TOMOYO: Support longer pathname.

Allow pathnames longer than 4000 bytes.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Signed-off-by: James Morris <jmorris@namei.org>

6 files changed, 208 insertions, 318 deletions

diff --git a/security/tomoyo/common.h b/security/tomoyo/common.h
index 6270a530c4d8..f4a8aa244af5 100644
--- a/security/tomoyo/common.h
+++ b/security/tomoyo/common.h
@@ -33,14 +33,7 @@ struct linux_binprm;
 #define TOMOYO_HASH_BITS  8
 #define TOMOYO_MAX_HASH (1u<<TOMOYO_HASH_BITS)
 
-/*
- * This is the max length of a token.
- *
- * A token consists of only ASCII printable characters.
- * Non printable characters in a token is represented in \ooo style
- * octal string. Thus, \ itself is represented as \\.
- */
-#define TOMOYO_MAX_PATHNAME_LEN 4000
+#define TOMOYO_EXEC_TMPSIZE     4096
 
 /* Profile number is an integer between 0 and 255. */
 #define TOMOYO_MAX_PROFILES 256
@@ -168,17 +161,6 @@ enum tomoyo_securityfs_interface_index {
 /********** Structure definitions. **********/
 
 /*
- * tomoyo_page_buffer is a structure which is used for holding a pathname
- * obtained from "struct dentry" and "struct vfsmount" pair.
- * As of now, it is 4096 bytes. If users complain that 4096 bytes is too small
- * (because TOMOYO escapes non ASCII printable characters using \ooo format),
- * we will make the buffer larger.
- */
-struct tomoyo_page_buffer {
-        char buffer[4096];
-};
-
-/*
  * tomoyo_request_info is a structure which is used for holding
  *
  * (1) Domain information of current process.
@@ -231,28 +213,6 @@ struct tomoyo_name_entry {
         struct tomoyo_path_info entry;
 };
 
-/*
- * tomoyo_path_info_with_data is a structure which is used for holding a
- * pathname obtained from "struct dentry" and "struct vfsmount" pair.
- *
- * "struct tomoyo_path_info_with_data" consists of "struct tomoyo_path_info"
- * and buffer for the pathname, while "struct tomoyo_page_buffer" consists of
- * buffer for the pathname only.
- *
- * "struct tomoyo_path_info_with_data" is intended to allow TOMOYO to release
- * both "struct tomoyo_path_info" and buffer for the pathname by single kfree()
- * so that we don't need to return two pointers to the caller. If the caller
- * puts "struct tomoyo_path_info" on stack memory, we will be able to remove
- * "struct tomoyo_path_info_with_data".
- */
-struct tomoyo_path_info_with_data {
-        /* Keep "head" first, for this pointer is passed to kfree(). */
-        struct tomoyo_path_info head;
-        char barrier1[16]; /* Safeguard for overrun. */
-        char body[TOMOYO_MAX_PATHNAME_LEN];
-        char barrier2[16]; /* Safeguard for overrun. */
-};
-
 struct tomoyo_name_union {
         const struct tomoyo_path_info *filename;
         struct tomoyo_path_group *group;
@@ -827,11 +787,7 @@ void tomoyo_load_policy(const char *filename);
 void tomoyo_put_number_union(struct tomoyo_number_union *ptr);
 
 /* Convert binary string to ascii string. */
-int tomoyo_encode(char *buffer, int buflen, const char *str);
-
-/* Returns realpath(3) of the given pathname but ignores chroot'ed root. */
-int tomoyo_realpath_from_path2(struct path *path, char *newname,
-                               int newname_len);
+char *tomoyo_encode(const char *str);
 
