Date: Sun, 28 Jun 2026 00:30:03 +0000 From: Konstantin Belousov <kib@FreeBSD.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org Subject: git: e7578e37d832 - stable/14 - proc: Allow to make proc_rwmem() operate on a consistent address space Message-ID: <6a406b0b.3f115.251a1b5c@gitrepo.freebsd.org>
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The branch stable/14 has been updated by kib: URL: https://cgit.FreeBSD.org/src/commit/?id=e7578e37d832ecf1eee8cd3fed10df0e0cb1aa7e commit e7578e37d832ecf1eee8cd3fed10df0e0cb1aa7e Author: Konstantin Belousov <kib@FreeBSD.org> AuthorDate: 2026-06-07 17:57:06 +0000 Commit: Konstantin Belousov <kib@FreeBSD.org> CommitDate: 2026-06-28 00:28:57 +0000 proc: Allow to make proc_rwmem() operate on a consistent address space (cherry picked from commit e1b0d051bbf7e4e730470cbd6622f71a639834c3) --- sys/fs/cuse/cuse.c | 4 +- sys/fs/procfs/procfs_mem.c | 2 +- sys/kern/kern_prot.c | 10 ++-- sys/kern/sys_process.c | 124 ++++++++++++++++++++++++++++++++++++++------- sys/sys/ptrace.h | 15 +++++- 5 files changed, 127 insertions(+), 28 deletions(-) diff --git a/sys/fs/cuse/cuse.c b/sys/fs/cuse/cuse.c index d63a7d4691cf..b9423fd3543d 100644 --- a/sys/fs/cuse/cuse.c +++ b/sys/fs/cuse/cuse.c @@ -914,7 +914,7 @@ cuse_proc2proc_copy(struct proc *proc_s, vm_offset_t data_s, }; PHOLD(proc_s); - error = proc_rwmem(proc_s, &uio); + error = proc_rwmem(proc_s, &uio, 0); PRELE(proc_s); } else if (proc_cur == proc_s) { @@ -933,7 +933,7 @@ cuse_proc2proc_copy(struct proc *proc_s, vm_offset_t data_s, }; PHOLD(proc_d); - error = proc_rwmem(proc_d, &uio); + error = proc_rwmem(proc_d, &uio, 0); PRELE(proc_d); } else { error = EINVAL; diff --git a/sys/fs/procfs/procfs_mem.c b/sys/fs/procfs/procfs_mem.c index c74954db37d6..50db7d3a0b96 100644 --- a/sys/fs/procfs/procfs_mem.c +++ b/sys/fs/procfs/procfs_mem.c @@ -65,7 +65,7 @@ procfs_doprocmem(PFS_FILL_ARGS) error = p_candebug(td, p); PROC_UNLOCK(p); if (error == 0) - error = proc_rwmem(p, uio); + error = proc_rwmem(p, uio, 0); return (error); } diff --git a/sys/kern/kern_prot.c b/sys/kern/kern_prot.c index e2accd7f7729..d6f8faf23814 100644 --- a/sys/kern/kern_prot.c +++ b/sys/kern/kern_prot.c @@ -2310,11 +2310,11 @@ p_candebug(struct thread *td, struct proc *p) } /* - * Can't trace a process that's currently exec'ing. - * - * XXX: Note, this is not a security policy decision, it's a - * basic correctness/functionality decision. Therefore, this check - * should be moved to the caller's of p_candebug(). + * Can't trace a process that's currently exec'ing. Otherwise + * the process vmspace might change, and the target might be + * loading a setugid image. The execve_block(9) and + * proc_vmspace_ref(9) allow to get the stable credentials and + * vmspace reference. */ if ((p->p_flag & P_INEXEC) != 0) return (EBUSY); diff --git a/sys/kern/sys_process.c b/sys/kern/sys_process.c index 3fb4595bb5f7..def87f8a1cd5 100644 --- a/sys/kern/sys_process.c +++ b/sys/kern/sys_process.c @@ -34,6 +34,7 @@ #include <sys/cdefs.h> #include <sys/param.h> #include <sys/systm.h> +#include <sys/imgact.h> #include <sys/ktr.h> #include <sys/limits.h> #include <sys/lock.h> @@ -345,25 +346,93 @@ proc_sstep(struct thread *td) PROC_ACTION(ptrace_single_step(td)); } +static int +proc_vmspace_check_access(struct thread *td, struct proc *p, int flags) +{ + PROC_ASSERT_HELD(p); + if ((flags & PRVM_CHECK_DEBUG) != 0) + return (p_candebug(td, p)); + if ((flags & PRVM_CHECK_VISIBILITY) != 0) + return (p_cansee(td, p)); + return (0); +} + int -proc_rwmem(struct proc *p, struct uio *uio) +proc_vmspace_ref(struct thread *td, struct proc *p, int flags, + struct vmspace **vmp) +{ + struct vmspace *vm; + int error; + + MPASS((flags & ~(PRVM_BLOCK_EXEC | PRVM_CHECK_VISIBILITY | + PRVM_CHECK_DEBUG)) == 0); + MPASS((flags & (PRVM_CHECK_VISIBILITY | PRVM_CHECK_DEBUG)) != + (PRVM_CHECK_VISIBILITY | PRVM_CHECK_DEBUG)); + + PROC_LOCK(p); + if (p != td->td_proc) { + PROC_ASSERT_HELD(p); + + /* + * Make sure that the vmspace doesn't switch out from + * under us. + */ + if ((flags & PRVM_BLOCK_EXEC) != 0) { + for (;;) { + if (!execve_block(td, p)) { + PROC_LOCK(p); + continue; + } + error = proc_vmspace_check_access(td, p, flags); + if (error != 0) { + execve_unblock(td, p); + PROC_UNLOCK(p); + return (error); + } + break; + } + } else { + error = proc_vmspace_check_access(td, p, flags); + if (error != 0) { + PROC_UNLOCK(p); + return (error); + } + } + } + vm = vmspace_acquire_ref(p); + if (vm == NULL) { + if (p != td->td_proc && (flags & PRVM_BLOCK_EXEC) != 0) + execve_unblock(td, p); + PROC_UNLOCK(p); + return (ESRCH); + } + PROC_UNLOCK(p); + *vmp = vm; + return (0); +} + +void +proc_vmspace_unref(struct thread *td, struct proc *p, int flags, + struct vmspace *vm) +{ + vmspace_free(vm); + if (p != td->td_proc && (flags & PRVM_BLOCK_EXEC) != 0) { + PROC_LOCK(p); + PROC_ASSERT_HELD(p); + execve_unblock(td, p); + PROC_UNLOCK(p); + } +} + +static int +vmspace_rwmem(struct vmspace *vm, struct uio *uio) { vm_map_t map; vm_offset_t pageno; /* page number */ vm_prot_t reqprot; int error, fault_flags, page_offset, writing; - /* - * Make sure that the process' vmspace remains live. - */ - if (p != curproc) - PROC_ASSERT_HELD(p); - PROC_LOCK_ASSERT(p, MA_NOTOWNED); - - /* - * The map we want... - */ - map = &p->p_vmspace->vm_map; + map = &vm->vm_map; /* * If we are writing, then we request vm_fault() to create a private @@ -432,13 +501,30 @@ proc_rwmem(struct proc *p, struct uio *uio) return (error); } -static ssize_t -proc_iop(struct thread *td, struct proc *p, vm_offset_t va, void *buf, +int +proc_rwmem(struct proc *p, struct uio *uio, int flags) +{ + struct vmspace *vm; + struct thread *td; + int error; + + td = curthread; + error = proc_vmspace_ref(td, p, flags, &vm); + if (error != 0) + return (error); + error = vmspace_rwmem(vm, uio); + proc_vmspace_unref(td, p, flags, vm); + return (error); +} + +ssize_t +vmspace_iop(struct thread *td, struct vmspace *vm, vm_offset_t va, void *buf, size_t len, enum uio_rw rw) { struct iovec iov; struct uio uio; ssize_t slen; + int error; MPASS(len < SSIZE_MAX); slen = (ssize_t)len; @@ -452,8 +538,8 @@ proc_iop(struct thread *td, struct proc *p, vm_offset_t va, void *buf, uio.uio_segflg = UIO_SYSSPACE; uio.uio_rw = rw; uio.uio_td = td; - proc_rwmem(p, &uio); - if (uio.uio_resid == slen) + error = vmspace_rwmem(vm, &uio); + if (error != 0 || uio.uio_resid == slen) return (-1); return (slen - uio.uio_resid); } @@ -463,7 +549,7 @@ proc_readmem(struct thread *td, struct proc *p, vm_offset_t va, void *buf, size_t len) { - return (proc_iop(td, p, va, buf, len, UIO_READ)); + return (vmspace_iop(td, p->p_vmspace, va, buf, len, UIO_READ)); } ssize_t @@ -471,7 +557,7 @@ proc_writemem(struct thread *td, struct proc *p, vm_offset_t va, void *buf, size_t len) { - return (proc_iop(td, p, va, buf, len, UIO_WRITE)); + return (vmspace_iop(td, p->p_vmspace, va, buf, len, UIO_WRITE)); } static int @@ -1465,7 +1551,7 @@ kern_ptrace(struct thread *td, int req, pid_t pid, void *addr, int data) goto out; } PROC_UNLOCK(p); - error = proc_rwmem(p, &uio); + error = proc_rwmem(p, &uio, 0); piod->piod_len -= uio.uio_resid; PROC_LOCK(p); break; diff --git a/sys/sys/ptrace.h b/sys/sys/ptrace.h index bb492f60a8ed..3e7c74dba815 100644 --- a/sys/sys/ptrace.h +++ b/sys/sys/ptrace.h @@ -249,7 +249,20 @@ int proc_write_fpregs(struct thread *_td, struct fpreg *_fpreg); int proc_read_dbregs(struct thread *_td, struct dbreg *_dbreg); int proc_write_dbregs(struct thread *_td, struct dbreg *_dbreg); int proc_sstep(struct thread *_td); -int proc_rwmem(struct proc *_p, struct uio *_uio); + +#define PRVM_BLOCK_EXEC 0x00000001 +#define PRVM_CHECK_VISIBILITY 0x00000002 +#define PRVM_CHECK_DEBUG 0x00000004 + +#include <sys/_uio.h> +struct vmspace; +int proc_vmspace_ref(struct thread *_td, struct proc *_p, int _flags, + struct vmspace **_vmp); +void proc_vmspace_unref(struct thread *_td, struct proc *_p, int _flags, + struct vmspace *_vm); +ssize_t vmspace_iop(struct thread *td, struct vmspace *vm, vm_offset_t va, + void *buf, size_t len, enum uio_rw rw); +int proc_rwmem(struct proc *_p, struct uio *_uio, int _flags); ssize_t proc_readmem(struct thread *_td, struct proc *_p, vm_offset_t _va, void *_buf, size_t _len); ssize_t proc_writemem(struct thread *_td, struct proc *_p, vm_offset_t _va,home | help
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