From 7ead53fe15ab016eeff34fac68c7c90f4bd5c6c1 Mon Sep 17 00:00:00 2001
From: John Johansen <john.johansen@canonical.com>
Date: Tue, 23 May 2017 03:25:14 -0700
Subject: [PATCH 10/65] apparmor: Move path lookup to using preallocated
buffers
Git-commit: 4227c333f65cddc6c2f048e5b67cfe796b9df9a6
Patch-mainline: v4.13-rc1
References: FATE#323500
Dynamically allocating buffers is problematic and is an extra layer
that is a potntial point of failure and can slow down mediation.
Change path lookup to use the preallocated per cpu buffers.
Signed-off-by: John Johansen <john.johansen@canonical.com>
Acked-by: Goldwyn Rodrigues <rgoldwyn@suse.com>
---
security/apparmor/domain.c | 8 +--
security/apparmor/file.c | 13 ++---
security/apparmor/include/path.h | 4 +-
security/apparmor/path.c | 114 ++++++++++++++-------------------------
4 files changed, 53 insertions(+), 86 deletions(-)
diff --git a/security/apparmor/domain.c b/security/apparmor/domain.c
index c92fd0e7b33c..ab8f23cdccff 100644
--- a/security/apparmor/domain.c
+++ b/security/apparmor/domain.c
@@ -357,6 +357,9 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
AA_BUG(!ctx);
profile = aa_get_newest_profile(ctx->profile);
+
+ /* buffer freed below, name is pointer into buffer */
+ get_buffers(buffer);
/*
* get the namespace from the replacement profile as replacement
* can change the namespace
@@ -364,8 +367,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
ns = profile->ns;
state = profile->file.start;
- /* buffer freed below, name is pointer into buffer */
- error = aa_path_name(&bprm->file->f_path, profile->path_flags, &buffer,
+ error = aa_path_name(&bprm->file->f_path, profile->path_flags, buffer,
&name, &info, profile->disconnected);
if (error) {
if (unconfined(profile) ||
@@ -515,7 +517,7 @@ int apparmor_bprm_set_creds(struct linux_binprm *bprm)
cleanup:
aa_put_profile(new_profile);
aa_put_profile(profile);
- kfree(buffer);
+ put_buffers(buffer);
return error;
}
diff --git a/security/apparmor/file.c b/security/apparmor/file.c
index 83d43ac72134..22be62f0fc73 100644
--- a/security/apparmor/file.c
+++ b/security/apparmor/file.c
@@ -285,7 +285,8 @@ int aa_path_perm(const char *op, struct aa_profile *profile,
int error;
flags |= profile->path_flags | (S_ISDIR(cond->mode) ? PATH_IS_DIR : 0);
- error = aa_path_name(path, flags, &buffer, &name, &info,
+ get_buffers(buffer);
+ error = aa_path_name(path, flags, buffer, &name, &info,
profile->disconnected);
if (error) {
if (error == -ENOENT && is_deleted(path->dentry)) {
@@ -304,7 +305,7 @@ int aa_path_perm(const char *op, struct aa_profile *profile,
}
error = aa_audit_file(profile, &perms, op, request, name, NULL,
cond->uid, info, error);
- kfree(buffer);
+ put_buffers(buffer);
return error;
}
@@ -363,16 +364,17 @@ int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
unsigned int state;
int error;
+ get_buffers(buffer, buffer2);
lperms = nullperms;
/* buffer freed below, lname is pointer in buffer */
- error = aa_path_name(&link, profile->path_flags, &buffer, &lname,
+ error = aa_path_name(&link, profile->path_flags, buffer, &lname,
&info, profile->disconnected);
if (error)
goto audit;
/* buffer2 freed below, tname is pointer in buffer2 */
- error = aa_path_name(&target, profile->path_flags, &buffer2, &tname,
+ error = aa_path_name(&target, profile->path_flags, buffer2, &tname,
&info, profile->disconnected);
if (error)
goto audit;
@@ -432,8 +434,7 @@ int aa_path_link(struct aa_profile *profile, struct dentry *old_dentry,