 /*
  * Returns realpath(3) of the given pathname but ignores chroot'ed root.
diff --git a/security/tomoyo/domain.c b/security/tomoyo/domain.c
index 08428bc082df..7b8693e29a13 100644
--- a/security/tomoyo/domain.c
+++ b/security/tomoyo/domain.c
@@ -676,47 +676,43 @@ struct tomoyo_domain_info *tomoyo_find_or_assign_new_domain(const char *
 int tomoyo_find_next_domain(struct linux_binprm *bprm)
 {
         struct tomoyo_request_info r;
-        /*
-         * This function assumes that the size of buffer returned by
-         * tomoyo_realpath() = TOMOYO_MAX_PATHNAME_LEN.
-         */
-        struct tomoyo_page_buffer *tmp = kzalloc(sizeof(*tmp), GFP_NOFS);
+        char *tmp = kzalloc(TOMOYO_EXEC_TMPSIZE, GFP_NOFS);
         struct tomoyo_domain_info *old_domain = tomoyo_domain();
         struct tomoyo_domain_info *domain = NULL;
         const char *old_domain_name = old_domain->domainname->name;
         const char *original_name = bprm->filename;
-        char *new_domain_name = NULL;
-        char *real_program_name = NULL;
-        char *symlink_program_name = NULL;
         const u8 mode = tomoyo_check_flags(old_domain, TOMOYO_MAC_FOR_FILE);
         const bool is_enforce = (mode == TOMOYO_CONFIG_ENFORCING);
         int retval = -ENOMEM;
-        struct tomoyo_path_info rn; /* real name */
-        struct tomoyo_path_info sn; /* symlink name */
+        bool need_kfree = false;
+        struct tomoyo_path_info rn = { }; /* real name */
+        struct tomoyo_path_info sn = { }; /* symlink name */
         struct tomoyo_path_info ln; /* last name */
 
+        ln.name = tomoyo_get_last_name(old_domain);
+        tomoyo_fill_path_info(&ln);
         tomoyo_init_request_info(&r, NULL);
         if (!tmp)
                 goto out;
 
  retry:
+        if (need_kfree) {
+                kfree(rn.name);
+                need_kfree = false;
+        }
         /* Get tomoyo_realpath of program. */
         retval = -ENOENT;
-        /* I hope tomoyo_realpath() won't fail with -ENOMEM. */
-        real_program_name = tomoyo_realpath(original_name);
-        if (!real_program_name)
+        rn.name = tomoyo_realpath(original_name);
+        if (!rn.name)
                 goto out;
+        tomoyo_fill_path_info(&rn);
+        need_kfree = true;
+
         /* Get tomoyo_realpath of symbolic link. */
-        symlink_program_name = tomoyo_realpath_nofollow(original_name);
-        if (!symlink_program_name)
+        sn.name = tomoyo_realpath_nofollow(original_name);
+        if (!sn.name)
                 goto out;
-
-        rn.name = real_program_name;
-        tomoyo_fill_path_info(&rn);
-        sn.name = symlink_program_name;
         tomoyo_fill_path_info(&sn);
-        ln.name = tomoyo_get_last_name(old_domain);
-        tomoyo_fill_path_info(&ln);
 
         /* Check 'alias' directive. */
         if (tomoyo_pathcmp(&rn, &sn)) {
@@ -727,10 +723,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
                             tomoyo_pathcmp(&rn, ptr->original_name) ||
                             tomoyo_pathcmp(&sn, ptr->aliased_name))
                                 continue;
-                        memset(real_program_name, 0, TOMOYO_MAX_PATHNAME_LEN);
-                        strncpy(real_program_name, ptr->aliased_name->name,
-                                TOMOYO_MAX_PATHNAME_LEN - 1);
-                        tomoyo_fill_path_info(&rn);
+                        kfree(rn.name);
+                        need_kfree = false;
+                        /* This is OK because it is read only. */
+                        rn = *ptr->aliased_name;
                         break;
                 }
         }
@@ -742,11 +738,10 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
         if (retval < 0)
                 goto out;
 
