AA_MAY_LINK;
+
+ /* Link always requires 'l' on the link, a subset of the
+ * target's 'r', 'w', 'x', and 'm' permissions on the link, and
+ * if the link has 'x', an exact match of all the execute flags
+ * ('i', 'u', 'U', 'p', 'P').
+ */
+#define RWXM (MAY_READ | MAY_WRITE | MAY_EXEC | AA_EXEC_MMAP)
+ denied_mask = ~l_mode & AA_MAY_LINK;
+ if (l_mode & RWXM)
+ denied_mask |= (l_mode & ~ AA_MAY_LINK) & ~t_mode;
+ else
+ denied_mask |= t_mode | AA_MAY_LINK;
+ if (denied_mask & AA_EXEC_MODIFIERS)
+ denied_mask |= MAY_EXEC;
+
+#undef RWXM
+
+ return denied_mask;
+}
+
+/**
+ * aa_get_name - compute the pathname of a file
+ * @dentry: dentry of the file
+ * @mnt: vfsmount of the file
+ * @buffer: buffer that aa_get_name() allocated
+ * @check: AA_CHECK_DIR is set if the file is a directory
+ *
+ * Returns a pointer to the beginning of the pathname (which usually differs
+ * from the beginning of the buffer), or an error code.
+ *
+ * We need @check to indicate whether the file is a directory or not because
+ * the file may not yet exist, and so we cannot check the inode's file type.
+ */
+static char *aa_get_name(struct dentry *dentry, struct vfsmount *mnt,
+ char **buffer, int check)
+{
+ char *name;
+ int is_dir, size = 256;
+
+ is_dir = (check & AA_CHECK_DIR) ? 1 : 0;
+
+ for (;;) {
+ char *buf = kmalloc(size, GFP_KERNEL);
+ if (!buf)
+ return ERR_PTR(-ENOMEM);
+
+ name = d_namespace_path(dentry, mnt, buf, size - is_dir);
+ if (!IS_ERR(name)) {
+ if (name[0] != '/') {
+ /*
+ * This dentry is not connected to the
+ * namespace root -- reject access.
+ */
+ kfree(buf);
+ return ERR_PTR(-ENOENT);
+ }
+ if (is_dir && name[1] != '\0') {
+ /*
+ * Append "/" to the pathname. The root
+ * directory is a special case; it already
+ * ends in slash.
+ */
+ buf[size - 2] = '/';
+ buf[size - 1] = '\0';
+ }
+
+ *buffer = buf;
+ return name;
+ }
+ if (PTR_ERR(name) != -ENAMETOOLONG)
+ return name;
+
+ kfree(buf);
+ size <<= 1;
+ if (size > apparmor_path_max)
+ return ERR_PTR(-ENAMETOOLONG);
+ }
+}
+
+static inline void aa_put_name_buffer(char *buffer)
+{
+ kfree(buffer);
+}
+
+/**
+ * aa_perm_dentry - check if @profile allows @mask for a file
+ * @profile: profile to check against
+ * @dentry: dentry of the file
+ * @mnt: vfsmount o the file
+ * @sa: audit context
+ * @mask: requested profile permissions
+ * @check: kind of check to perform
+ *
+ * Returns 0 upon success, or else an error code.
+ *
+ * @check indicates the file type, and whether the file was accessed through
+ * an open file descriptor (AA_CHECK_FD) or not.
+ */
+static int aa_perm_dentry(struct aa_profile *profile, struct dentry *dentry,
+ struct vfsmount *mnt, struct aa_audit *sa, int check)
+{
+ int error;
+ char *buffer = NULL;
+
+ sa->name = aa_get_name(dentry, mnt, &buffer, check);
+
+ if (IS_ERR(sa->name)) {
+ /*
+ * deleted files are given a pass on permission checks when
+ * accessed through a file descriptor.
+ */
+ if (PTR_ERR(sa->name) == -ENOENT && (check & AA_CHECK_FD))
+ sa->denied_mask = 0;
+ else
+ sa->denied_mask = PTR_ERR(sa->name);
+ sa->name = NULL;
+ } else
+ sa->denied_mask = aa_file_denied(profile, sa->name,
+ sa->requested_mask);
+
+ if (!sa->denied_mask)
+ sa->error_code = 0;
+
+ error = aa_audit(profile, sa);
+ aa_put_name_buffer(buffer);
+
+ return error;
+}
+
+/**
+ * alloc_null_complain_profile - Allocate the global null_complain_profile.
