The patch titled
Subject: fs: create and use seq_show_option for escaping
has been added to the -mm tree. Its filename is
fs-create-and-use-seq_show_option-for-escaping.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/fs-create-and-use-seq_show_option-for-escaping.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/fs-create-and-use-seq_show_option-for-escaping.patch
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*** Remember to use Documentation/SubmitChecklist when testing your code ***
The -mm tree is included into linux-next and is updated
there every 3-4 working days
------------------------------------------------------
From: Kees Cook <[email protected]>
Subject: fs: create and use seq_show_option for escaping
Many file systems that implement the show_options hook fail to correctly
escape their output which could lead to unescaped characters (e.g. new
lines) leaking into /proc/mounts and /proc/[pid]/mountinfo files. This
could lead to confusion, spoofed entries (resulting in things like systemd
issuing false d-bus "mount" notifications), and who knows what else. This
looks like it would only be the root user stepping on themselves, but it's
possible weird things could happen in containers or in other situations
with delegated mount privileges.
Here's an example using overlay with setuid fusermount trusting the
contents of /proc/mounts (via the /etc/mtab symlink). Imagine the use of
"sudo" is something more sneaky:
$ BASE="ovl"
$ MNT="$BASE/mnt"
$ LOW="$BASE/lower"
$ UP="$BASE/upper"
$ WORK="$BASE/work/ 0 0
none /proc fuse.pwn user_id=1000"
$ mkdir -p "$LOW" "$UP" "$WORK"
$ sudo mount -t overlay -o "lowerdir=$LOW,upperdir=$UP,workdir=$WORK" none /mnt
$ cat /proc/mounts
none /root/ovl/mnt overlay
rw,relatime,lowerdir=ovl/lower,upperdir=ovl/upper,workdir=ovl/work/ 0 0
none /proc fuse.pwn user_id=1000 0 0
$ fusermount -u /proc
$ cat /proc/mounts
cat: /proc/mounts: No such file or directory
This fixes the problem by adding new seq_show_option and seq_show_option_n
helpers, and updating the vulnerable show_option handlers to use them as
needed. Some, like SELinux, need to be open coded due to unusual existing
escape mechanisms.
Signed-off-by: Kees Cook <[email protected]>
Acked-by: Serge Hallyn <[email protected]>
Acked-by: Jan Kara <[email protected]>
Acked-by: Paul Moore <[email protected]>
Cc: J. R. Okajima <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
---
fs/ceph/super.c | 2 +-
fs/cifs/cifsfs.c | 6 +++---
fs/ext3/super.c | 4 ++--
fs/ext4/super.c | 4 ++--
fs/gfs2/super.c | 6 +++---
fs/hfs/super.c | 4 ++--
fs/hfsplus/options.c | 4 ++--
fs/hostfs/hostfs_kern.c | 2 +-
fs/ocfs2/super.c | 4 ++--
fs/overlayfs/super.c | 6 +++---
fs/reiserfs/super.c | 8 +++++---
fs/xfs/xfs_super.c | 4 ++--
include/linux/seq_file.h | 34 ++++++++++++++++++++++++++++++++++
kernel/cgroup.c | 7 ++++---
net/ceph/ceph_common.c | 7 +++++--
security/selinux/hooks.c | 2 +-
16 files changed, 72 insertions(+), 32 deletions(-)
diff -puN fs/ceph/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/ceph/super.c
--- a/fs/ceph/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/ceph/super.c