-        new_domain_name = tmp->buffer;
         if (tomoyo_is_domain_initializer(old_domain->domainname, &rn, &ln)) {
                 /* Transit to the child of tomoyo_kernel_domain domain. */
-                snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
-                         TOMOYO_ROOT_NAME " " "%s", real_program_name);
+                snprintf(tmp, TOMOYO_EXEC_TMPSIZE - 1,
+                         TOMOYO_ROOT_NAME " " "%s", rn.name);
         } else if (old_domain == &tomoyo_kernel_domain &&
                    !tomoyo_policy_loaded) {
                 /*
@@ -760,29 +755,27 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
                 domain = old_domain;
         } else {
                 /* Normal domain transition. */
-                snprintf(new_domain_name, TOMOYO_MAX_PATHNAME_LEN + 1,
-                         "%s %s", old_domain_name, real_program_name);
+                snprintf(tmp, TOMOYO_EXEC_TMPSIZE - 1,
+                         "%s %s", old_domain_name, rn.name);
         }
-        if (domain || strlen(new_domain_name) >= TOMOYO_MAX_PATHNAME_LEN)
+        if (domain || strlen(tmp) >= TOMOYO_EXEC_TMPSIZE - 10)
                 goto done;
-        domain = tomoyo_find_domain(new_domain_name);
+        domain = tomoyo_find_domain(tmp);
         if (domain)
                 goto done;
         if (is_enforce) {
                 int error = tomoyo_supervisor(&r, "# wants to create domain\n"
-                                              "%s\n", new_domain_name);
+                                              "%s\n", tmp);
                 if (error == TOMOYO_RETRY_REQUEST)
                         goto retry;
                 if (error < 0)
                         goto done;
         }
-        domain = tomoyo_find_or_assign_new_domain(new_domain_name,
-                                                  old_domain->profile);
+        domain = tomoyo_find_or_assign_new_domain(tmp, old_domain->profile);
  done:
         if (domain)
                 goto out;
-        printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n",
-               new_domain_name);
+        printk(KERN_WARNING "TOMOYO-ERROR: Domain '%s' not defined.\n", tmp);
         if (is_enforce)
                 retval = -EPERM;
         else
@@ -793,8 +786,9 @@ int tomoyo_find_next_domain(struct linux_binprm *bprm)
         /* Update reference count on "struct tomoyo_domain_info". */
         atomic_inc(&domain->users);
         bprm->cred->security = domain;
-        kfree(real_program_name);
-        kfree(symlink_program_name);
+        if (need_kfree)
+                kfree(rn.name);
+        kfree(sn.name);
         kfree(tmp);
         return retval;
 }
diff --git a/security/tomoyo/file.c b/security/tomoyo/file.c
index c13806937dc6..cef685415df1 100644
--- a/security/tomoyo/file.c
+++ b/security/tomoyo/file.c
@@ -148,6 +148,17 @@ const char *tomoyo_path_number2keyword(const u8 operation)
                 ? tomoyo_path_number_keyword[operation] : NULL;
 }
 
+static void tomoyo_add_slash(struct tomoyo_path_info *buf)
+{
+        if (buf->is_dir)
+                return;
+        /*
+         * This is OK because tomoyo_encode() reserves space for appending "/".
+         */
+        strcat((char *) buf->name, "/");
+        tomoyo_fill_path_info(buf);
+}
+
 /**
  * tomoyo_strendswith - Check whether the token ends with the given token.
  *
@@ -167,30 +178,21 @@ static bool tomoyo_strendswith(const char *name, const char *tail)
 }
 
 /**
- * tomoyo_get_path - Get realpath.
+ * tomoyo_get_realpath - Get realpath.
  *
+ * @buf:  Pointer to "struct tomoyo_path_info".
  * @path: Pointer to "struct path".
  *
- * Returns pointer to "struct tomoyo_path_info" on success, NULL otherwise.
+ * Returns true on success, false otherwise.
  */
-static struct tomoyo_path_info *tomoyo_get_path(struct path *path)
+static bool tomoyo_get_realpath(struct tomoyo_path_info *buf, struct path *path)
 {
-        int error;
-        struct tomoyo_path_info_with_data *buf = kzalloc(sizeof(*buf),
-                                                         GFP_NOFS);
-
-        if (!buf)
-                return NULL;
-        /* Reserve one byte for appending "/". */
-        error = tomoyo_realpath_from_path2(path, buf->body,
-                                           sizeof(buf->body) - 2);
-        if (!error) {
-                buf->head.name = buf->body;
-                tomoyo_fill_path_info(&buf->head);
-                return &buf->head;
+        buf->name = tomoyo_realpath_from_path(path);
+        if (buf->name) {
+                tomoyo_fill_path_info(buf);
+                return true;
         }
-        kfree(buf);
-        return NULL;
+        return false;
 }
 