+ *
+ * Return %0 (success) or error (-%ENOMEM)
+ */
+int alloc_null_complain_profile(void)
+{
+ null_complain_profile = alloc_aa_profile();
+ if (!null_complain_profile)
+ goto fail;
+
+ null_complain_profile->name =
+ kstrdup("null-complain-profile", GFP_KERNEL);
+
+ if (!null_complain_profile->name)
+ goto fail;
+
+ null_complain_profile->flags.complain = 1;
+
+ return 0;
+
+fail:
+ /* free_aa_profile is safe for freeing partially constructed objects */
+ free_aa_profile(null_complain_profile);
+ null_complain_profile = NULL;
+
+ return -ENOMEM;
+}
+
+/**
+ * free_null_complain_profile - Free null profiles
+ */
+void free_null_complain_profile(void)
+{
+ aa_put_profile(null_complain_profile);
+ null_complain_profile = NULL;
+}
+
+static void aa_audit_file_mask(struct audit_buffer *ab, const char *name,
+ int mask)
+{
+ char mask_str[10], *m = mask_str;
+
+ if (mask & AA_EXEC_MMAP)
+ *m++ = 'm';
+ if (mask & MAY_READ)
+ *m++ = 'r';
+ if (mask & MAY_WRITE)
+ *m++ = 'w';
+ if (mask & (MAY_EXEC | AA_EXEC_MODIFIERS)) {
+ if (mask & AA_EXEC_UNSAFE) {
+ if (mask & AA_EXEC_INHERIT)
+ *m++ = 'i';
+ if (mask & AA_EXEC_UNCONFINED)
+ *m++ = 'u';
+ if (mask & AA_EXEC_PROFILE)
+ *m++ = 'p';
+ } else {
+ if (mask & AA_EXEC_INHERIT)
+ *m++ = 'I';
+ if (mask & AA_EXEC_UNCONFINED)
+ *m++ = 'U';
+ if (mask & AA_EXEC_PROFILE)
+ *m++ = 'P';
+ }
+ if (mask & MAY_EXEC)
+ *m++ = 'x';
+ }
+ if (mask & AA_MAY_LINK)
+ *m++ = 'l';
+ *m++ = '\0';
+
+ audit_log_format(ab, " %s=\"%s\"", name, mask_str);
+}
+
+/**
+ * aa_audit - Log an audit event to the audit subsystem
+ * @profile: profile to check against
+ * @sa: audit event
+ * @audit_cxt: audit context to log message to
+ * @type: audit event number
+ */
+static int aa_audit_base(struct aa_profile *profile, struct aa_audit *sa,
+ struct audit_context *audit_cxt, int type)
+{
+ struct audit_buffer *ab = NULL;
+
+ ab = audit_log_start(audit_cxt, sa->gfp_mask, type);
+
+ if (!ab) {
+ AA_ERROR("Unable to log event (%d) to audit subsys\n",
+ type);
+ /* don't fail operations in complain mode even if logging
+ * fails */
+ return type == AUDIT_APPARMOR_ALLOWED ? 0 : -ENOMEM;
+ }
+
+ if (sa->operation)
+ audit_log_format(ab, "operation=\"%s\"", sa->operation);
+
+ if (sa->info)
+ audit_log_format(ab, " info=\"%s\"", sa->info);
+
+ if (sa->requested_mask)
+ aa_audit_file_mask(ab, "requested_mask", sa->requested_mask);
+
+ if (sa->denied_mask)
+ aa_audit_file_mask(ab, "denied_mask", sa->denied_mask);
+
+ if (sa->iattr) {
+ struct iattr *iattr = sa->iattr;
+
+ audit_log_format(ab, " attribute=\"%s%s%s%s%s%s%s\"",
+ iattr->ia_valid & ATTR_MODE ? "mode," : "",
+ iattr->ia_valid & ATTR_UID ? "uid," : "",
+ iattr->ia_valid & ATTR_GID ? "gid," : "",
+ iattr->ia_valid & ATTR_SIZE ? "size," : "",
+ iattr->ia_valid & (ATTR_ATIME | ATTR_ATIME_SET) ?
+ "atime," : "",
+ iattr->ia_valid & (ATTR_MTIME | ATTR_MTIME_SET) ?
