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author | Scott Mayhew <smayhew@redhat.com> | 2017-06-05 11:45:04 -0400 |
---|---|---|
committer | Paul Moore <paul@paul-moore.com> | 2017-06-09 16:17:47 -0400 |
commit | 0b4d3452b8b4a5309b4445b900e3cec022cca95a (patch) | |
tree | 3c758827bc8bab1cd36f9c551840cdae00636e97 /security | |
parent | b4958c892e02241b9bd121f3397b76225ff6f4a3 (diff) | |
download | linux-stable-0b4d3452b8b4a5309b4445b900e3cec022cca95a.tar.gz linux-stable-0b4d3452b8b4a5309b4445b900e3cec022cca95a.tar.bz2 linux-stable-0b4d3452b8b4a5309b4445b900e3cec022cca95a.zip |
security/selinux: allow security_sb_clone_mnt_opts to enable/disable native labeling behavior
When an NFSv4 client performs a mount operation, it first mounts the
NFSv4 root and then does path walk to the exported path and performs a
submount on that, cloning the security mount options from the root's
superblock to the submount's superblock in the process.
Unless the NFS server has an explicit fsid=0 export with the
"security_label" option, the NFSv4 root superblock will not have
SBLABEL_MNT set, and neither will the submount superblock after cloning
the security mount options. As a result, setxattr's of security labels
over NFSv4.2 will fail. In a similar fashion, NFSv4.2 mounts mounted
with the context= mount option will not show the correct labels because
the nfs_server->caps flags of the cloned superblock will still have
NFS_CAP_SECURITY_LABEL set.
Allowing the NFSv4 client to enable or disable SECURITY_LSM_NATIVE_LABELS
behavior will ensure that the SBLABEL_MNT flag has the correct value
when the client traverses from an exported path without the
"security_label" option to one with the "security_label" option and
vice versa. Similarly, checking to see if SECURITY_LSM_NATIVE_LABELS is
set upon return from security_sb_clone_mnt_opts() and clearing
NFS_CAP_SECURITY_LABEL if necessary will allow the correct labels to
be displayed for NFSv4.2 mounts mounted with the context= mount option.
Resolves: https://github.com/SELinuxProject/selinux-kernel/issues/35
Signed-off-by: Scott Mayhew <smayhew@redhat.com>
Reviewed-by: Stephen Smalley <sds@tycho.nsa.gov>
Tested-by: Stephen Smalley <sds@tycho.nsa.gov>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Diffstat (limited to 'security')
-rw-r--r-- | security/security.c | 7 | ||||
-rw-r--r-- | security/selinux/hooks.c | 35 |
2 files changed, 38 insertions, 4 deletions
diff --git a/security/security.c b/security/security.c index 714433e3e9a2..30132378d103 100644 --- a/security/security.c +++ b/security/security.c @@ -420,9 +420,12 @@ int security_sb_set_mnt_opts(struct super_block *sb, EXPORT_SYMBOL(security_sb_set_mnt_opts); int security_sb_clone_mnt_opts(const struct super_block *oldsb, - struct super_block *newsb) + struct super_block *newsb, + unsigned long kern_flags, + unsigned long *set_kern_flags) { - return call_int_hook(sb_clone_mnt_opts, 0, oldsb, newsb); + return call_int_hook(sb_clone_mnt_opts, 0, oldsb, newsb, + kern_flags, set_kern_flags); } EXPORT_SYMBOL(security_sb_clone_mnt_opts); diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c index 9926adbd50a9..9cc042df10d1 100644 --- a/security/selinux/hooks.c +++ b/security/selinux/hooks.c @@ -525,8 +525,16 @@ static int sb_finish_set_opts(struct super_block *sb) } sbsec->flags |= SE_SBINITIALIZED; + + /* + * Explicitly set or clear SBLABEL_MNT. It's not sufficient to simply + * leave the flag untouched because sb_clone_mnt_opts might be handing + * us a superblock that needs the flag to be cleared. + */ if (selinux_is_sblabel_mnt(sb)) sbsec->flags |= SBLABEL_MNT; + else + sbsec->flags &= ~SBLABEL_MNT; /* Initialize the root inode. */ rc = inode_doinit_with_dentry(root_inode, root); @@ -959,8 +967,11 @@ mismatch: } static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb, - struct super_block *newsb) + struct super_block *newsb, + unsigned long kern_flags, + unsigned long *set_kern_flags) { + int rc = 0; const struct superblock_security_struct *oldsbsec = oldsb->s_security; struct superblock_security_struct *newsbsec = newsb->s_security; @@ -975,6 +986,13 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb, if (!ss_initialized) return 0; + /* + * Specifying internal flags without providing a place to + * place the results is not allowed. + */ + if (kern_flags && !set_kern_flags) + return -EINVAL; + /* how can we clone if the old one wasn't set up?? */ BUG_ON(!(oldsbsec->flags & SE_SBINITIALIZED)); @@ -990,6 +1008,18 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb, newsbsec->def_sid = oldsbsec->def_sid; newsbsec->behavior = oldsbsec->behavior; + if (newsbsec->behavior == SECURITY_FS_USE_NATIVE && + !(kern_flags & SECURITY_LSM_NATIVE_LABELS) && !set_context) { + rc = security_fs_use(newsb); + if (rc) + goto out; + } + + if (kern_flags & SECURITY_LSM_NATIVE_LABELS && !set_context) { + newsbsec->behavior = SECURITY_FS_USE_NATIVE; + *set_kern_flags |= SECURITY_LSM_NATIVE_LABELS; + } + if (set_context) { u32 sid = oldsbsec->mntpoint_sid; @@ -1009,8 +1039,9 @@ static int selinux_sb_clone_mnt_opts(const struct super_block *oldsb, } sb_finish_set_opts(newsb); +out: mutex_unlock(&newsbsec->lock); - return 0; + return rc; } static int selinux_parse_opts_str(char *options, |