 static int tomoyo_update_path2_acl(const u8 type, const char *filename1,
@@ -1259,26 +1261,20 @@ int tomoyo_path_number_perm(const u8 type, struct path *path,
 {
         struct tomoyo_request_info r;
         int error = -ENOMEM;
-        struct tomoyo_path_info *buf;
+        struct tomoyo_path_info buf;
         int idx;
 
         if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
             !path->mnt || !path->dentry)
                 return 0;
         idx = tomoyo_read_lock();
-        buf = tomoyo_get_path(path);
-        if (!buf)
+        if (!tomoyo_get_realpath(&buf, path))
                 goto out;
-        if (type == TOMOYO_TYPE_MKDIR && !buf->is_dir) {
-                /*
-                 * tomoyo_get_path() reserves space for appending "/."
-                 */
-                strcat((char *) buf->name, "/");
-                tomoyo_fill_path_info(buf);
-        }
-        error = tomoyo_path_number_perm2(&r, type, buf, number);
+        if (type == TOMOYO_TYPE_MKDIR)
+                tomoyo_add_slash(&buf);
+        error = tomoyo_path_number_perm2(&r, type, &buf, number);
  out:
-        kfree(buf);
+        kfree(buf.name);
         tomoyo_read_unlock(idx);
         if (r.mode != TOMOYO_CONFIG_ENFORCING)
                 error = 0;
@@ -1319,7 +1315,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 {
         const u8 acc_mode = ACC_MODE(flag);
         int error = -ENOMEM;
-        struct tomoyo_path_info *buf;
+        struct tomoyo_path_info buf;
         struct tomoyo_request_info r;
         int idx;
 
@@ -1335,8 +1331,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
                  */
                 return 0;
         idx = tomoyo_read_lock();
-        buf = tomoyo_get_path(path);
-        if (!buf)
+        if (!tomoyo_get_realpath(&buf, path))
                 goto out;
         error = 0;
         /*
@@ -1346,15 +1341,15 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
          */
         if ((acc_mode & MAY_WRITE) &&
             ((flag & O_TRUNC) || !(flag & O_APPEND)) &&
-            (tomoyo_is_no_rewrite_file(buf))) {
-                error = tomoyo_path_permission(&r, TOMOYO_TYPE_REWRITE, buf);
+            (tomoyo_is_no_rewrite_file(&buf))) {
+                error = tomoyo_path_permission(&r, TOMOYO_TYPE_REWRITE, &buf);
         }
         if (!error)
-                error = tomoyo_file_perm(&r, buf, acc_mode);
+                error = tomoyo_file_perm(&r, &buf, acc_mode);
         if (!error && (flag & O_TRUNC))
-                error = tomoyo_path_permission(&r, TOMOYO_TYPE_TRUNCATE, buf);
+                error = tomoyo_path_permission(&r, TOMOYO_TYPE_TRUNCATE, &buf);
  out:
-        kfree(buf);
+        kfree(buf.name);
         tomoyo_read_unlock(idx);
         if (r.mode != TOMOYO_CONFIG_ENFORCING)
                 error = 0;
@@ -1372,7 +1367,7 @@ int tomoyo_check_open_permission(struct tomoyo_domain_info *domain,
 int tomoyo_path_perm(const u8 operation, struct path *path)
 {
         int error = -ENOMEM;
-        struct tomoyo_path_info *buf;
+        struct tomoyo_path_info buf;
         struct tomoyo_request_info r;
         int idx;
 
@@ -1380,29 +1375,23 @@ int tomoyo_path_perm(const u8 operation, struct path *path)
             !path->mnt)
                 return 0;
         idx = tomoyo_read_lock();
-        buf = tomoyo_get_path(path);
-        if (!buf)
+        if (!tomoyo_get_realpath(&buf, path))
                 goto out;
         switch (operation) {
         case TOMOYO_TYPE_REWRITE:
-                if (!tomoyo_is_no_rewrite_file(buf)) {
+                if (!tomoyo_is_no_rewrite_file(&buf)) {
                         error = 0;
                         goto out;
                 }
                 break;
         case TOMOYO_TYPE_RMDIR:
         case TOMOYO_TYPE_CHROOT:
-                if (!buf->is_dir) {
-                        /*
-                         * tomoyo_get_path() reserves space for appending "/."
-                         */
-                        strcat((char *) buf->name, "/");
-                        tomoyo_fill_path_info(buf);
-                }
+                tomoyo_add_slash(&buf);
+                break;
         }
-        error = tomoyo_path_permission(&r, operation, buf);
+        error = tomoyo_path_permission(&r, operation, &buf);
  out:
-        kfree(buf);
+        kfree(buf.name);
         tomoyo_read_unlock(idx);
         if (r.mode != TOMOYO_CONFIG_ENFORCING)
                 error = 0;
@@ -1465,7 +1454,7 @@ int tomoyo_path_number3_perm(const u8 operation, struct path *path,
 {
         struct tomoyo_request_info r;
         int error = -ENOMEM;
-        struct tomoyo_path_info *buf;
+        struct tomoyo_path_info buf;
         int idx;
 