+ "mtime," : "",
+ iattr->ia_valid & ATTR_CTIME ? "ctime," : "");
+ }
+
+ if (sa->task)
+ audit_log_format(ab, " task=%d", sa->task);
+
+ if (sa->parent)
+ audit_log_format(ab, " parent=%d", sa->parent);
+
+ if (sa->name) {
+ audit_log_format(ab, " name=");
+ audit_log_untrustedstring(ab, sa->name);
+ }
+
+ if (sa->name2) {
+ audit_log_format(ab, " name2=");
+ audit_log_untrustedstring(ab, sa->name2);
+ }
+
+ if (sa->cookie)
+ audit_log_format(ab, " cookie=%llu", sa->cookie);
+
+ audit_log_format(ab, " pid=%d", current->pid);
+
+ if (profile) {
+ audit_log_format(ab, " profile=");
+ audit_log_untrustedstring(ab, profile->name);
+ }
+
+ audit_log_end(ab);
+
+ return type == AUDIT_APPARMOR_ALLOWED ? 0 : sa->error_code;
+}
+
+/**
+ * aa_audit_syscallreject - Log a syscall rejection to the audit subsystem
+ * @profile: profile to check against
+ * @gfp: memory allocation flags
+ * @msg: string describing syscall being rejected
+ */
+int aa_audit_syscallreject(struct aa_profile *profile, gfp_t gfp,
+ const char *msg)
+{
+ struct aa_audit sa;
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = "syscall";
+ sa.name = msg;
+ sa.gfp_mask = gfp;
+ sa.error_code = -EPERM;
+
+ return aa_audit_base(profile, &sa, current->audit_context,
+ AUDIT_APPARMOR_DENIED);
+}
+
+int aa_audit_message(struct aa_profile *profile, struct aa_audit *sa,
+ int type)
+{
+ struct audit_context *audit_cxt;
+
+ audit_cxt = apparmor_logsyscall ? current->audit_context : NULL;
+ return aa_audit_base(profile, sa, audit_cxt, type);
+}
+
+void aa_audit_hint(struct aa_profile *profile, struct aa_audit *sa)
+{
+ aa_audit_message(profile, sa, AUDIT_APPARMOR_HINT);
+}
+
+void aa_audit_status(struct aa_profile *profile, struct aa_audit *sa)
+{
+ aa_audit_message(profile, sa, AUDIT_APPARMOR_STATUS);
+}
+
+int aa_audit_reject(struct aa_profile *profile, struct aa_audit *sa)
+{
+ return aa_audit_message(profile, sa, AUDIT_APPARMOR_DENIED);
+}
+
+/**
+ * aa_audit - Log an audit event to the audit subsystem
+ * @profile: profile to check against
+ * @sa: audit event
+ */
+int aa_audit(struct aa_profile *profile, struct aa_audit *sa)
+{
+ int type = AUDIT_APPARMOR_DENIED;
+ struct audit_context *audit_cxt;
+
+ if (likely(!sa->error_code)) {
+ if (likely(!PROFILE_AUDIT(profile)))
+ /* nothing to log */
+ return 0;
+ else
+ type = AUDIT_APPARMOR_AUDIT;
+ } else if (PROFILE_COMPLAIN(profile)) {
+ type = AUDIT_APPARMOR_ALLOWED;
+ }
+
+ audit_cxt = apparmor_logsyscall ? current->audit_context : NULL;
+ return aa_audit_base(profile, sa, audit_cxt, type);
+}
+
+/**
+ * aa_attr - check if attribute change is allowed
+ * @profile: profile to check against
+ * @dentry: dentry of the file to check
+ * @mnt: vfsmount of the file to check
+ * @iattr: attribute changes requested
+ */
+int aa_attr(struct aa_profile *profile, struct dentry *dentry,
+ struct vfsmount *mnt, struct iattr *iattr)
+{
+ struct inode *inode = dentry->d_inode;
+ int error, check;
+ struct aa_audit sa;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = "setattr";
+ sa.gfp_mask = GFP_KERNEL;
+ sa.iattr = iattr;
+ sa.requested_mask = MAY_WRITE;
+ sa.error_code = -EACCES;
+
+ check = 0;
+ if (inode && S_ISDIR(inode->i_mode))
+ check |= AA_CHECK_DIR;
+ if (iattr->ia_valid & ATTR_FILE)
+ check |= AA_CHECK_FD;
+
+ error = aa_perm_dentry(profile, dentry, mnt, &sa, check);
+
+ return error;
+}
+
+/**
+ * aa_perm_xattr - check if xattr attribute change is allowed
+ * @profile: profile to check against
+ * @dentry: dentry of the file to check
+ * @mnt: vfsmount of the file to check
+ * @operation: xattr operation being done
+ * @mask: access mode requested
+ * @check: kind of check to perform
+ */
+int aa_perm_xattr(struct aa_profile *profile, const char *operation,
+ struct dentry *dentry, struct vfsmount *mnt, int mask,
+ int check)
+{
+ struct inode *inode = dentry->d_inode;
+ int error;
+ struct aa_audit sa;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = operation;
+ sa.gfp_mask = GFP_KERNEL;
+ sa.requested_mask = mask;
+ sa.error_code = -EACCES;
+
+ if (inode && S_ISDIR(inode->i_mode))
+ check |= AA_CHECK_DIR;
+
+ error = aa_perm_dentry(profile, dentry, mnt, &sa, check);
+
+ return error;
+}
+
+/**
+ * aa_perm - basic apparmor permissions check
+ * @profile: profile to check against
+ * @dentry: dentry of the file to check
+ * @mnt: vfsmount of the file to check
+ * @mask: access mode requested
+ * @check: kind of check to perform
+ *
+ * Determine if access @mask for the file is authorized by @profile.
+ * Returns 0 on success, or else an error code.