@@ -479,7 +479,7 @@ static int ceph_show_options(struct seq_
if (fsopt->max_readdir_bytes != CEPH_MAX_READDIR_BYTES_DEFAULT)
seq_printf(m, ",readdir_max_bytes=%d",
fsopt->max_readdir_bytes);
if (strcmp(fsopt->snapdir_name, CEPH_SNAPDIRNAME_DEFAULT))
- seq_printf(m, ",snapdirname=%s", fsopt->snapdir_name);
+ seq_show_option(m, "snapdirname", fsopt->snapdir_name);
return 0;
}
diff -puN fs/cifs/cifsfs.c~fs-create-and-use-seq_show_option-for-escaping
fs/cifs/cifsfs.c
--- a/fs/cifs/cifsfs.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/cifs/cifsfs.c
@@ -394,17 +394,17 @@ cifs_show_options(struct seq_file *s, st
struct sockaddr *srcaddr;
srcaddr = (struct sockaddr *)&tcon->ses->server->srcaddr;
- seq_printf(s, ",vers=%s", tcon->ses->server->vals->version_string);
+ seq_show_option(s, "vers", tcon->ses->server->vals->version_string);
cifs_show_security(s, tcon->ses);
cifs_show_cache_flavor(s, cifs_sb);
if (cifs_sb->mnt_cifs_flags & CIFS_MOUNT_MULTIUSER)
seq_puts(s, ",multiuser");
else if (tcon->ses->user_name)
- seq_printf(s, ",username=%s", tcon->ses->user_name);
+ seq_show_option(s, "username", tcon->ses->user_name);
if (tcon->ses->domainName)
- seq_printf(s, ",domain=%s", tcon->ses->domainName);
+ seq_show_option(s, "domain", tcon->ses->domainName);
if (srcaddr->sa_family != AF_UNSPEC) {
struct sockaddr_in *saddr4;
diff -puN fs/ext3/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/ext3/super.c
--- a/fs/ext3/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/ext3/super.c
@@ -578,10 +578,10 @@ static inline void ext3_show_quota_optio
}
if (sbi->s_qf_names[USRQUOTA])
- seq_printf(seq, ",usrjquota=%s", sbi->s_qf_names[USRQUOTA]);
+ seq_show_option(seq, "usrjquota", sbi->s_qf_names[USRQUOTA]);
if (sbi->s_qf_names[GRPQUOTA])
- seq_printf(seq, ",grpjquota=%s", sbi->s_qf_names[GRPQUOTA]);
+ seq_show_option(seq, "grpjquota", sbi->s_qf_names[GRPQUOTA]);
if (test_opt(sb, USRQUOTA))
seq_puts(seq, ",usrquota");
diff -puN fs/ext4/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/ext4/super.c
--- a/fs/ext4/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/ext4/super.c
@@ -1763,10 +1763,10 @@ static inline void ext4_show_quota_optio
}
if (sbi->s_qf_names[USRQUOTA])
- seq_printf(seq, ",usrjquota=%s", sbi->s_qf_names[USRQUOTA]);
+ seq_show_option(seq, "usrjquota", sbi->s_qf_names[USRQUOTA]);
if (sbi->s_qf_names[GRPQUOTA])
- seq_printf(seq, ",grpjquota=%s", sbi->s_qf_names[GRPQUOTA]);
+ seq_show_option(seq, "grpjquota", sbi->s_qf_names[GRPQUOTA]);
#endif
}
diff -puN fs/gfs2/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/gfs2/super.c
--- a/fs/gfs2/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/gfs2/super.c
@@ -1334,11 +1334,11 @@ static int gfs2_show_options(struct seq_
if (is_ancestor(root, sdp->sd_master_dir))
seq_puts(s, ",meta");
if (args->ar_lockproto[0])
- seq_printf(s, ",lockproto=%s", args->ar_lockproto);
+ seq_show_option(s, "lockproto", args->ar_lockproto);
if (args->ar_locktable[0])
- seq_printf(s, ",locktable=%s", args->ar_locktable);
+ seq_show_option(s, "locktable", args->ar_locktable);
if (args->ar_hostdata[0])
