linux/fs/befs/linuxvfs.c

1027 lines
26 KiB

befs: Define usercopy region in befs_inode_cache slab cache befs symlink pathnames, stored in struct befs_inode_info.i_data.symlink and therefore contained in the befs_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/befs/linuxvfs.c: befs_alloc_inode(...): ... bi = kmem_cache_alloc(befs_inode_cachep, GFP_KERNEL); ... return &bi->vfs_inode; befs_iget(...): ... strlcpy(befs_ino->i_data.symlink, raw_inode->data.symlink, BEFS_SYMLINK_LEN); ... inode->i_link = befs_ino->i_data.symlink; example usage trace: readlink_copy+0x43/0x70 vfs_readlink+0x62/0x110 SyS_readlinkat+0x100/0x130 fs/namei.c: readlink_copy(..., link): ... copy_to_user(..., link, len); (inlined in vfs_readlink) generic_readlink(dentry, ...): struct inode *inode = d_inode(dentry); const char *link = inode->i_link; ... readlink_copy(..., link); In support of usercopy hardening, this patch defines a region in the befs_inode_cache slab cache in which userspace copy operations are allowed. This region is known as the slab cache's usercopy region. Slab caches can now check that each dynamically sized copy operation involving cache-managed memory falls entirely within the slab's usercopy region. This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY whitelisting code in the last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Signed-off-by: David Windsor <dave@nullcore.net> [kees: adjust commit log, provide usage trace] Cc: Luis de Bethencourt <luisbg@kernel.org> Cc: Salah Triki <salah.triki@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Luis de Bethencourt <luisbg@kernel.org>
2017-06-10 22:50:32 -04:00
befs: Define usercopy region in befs_inode_cache slab cache befs symlink pathnames, stored in struct befs_inode_info.i_data.symlink and therefore contained in the befs_inode_cache slab cache, need to be copied to/from userspace. cache object allocation: fs/befs/linuxvfs.c: befs_alloc_inode(...): ... bi = kmem_cache_alloc(befs_inode_cachep, GFP_KERNEL); ... return &bi->vfs_inode; befs_iget(...): ... strlcpy(befs_ino->i_data.symlink, raw_inode->data.symlink, BEFS_SYMLINK_LEN); ... inode->i_link = befs_ino->i_data.symlink; example usage trace: readlink_copy+0x43/0x70 vfs_readlink+0x62/0x110 SyS_readlinkat+0x100/0x130 fs/namei.c: readlink_copy(..., link): ... copy_to_user(..., link, len); (inlined in vfs_readlink) generic_readlink(dentry, ...): struct inode *inode = d_inode(dentry); const char *link = inode->i_link; ... readlink_copy(..., link); In support of usercopy hardening, this patch defines a region in the befs_inode_cache slab cache in which userspace copy operations are allowed. This region is known as the slab cache's usercopy region. Slab caches can now check that each dynamically sized copy operation involving cache-managed memory falls entirely within the slab's usercopy region. This patch is modified from Brad Spengler/PaX Team's PAX_USERCOPY whitelisting code in the last public patch of grsecurity/PaX based on my understanding of the code. Changes or omissions from the original code are mine and don't reflect the original grsecurity/PaX code. Signed-off-by: David Windsor <dave@nullcore.net> [kees: adjust commit log, provide usage trace] Cc: Luis de Bethencourt <luisbg@kernel.org> Cc: Salah Triki <salah.triki@gmail.com> Signed-off-by: Kees Cook <keescook@chromium.org> Acked-by: Luis de Bethencourt <luisbg@kernel.org>
2017-06-10 22:50:32 -04:00
Rename superblock flags (MS_xyz -> SB_xyz) This is a pure automated search-and-replace of the internal kernel superblock flags. The s_flags are now called SB_*, with the names and the values for the moment mirroring the MS_* flags that they're equivalent to. Note how the MS_xyz flags are the ones passed to the mount system call, while the SB_xyz flags are what we then use in sb->s_flags. The script to do this was: # places to look in; re security/*: it generally should *not* be # touched (that stuff parses mount(2) arguments directly), but # there are two places where we really deal with superblock flags. FILES="drivers/mtd drivers/staging/lustre fs ipc mm \ include/linux/fs.h include/uapi/linux/bfs_fs.h \ security/apparmor/apparmorfs.c security/apparmor/include/lib.h" # the list of MS_... constants SYMS="RDONLY NOSUID NODEV NOEXEC SYNCHRONOUS REMOUNT MANDLOCK \ DIRSYNC NOATIME NODIRATIME BIND MOVE REC VERBOSE SILENT \ POSIXACL UNBINDABLE PRIVATE SLAVE SHARED RELATIME KERNMOUNT \ I_VERSION STRICTATIME LAZYTIME SUBMOUNT NOREMOTELOCK NOSEC BORN \ ACTIVE NOUSER" SED_PROG= for i in $SYMS; do SED_PROG="$SED_PROG -e s/MS_$i/SB_$i/g"; done # we want files that contain at least one of MS_..., # with fs/namespace.c and fs/pnode.c excluded. L=$(for i in $SYMS; do git grep -w -l MS_$i $FILES; done| sort|uniq|grep -v '^fs/namespace.c'|grep -v '^fs/pnode.c') for f in $L; do sed -i $f $SED_PROG; done Requested-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2017-11-27 13:05:09 -08:00
