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Differential D17396

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Authored by rigoletto on Oct 3 2018, 8:50 PM.
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tcberner
mat
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rS339457: Add myself to calendar, and update mentors-mentee relationships.
Summary

src changes by the FreeBSD Committers Guide.

Thanks!

Diff Detail

Repository
rS FreeBSD src repository - subversion
Lint
Lint Passed
Unit
No Test Coverage
Build Status
Buildable 20017
Build 19521: arc lint + arc unit

Event Timeline

rigoletto created this revision.Oct 3 2018, 8:50 PM
Herald added a subscriber: imp. · View Herald TranscriptOct 3 2018, 8:50 PM
Harbormaster completed remote builds in B19940: Diff 48694.Oct 3 2018, 8:50 PM
tcberner added inline comments.Oct 3 2018, 9:19 PM
share/misc/committers-ports.dot
222

^ it looks like you're missing a n in the new line after the last name

rigoletto updated this revision to Diff 48722.Oct 4 2018, 2:39 PM
rigoletto marked an inline comment as done.

Done. ^^

Harbormaster completed remote builds in B19961: Diff 48722.Oct 4 2018, 2:39 PM
mat added a comment.Oct 4 2018, 3:11 PM

I would like to see the commit message you plan to use.

rigoletto added a comment.Oct 4 2018, 3:51 PM

Add myself.

Approved by: tcberner (mentor), mat (mentor)

rigoletto updated this revision to Diff 48812.Oct 5 2018, 8:52 PM

Remove UTF-8 character.

Harbormaster completed remote builds in B20017: Diff 48812.Oct 5 2018, 8:52 PM
tcberner accepted this revision.Oct 5 2018, 8:54 PM

Looks good to me now.

This revision is now accepted and ready to land.Oct 5 2018, 8:54 PM
rigoletto added a comment.EditedOct 5 2018, 9:06 PM

@mat

I got this message while commiting with @tcberner:

Sending share/misc/committers-ports.dot
Sending usr.bin/calendar/calendars/calendar.freebsd
Transmitting file data ..done
Committing transaction...
svn: E165001: Commit failed (details follow):
svn: E165001: Commit blocked by pre-commit hook (exit code 1) with output:

  • You need "Approved by: re" line in your log entry.

svn: E165001: Your commit message was left in a temporary file:
svn: E165001: '/home/rigoletto/Dev/FreeBSD/src/svn-commit.tmp'

Thanks!

mat added a comment.Oct 6 2018, 8:09 AM

The src tree is in freeze for a few more weeks, see FreeBSD 12.0 Release Process. You'll be able to commit this when the freeze is over.

rigoletto added a comment.Oct 6 2018, 8:33 AM
In D17396#372140, @mat wrote:

The src tree is in freeze for a few more weeks, see FreeBSD 12.0 Release Process. You'll be able to commit this when the freeze is over.

Thank you @mat. I will wait. :-D

rigoletto added a comment.Oct 20 2018, 5:18 PM

Can I go now? :-)

tcberner added a comment.Oct 20 2018, 5:25 PM

Make sure that it still looks fine, then yes :)

Closed by commit rS339457: Add myself to calendar, and update mentors-mentee relationships. (authored by rigoletto). · Explain WhyOct 20 2018, 5:46 PM
This revision was automatically updated to reflect the committed changes.
rigoletto added a comment.Oct 20 2018, 5:47 PM

Thanks! :-)

Revision Contents
Changeset List

PathSize
share/
misc/
3 lines
usr.bin/
calendar/
calendars/
1 line

Diff 48812

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share/misc/committers-ports.dot

