| Message ID | 20180301123845.26189-1-s.hauer@pengutronix.de (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Thu, 2018-03-01 at 13:38 +0100, Sascha Hauer wrote: > EVM might update the evm xattr while the VFS performs a remount to > readonly mode. This is not properly checked for, additionally check > the s_readonly_remount superblock flag before writing. > The bug can for example be observed with UBIFS. UBIFS checks the free > space on the device before and after a remount. With EVM enabled the > free space sometimes differs between both checks. > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> > --- > security/integrity/evm/evm_main.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > index a8d502827270..4a147a998aa7 100644 > --- a/security/integrity/evm/evm_main.c > +++ b/security/integrity/evm/evm_main.c > @@ -185,6 +185,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, > iint->flags |= EVM_IMMUTABLE_DIGSIG; > evm_status = INTEGRITY_PASS_IMMUTABLE; > } else if (!IS_RDONLY(d_backing_inode(dentry)) && > + !(dentry->d_inode->i_sb->s_readonly_remount) && > !IS_IMMUTABLE(d_backing_inode(dentry))) { > evm_update_evmxattr(dentry, xattr_name, > xattr_value, Mathew's EVM Portable signature patch should have inverted the (!rc) test, but didn't. With this patch, there's now a checkpatch over 80 character line warning. Mimi
On Thu, 2018-03-01 at 13:38 +0100, Sascha Hauer wrote: > EVM might update the evm xattr while the VFS performs a remount to > readonly mode. This is not properly checked for, additionally check > the s_readonly_remount superblock flag before writing. > The bug can for example be observed with UBIFS. UBIFS checks the free > space on the device before and after a remount. With EVM enabled the > free space sometimes differs between both checks. > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> > --- > security/integrity/evm/evm_main.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > index a8d502827270..4a147a998aa7 100644 > --- a/security/integrity/evm/evm_main.c > +++ b/security/integrity/evm/evm_main.c > @@ -185,6 +185,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, > iint->flags |= EVM_IMMUTABLE_DIGSIG; > evm_status = INTEGRITY_PASS_IMMUTABLE; > } else if (!IS_RDONLY(d_backing_inode(dentry)) && > + !(dentry->d_inode->i_sb->s_readonly_remount) && The other 2 conditions are using d_back_inode(). Shouldn't this one be too? Mimi > !IS_IMMUTABLE(d_backing_inode(dentry))) { > evm_update_evmxattr(dentry, xattr_name, > xattr_value,
On Thu, 2018-03-01 at 13:38 +0100, Sascha Hauer wrote: > EVM might update the evm xattr while the VFS performs a remount to > readonly mode. This is not properly checked for, additionally check > the s_readonly_remount superblock flag before writing. > The bug can for example be observed with UBIFS. UBIFS checks the free > space on the device before and after a remount. With EVM enabled the > free space sometimes differs between both checks. > > Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> I've modified the patch to use d_backing_inode() and fixed the checkpatch over 80 character warning. It's now applied. thanks! Mimi > --- > security/integrity/evm/evm_main.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c > index a8d502827270..4a147a998aa7 100644 > --- a/security/integrity/evm/evm_main.c > +++ b/security/integrity/evm/evm_main.c > @@ -185,6 +185,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, > iint->flags |= EVM_IMMUTABLE_DIGSIG; > evm_status = INTEGRITY_PASS_IMMUTABLE; > } else if (!IS_RDONLY(d_backing_inode(dentry)) && > + !(dentry->d_inode->i_sb->s_readonly_remount) && > !IS_IMMUTABLE(d_backing_inode(dentry))) { > evm_update_evmxattr(dentry, xattr_name, > xattr_value,
diff --git a/security/integrity/evm/evm_main.c b/security/integrity/evm/evm_main.c index a8d502827270..4a147a998aa7 100644 --- a/security/integrity/evm/evm_main.c +++ b/security/integrity/evm/evm_main.c @@ -185,6 +185,7 @@ static enum integrity_status evm_verify_hmac(struct dentry *dentry, iint->flags |= EVM_IMMUTABLE_DIGSIG; evm_status = INTEGRITY_PASS_IMMUTABLE; } else if (!IS_RDONLY(d_backing_inode(dentry)) && + !(dentry->d_inode->i_sb->s_readonly_remount) && !IS_IMMUTABLE(d_backing_inode(dentry))) { evm_update_evmxattr(dentry, xattr_name, xattr_value,
EVM might update the evm xattr while the VFS performs a remount to readonly mode. This is not properly checked for, additionally check the s_readonly_remount superblock flag before writing. The bug can for example be observed with UBIFS. UBIFS checks the free space on the device before and after a remount. With EVM enabled the free space sometimes differs between both checks. Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de> --- security/integrity/evm/evm_main.c | 1 + 1 file changed, 1 insertion(+)