On 2026-07-13 14:00, Ricardo Robaina wrote: > Modern mount tools (util-linux >= 2.39.1) use the new mount API > (fsopen, fsconfig, fsmount, move_mount) instead of the legacy mount(2) > syscall. The generic SYSCALL audit record logs the fsconfig syscall but > does not capture the configuration parameters, creating an audit gap for > critical mount information such as the device being mounted. > > Add an FSCONFIG auxiliary record that logs the command type, parameter > name (key), parameter value, and aux parameter passed to fsconfig(2). > > ---- > type=SYSCALL : syscall=fsconfig a1=FSCONFIG_SET_STRING ...
This looks like it is missing "a0=..."? > type=FSCONFIG : fs_cmd=1 fs_key=source fs_val="tmpfs" fs_aux=0 > ---- > type=SYSCALL : syscall=fsconfig a1=FSCONFIG_CMD_CREATE ... This looks like it is missing "a0=..."? I'm guessing this isn't actually real test output? > type=FSCONFIG : fs_cmd=6 fs_key=(null) fs_val=(null) fs_aux=0 Was there a fs_key output here that didn't make it due to the issue below? > ---- > type=SYSCALL : syscall=fsconfig a0=0x4 a1=FSCONFIG_SET_BINARY ... > type=FSCONFIG : fs_cmd=2 fs_key=hidepid fs_val="<binary>" fs_aux=4 > > Link: https://github.com/linux-audit/audit-kernel/issues/153 > Signed-off-by: Ricardo Robaina <[email protected]> > --- > fs/fsopen.c | 7 +++++++ > include/linux/audit.h | 13 +++++++++++++ > include/uapi/linux/audit.h | 1 + > kernel/auditsc.c | 27 +++++++++++++++++++++++++++ > 4 files changed, 48 insertions(+) > > diff --git a/fs/fsopen.c b/fs/fsopen.c > index ae19e5136598..9b3c02f59df4 100644 > --- a/fs/fsopen.c > +++ b/fs/fsopen.c > @@ -15,6 +15,7 @@ > #include <linux/namei.h> > #include <linux/file.h> > #include <uapi/linux/mount.h> > +#include <linux/audit.h> > #include "internal.h" > #include "mount.h" > > @@ -357,6 +358,7 @@ SYSCALL_DEFINE5(fsconfig, > struct fs_context *fc; > int ret; > int lookup_flags = 0; > + const char *value_str = NULL; > > struct fs_parameter param = { > .type = fs_value_is_undefined, > @@ -423,6 +425,7 @@ SYSCALL_DEFINE5(fsconfig, > goto out_key; > } > param.size = strlen(param.string); > + value_str = param.string; > break; > case FSCONFIG_SET_BINARY: > param.type = fs_value_is_blob; > @@ -432,6 +435,7 @@ SYSCALL_DEFINE5(fsconfig, > ret = PTR_ERR(param.blob); > goto out_key; > } > + value_str = "<binary>"; > break; > case FSCONFIG_SET_PATH_EMPTY: > lookup_flags = LOOKUP_EMPTY; > @@ -445,6 +449,7 @@ SYSCALL_DEFINE5(fsconfig, > } > param.dirfd = aux; > param.size = strlen(param.name->name); > + value_str = param.name->name; > break; > case FSCONFIG_SET_FD: > param.type = fs_value_is_file; > @@ -458,6 +463,8 @@ SYSCALL_DEFINE5(fsconfig, > break; > } > > + audit_log_fsconfig(cmd, param.key, value_str, aux); > + > ret = mutex_lock_interruptible(&fc->uapi_mutex); > if (ret == 0) { > ret = vfs_fsconfig_locked(fc, cmd, ¶m); > diff --git a/include/linux/audit.h b/include/linux/audit.h > index 45abb3722d30..978eb881974c 100644 > --- a/include/linux/audit.h > +++ b/include/linux/audit.h > @@ -449,6 +449,8 @@ extern