Show First 20 Lines • Show All 97 Lines • ▼ Show 20 Lines
#endif #endif
int old_mlock = 0; int old_mlock = 0;
SYSCTL_INT(_vm, OID_AUTO, old_mlock, CTLFLAG_RWTUN, &old_mlock, 0, SYSCTL_INT(_vm, OID_AUTO, old_mlock, CTLFLAG_RWTUN, &old_mlock, 0,
"Do not apply RLIMIT_MEMLOCK on mlockall"); "Do not apply RLIMIT_MEMLOCK on mlockall");
static int mincore_mapped = 1; static int mincore_mapped = 1;
SYSCTL_INT(_vm, OID_AUTO, mincore_mapped, CTLFLAG_RWTUN, &mincore_mapped, 0, SYSCTL_INT(_vm, OID_AUTO, mincore_mapped, CTLFLAG_RWTUN, &mincore_mapped, 0,
"mincore reports mappings, not residency"); "mincore reports mappings, not residency");
static int imply_prot_max = 0;
SYSCTL_INT(_vm, OID_AUTO, imply_prot_max, CTLFLAG_RWTUN, &imply_prot_max, 0,
emasteUnsubmitted
Done
Inline Actions

s/mincore_mapped/imply_prot_max/

emaste: `s/mincore_mapped/imply_prot_max/`
"Imply maximum page permissions in mmap() when none are specified.");
markjUnsubmitted
Done
Inline Actions

sysctl description strings usually don't contain a period.

markj: sysctl description strings usually don't contain a period.
#ifdef MAP_32BIT #ifdef MAP_32BIT
#define MAP_32BIT_MAX_ADDR ((vm_offset_t)1 << 31) #define MAP_32BIT_MAX_ADDR ((vm_offset_t)1 << 31)
#endif #endif
#ifndef _SYS_SYSPROTO_H_ #ifndef _SYS_SYSPROTO_H_
struct sbrk_args { struct sbrk_args {
int incr; int incr;
▲ Show 20 Lines • Show All 68 Lines • ▼ Show 20 Lines
kern_mmap(struct thread *td, uintptr_t addr0, size_t size, int prot, int flags, kern_mmap(struct thread *td, uintptr_t addr0, size_t size, int prot, int flags,
int fd, off_t pos) int fd, off_t pos)
{ {
struct vmspace *vms; struct vmspace *vms;
struct file *fp; struct file *fp;
vm_offset_t addr; vm_offset_t addr;
vm_size_t pageoff; vm_size_t pageoff;
vm_prot_t cap_maxprot; vm_prot_t cap_maxprot;
int align, error; int align, error, max_prot;
cap_rights_t rights; cap_rights_t rights;
if ((prot & ~(_PROT_ALL | PROT_MAX(_PROT_ALL))) != 0)
return (EINVAL);
emasteUnsubmitted
Done
Inline Actions

This has the effect of masking invalid flags (e.g. PROT_READ | PROT_WRITE | 0x100000 or 0xffff in tests/sys/vm/mmap_test.c).

emaste: This has the effect of masking invalid flags (e.g. `PROT_READ | PROT_WRITE | 0x100000` or…
max_prot = PROT_MAX_EXTRACT(prot);
prot = PROT_EXTRACT(prot);
markjUnsubmitted
Done
Inline Actions

Don't we also need to verify that prot is a subset of max_prot?

markj: Don't we also need to verify that prot is a subset of max_prot?
/*
* Always honor PROT_MAX if set. If not, default to all
* permissions unless we're implying maximum permissions.
*
* XXX: should be tunable per process and ABI.
*/
if (max_prot == 0)
max_prot = (imply_prot_max && prot != PROT_NONE) ?
prot : _PROT_ALL;
kibUnsubmitted
Done
Inline Actions