+ */
+int aa_perm(struct aa_profile *profile, const char *operation,
+ struct dentry *dentry, struct vfsmount *mnt, int mask, int check)
+{
+ struct aa_audit sa;
+ int error = 0;
+
+ if (mask == 0)
+ goto out;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = operation;
+ sa.gfp_mask = GFP_KERNEL;
+ sa.requested_mask = mask;
+ sa.error_code = -EACCES;
+
+ error = aa_perm_dentry(profile, dentry, mnt, &sa, check);
+
+out:
+ return error;
+}
+
+/**
+ * aa_perm_dir
+ * @profile: profile to check against
+ * @dentry: dentry of directory to check
+ * @mnt: vfsmount of directory to check
+ * @operation: directory operation being performed
+ * @mask: access mode requested
+ *
+ * Determine if directory operation (make/remove) for dentry is authorized
+ * by @profile.
+ * Returns 0 on success, or else an error code.
+ */
+int aa_perm_dir(struct aa_profile *profile, const char *operation,
+ struct dentry *dentry, struct vfsmount *mnt, int mask)
+{
+ struct aa_audit sa;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = operation;
+ sa.gfp_mask = GFP_KERNEL;
+ sa.requested_mask = mask;
+ sa.error_code = -EACCES;
+
+ return aa_perm_dentry(profile, dentry, mnt, &sa, AA_CHECK_DIR);
+}
+
+int aa_perm_path(struct aa_profile *profile, const char *operation,
+ const char *name, int mask)
+{
+ struct aa_audit sa;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = operation;
+ sa.gfp_mask = GFP_KERNEL;
+ sa.requested_mask = mask;
+ sa.name = name;
+
+ sa.denied_mask = aa_file_denied(profile, name, mask);
+ sa.error_code = sa.denied_mask ? -EACCES : 0;
+
+ return aa_audit(profile, &sa);
+}
+
+/**
+ * aa_capability - test permission to use capability
+ * @cxt: aa_task_context with profile to check against
+ * @cap: capability to be tested
+ *
+ * Look up capability in profile capability set.
+ * Returns 0 on success, or else an error code.
+ */
+int aa_capability(struct aa_task_context *cxt, int cap)
+{
+ int error = cap_raised(cxt->profile->capabilities, cap) ? 0 : -EPERM;
+ struct aa_audit sa;
+
+ /* test if cap has alread been logged */
+ if (cap_raised(cxt->caps_logged, cap)) {
+ if (PROFILE_COMPLAIN(cxt->profile))
+ error = 0;
+ return error;
+ } else
+ /* don't worry about rcu replacement of the cxt here.
+ * caps_logged is a cache to reduce the occurence of
+ * duplicate messages in the log. The worst that can
+ * happen is duplicate capability messages shows up in
+ * the audit log
+ */
+ cap_raise(cxt->caps_logged, cap);
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = "capable";
+ sa.gfp_mask = GFP_ATOMIC;
+ sa.name = capability_names[cap];
+ sa.error_code = error;
+
+ error = aa_audit(cxt->profile, &sa);
+
+ return error;
+}
+
+/* must be used inside rcu_read_lock or task_lock */
+int aa_may_ptrace(struct aa_task_context *cxt, struct aa_profile *tracee)
+{
+ if (!cxt || cxt->profile == tracee)
+ return 0;
+ return aa_capability(cxt, CAP_SYS_PTRACE);
+}
+
+/**
+ * aa_link - hard link check
+ * @profile: profile to check against
+ * @link: dentry of link being created
+ * @link_mnt: vfsmount of link being created
+ * @target: dentry of link target
+ * @target_mnt: vfsmunt of link target
+ *
+ * Returns 0 on success, or else an error code.
+ */
+int aa_link(struct aa_profile *profile,
+ struct dentry *link, struct vfsmount *link_mnt,
+ struct dentry *target, struct vfsmount *target_mnt)
+{
+ int error, check = 0;
+ struct aa_audit sa;
+ char *buffer = NULL, *buffer2 = NULL;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = "inode_link";
+ sa.gfp_mask = GFP_KERNEL;
+ sa.name = aa_get_name(link, link_mnt, &buffer, check);
+ sa.name2 = aa_get_name(target, target_mnt, &buffer2, check);
+
+ if (IS_ERR(sa.name)) {
+ sa.error_code = PTR_ERR(sa.name);
+ sa.name = NULL;
+ }
+ if (IS_ERR(sa.name2)) {
+ sa.error_code = PTR_ERR(sa.name2);
+ sa.name2 = NULL;
+ }
+
+ if (sa.name && sa.name2) {
+ sa.requested_mask = AA_MAY_LINK;
+ sa.denied_mask = aa_link_denied(profile, sa.name, sa.name2,
+ &sa.requested_mask);
+ sa.error_code = sa.denied_mask ? -EACCES : 0;
+ }
+
+ error = aa_audit(profile, &sa);
+
+ aa_put_name_buffer(buffer);
+ aa_put_name_buffer(buffer2);
+
+ return error;
+}
+
+/*******************************
+ * Global task related functions
+ *******************************/
+
+/**
+ * aa_clone - initialize the task context for a new task
+ * @child: task that is being created
+ *
+ * Returns 0 on success, or else an error code.