         if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
@@ -1473,11 +1462,10 @@ int tomoyo_path_number3_perm(const u8 operation, struct path *path,
                 return 0;
         idx = tomoyo_read_lock();
         error = -ENOMEM;
-        buf = tomoyo_get_path(path);
-        if (buf) {
-                error = tomoyo_path_number3_perm2(&r, operation, buf, mode,
+        if (tomoyo_get_realpath(&buf, path)) {
+                error = tomoyo_path_number3_perm2(&r, operation, &buf, mode,
                                                   new_decode_dev(dev));
-                kfree(buf);
+                kfree(buf.name);
         }
         tomoyo_read_unlock(idx);
         if (r.mode != TOMOYO_CONFIG_ENFORCING)
@@ -1499,48 +1487,40 @@ int tomoyo_path2_perm(const u8 operation, struct path *path1,
 {
         int error = -ENOMEM;
         const char *msg;
-        struct tomoyo_path_info *buf1;
-        struct tomoyo_path_info *buf2;
+        struct tomoyo_path_info buf1;
+        struct tomoyo_path_info buf2;
         struct tomoyo_request_info r;
         int idx;
 
         if (tomoyo_init_request_info(&r, NULL) == TOMOYO_CONFIG_DISABLED ||
             !path1->mnt || !path2->mnt)
                 return 0;
+        buf1.name = NULL;
+        buf2.name = NULL;
         idx = tomoyo_read_lock();
-        buf1 = tomoyo_get_path(path1);
-        buf2 = tomoyo_get_path(path2);
-        if (!buf1 || !buf2)
+        if (!tomoyo_get_realpath(&buf1, path1) ||
+            !tomoyo_get_realpath(&buf2, path2))
                 goto out;
         {
                 struct dentry *dentry = path1->dentry;
                 if (dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)) {
-                        /*
-                         * tomoyo_get_path() reserves space for appending "/."
-                         */
-                        if (!buf1->is_dir) {
-                                strcat((char *) buf1->name, "/");
-                                tomoyo_fill_path_info(buf1);
-                        }
-                        if (!buf2->is_dir) {
-                                strcat((char *) buf2->name, "/");
-                                tomoyo_fill_path_info(buf2);
-                        }
+                        tomoyo_add_slash(&buf1);
+                        tomoyo_add_slash(&buf2);
                 }
         }
         do {
-                error = tomoyo_path2_acl(&r, operation, buf1, buf2);
+                error = tomoyo_path2_acl(&r, operation, &buf1, &buf2);
                 if (!error)
                         break;
                 msg = tomoyo_path22keyword(operation);
-                tomoyo_warn_log(&r, "%s %s %s", msg, buf1->name, buf2->name);
+                tomoyo_warn_log(&r, "%s %s %s", msg, buf1.name, buf2.name);
                 error = tomoyo_supervisor(&r, "allow_%s %s %s\n", msg,
-                                          tomoyo_file_pattern(buf1),
-                                          tomoyo_file_pattern(buf2));
+                                          tomoyo_file_pattern(&buf1),
+                                          tomoyo_file_pattern(&buf2));
         } while (error == TOMOYO_RETRY_REQUEST);
  out:
-        kfree(buf1);
-        kfree(buf2);
+        kfree(buf1.name);
+        kfree(buf2.name);
         tomoyo_read_unlock(idx);
         if (r.mode != TOMOYO_CONFIG_ENFORCING)
                 error = 0;
diff --git a/security/tomoyo/memory.c b/security/tomoyo/memory.c
index 8fb73ff5cb63..4809febc1acb 100644
--- a/security/tomoyo/memory.c
+++ b/security/tomoyo/memory.c
@@ -153,7 +153,6 @@ void __init tomoyo_mm_init(void)
 {
         int idx;
 