I would write this as
`
max_prot = imply_prot_max ? prot : _PROT_ALL
`

kib: I would write this as ` max_prot = imply_prot_max ? prot : _PROT_ALL `
vms = td->td_proc->p_vmspace; vms = td->td_proc->p_vmspace;
fp = NULL; fp = NULL;
AUDIT_ARG_FD(fd); AUDIT_ARG_FD(fd);
addr = addr0; addr = addr0;
/* /*
* Ignore old flags that used to be defined but did not do anything. * Ignore old flags that used to be defined but did not do anything.
*/ */
▲ Show 20 Lines • Show All 126 Lines • ▼ Show 20 Lines error = vm_mmap_object(&vms->vm_map, &addr, size, VM_PROT_NONE,
VM_PROT_NONE, flags, NULL, pos, FALSE, td); VM_PROT_NONE, flags, NULL, pos, FALSE, td);
} else if ((flags & MAP_ANON) != 0) { } else if ((flags & MAP_ANON) != 0) {
/* /*
* Mapping blank space is trivial. * Mapping blank space is trivial.
* *
* This relies on VM_PROT_* matching PROT_*. * This relies on VM_PROT_* matching PROT_*.
*/ */
error = vm_mmap_object(&vms->vm_map, &addr, size, prot, error = vm_mmap_object(&vms->vm_map, &addr, size, prot,
VM_PROT_ALL, flags, NULL, pos, FALSE, td); max_prot, flags, NULL, pos, FALSE, td);
} else { } else {
/* /*
* Mapping file, get fp for validation and don't let the * Mapping file, get fp for validation and don't let the
* descriptor disappear on us if we block. Check capability * descriptor disappear on us if we block. Check capability
* rights, but also return the maximum rights to be combined * rights, but also return the maximum rights to be combined
* with maxprot later. * with maxprot later.
*/ */
cap_rights_init(&rights, CAP_MMAP); cap_rights_init(&rights, CAP_MMAP);
if (prot & PROT_READ) if (prot & PROT_READ)
cap_rights_set(&rights, CAP_MMAP_R); cap_rights_set(&rights, CAP_MMAP_R);
if ((flags & MAP_SHARED) != 0) { if ((flags & MAP_SHARED) != 0) {
if (prot & PROT_WRITE) if (prot & PROT_WRITE)
cap_rights_set(&rights, CAP_MMAP_W); cap_rights_set(&rights, CAP_MMAP_W);
} }
if (prot & PROT_EXEC) if (prot & PROT_EXEC)
cap_rights_set(&rights, CAP_MMAP_X); cap_rights_set(&rights, CAP_MMAP_X);
error = fget_mmap(td, fd, &rights, &cap_maxprot, &fp); error = fget_mmap(td, fd, &rights, &cap_maxprot, &fp);
if (error != 0) if (error != 0)
goto done; goto done;
if ((flags & (MAP_SHARED | MAP_PRIVATE)) == 0 && if ((flags & (MAP_SHARED | MAP_PRIVATE)) == 0 &&
markjUnsubmitted
Not Done
Inline Actions

Shouldn't it be (max_prot & cap_maxprot) == max_prot? Otherwise userland can trigger this assertion by requesting a PROT_MAX(PROT_READ) | PROT_READ mapping using a descriptor with read and write rights.

markj: Shouldn't it be `(max_prot & cap_maxprot) == max_prot`? Otherwise userland can trigger this…
brooksAuthorUnsubmitted
Done
Inline Actions

My belief was that this can't happen because of the way fget_mmap is implemented, but rereading, it looks like that's only true when CAPABILITIES is defined (in which case cap_maxprot == prot so this is safe because prot must be a subset of max_prot per the check above). In the non-CAPABILITIES case cap_maxprot is VM_PROT_ALL so this will fail. Dropping the assertion may be the best fix.

brooks: My belief was that this can't happen because of the way fget_mmap is implemented, but rereading…
markjUnsubmitted
Done
Inline Actions

Sorry, I don't see why that assertion worked even with CAPABILITIES defined. fget_mmap() returns the maximum protections permitted by capabilities on the descriptor.

markj: Sorry, I don't see why that assertion worked even with CAPABILITIES defined. fget_mmap()…
brooksAuthorUnsubmitted
Done
Inline Actions

On further reading, you're correct.