audit:
error = aa_audit_file(profile, &lperms, OP_LINK, request,
lname, tname, cond.uid, info, error);
- kfree(buffer);
- kfree(buffer2);
+ put_buffers(buffer, buffer2);
return error;
}
diff --git a/security/apparmor/include/path.h b/security/apparmor/include/path.h
index 78e4909dcc6a..05fb3305671e 100644
--- a/security/apparmor/include/path.h
+++ b/security/apparmor/include/path.h
@@ -23,10 +23,10 @@ enum path_flags {
PATH_CHROOT_NSCONNECT = 0x10, /* connect paths that are at ns root */
PATH_DELEGATE_DELETED = 0x08000, /* delegate deleted files */
- PATH_MEDIATE_DELETED = 0x10000, /* mediate deleted paths */
+ PATH_MEDIATE_DELETED = 0x10000, /* mediate deleted paths */
};
-int aa_path_name(const struct path *path, int flags, char **buffer,
+int aa_path_name(const struct path *path, int flags, char *buffer,
const char **name, const char **info,
const char *disconnected);
diff --git a/security/apparmor/path.c b/security/apparmor/path.c
index 9490f8e89630..9d5de1d05be4 100644
--- a/security/apparmor/path.c
+++ b/security/apparmor/path.c
@@ -79,7 +79,6 @@ static int disconnect(const struct path *path, char *buf, char **name,
* d_namespace_path - lookup a name associated with a given path
* @path: path to lookup (NOT NULL)
* @buf: buffer to store path to (NOT NULL)
- * @buflen: length of @buf
* @name: Returns - pointer for start of path name with in @buf (NOT NULL)
* @flags: flags controlling path lookup
* @disconnected: string to prefix to disconnected paths
@@ -90,12 +89,14 @@ static int disconnect(const struct path *path, char *buf, char **name,
* When no error the path name is returned in @name which points to
* to a position in @buf
*/
-static int d_namespace_path(const struct path *path, char *buf, int buflen,
- char **name, int flags, const char *disconnected)
+static int d_namespace_path(const struct path *path, char *buf, char **name,
+ int flags, const char *disconnected)
{
char *res;
int error = 0;
int connected = 1;
+ int isdir = (flags & PATH_IS_DIR) ? 1 : 0;
+ int buflen = aa_g_path_max - isdir;
if (path->mnt->mnt_flags & MNT_INTERNAL) {
/* it's not mounted anywhere */
@@ -110,10 +111,12 @@ static int d_namespace_path(const struct path *path, char *buf, int buflen,
/* TODO: convert over to using a per namespace
* control instead of hard coded /proc
*/
- return prepend(name, *name - buf, "/proc", 5);
+ error = prepend(name, *name - buf, "/proc", 5);
+ goto out;
} else
- return disconnect(path, buf, name, flags,
- disconnected);
+ error = disconnect(path, buf, name, flags,
+ disconnected);
+ goto out;
}
/* resolve paths relative to chroot?*/
@@ -132,8 +135,11 @@ static int d_namespace_path(const struct path *path, char *buf, int buflen,
* be returned.
*/
if (!res || IS_ERR(res)) {
- if (PTR_ERR(res) == -ENAMETOOLONG)
- return -ENAMETOOLONG;
+ if (PTR_ERR(res) == -ENAMETOOLONG) {
+ error = -ENAMETOOLONG;
+ *name = buf;
+ goto out;
+ }
connected = 0;
res = dentry_path_raw(path->dentry, buf, buflen);
if (IS_ERR(res)) {
@@ -146,6 +152,9 @@ static int d_namespace_path(const struct path *path, char *buf, int buflen,
*name = res;
+ if (!connected)
+ error = disconnect(path, buf, name, flags, disconnected);
+
/* Handle two cases:
* 1. A deleted dentry && profile is not allowing mediation of deleted
* 2. On some filesystems, newly allocated dentries appear to the
@@ -153,62 +162,27 @@ static int d_namespace_path(const struct path *path, char *buf, int buflen,
* allocated.
