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fd: Avoid truncating output buffers for KERN_PROC_{CWD,FILEDESC}

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These sysctls failed to return an error if the caller had provided too
short an output buffer.  Change them to return ENOMEM instead, to ensure
that callers can detect truncation in the face of a concurrently
changing fd table.

PR:		228432
Discussed with:	cem, jhb
MFC after:	1 month
Differential Revision:	https://reviews.freebsd.org/D15607
This commit is contained in:
Mark Johnston 2021-12-16 16:07:04 -05:00
parent 327060bd77
commit 36bd49ac4d
1 changed files with 30 additions and 26 deletions
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56
sys/kern/kern_descrip.c
View File

@ -4290,14 +4290,13 @@ export_kinfo_to_sb(struct export_fd_buf *efbuf)
kif = &efbuf->kif;
if (efbuf->remainder != -1) {
if (efbuf->remainder < kif->kf_structsize) {
/* Terminate export. */
efbuf->remainder = 0;
return (0);
}
if (efbuf->remainder < kif->kf_structsize)
return (ENOMEM);
efbuf->remainder -= kif->kf_structsize;
}
return (sbuf_bcat(efbuf->sb, kif, kif->kf_structsize) == 0 ? 0 : ENOMEM);
if (sbuf_bcat(efbuf->sb, kif, kif->kf_structsize) != 0)
return (sbuf_error(efbuf->sb));
return (0);
}
static int
@ -4307,7 +4306,7 @@ export_file_to_sb(struct file *fp, int fd, cap_rights_t *rightsp,
int error;
if (efbuf->remainder == 0)
return (0);
return (ENOMEM);
export_file_to_kinfo(fp, fd, rightsp, &efbuf->kif, efbuf->fdp,
efbuf->flags);
FILEDESC_SUNLOCK(efbuf->fdp);
@ -4323,7 +4322,7 @@ export_vnode_to_sb(struct vnode *vp, int fd, int fflags,
int error;
if (efbuf->remainder == 0)
return (0);
return (ENOMEM);
if (efbuf->pdp != NULL)
PWDDESC_XUNLOCK(efbuf->pdp);
export_vnode_to_kinfo(vp, fd, fflags, &efbuf->kif, efbuf->flags);
@ -4369,22 +4368,25 @@ kern_proc_filedesc_out(struct proc *p, struct sbuf *sb, ssize_t maxlen,
fdp = fdhold(p);
pdp = pdhold(p);
PROC_UNLOCK(p);
efbuf = malloc(sizeof(*efbuf), M_TEMP, M_WAITOK);
efbuf->fdp = NULL;
efbuf->pdp = NULL;
efbuf->sb = sb;
efbuf->remainder = maxlen;
efbuf->flags = flags;
if (tracevp != NULL)
export_vnode_to_sb(tracevp, KF_FD_TYPE_TRACE, FREAD | FWRITE,
efbuf);
if (textvp != NULL)
export_vnode_to_sb(textvp, KF_FD_TYPE_TEXT, FREAD, efbuf);
if (cttyvp != NULL)
export_vnode_to_sb(cttyvp, KF_FD_TYPE_CTTY, FREAD | FWRITE,
efbuf);
error = 0;
if (pdp == NULL || fdp == NULL)
if (tracevp != NULL)
error = export_vnode_to_sb(tracevp, KF_FD_TYPE_TRACE,
FREAD | FWRITE, efbuf);
if (error == 0 && textvp != NULL)
error = export_vnode_to_sb(textvp, KF_FD_TYPE_TEXT, FREAD,
efbuf);
if (error == 0 && cttyvp != NULL)
error = export_vnode_to_sb(cttyvp, KF_FD_TYPE_CTTY,
FREAD | FWRITE, efbuf);
if (error != 0 || pdp == NULL || fdp == NULL)
goto fail;
efbuf->fdp = fdp;
efbuf->pdp = pdp;
@ -4394,23 +4396,25 @@ kern_proc_filedesc_out(struct proc *p, struct sbuf *sb, ssize_t maxlen,
/* working directory */
if (pwd->pwd_cdir != NULL) {
vrefact(pwd->pwd_cdir);
export_vnode_to_sb(pwd->pwd_cdir, KF_FD_TYPE_CWD,
FREAD, efbuf);
error = export_vnode_to_sb(pwd->pwd_cdir,
KF_FD_TYPE_CWD, FREAD, efbuf);
}
/* root directory */
if (pwd->pwd_rdir != NULL) {
if (error == 0 && pwd->pwd_rdir != NULL) {
vrefact(pwd->pwd_rdir);
export_vnode_to_sb(pwd->pwd_rdir, KF_FD_TYPE_ROOT,
FREAD, efbuf);
error = export_vnode_to_sb(pwd->pwd_rdir,
KF_FD_TYPE_ROOT, FREAD, efbuf);
}
/* jail directory */
if (pwd->pwd_jdir != NULL) {
if (error == 0 && pwd->pwd_jdir != NULL) {
vrefact(pwd->pwd_jdir);
export_vnode_to_sb(pwd->pwd_jdir, KF_FD_TYPE_JAIL,
FREAD, efbuf);
error = export_vnode_to_sb(pwd->pwd_jdir,
KF_FD_TYPE_JAIL, FREAD, efbuf);
}
}
PWDDESC_XUNLOCK(pdp);
if (error != 0)
goto fail;
if (pwd != NULL)
pwd_drop(pwd);
FILEDESC_SLOCK(fdp);
@ -4430,7 +4434,7 @@ kern_proc_filedesc_out(struct proc *p, struct sbuf *sb, ssize_t maxlen,
* loop continues.
*/
error = export_file_to_sb(fp, i, &rights, efbuf);
if (error != 0 || efbuf->remainder == 0)
if (error != 0)
break;
}
FILEDESC_SUNLOCK(fdp);