brooks: On further reading, you're correct.
td->td_proc->p_osrel >= P_OSREL_MAP_FSTRICT) { td->td_proc->p_osrel >= P_OSREL_MAP_FSTRICT) {
error = EINVAL; error = EINVAL;
goto done; goto done;
} }
/* This relies on VM_PROT_* matching PROT_*. */ /* This relies on VM_PROT_* matching PROT_*. */
error = fo_mmap(fp, &vms->vm_map, &addr, size, prot, error = fo_mmap(fp, &vms->vm_map, &addr, size, prot,
cap_maxprot, flags, pos, td); max_prot & cap_maxprot, flags, pos, td);
kibUnsubmitted
Not Done
Inline Actions

Should we deny the request if (max_prot & cap_maxprot) != max_prot, so that user knows that the call was not really satisfied ?

kib: Should we deny the request if `(max_prot & cap_maxprot) != max_prot`, so that user knows that…
brooksAuthorUnsubmitted
Done
Inline Actions

I'm leaning toward not. I think we'd only want to error when we'd explicitly passed a PROT_MAX(FOO) expression so we'd have to add state for that since we don't want to fail when max_prot defaults to _PROT_ALL or when it's implied. We'd also just add yet another inexplicable EINVAL for a rare case.

brooks: I'm leaning toward not. I think we'd only want to error when we'd explicitly passed a PROT_MAX…
brooksAuthorUnsubmitted
Done
Inline Actions

I've added a KASSERT of this because I'm convinced that with the (prot & max_prot) == prot check above that this will always be safe (cap_maxprot ends up set to something derived directly from prot).

brooks: I've added a KASSERT of this because I'm convinced that with the `(prot & max_prot) == prot`…
} }
if (error == 0) if (error == 0)
td->td_retval[0] = (register_t) (addr + pageoff); td->td_retval[0] = (register_t) (addr + pageoff);
done: done:
if (fp) if (fp)
fdrop(fp, td); fdrop(fp, td);
▲ Show 20 Lines • Show All 214 Lines • ▼ Show 20 Linessys_mprotect(struct thread *td, struct mprotect_args *uap)
return (kern_mprotect(td, (uintptr_t)uap->addr, uap->len, uap->prot)); return (kern_mprotect(td, (uintptr_t)uap->addr, uap->len, uap->prot));
} }
int int
kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot) kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot)
{ {
vm_offset_t addr; vm_offset_t addr;
vm_size_t pageoff; vm_size_t pageoff;
int vm_error, max_prot;
addr = addr0; addr = addr0;
if ((prot & ~(_PROT_ALL | PROT_MAX(_PROT_ALL))) != 0)
return (EINVAL);
brooksAuthorUnsubmitted
Done
Inline Actions

This check is interesting. Linux documents this behavior (EINVAL for invalid protections), but POSIX seems to endorse our silent stripping. I'm inclined to think Linux is more correct here.

brooks: This check is interesting. Linux documents this behavior (EINVAL for invalid protections), but…
markjUnsubmitted
Done
Inline Actions

We should probably document this error in the man page too.

markj: We should probably document this error in the man page too.
max_prot = PROT_MAX_EXTRACT(prot);
prot = (prot & VM_PROT_ALL); prot = (prot & VM_PROT_ALL);
alcUnsubmitted
Done
Inline Actions

While not strictly necessary for correctness, I would advocate changing this to

prot = PROT_EXTRACT(prot);
alc: While not strictly necessary for correctness, I would advocate changing this to ``` prot =…
pageoff = (addr & PAGE_MASK); pageoff = (addr & PAGE_MASK);
addr -= pageoff; addr -= pageoff;
size += pageoff; size += pageoff;
size = (vm_size_t) round_page(size); size = (vm_size_t) round_page(size);
#ifdef COMPAT_FREEBSD32 #ifdef COMPAT_FREEBSD32
if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
if (((addr + size) & 0xffffffff) < addr) if (((addr + size) & 0xffffffff) < addr)
return (EINVAL); return (EINVAL);
} else } else
#endif #endif
if (addr + size < addr) if (addr + size < addr)
return (EINVAL); return (EINVAL);
switch (vm_map_protect(&td->td_proc->p_vmspace->vm_map, addr, if (max_prot != 0) {
addr + size, prot, FALSE)) { if ((max_prot & prot) != prot)
return (EINVAL);
vm_error = vm_map_protect(&td->td_proc->p_vmspace->vm_map,
kibUnsubmitted
Not Done
Inline Actions

I do not understand this.