+ */
+int aa_clone(struct task_struct *child)
+{
+ struct aa_task_context *cxt, *child_cxt;
+ struct aa_profile *profile;
+
+ if (!aa_task_context(current))
+ return 0;
+ child_cxt = aa_alloc_task_context(GFP_KERNEL);
+ if (!child_cxt)
+ return -ENOMEM;
+
+repeat:
+ profile = aa_get_profile(current);
+ if (profile) {
+ lock_profile(profile);
+ cxt = aa_task_context(current);
+ if (unlikely(profile->isstale || !cxt ||
+ cxt->profile != profile)) {
+ /**
+ * Race with profile replacement or removal, or with
+ * task context removal.
+ */
+ unlock_profile(profile);
+ aa_put_profile(profile);
+ goto repeat;
+ }
+
+ /* No need to grab the child's task lock here. */
+ aa_change_task_context(child, child_cxt, profile,
+ cxt->cookie, cxt->previous_profile);
+ unlock_profile(profile);
+
+ if (APPARMOR_COMPLAIN(child_cxt) &&
+ profile == null_complain_profile) {
+ struct aa_audit sa;
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = "clone";
+ sa.gfp_mask = GFP_KERNEL;
+ sa.task = child->pid;
+ aa_audit_hint(profile, &sa);
+ }
+ aa_put_profile(profile);
+ } else
+ aa_free_task_context(child_cxt);
+
+ return 0;
+}
+
+static struct aa_profile *
+aa_register_find(struct aa_profile *profile, const char *name, int mandatory,
+ int complain, struct aa_audit *sa)
+{
+ struct aa_profile *new_profile;
+
+ /* Locate new profile */
+ new_profile = aa_find_profile(name);
+ if (new_profile) {
+ AA_DEBUG("%s: setting profile %s\n",
+ __FUNCTION__, new_profile->name);
+ } else if (mandatory && profile) {
+ sa->info = "mandatory profile missing";
+ sa->denied_mask = MAY_EXEC;
+ if (complain) {
+ aa_audit_hint(profile, sa);
+ profile = aa_dup_profile(null_complain_profile);
+ } else {
+ aa_audit_reject(profile, sa);
+ return ERR_PTR(-EACCES); /* was -EPERM */
+ }
+ } else {
+ /* Only way we can get into this code is if task
+ * is unconfined.
+ */
+ AA_DEBUG("%s: No profile found for exec image '%s'\n",
+ __FUNCTION__,
+ name);
+ }
+ return new_profile;
+}
+
+/**
+ * aa_register - register a new program
+ * @bprm: binprm of program being registered
+ *
+ * Try to register a new program during execve(). This should give the
+ * new program a valid aa_task_context if confined.
+ */
+int aa_register(struct linux_binprm *bprm)
+{
+ const char *filename;
+ char *buffer = NULL;
+ struct file *filp = bprm->file;
+ struct aa_profile *profile, *old_profile, *new_profile = NULL;
+ int exec_mode = AA_EXEC_UNSAFE, complain = 0;
+ struct aa_audit sa;
+
+ AA_DEBUG("%s\n", __FUNCTION__);
+
+ filename = aa_get_name(filp->f_dentry, filp->f_vfsmnt, &buffer, 0);
+ if (IS_ERR(filename)) {
+ AA_ERROR("%s: Failed to get filename", __FUNCTION__);
+ return -ENOENT;
+ }
+
+ memset(&sa, 0, sizeof(sa));
+ sa.operation = "exec";
+ sa.gfp_mask = GFP_KERNEL;
+ sa.name = filename;
+ sa.requested_mask = MAY_EXEC;
+
+repeat:
+ profile = aa_get_profile(current);
+ if (profile) {
+ complain = PROFILE_COMPLAIN(profile);
+
+ /* Confined task, determine what mode inherit, unconfined or
+ * mandatory to load new profile
+ */
+ exec_mode = aa_match(profile->file_rules, filename);
+
+ if (exec_mode & (MAY_EXEC | AA_EXEC_MODIFIERS)) {
+ switch (exec_mode & (MAY_EXEC | AA_EXEC_MODIFIERS)) {
+ case MAY_EXEC | AA_EXEC_INHERIT:
+ AA_DEBUG("%s: INHERIT %s\n",
+ __FUNCTION__,
+ filename);
+ /* nothing to be done here */
+ goto cleanup;
+
+ case MAY_EXEC | AA_EXEC_UNCONFINED:
+ AA_DEBUG("%s: UNCONFINED %s\n",
+ __FUNCTION__,
+ filename);
+
+ /* detach current profile */
+ new_profile = NULL;
+ break;
+
+ case MAY_EXEC | AA_EXEC_PROFILE:
+ AA_DEBUG("%s: PROFILE %s\n",
+ __FUNCTION__,
+ filename);
+ new_profile = aa_register_find(profile,
+ filename,
+ 1, complain,
+ &sa);
+ break;
+ }
+
+ } else if (complain) {
+ /* There was no entry in calling profile
+ * describing mode to execute image in.
