Re: [PATCH ghak96] audit: set cwd in audit context for file-related LSM audit records

Hello, Casey, all, ----- Original Message ----- > From: "Casey Schaufler" <casey(a)schaufler-ca.com&gt; > Subject: Re: [PATCH ghak96] audit: set cwd in audit context for file-related LSM audit records > > On 4/2/2020 7:13 AM, Vladis Dronov wrote: > > Set a current working directory in an audit context for the following > > record > > types in dump_common_audit_data(): LSM_AUDIT_DATA_PATH, > > LSM_AUDIT_DATA_FILE, > > LSM_AUDIT_DATA_IOCTL_OP, LSM_AUDIT_DATA_DENTRY, LSM_AUDIT_DATA_INODE so a > > separate CWD record is emitted later. > > > > Link: https://github.com/linux-audit/audit-kernel/issues/96 > > I don't have a problem with the patch, but it sure would be nice > if you explained why these events "could use a CWD record". (adding Richard Guy Briggs <rgb(a)redhat.com&gt; which I should have been done earlier) I would agree, adding "cwd=" field in the LSM record itself is simpler to me.

Unfortunately, all I can say for now is "The intent was a separate CWD record, that is already defined" requirement from the ghak#96 issue. Richard, could you, please, clarify since you've posted this requirement in the ghak#96's description? > > Signed-off-by: Vladis Dronov <vdronov(a)redhat.com&gt; > > --- > > out-of-commit-message-note: > > > > Hello, > > Honestly, I'm not sure about "if (!context->in_syscall)" check in > > __audit_getcwd(). It was copied from __audit_getname() and I do > > not quite understand why it is there and if __audit_getcwd() needs > > it. If you have an idea on this, could you please, tell? > > > > include/linux/audit.h | 9 ++++++++- > > kernel/auditsc.c | 17 +++++++++++++++++ > > security/lsm_audit.c | 5 +++++ > > 3 files changed, 30 insertions(+), 1 deletion(-) > > > > diff --git a/include/linux/audit.h b/include/linux/audit.h > > index f9ceae57ca8d..b4306abc5891 100644 > > --- a/include/linux/audit.h > > +++ b/include/linux/audit.h > > @@ -268,7 +268,7 @@ extern void __audit_syscall_entry(int major, unsigned > > long a0, unsigned long a1, > > extern void __audit_syscall_exit(int ret_success, long ret_value); > > extern struct filename *__audit_reusename(const __user char *uptr); > > extern void __audit_getname(struct filename *name); > > - > > +extern void __audit_getcwd(void); > > extern void __audit_inode(struct filename *name, const struct dentry > > *dentry, > > unsigned int flags); > > extern void __audit_file(const struct file *); > > @@ -327,6 +327,11 @@ static inline void audit_getname(struct filename > > *name) > > if (unlikely(!audit_dummy_context())) > > __audit_getname(name); > > } > > +static inline void audit_getcwd(void) > > +{ > > + if (unlikely(!audit_dummy_context())) > > + __audit_getcwd(); > > +} > > static inline void audit_inode(struct filename *name, > > const struct dentry *dentry, > > unsigned int aflags) { > > @@ -545,6 +550,8 @@ static inline struct filename *audit_reusename(const > > __user char *name) > > } > > static inline void audit_getname(struct filename *name) > > { } > > +static inline void audit_getcwd(void) > > +{ } > > static inline void __audit_inode(struct filename *name, > > const struct dentry *dentry, > > unsigned int flags) > > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > > index 814406a35db1..16316032ef9f 100644 > > --- a/kernel/auditsc.c > > +++ b/kernel/auditsc.c > > @@ -1890,6 +1890,23 @@ void __audit_getname(struct filename *name) > > get_fs_pwd(current->fs, &context->pwd); > > } > > > > +/** > > + * __audit_getcwd - set a current working directory > > + * > > + * Set a current working directory of an audited process for this context. > > + * Called from security/lsm_audit.c:dump_common_audit_data(). > > + */ > > +void __audit_getcwd(void) > > +{ > > + struct audit_context *context = audit_context(); > > + > > + if (!context->in_syscall) > > + return; > > + > > + if (!context->pwd.dentry) > > + get_fs_pwd(current->fs, &context->pwd); > > +} > > + > > static inline int audit_copy_fcaps(struct audit_names *name, > > const struct dentry *dentry) > > { > > diff --git a/security/lsm_audit.c b/security/lsm_audit.c > > index 2d2bf49016f4..7c555621c2bd 100644 > > --- a/security/lsm_audit.c > > +++ b/security/lsm_audit.c > > @@ -241,6 +241,7 @@ static void dump_common_audit_data(struct audit_buffer > > *ab, > > audit_log_untrustedstring(ab, inode->i_sb->s_id); > > audit_log_format(ab, " ino=%lu", inode->i_ino); > > } > > + audit_getcwd(); > > break; > > } > > case LSM_AUDIT_DATA_FILE: { > > @@ -254,6 +255,7 @@ static void dump_common_audit_data(struct audit_buffer > > *ab, > > audit_log_untrustedstring(ab, inode->i_sb->s_id); > > audit_log_format(ab, " ino=%lu", inode->i_ino); > > } > > + audit_getcwd(); > > break; > > } > > case LSM_AUDIT_DATA_IOCTL_OP: { > > @@ -269,6 +271,7 @@ static void dump_common_audit_data(struct audit_buffer > > *ab, > > } > > > > audit_log_format(ab, " ioctlcmd=0x%hx", a->u.op->cmd); > > + audit_getcwd(); > > break; > > } > > case LSM_AUDIT_DATA_DENTRY: { > > @@ -283,6 +286,7 @@ static void dump_common_audit_data(struct audit_buffer > > *ab, > > audit_log_untrustedstring(ab, inode->i_sb->s_id); > > audit_log_format(ab, " ino=%lu", inode->i_ino); > > } > > + audit_getcwd(); > > break; > > } > > case LSM_AUDIT_DATA_INODE: { > > @@ -300,6 +304,7 @@ static void dump_common_audit_data(struct audit_buffer > > *ab, > > audit_log_format(ab, " dev="); > > audit_log_untrustedstring(ab, inode->i_sb->s_id); > > audit_log_format(ab, " ino=%lu", inode->i_ino); > > + audit_getcwd(); > > break; > > } > > case LSM_AUDIT_DATA_TASK: { Best regards, Vladis Dronov | Red Hat, Inc. | The Core Kernel | Senior Software Engineer