Suppose you have a readonly shared mapping of the file, which was created using O_RDONLY file descriptor. Isn't this addition allows to add VM_PROT_WRITE to the corresponding vm_map_entry max_prot ? Then on the next step user can mprotect(2) the mapping to modify the file.

kib: I do not understand this. Suppose you have a readonly shared mapping of the file, which was…
brooksAuthorUnsubmitted
Done
Inline Actions

I think this does the right thing, but I had to read the implementation a couple times to convince myself. In vm_map_protect, when set_max is true, the new max_prot is checked against existing entries max_protection in the first loop over the region:

if ((new_prot & current->max_protection) != new_prot) {
  vm_map_unlock(map);
  return (KERN_PROTECTION_FAILURE);
}

This rejects attempts to upgrade max_prot.

brooks: I think this does the right thing, but I had to read the implementation a couple times to…
addr, addr + size, max_prot, TRUE);
if (vm_error != KERN_SUCCESS)
goto error_out;
markjUnsubmitted
Done
Inline Actions

You can avoid a goto by initializing vm_error to KERN_SUCCESS and skipping the final vm_map_protect() if vm_error != KERN_SUCCESS.

markj: You can avoid a goto by initializing `vm_error` to `KERN_SUCCESS` and skipping the final…
}
vm_error = vm_map_protect(&td->td_proc->p_vmspace->vm_map, addr,
addr + size, prot, FALSE);
error_out:
switch (vm_error) {
case KERN_SUCCESS: case KERN_SUCCESS:
return (0); return (0);
case KERN_PROTECTION_FAILURE: case KERN_PROTECTION_FAILURE:
return (EACCES); return (EACCES);
case KERN_RESOURCE_SHORTAGE: case KERN_RESOURCE_SHORTAGE:
return (ENOMEM); return (ENOMEM);
} }
return (EINVAL); return (EINVAL);
▲ Show 20 Lines • Show All 977 Lines • Show Last 20 Lines
View Options

usr.bin/calendar/calendars/calendar.freebsd

Show First 20 Lines • Show All 97 Lines • ▼ Show 20 Lines
#endif #endif
int old_mlock = 0; int old_mlock = 0;
SYSCTL_INT(_vm, OID_AUTO, old_mlock, CTLFLAG_RWTUN, &old_mlock, 0, SYSCTL_INT(_vm, OID_AUTO, old_mlock, CTLFLAG_RWTUN, &old_mlock, 0,
"Do not apply RLIMIT_MEMLOCK on mlockall"); "Do not apply RLIMIT_MEMLOCK on mlockall");
static int mincore_mapped = 1; static int mincore_mapped = 1;
SYSCTL_INT(_vm, OID_AUTO, mincore_mapped, CTLFLAG_RWTUN, &mincore_mapped, 0, SYSCTL_INT(_vm, OID_AUTO, mincore_mapped, CTLFLAG_RWTUN, &mincore_mapped, 0,
"mincore reports mappings, not residency"); "mincore reports mappings, not residency");
static int imply_prot_max = 0;
SYSCTL_INT(_vm, OID_AUTO, imply_prot_max, CTLFLAG_RWTUN, &imply_prot_max, 0,
emasteUnsubmitted
Done
Inline Actions

s/mincore_mapped/imply_prot_max/

emaste: `s/mincore_mapped/imply_prot_max/`
"Imply maximum page permissions in mmap() when none are specified.");
markjUnsubmitted
Done
Inline Actions

sysctl description strings usually don't contain a period.