-        BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
         for (idx = 0; idx < TOMOYO_MAX_HASH; idx++)
                 INIT_LIST_HEAD(&tomoyo_name_list[idx]);
         INIT_LIST_HEAD(&tomoyo_kernel_domain.acl_info_list);
diff --git a/security/tomoyo/mount.c b/security/tomoyo/mount.c
index aeac619f787d..7c1c7fdd3681 100644
--- a/security/tomoyo/mount.c
+++ b/security/tomoyo/mount.c
@@ -25,57 +25,6 @@
 #define TOMOYO_MOUNT_MAKE_SHARED_KEYWORD                 "--make-shared"
 
 /**
- * tomoyo_encode2: Encode binary string to ascii string.
- *
- * @str: String in binary format.
- *
- * Returns pointer to @str in ascii format on success, NULL otherwise.
- *
- * This function uses kzalloc(), so caller must kfree() if this function
- * didn't return NULL.
- */
-static char *tomoyo_encode2(const char *str)
-{
-        int len = 0;
-        const char *p = str;
-        char *cp;
-        char *cp0;
-        if (!p)
-                return NULL;
-        while (*p) {
-                const unsigned char c = *p++;
-                if (c == '\\')
-                        len += 2;
-                else if (c > ' ' && c < 127)
-                        len++;
-                else
-                        len += 4;
-        }
-        len++;
-        /* Reserve space for appending "/". */
-        cp = kzalloc(len + 10, GFP_NOFS);
-        if (!cp)
-                return NULL;
-        cp0 = cp;
-        p = str;
-        while (*p) {
-                const unsigned char c = *p++;
-                if (c == '\\') {
-                        *cp++ = '\\';
-                        *cp++ = '\\';
-                } else if (c > ' ' && c < 127) {
-                        *cp++ = c;
-                } else {
-                        *cp++ = '\\';
-                        *cp++ = (c >> 6) + '0';
-                        *cp++ = ((c >> 3) & 7) + '0';
-                        *cp++ = (c & 7) + '0';
-                }
-        }
-        return cp0;
-}
-
-/**
  * tomoyo_mount_acl2 - Check permission for mount() operation.
  *
  * @r:        Pointer to "struct tomoyo_request_info".
@@ -104,7 +53,7 @@ static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
         int error = -ENOMEM;
 
         /* Get fstype. */
-        requested_type = tomoyo_encode2(type);
+        requested_type = tomoyo_encode(type);
         if (!requested_type)
                 goto out;
         rtype.name = requested_type;
@@ -155,7 +104,7 @@ static int tomoyo_mount_acl2(struct tomoyo_request_info *r, char *dev_name,
                 /* Map dev_name to "<NULL>" if no dev_name given. */
                 if (!dev_name)
                         dev_name = "<NULL>";
-                requested_dev_name = tomoyo_encode2(dev_name);
+                requested_dev_name = tomoyo_encode(dev_name);
                 if (!requested_dev_name) {
                         error = -ENOMEM;
                         goto out;
diff --git a/security/tomoyo/realpath.c b/security/tomoyo/realpath.c
index 1fd685a94ad1..153fa23a05cc 100644
--- a/security/tomoyo/realpath.c
+++ b/security/tomoyo/realpath.c
@@ -12,141 +12,153 @@
 #include <linux/fs_struct.h>
 #include <linux/magic.h>
 #include <linux/slab.h>
+#include <net/sock.h>
 #include "common.h"
 
 /**
  * tomoyo_encode: Convert binary string to ascii string.
  *
- * @buffer:  Buffer for ASCII string.
- * @buflen:  Size of @buffer.
- * @str:     Binary string.
+ * @str: String in binary format.
  *
- * Returns 0 on success, -ENOMEM otherwise.
+ * Returns pointer to @str in ascii format on success, NULL otherwise.
+ *
+ * This function uses kzalloc(), so caller must kfree() if this function
+ * didn't return NULL.
  */
-int tomoyo_encode(char *buffer, int buflen, const char *str)
+char *tomoyo_encode(const char *str)
 {
-        while (1) {
-                const unsigned char c = *(unsigned char *) str++;
+        int len = 0;
+        const char *p = str;
+        char *cp;
+        char *cp0;
 