- seq_printf(s, ",hostdata=%s", args->ar_hostdata);
+ seq_show_option(s, "hostdata", args->ar_hostdata);
if (args->ar_spectator)
seq_puts(s, ",spectator");
if (args->ar_localflocks)
diff -puN fs/hfs/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/hfs/super.c
--- a/fs/hfs/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/hfs/super.c
@@ -136,9 +136,9 @@ static int hfs_show_options(struct seq_f
struct hfs_sb_info *sbi = HFS_SB(root->d_sb);
if (sbi->s_creator != cpu_to_be32(0x3f3f3f3f))
- seq_printf(seq, ",creator=%.4s", (char *)&sbi->s_creator);
+ seq_show_option_n(seq, "creator", (char *)&sbi->s_creator, 4);
if (sbi->s_type != cpu_to_be32(0x3f3f3f3f))
- seq_printf(seq, ",type=%.4s", (char *)&sbi->s_type);
+ seq_show_option_n(seq, "type", (char *)&sbi->s_type, 4);
seq_printf(seq, ",uid=%u,gid=%u",
from_kuid_munged(&init_user_ns, sbi->s_uid),
from_kgid_munged(&init_user_ns, sbi->s_gid));
diff -puN fs/hfsplus/options.c~fs-create-and-use-seq_show_option-for-escaping
fs/hfsplus/options.c
--- a/fs/hfsplus/options.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/hfsplus/options.c
@@ -218,9 +218,9 @@ int hfsplus_show_options(struct seq_file
struct hfsplus_sb_info *sbi = HFSPLUS_SB(root->d_sb);
if (sbi->creator != HFSPLUS_DEF_CR_TYPE)
- seq_printf(seq, ",creator=%.4s", (char *)&sbi->creator);
+ seq_show_option_n(seq, "creator", (char *)&sbi->creator, 4);
if (sbi->type != HFSPLUS_DEF_CR_TYPE)
- seq_printf(seq, ",type=%.4s", (char *)&sbi->type);
+ seq_show_option_n(seq, "type", (char *)&sbi->type, 4);
seq_printf(seq, ",umask=%o,uid=%u,gid=%u", sbi->umask,
from_kuid_munged(&init_user_ns, sbi->uid),
from_kgid_munged(&init_user_ns, sbi->gid));
diff -puN
fs/hostfs/hostfs_kern.c~fs-create-and-use-seq_show_option-for-escaping
fs/hostfs/hostfs_kern.c
--- a/fs/hostfs/hostfs_kern.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/hostfs/hostfs_kern.c
@@ -260,7 +260,7 @@ static int hostfs_show_options(struct se
size_t offset = strlen(root_ino) + 1;
if (strlen(root_path) > offset)
- seq_printf(seq, ",%s", root_path + offset);
+ seq_show_option(seq, root_path + offset, NULL);
if (append)
seq_puts(seq, ",append");
diff -puN fs/ocfs2/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/ocfs2/super.c
--- a/fs/ocfs2/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/ocfs2/super.c
@@ -1567,8 +1567,8 @@ static int ocfs2_show_options(struct seq
seq_printf(s, ",localflocks,");
if (osb->osb_cluster_stack[0])
- seq_printf(s, ",cluster_stack=%.*s", OCFS2_STACK_LABEL_LEN,
- osb->osb_cluster_stack);
+ seq_show_option_n(s, "cluster_stack", osb->osb_cluster_stack,
+ OCFS2_STACK_LABEL_LEN);
if (opts & OCFS2_MOUNT_USRQUOTA)
seq_printf(s, ",usrquota");
if (opts & OCFS2_MOUNT_GRPQUOTA)
diff -puN fs/overlayfs/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/overlayfs/super.c
--- a/fs/overlayfs/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/overlayfs/super.c
@@ -588,10 +588,10 @@ static int ovl_show_options(struct seq_f
struct super_block *sb = dentry->d_sb;
struct ovl_fs *ufs = sb->s_fs_info;
- seq_printf(m, ",lowerdir=%s", ufs->config.lowerdir);