befs: annotate fs32 on tests for superblock endianness Does compile-time byteswapping rather than runtime. Noticed by sparse: fs/befs/super.c:29:6: warning: cast to restricted __le32 fs/befs/super.c:29:6: warning: cast from restricted fs32 fs/befs/super.c:31:11: warning: cast to restricted __be32 fs/befs/super.c:31:11: warning: cast from restricted fs32 fs/befs/super.c:31:11: warning: cast to restricted __be32 fs/befs/super.c:31:11: warning: cast from restricted fs32 fs/befs/super.c:31:11: warning: cast to restricted __be32 fs/befs/super.c:31:11: warning: cast from restricted fs32 fs/befs/super.c:31:11: warning: cast to restricted __be32 fs/befs/super.c:31:11: warning: cast from restricted fs32 fs/befs/super.c:31:11: warning: cast to restricted __be32 fs/befs/super.c:31:11: warning: cast from restricted fs32 fs/befs/super.c:31:11: warning: cast to restricted __be32 fs/befs/super.c:31:11: warning: cast from restricted fs32 fs/befs/linuxvfs.c:811:7: warning: cast to restricted __le32 fs/befs/linuxvfs.c:811:7: warning: cast from restricted fs32 fs/befs/linuxvfs.c:812:7: warning: cast to restricted __be32 fs/befs/linuxvfs.c:812:7: warning: cast from restricted fs32 fs/befs/linuxvfs.c:812:7: warning: cast to restricted __be32 fs/befs/linuxvfs.c:812:7: warning: cast from restricted fs32 fs/befs/linuxvfs.c:812:7: warning: cast to restricted __be32 fs/befs/linuxvfs.c:812:7: warning: cast from restricted fs32 fs/befs/linuxvfs.c:812:7: warning: cast to restricted __be32 fs/befs/linuxvfs.c:812:7: warning: cast from restricted fs32 fs/befs/linuxvfs.c:812:7: warning: cast to restricted __be32 fs/befs/linuxvfs.c:812:7: warning: cast from restricted fs32 fs/befs/linuxvfs.c:812:7: warning: cast to restricted __be32 fs/befs/linuxvfs.c:812:7: warning: cast from restricted fs32 Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com> Cc: "Sergey S. Kostyliov" <rathamahata@php4.ru> Cc: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-10-15 22:04:03 -07:00
fs: Limit sys_mount to only request filesystem modules. Modify the request_module to prefix the file system type with "fs-" and add aliases to all of the filesystems that can be built as modules to match. A common practice is to build all of the kernel code and leave code that is not commonly needed as modules, with the result that many users are exposed to any bug anywhere in the kernel. Looking for filesystems with a fs- prefix limits the pool of possible modules that can be loaded by mount to just filesystems trivially making things safer with no real cost. Using aliases means user space can control the policy of which filesystem modules are auto-loaded by editing /etc/modprobe.d/*.conf with blacklist and alias directives. Allowing simple, safe, well understood work-arounds to known problematic software. This also addresses a rare but unfortunate problem where the filesystem name is not the same as it's module name and module auto-loading would not work. While writing this patch I saw a handful of such cases. The most significant being autofs that lives in the module autofs4. This is relevant to user namespaces because we can reach the request module in get_fs_type() without having any special permissions, and people get uncomfortable when a user specified string (in this case the filesystem type) goes all of the way to request_module. After having looked at this issue I don't think there is any particular reason to perform any filtering or permission checks beyond making it clear in the module request that we want a filesystem module. The common pattern in the kernel is to call request_module() without regards to the users permissions. In general all a filesystem module does once loaded is call register_filesystem() and go to sleep. Which means there is not much attack surface exposed by loading a filesytem module unless the filesystem is mounted. In a user namespace filesystems are not mounted unless .fs_flags = FS_USERNS_MOUNT, which most filesystems do not set today. Acked-by: Serge Hallyn <serge.hallyn@canonical.com> Acked-by: Kees Cook <keescook@chromium.org> Reported-by: Kees Cook <keescook@google.com> Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
2013-03-02 19:39:14 -08:00