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authorJohn Johansen <john.johansen@canonical.com>2017-05-23 03:25:14 -0700
committerJohn Johansen <john.johansen@canonical.com>2017-06-08 11:29:34 -0700
commit4227c333f65cddc6c2f048e5b67cfe796b9df9a6 (patch)
tree4deee8d16246bc879036da19642451b8e7cdcde0 /security/apparmor/path.c
parent72c8a768641dc6ee8d1d9dcebd51bbec2817459b (diff)
apparmor: Move path lookup to using preallocated buffers
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>
Diffstat (limited to 'security/apparmor/path.c')
-rw-r--r--security/apparmor/path.c114
1 files changed, 39 insertions, 75 deletions
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;