+ seq_show_option(m, "lowerdir", ufs->config.lowerdir);
if (ufs->config.upperdir) {
- seq_printf(m, ",upperdir=%s", ufs->config.upperdir);
- seq_printf(m, ",workdir=%s", ufs->config.workdir);
+ seq_show_option(m, "upperdir", ufs->config.upperdir);
+ seq_show_option(m, "workdir", ufs->config.workdir);
}
return 0;
}
diff -puN fs/reiserfs/super.c~fs-create-and-use-seq_show_option-for-escaping
fs/reiserfs/super.c
--- a/fs/reiserfs/super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/reiserfs/super.c
@@ -714,18 +714,20 @@ static int reiserfs_show_options(struct
seq_puts(seq, ",acl");
if (REISERFS_SB(s)->s_jdev)
- seq_printf(seq, ",jdev=%s", REISERFS_SB(s)->s_jdev);
+ seq_show_option(seq, "jdev", REISERFS_SB(s)->s_jdev);
if (journal->j_max_commit_age != journal->j_default_max_commit_age)
seq_printf(seq, ",commit=%d", journal->j_max_commit_age);
#ifdef CONFIG_QUOTA
if (REISERFS_SB(s)->s_qf_names[USRQUOTA])
- seq_printf(seq, ",usrjquota=%s",
REISERFS_SB(s)->s_qf_names[USRQUOTA]);
+ seq_show_option(seq, "usrjquota",
+ REISERFS_SB(s)->s_qf_names[USRQUOTA]);
else if (opts & (1 << REISERFS_USRQUOTA))
seq_puts(seq, ",usrquota");
if (REISERFS_SB(s)->s_qf_names[GRPQUOTA])
- seq_printf(seq, ",grpjquota=%s",
REISERFS_SB(s)->s_qf_names[GRPQUOTA]);
+ seq_show_option(seq, "grpjquota",
+ REISERFS_SB(s)->s_qf_names[GRPQUOTA]);
else if (opts & (1 << REISERFS_GRPQUOTA))
seq_puts(seq, ",grpquota");
if (REISERFS_SB(s)->s_jquota_fmt) {
diff -puN fs/xfs/xfs_super.c~fs-create-and-use-seq_show_option-for-escaping
fs/xfs/xfs_super.c
--- a/fs/xfs/xfs_super.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/fs/xfs/xfs_super.c
@@ -511,9 +511,9 @@ xfs_showargs(
seq_printf(m, "," MNTOPT_LOGBSIZE "=%dk", mp->m_logbsize >> 10);
if (mp->m_logname)
- seq_printf(m, "," MNTOPT_LOGDEV "=%s", mp->m_logname);
+ seq_show_option(m, MNTOPT_LOGDEV, mp->m_logname);
if (mp->m_rtname)
- seq_printf(m, "," MNTOPT_RTDEV "=%s", mp->m_rtname);
+ seq_show_option(m, MNTOPT_RTDEV, mp->m_rtname);
if (mp->m_dalign > 0)
seq_printf(m, "," MNTOPT_SUNIT "=%d",
diff -puN
include/linux/seq_file.h~fs-create-and-use-seq_show_option-for-escaping
include/linux/seq_file.h
--- a/include/linux/seq_file.h~fs-create-and-use-seq_show_option-for-escaping
+++ a/include/linux/seq_file.h
@@ -149,6 +149,40 @@ static inline struct user_namespace *seq
#endif
}
+/**
+ * seq_show_options - display mount options with appropriate escapes.
+ * @m: the seq_file handle
+ * @name: the mount option name
+ * @value: the mount option name's value, can be NULL
+ */
+static inline void seq_show_option(struct seq_file *m, char *name, char *value)
+{
+ seq_putc(m, ',');
+ seq_escape(m, name, ",= \t\n\\");
+ if (value) {
+ seq_putc(m, '=');
+ seq_escape(m, value, ", \t\n\\");
+ }
+}
+
+/**
+ * seq_show_option_n - display mount options with appropriate escapes
+ * where @value must be a specific length.
+ * @m: the seq_file handle
+ * @name: the mount option name
+ * @value: the mount option name's value, cannot be NULL
+ * @length: the length of @value to display
+ *
+ * This is a macro since this uses "length" to define the size of the
+ * stack buffer.