+ * Drop into null-profile (disabling secure exec).
+ */
+ new_profile = aa_dup_profile(null_complain_profile);
+ exec_mode |= AA_EXEC_UNSAFE;
+ } else {
+ sa.denied_mask = MAY_EXEC;
+ aa_audit_reject(profile, &sa);
+ new_profile = ERR_PTR(-EPERM);
+ }
+ } else {
+ /* Unconfined task, load profile if it exists */
+ new_profile = aa_register_find(NULL, filename, 0, 0, &sa);
+ if (new_profile == NULL)
+ goto cleanup;
+ }
+
+ if (IS_ERR(new_profile))
+ goto cleanup;
+
+ old_profile = __aa_replace_profile(current, new_profile);
+ if (IS_ERR(old_profile)) {
+ aa_put_profile(new_profile);
+ aa_put_profile(profile);
+ if (PTR_ERR(old_profile) == -ESTALE)
+ goto repeat;
+ if (PTR_ERR(old_profile) == -EPERM) {
+ sa.denied_mask = MAY_EXEC;
+ sa.info = "unable to set profile due to ptrace";
+ sa.task = current->parent->pid;
+ aa_audit_reject(profile, &sa);
+ }
+ new_profile = old_profile;
+ goto cleanup;
+ }
+ aa_put_profile(old_profile);
+ aa_put_profile(profile);
+
+ /* Handle confined exec.
+ * Can be at this point for the following reasons:
+ * 1. unconfined switching to confined
+ * 2. confined switching to different confinement
+ * 3. confined switching to unconfined
+ *
+ * Cases 2 and 3 are marked as requiring secure exec
+ * (unless policy specified "unsafe exec")
+ */
+ if (!(exec_mode & AA_EXEC_UNSAFE)) {
+ unsigned long bprm_flags;
+
+ bprm_flags = AA_SECURE_EXEC_NEEDED;
+ bprm->security = (void*)
+ ((unsigned long)bprm->security | bprm_flags);
+ }
+
+ if (complain && new_profile == null_complain_profile) {
+ sa.requested_mask = 0;
+ sa.name = NULL;
+ sa.info = "set profile";
+ aa_audit_hint(new_profile, &sa);
+ }
+cleanup:
+ aa_put_name_buffer(buffer);
+ if (IS_ERR(new_profile))
+ return PTR_ERR(new_profile);
+ aa_put_profile(new_profile);
+ return 0;
+}
+
+/**
+ * aa_release - release a task context
+ * @task: task being released
+ *
+ * This is called after a task has exited and the parent has reaped it.
+ */
+void aa_release(struct task_struct *task)
+{
+ struct aa_task_context *cxt;
+ struct aa_profile *profile;
+ /*
+ * While the task context is still on a profile's task context
+ * list, another process could replace the profile under us,
+ * leaving us with a locked profile that is no longer attached
+ * to this task. So after locking the profile, we check that
+ * the profile is still attached. The profile lock is
+ * sufficient to prevent the replacement race so we do not lock
+ * the task.
+ *
+ * Use lock subtyping to avoid lockdep reporting a false irq
+ * possible inversion between the task_lock and profile_lock
+ *
+ * We also avoid taking the task_lock here because lock_dep
+ * would report another false {softirq-on-W} potential irq_lock
+ * inversion.
+ *
+ * If the task does not have a profile attached we are safe;
+ * nothing can race with us at this point.