void __audit_tk_injoffset(struct timespec64 > offset); > extern void __audit_ntp_log(const struct audit_ntp_data *ad); > extern void __audit_log_nfcfg(const char *name, u8 af, unsigned int nentries, > enum audit_nfcfgop op, gfp_t gfp); > +extern void __audit_log_fsconfig(unsigned int cmd, const char *key, > + const char *value, int aux); > > static inline void audit_ipc_obj(struct kern_ipc_perm *ipcp) > { > @@ -598,6 +600,13 @@ static inline void audit_log_nfcfg(const char *name, u8 > af, > __audit_log_nfcfg(name, af, nentries, op, gfp); > } > > +static inline void audit_log_fsconfig(unsigned int cmd, const char *key, > + const char *value, int aux) > +{ > + if (!audit_dummy_context()) > + __audit_log_fsconfig(cmd, key, value, aux); > +} > + > extern int audit_n_rules; > extern int audit_signals; > #else /* CONFIG_AUDITSYSCALL */ > @@ -730,6 +739,10 @@ static inline void audit_log_nfcfg(const char *name, u8 > af, > enum audit_nfcfgop op, gfp_t gfp) > { } > > +static inline void audit_log_fsconfig(unsigned int cmd, const char *key, > + const char *value, int aux) > +{ } > + > #define audit_n_rules 0 > #define audit_signals 0 > #endif /* CONFIG_AUDITSYSCALL */ > diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h > index e8f5ce677df7..5cd0eb602528 100644 > --- a/include/uapi/linux/audit.h > +++ b/include/uapi/linux/audit.h > @@ -122,6 +122,7 @@ > #define AUDIT_OPENAT2 1337 /* Record showing openat2 how > args */ > #define AUDIT_DM_CTRL 1338 /* Device Mapper target control > */ > #define AUDIT_DM_EVENT 1339 /* Device Mapper events */ > +#define AUDIT_FSCONFIG 1341 /* Record showing fsconfig args > */ > > #define AUDIT_AVC 1400 /* SE Linux avc denial or grant */ > #define AUDIT_SELINUX_ERR 1401 /* Internal SE Linux Errors */ > diff --git a/kernel/auditsc.c b/kernel/auditsc.c > index 6610e667c728..222bf79ee9bd 100644 > --- a/kernel/auditsc.c > +++ b/kernel/auditsc.c > @@ -2882,6 +2882,33 @@ void __audit_log_nfcfg(const char *name, u8 af, > unsigned int nentries, > } > EXPORT_SYMBOL_GPL(__audit_log_nfcfg); > > +void __audit_log_fsconfig(unsigned int cmd, const char *key, > + const char *value, int aux) > +{ > + struct audit_buffer *ab; > + > + ab = audit_log_start(audit_context(), GFP_KERNEL, AUDIT_FSCONFIG); > + if (!ab) > + return; > + > + audit_log_format(ab, "fs_cmd=%u", cmd); > + audit_log_format(ab, " fs_key="); > + if (value) This looks like it should be "if (key)". > + audit_log_untrustedstring(ab, key); > + else > + audit_log_format(ab, "(null)"); > + > + audit_log_format(ab, " fs_val="); > + if (value) > + audit_log_untrustedstring(ab, value); > + else > + audit_log_format(ab, "(null)"); > + > + audit_log_format(ab, " fs_aux=%d", aux); > + > + audit_log_end(ab); > +} > + > static void audit_log_task(struct audit_buffer *ab) > { > kuid_t auid, uid; > -- > 2.53.0 - RGB -- Richard Guy Briggs <[email protected]> Sr. S/W Engineer, Kernel Security, Base Operating Systems Remote, Ottawa, Red Hat Canada Upstream IRC: SunRaycer Voice: +1.613.860 2354 SMS: +1.613.518.6570