*/
if (d_unlinked(path->dentry) && d_is_positive(path->dentry) &&
- !(flags & PATH_MEDIATE_DELETED)) {
+ !(flags & (PATH_MEDIATE_DELETED | PATH_DELEGATE_DELETED))) {
error = -ENOENT;
goto out;
}
- if (!connected)
- error = disconnect(path, buf, name, flags, disconnected);
-
out:
- return error;
-}
-
-/**
- * get_name_to_buffer - get the pathname to a buffer ensure dir / is appended
- * @path: path to get name for (NOT NULL)
- * @flags: flags controlling path lookup
- * @buffer: buffer to put name in (NOT NULL)
- * @size: size of buffer
- * @name: Returns - contains position of path name in @buffer (NOT NULL)
- *
- * Returns: %0 else error on failure
- */
-static int get_name_to_buffer(const struct path *path, int flags, char *buffer,
- int size, char **name, const char **info,
- const char *disconnected)
-{
- int adjust = (flags & PATH_IS_DIR) ? 1 : 0;
- int error = d_namespace_path(path, buffer, size - adjust, name, flags,
- disconnected);
-
- if (!error && (flags & PATH_IS_DIR) && (*name)[1] != '\0')
- /*
- * Append "/" to the pathname. The root directory is a special
- * case; it already ends in slash.
- */
- strcpy(&buffer[size - 2], "/");
-
- if (info && error) {
- if (error == -ENOENT)
- *info = "Failed name lookup - deleted entry";
- else if (error == -EACCES)
- *info = "Failed name lookup - disconnected path";
- else if (error == -ENAMETOOLONG)
- *info = "Failed name lookup - name too long";
- else
- *info = "Failed name lookup";
- }
+ /*
+ * Append "/" to the pathname. The root directory is a special
+ * case; it already ends in slash.
+ */
+ if (!error && isdir && ((*name)[1] != '\0' || (*name)[0] != '/'))
+ strcpy(&buf[aa_g_path_max - 2], "/");
return error;
}
/**
- * aa_path_name - compute the pathname of a file
+ * aa_path_name - get the pathname to a buffer ensure dir / is appended
* @path: path the file (NOT NULL)
* @flags: flags controlling path name generation
- * @buffer: buffer that aa_get_name() allocated (NOT NULL)
+ * @buffer: buffer to put name in (NOT NULL)
* @name: Returns - the generated path name if !error (NOT NULL)
* @info: Returns - information on why the path lookup failed (MAYBE NULL)
* @disconnected: string to prepend to disconnected paths
@@ -224,33 +198,23 @@ static int get_name_to_buffer(const struct path *path, int flags, char *buffer,
*
* Returns: %0 else error code if could retrieve name
*/
-int aa_path_name(const struct path *path, int flags, char **buffer,
+int aa_path_name(const struct path *path, int flags, char *buffer,
const char **name, const char **info, const char *disconnected)
{
- char *buf, *str = NULL;
- int size = 256;
- int error;
-
- *name = NULL;
- *buffer = NULL;
- for (;;) {
- /* freed by caller */
- buf = kmalloc(size, GFP_KERNEL);
- if (!buf)
- return -ENOMEM;
+ char *str = NULL;
+ int error = d_namespace_path(path, buffer, &str, flags, disconnected);
- error = get_name_to_buffer(path, flags, buf, size, &str, info,
- disconnected);
- if (error != -ENAMETOOLONG)
- break;
-
- kfree(buf);
- size <<= 1;
- if (size > aa_g_path_max)
- return -ENAMETOOLONG;
- *info = NULL;
+ if (info && error) {
+ if (error == -ENOENT)
+ *info = "Failed name lookup - deleted entry";
+ else if (error == -EACCES)
+ *info = "Failed name lookup - disconnected path";
+ else if (error == -ENAMETOOLONG)
+ *info = "Failed name lookup - name too long";
+ else
+ *info = "Failed name lookup";
}
- *buffer = buf;
+
*name = str;
return error;
--
2.12.3