+ */
+
+repeat:
+ profile = aa_get_profile(task);
+ if (profile) {
+ lock_profile_nested(profile, aa_lock_task_release);
+ cxt = aa_task_context(task);
+ if (unlikely(!cxt || cxt->profile != profile)) {
+ unlock_profile(profile);
+ aa_put_profile(profile);
+ goto repeat;
+ }
+ aa_change_task_context(task, NULL, NULL, 0, NULL);
+ unlock_profile(profile);
+ aa_put_profile(profile);
+ }
+}
+
+static int do_change_profile(struct aa_profile *expected, const char *name,
+ u64 cookie, int restore, struct aa_audit *sa)
+{
+ struct aa_profile *profile = NULL, *old_profile = NULL,
+ *previous_profile = NULL;
+ struct aa_task_context *new_cxt, *cxt;
+ int error = 0;
+
+ sa->name = name;
+
+ new_cxt = aa_alloc_task_context(GFP_KERNEL);
+ if (!new_cxt)
+ return -ENOMEM;
+
+ profile = aa_find_profile(name);
+ if (!profile && !restore)
+ profile = aa_dup_profile(null_complain_profile);
+
+ cxt = lock_task_and_profiles(current, profile);
+ if (!cxt) {
+ error = -EPERM;
+ goto out;
+ }
+ old_profile = cxt->profile;
+
+ if (cxt->profile != expected || (profile && profile->isstale)) {
+ error = -ESTALE;
+ goto out;
+ }
+
+ if (cxt->previous_profile) {
+ if (cxt->cookie != cookie) {
+ error = -EACCES;
+ sa->info = "killing process";
+ aa_audit_reject(cxt->profile, sa);
+ /* terminate process */
+ (void)send_sig_info(SIGKILL, NULL, current);
+ goto out;
+ }
+
+ if (!restore)
+ previous_profile = cxt->previous_profile;
+ } else
+ previous_profile = cxt->profile;
+
+ if ((current->ptrace & PT_PTRACED) && aa_may_ptrace(cxt, profile)) {
+ error = -EACCES;
+ goto out;
+ }
+
+ if (profile == null_complain_profile) {
+ if (APPARMOR_COMPLAIN(cxt)) {
+ aa_audit_hint(cxt->profile, sa);
+ } else {
+ error = -ENOENT;
+ goto out;
+ }
+ }
+
+ if (APPARMOR_AUDIT(cxt))
+ aa_audit_message(cxt->profile, sa, AUDIT_APPARMOR_AUDIT);
+
+ if (!restore && cookie)
+ aa_change_task_context(current, new_cxt, profile, cookie,
+ previous_profile);
+ else
+ /* either return to previous_profile, or a permanent change */
+ aa_change_task_context(current, new_cxt, profile, 0, NULL);
+
+out:
+ if (aa_task_context(current) != new_cxt)
+ aa_free_task_context(new_cxt);
+ task_unlock(current);
+ unlock_both_profiles(old_profile, profile);
+ aa_put_profile(profile);
+ return error;
+}
+
+
+/**
+ * aa_change_profile - change profile to/from previous stored profile
+ * @name: name of profile to change to
+ * @cookie: magic value to validate the profile change
+ *
+ * Change to new profile @name, and store the @cookie in the current task
+ * context. If the new @name is %NULL and the @cookie matches that
+ * stored in the current task context, return to the previous profile.
+ *
+ * Returns %0 on success, error otherwise.
+ */
+int aa_change_profile(const char *name, u64 cookie)
+{
+ struct aa_task_context *cxt;
+ struct aa_profile *profile, *previous_profile;
+ struct aa_audit sa;
+ int error = 0;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.gfp_mask = GFP_ATOMIC;
+ sa.cookie = cookie;
+ sa.operation = "change_profile";
+
+repeat:
+ task_lock(current);
+ cxt = aa_task_context(current);
+ if (!cxt) {
+ task_unlock(current);
+ return -EPERM;
+ }
+ profile = aa_dup_profile(cxt->profile);
+ previous_profile = aa_dup_profile(cxt->previous_profile);
+ task_unlock(current);
+
+ if (name) {
+ if (profile != null_complain_profile &&
+ !(aa_match(profile->file_rules, name) &
+ AA_CHANGE_PROFILE)) {
+ /* no permission to transition to profile @name */
+ aa_put_profile(profile);
+ return -EACCES;
+ }
+ error = do_change_profile(profile, name, cookie, 0, &sa);
+ } else if (previous_profile)
+ error = do_change_profile(profile, previous_profile->name,
+ cookie, 1, &sa);
+ /* else ignore restores when there is no saved profile */
+
+ aa_put_profile(previous_profile);
+ aa_put_profile(profile);
+ if (error == -ESTALE)
+ goto repeat;
+
+ return error;
+}
+
+/**
+ * aa_change_hat - change hat to/from subprofile
+ * @hat_name: hat to change to
+ * @cookie: magic value to validate the hat change
+ *
+ * Change to new @hat_name, and store the @hat_magic in the current task
+ * context. If the new @hat_name is %NULL and the @cookie matches that
+ * stored in the current task context and is not 0, return to the top level
+ * profile.
+ * Returns %0 on success, error otherwise.
+ */
+int aa_change_hat(const char *hat_name, u64 cookie)
+{
+ struct aa_task_context *cxt;
+ struct aa_profile *profile, *previous_profile;
+ struct aa_audit sa;
+ int error = 0;
+
+ memset(&sa, 0, sizeof(sa));
+ sa.gfp_mask = GFP_ATOMIC;
+ sa.cookie = cookie;
+ sa.operation = "change_hat";
+
+repeat:
+ task_lock(current);
+ cxt = aa_task_context(current);
+ if (!cxt) {
+ task_unlock(current);
+ return -EPERM;
+ }
+ profile = aa_dup_profile(cxt->profile);
+ previous_profile = aa_dup_profile(cxt->previous_profile);
+ task_unlock(current);
+
+ if (hat_name) {
+ char *name, *profile_name;
+ if (previous_profile)
+ profile_name = previous_profile->name;
+ else
+ profile_name = profile->name;
+
+ name = kmalloc(strlen(hat_name) + 3 + strlen(profile_name),
+ GFP_KERNEL);
+ if (!name) {
+ error = -ENOMEM;
+ goto out;
+ }
+ sprintf(name, "%s//%s", profile_name, hat_name);
+ error = do_change_profile(profile, name, cookie, 0, &sa);
+ kfree(name);
+ } else if (previous_profile)
+ error = do_change_profile(profile, previous_profile->name,
+ cookie, 1, &sa);
+ /* else ignore restores when there is no saved profile */
+
+out:
+ aa_put_profile(previous_profile);
+ aa_put_profile(profile);
+ if (error == -ESTALE)
+ goto repeat;
+
+ return error;
+}
+
+/**
+ * __aa_replace_profile - replace a task's profile
+ * @task: task to switch the profile of
+ * @profile: profile to switch to
+ *
+ * Returns a handle to the previous profile upon success, or else an
+ * error code.