-                if (tomoyo_is_valid(c)) {
-                        if (--buflen <= 0)
-                                break;
-                        *buffer++ = (char) c;
-                        if (c != '\\')
-                                continue;
-                        if (--buflen <= 0)
-                                break;
-                        *buffer++ = (char) c;
-                        continue;
-                }
-                if (!c) {
-                        if (--buflen <= 0)
-                                break;
-                        *buffer = '\0';
-                        return 0;
+        if (!p)
+                return NULL;
+        while (*p) {
+                const unsigned char c = *p++;
+                if (c == '\\')
+                        len += 2;
+                else if (c > ' ' && c < 127)
+                        len++;
+                else
+                        len += 4;
+        }
+        len++;
+        /* Reserve space for appending "/". */
+        cp = kzalloc(len + 10, GFP_NOFS);
+        if (!cp)
+                return NULL;
+        cp0 = cp;
+        p = str;
+        while (*p) {
+                const unsigned char c = *p++;
+
+                if (c == '\\') {
+                        *cp++ = '\\';
+                        *cp++ = '\\';
+                } else if (c > ' ' && c < 127) {
+                        *cp++ = c;
+                } else {
+                        *cp++ = '\\';
+                        *cp++ = (c >> 6) + '0';
+                        *cp++ = ((c >> 3) & 7) + '0';
+                        *cp++ = (c & 7) + '0';
                 }
-                buflen -= 4;
-                if (buflen <= 0)
-                        break;
-                *buffer++ = '\\';
-                *buffer++ = (c >> 6) + '0';
-                *buffer++ = ((c >> 3) & 7) + '0';
-                *buffer++ = (c & 7) + '0';
         }
-        return -ENOMEM;
+        return cp0;
 }
 