+ */
+#define seq_show_option_n(m, name, value, length) { \
+ char val_buf[length + 1]; \
+ strncpy(val_buf, value, length); \
+ val_buf[length] = '\0'; \
+ seq_show_option(m, name, val_buf); \
+}
+
#define SEQ_START_TOKEN ((void *)1)
/*
* Helpers for iteration over list_head-s in seq_files
diff -puN kernel/cgroup.c~fs-create-and-use-seq_show_option-for-escaping
kernel/cgroup.c
--- a/kernel/cgroup.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/kernel/cgroup.c
@@ -1334,7 +1334,7 @@ static int cgroup_show_options(struct se
for_each_subsys(ss, ssid)
if (root->subsys_mask & (1 << ssid))
- seq_printf(seq, ",%s", ss->name);
+ seq_show_option(seq, ss->name, NULL);
if (root->flags & CGRP_ROOT_NOPREFIX)
seq_puts(seq, ",noprefix");
if (root->flags & CGRP_ROOT_XATTR)
@@ -1342,13 +1342,14 @@ static int cgroup_show_options(struct se
spin_lock(&release_agent_path_lock);
if (strlen(root->release_agent_path))
- seq_printf(seq, ",release_agent=%s", root->release_agent_path);
+ seq_show_option(seq, "release_agent",
+ root->release_agent_path);
spin_unlock(&release_agent_path_lock);
if (test_bit(CGRP_CPUSET_CLONE_CHILDREN, &root->cgrp.flags))
seq_puts(seq, ",clone_children");
if (strlen(root->name))
- seq_printf(seq, ",name=%s", root->name);
+ seq_show_option(seq, "name", root->name);
return 0;
}
diff -puN net/ceph/ceph_common.c~fs-create-and-use-seq_show_option-for-escaping
net/ceph/ceph_common.c
--- a/net/ceph/ceph_common.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/net/ceph/ceph_common.c
@@ -517,8 +517,11 @@ int ceph_print_client_options(struct seq
struct ceph_options *opt = client->options;
size_t pos = m->count;
- if (opt->name)
- seq_printf(m, "name=%s,", opt->name);
+ if (opt->name) {
+ seq_puts(m, "name=");
+ seq_escape(m, opt->name, ", \t\n\\");
+ seq_putc(',');
+ }
if (opt->key)
seq_puts(m, "secret=<hidden>,");
diff -puN
security/selinux/hooks.c~fs-create-and-use-seq_show_option-for-escaping
security/selinux/hooks.c
--- a/security/selinux/hooks.c~fs-create-and-use-seq_show_option-for-escaping
+++ a/security/selinux/hooks.c
@@ -1100,7 +1100,7 @@ static void selinux_write_opts(struct se
seq_puts(m, prefix);
if (has_comma)
seq_putc(m, '\"');
- seq_puts(m, opts->mnt_opts[i]);
+ seq_escape(m, opts->mnt_opts[i], "\"\n\\");
if (has_comma)
seq_putc(m, '\"');
}
_
Patches currently in -mm which might be from [email protected] are
origin.patch
user_ns-use-correct-check-for-single-threadedness.patch
capabilities-ambient-capabilities.patch
capabilities-add-a-securebit-to-disable-pr_cap_ambient_raise.patch
clk_register_clkdev-handle-callers-needing-format-string.patch
scripts-spellingtxt-adding-misspelled-word-for-check.patch
scripts-spellingtxt-adding-misspelled-word-for-check-fix.patch
fs-create-and-use-seq_show_option-for-escaping.patch
fs-create-and-use-seq_show_option-for-escaping-fix.patch
procfs-always-expose-proc-pid-map_files-and-make-it-readable.patch
procfs-always-expose-proc-pid-map_files-and-make-it-readable-fix.patch
procfs-always-expose-proc-pid-map_files-and-make-it-readable-fix-fix.patch
lib-vsprintf-add-%pt-format-specifier.patch
lib-string_helpers-clarify-esc-arg-in-string_escape_mem.patch
lib-string_helpers-rename-esc-arg-to-only.patch
fs-if-a-coredump-already-exists-unlink-and-recreate-with-o_excl.patch
fs-dont-dump-core-if-the-corefile-would-become-world-readable.patch
sysctl-fix-int-unsigned-long-assignments-in-int_min-case.patch
linux-next.patch
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