+ */
+struct aa_profile *__aa_replace_profile(struct task_struct *task,
+ struct aa_profile *profile)
+{
+ struct aa_task_context *cxt, *new_cxt = NULL;
+ struct aa_profile *old_profile = NULL;
+
+ if (profile) {
+ new_cxt = aa_alloc_task_context(GFP_KERNEL);
+ if (!new_cxt)
+ return ERR_PTR(-ENOMEM);
+ }
+
+ cxt = lock_task_and_profiles(task, profile);
+ if (unlikely(profile && profile->isstale)) {
+ task_unlock(task);
+ unlock_both_profiles(profile, cxt ? cxt->profile : NULL);
+ aa_free_task_context(new_cxt);
+ return ERR_PTR(-ESTALE);
+ }
+
+ if ((current->ptrace & PT_PTRACED) && aa_may_ptrace(cxt, profile)) {
+ task_unlock(task);
+ unlock_both_profiles(profile, cxt ? cxt->profile : NULL);
+ aa_free_task_context(new_cxt);
+ return ERR_PTR(-EPERM);
+ }
+
+ if (cxt)
+ old_profile = aa_dup_profile(cxt->profile);
+ aa_change_task_context(task, new_cxt, profile, 0, NULL);
+
+ task_unlock(task);
+ unlock_both_profiles(profile, old_profile);
+ return old_profile;
+}
+
+/**
+ * lock_task_and_profiles - lock the task and confining profiles and @profile
+ * @task: task to lock
+ * @profile: extra profile to lock in addition to the current profile
+ *
+ * Handle the spinning on locking to make sure the task context and
+ * profile are consistent once all locks are aquired.
+ *
+ * return the aa_task_context currently confining the task. The task lock
+ * will be held whether or not the task is confined.
+ */
+struct aa_task_context *
+lock_task_and_profiles(struct task_struct *task, struct aa_profile *profile)
+{
+ struct aa_task_context *cxt;
+ struct aa_profile *old_profile = NULL;
+
+ rcu_read_lock();
+repeat:
+ cxt = aa_task_context(task);
+ if (cxt)
+ old_profile = cxt->profile;
+
+ lock_both_profiles(profile, old_profile);
+ task_lock(task);
+
+ /* check for race with profile transition, replacement or removal */
+ if (unlikely(cxt != aa_task_context(task))) {
+ task_unlock(task);
+ unlock_both_profiles(profile, old_profile);
+ old_profile = NULL;
+ goto repeat;
+ }
+ rcu_read_unlock();
+ return cxt;
+}
+
+static void free_aa_task_context_rcu_callback(struct rcu_head *head)
+{
+ struct aa_task_context *cxt;
+
+ cxt = container_of(head, struct aa_task_context, rcu);
+ aa_free_task_context(cxt);
+}
+
+/**
+ * aa_change_task_context - switch a task to use a new context and profile
+ * @task: task that is having its task context changed
+ * @new_cxt: new task context to use after the switch
+ * @profile: new profile to use after the switch
+ * @cookie: magic value to switch to
+ * @previous_profile: profile the task can return to
+ */
+void aa_change_task_context(struct task_struct *task,
+ struct aa_task_context *new_cxt,
+ struct aa_profile *profile, u64 cookie,
+ struct aa_profile *previous_profile)
+{
+ struct aa_task_context *old_cxt = aa_task_context(task);
+
+ if (old_cxt) {
+ list_del_init(&old_cxt->list);
+ call_rcu(&old_cxt->rcu, free_aa_task_context_rcu_callback);
+ }
+ if (new_cxt) {
+ /* clear the caps_logged cache, so that new profile/hat has
+ * chance to emit its own set of cap messages */
+ new_cxt->caps_logged = CAP_EMPTY_SET;
+ new_cxt->cookie = cookie;
+ new_cxt->task = task;
+ new_cxt->profile = aa_dup_profile(profile);
+ new_cxt->previous_profile = aa_dup_profile(previous_profile);
+ list_move(&new_cxt->list, &profile->task_contexts);
+ }
+ rcu_assign_pointer(task->security, new_cxt);
+}

--