 /**
- * tomoyo_realpath_from_path2 - Returns realpath(3) of the given dentry but ignores chroot'ed root.
+ * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
  *
- * @path:        Pointer to "struct path".
- * @newname:     Pointer to buffer to return value in.
- * @newname_len: Size of @newname.
+ * @path: Pointer to "struct path".
  *
- * Returns 0 on success, negative value otherwise.
+ * Returns the realpath of the given @path on success, NULL otherwise.
  *
  * If dentry is a directory, trailing '/' is appended.
  * Characters out of 0x20 < c < 0x7F range are converted to
  * \ooo style octal string.
  * Character \ is converted to \\ string.
+ *
+ * These functions use kzalloc(), so the caller must call kfree()
+ * if these functions didn't return NULL.
  */
-int tomoyo_realpath_from_path2(struct path *path, char *newname,
-                               int newname_len)
+char *tomoyo_realpath_from_path(struct path *path)
 {
-        int error = -ENOMEM;
+        char *buf = NULL;
+        char *name = NULL;
+        unsigned int buf_len = PAGE_SIZE / 2;
         struct dentry *dentry = path->dentry;
-        char *sp;
-
-        if (!dentry || !path->mnt || !newname || newname_len <= 2048)
-                return -EINVAL;
-        if (dentry->d_op && dentry->d_op->d_dname) {
+        bool is_dir;
+        if (!dentry)
+                return NULL;
+        is_dir = dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode);
+        while (1) {
+                struct path ns_root = { .mnt = NULL, .dentry = NULL };
+                char *pos;
+                buf_len <<= 1;
+                kfree(buf);
+                buf = kmalloc(buf_len, GFP_NOFS);
+                if (!buf)
+                        break;
+                /* Get better name for socket. */
+                if (dentry->d_sb && dentry->d_sb->s_magic == SOCKFS_MAGIC) {
+                        struct inode *inode = dentry->d_inode;
+                        struct socket *sock = inode ? SOCKET_I(inode) : NULL;
+                        struct sock *sk = sock ? sock->sk : NULL;
+                        if (sk) {
+                                snprintf(buf, buf_len - 1, "socket:[family=%u:"
+                                         "type=%u:protocol=%u]", sk->sk_family,
+                                         sk->sk_type, sk->sk_protocol);
+                        } else {
+                                snprintf(buf, buf_len - 1, "socket:[unknown]");
+                        }
+                        name = tomoyo_encode(buf);
+                        break;
+                }
                 /* For "socket:[\$]" and "pipe:[\$]". */
-                static const int offset = 1536;
-                sp = dentry->d_op->d_dname(dentry, newname + offset,
-                                           newname_len - offset);
-        } else {
-                struct path ns_root = {.mnt = NULL, .dentry = NULL};
-
+                if (dentry->d_op && dentry->d_op->d_dname) {
+                        pos = dentry->d_op->d_dname(dentry, buf, buf_len - 1);
+                        if (IS_ERR(pos))
+                                continue;
+                        name = tomoyo_encode(pos);
+                        break;
+                }
+                /* If we don't have a vfsmount, we can't calculate. */
+                if (!path->mnt)
+                        break;
                 spin_lock(&dcache_lock);
                 /* go to whatever namespace root we are under */
-                sp = __d_path(path, &ns_root, newname, newname_len);
+                pos = __d_path(path, &ns_root, buf, buf_len);
                 spin_unlock(&dcache_lock);
                 /* Prepend "/proc" prefix if using internal proc vfs mount. */
-                if (!IS_ERR(sp) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
+                if (!IS_ERR(pos) && (path->mnt->mnt_flags & MNT_INTERNAL) &&
                     (path->mnt->mnt_sb->s_magic == PROC_SUPER_MAGIC)) {
-                        sp -= 5;
-                        if (sp >= newname)
-                                memcpy(sp, "/proc", 5);
+                        pos -= 5;
+                        if (pos >= buf)
+                                memcpy(pos, "/proc", 5);
                         else
-                                sp = ERR_PTR(-ENOMEM);
-                }
-        }
-        if (IS_ERR(sp))
-                error = PTR_ERR(sp);
-        else
-                error = tomoyo_encode(newname, sp - newname, sp);
-        /* Append trailing '/' if dentry is a directory. */
-        if (!error && dentry->d_inode && S_ISDIR(dentry->d_inode->i_mode)
-            && *newname) {
-                sp = newname + strlen(newname);
-                if (*(sp - 1) != '/') {
-                        if (sp < newname + newname_len - 4) {
-                                *sp++ = '/';
-                                *sp = '\0';
-                        } else {
-                                error = -ENOMEM;
-                        }
+                                pos = ERR_PTR(-ENOMEM);
                 }
+                if (IS_ERR(pos))
+                        continue;
+                name = tomoyo_encode(pos);
+                break;
         }
-        if (error)
-                tomoyo_warn_oom(__func__);
-        return error;
-}
-
-/**
- * tomoyo_realpath_from_path - Returns realpath(3) of the given pathname but ignores chroot'ed root.
- *
- * @path: Pointer to "struct path".
- *
- * Returns the realpath of the given @path on success, NULL otherwise.
- *
- * These functions use kzalloc(), so the caller must call kfree()
- * if these functions didn't return NULL.
- */
-char *tomoyo_realpath_from_path(struct path *path)
-{
-        char *buf = kzalloc(sizeof(struct tomoyo_page_buffer), GFP_NOFS);
-
-        BUILD_BUG_ON(TOMOYO_MAX_PATHNAME_LEN > PATH_MAX);
-        BUILD_BUG_ON(sizeof(struct tomoyo_page_buffer)
-                     <= TOMOYO_MAX_PATHNAME_LEN - 1);
-        if (!buf)
-                return NULL;
-        if (tomoyo_realpath_from_path2(path, buf,
-                                       TOMOYO_MAX_PATHNAME_LEN - 1) == 0)
-                return buf;
         kfree(buf);
-        return NULL;
+        if (!name)
+                tomoyo_warn_oom(__func__);
+        else if (is_dir && *name) {
+                /* Append trailing '/' if dentry is a directory. */
+                char *pos = name + strlen(name) - 1;
+                if (*pos != '/')
+                        /*
+                         * This is OK because tomoyo_encode() reserves space
+                         * for appending "/".
+                         */
+                        *++pos = '/';
+        }
+        return name;
 }
 
 /**