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-rw-r--r--Documentation/filesystems/Locking4
-rw-r--r--Documentation/sysctl/fs.txt42
2 files changed, 44 insertions, 2 deletions
diff --git a/Documentation/filesystems/Locking b/Documentation/filesystems/Locking
index 7f647e17830c..0f103e39b4f6 100644
--- a/Documentation/filesystems/Locking
+++ b/Documentation/filesystems/Locking
@@ -138,8 +138,8 @@ evict_inode:
put_super: write
write_super: read
sync_fs: read
-freeze_fs: read
-unfreeze_fs: read
+freeze_fs: write
+unfreeze_fs: write
statfs: maybe(read) (see below)
remount_fs: write
umount_begin: no
diff --git a/Documentation/sysctl/fs.txt b/Documentation/sysctl/fs.txt
index 8c235b6e4246..88152f214f48 100644
--- a/Documentation/sysctl/fs.txt
+++ b/Documentation/sysctl/fs.txt
@@ -32,6 +32,8 @@ Currently, these files are in /proc/sys/fs:
- nr_open
- overflowuid
- overflowgid
+- protected_hardlinks
+- protected_symlinks
- suid_dumpable
- super-max
- super-nr
@@ -157,6 +159,46 @@ The default is 65534.
==============================================================
+protected_hardlinks:
+
+A long-standing class of security issues is the hardlink-based
+time-of-check-time-of-use race, most commonly seen in world-writable
+directories like /tmp. The common method of exploitation of this flaw
+is to cross privilege boundaries when following a given hardlink (i.e. a
+root process follows a hardlink created by another user). Additionally,
+on systems without separated partitions, this stops unauthorized users
+from "pinning" vulnerable setuid/setgid files against being upgraded by
+the administrator, or linking to special files.
+
+When set to "0", hardlink creation behavior is unrestricted.
+
+When set to "1" hardlinks cannot be created by users if they do not
+already own the source file, or do not have read/write access to it.
+
+This protection is based on the restrictions in Openwall and grsecurity.
+
+==============================================================
+
+protected_symlinks:
+
+A long-standing class of security issues is the symlink-based
+time-of-check-time-of-use race, most commonly seen in world-writable
+directories like /tmp. The common method of exploitation of this flaw
+is to cross privilege boundaries when following a given symlink (i.e. a
+root process follows a symlink belonging to another user). For a likely
+incomplete list of hundreds of examples across the years, please see:
+http://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=/tmp
+
+When set to "0", symlink following behavior is unrestricted.
+
+When set to "1" symlinks are permitted to be followed only when outside
+a sticky world-writable directory, or when the uid of the symlink and
+follower match, or when the directory owner matches the symlink's owner.
+
+This protection is based on the restrictions in Openwall and grsecurity.
+
+==============================================================
+
suid_dumpable:
This value can be used to query and set the core dump mode for setuid