markj: sysctl description strings usually don't contain a period.
#ifdef MAP_32BIT #ifdef MAP_32BIT
#define MAP_32BIT_MAX_ADDR ((vm_offset_t)1 << 31) #define MAP_32BIT_MAX_ADDR ((vm_offset_t)1 << 31)
#endif #endif
#ifndef _SYS_SYSPROTO_H_ #ifndef _SYS_SYSPROTO_H_
struct sbrk_args { struct sbrk_args {
int incr; int incr;
▲ Show 20 Lines • Show All 68 Lines • ▼ Show 20 Lines
kern_mmap(struct thread *td, uintptr_t addr0, size_t size, int prot, int flags, kern_mmap(struct thread *td, uintptr_t addr0, size_t size, int prot, int flags,
int fd, off_t pos) int fd, off_t pos)
{ {
struct vmspace *vms; struct vmspace *vms;
struct file *fp; struct file *fp;
vm_offset_t addr; vm_offset_t addr;
vm_size_t pageoff; vm_size_t pageoff;
vm_prot_t cap_maxprot; vm_prot_t cap_maxprot;
int align, error; int align, error, max_prot;
cap_rights_t rights; cap_rights_t rights;
if ((prot & ~(_PROT_ALL | PROT_MAX(_PROT_ALL))) != 0)
return (EINVAL);
emasteUnsubmitted
Done
Inline Actions

This has the effect of masking invalid flags (e.g. PROT_READ | PROT_WRITE | 0x100000 or 0xffff in tests/sys/vm/mmap_test.c).

emaste: This has the effect of masking invalid flags (e.g. `PROT_READ | PROT_WRITE | 0x100000` or…
max_prot = PROT_MAX_EXTRACT(prot);
prot = PROT_EXTRACT(prot);
markjUnsubmitted
Done
Inline Actions

Don't we also need to verify that prot is a subset of max_prot?

markj: Don't we also need to verify that prot is a subset of max_prot?
/*
* Always honor PROT_MAX if set. If not, default to all
* permissions unless we're implying maximum permissions.
*
* XXX: should be tunable per process and ABI.
*/
if (max_prot == 0)
max_prot = (imply_prot_max && prot != PROT_NONE) ?
prot : _PROT_ALL;
kibUnsubmitted
Done
Inline Actions

I would write this as
`
max_prot = imply_prot_max ? prot : _PROT_ALL
`

kib: I would write this as ` max_prot = imply_prot_max ? prot : _PROT_ALL `
vms = td->td_proc->p_vmspace; vms = td->td_proc->p_vmspace;
fp = NULL; fp = NULL;
AUDIT_ARG_FD(fd); AUDIT_ARG_FD(fd);
addr = addr0; addr = addr0;
/* /*
* Ignore old flags that used to be defined but did not do anything. * Ignore old flags that used to be defined but did not do anything.
*/ */
▲ Show 20 Lines • Show All 126 Lines • ▼ Show 20 Lines error = vm_mmap_object(&vms->vm_map, &addr, size, VM_PROT_NONE,
VM_PROT_NONE, flags, NULL, pos, FALSE, td); VM_PROT_NONE, flags, NULL, pos, FALSE, td);
} else if ((flags & MAP_ANON) != 0) { } else if ((flags & MAP_ANON) != 0) {
/* /*
* Mapping blank space is trivial. * Mapping blank space is trivial.
* *
* This relies on VM_PROT_* matching PROT_*. * This relies on VM_PROT_* matching PROT_*.
*/ */
error = vm_mmap_object(&vms->vm_map, &addr, size, prot, error = vm_mmap_object(&vms->vm_map, &addr, size, prot,
VM_PROT_ALL, flags, NULL, pos, FALSE, td); max_prot, flags, NULL, pos, FALSE, td);
} else { } else {
/* /*
* Mapping file, get fp for validation and don't let the * Mapping file, get fp for validation and don't let the
* descriptor disappear on us if we block. Check capability * descriptor disappear on us if we block. Check capability
* rights, but also return the maximum rights to be combined * rights, but also return the maximum rights to be combined
* with maxprot later. * with maxprot later.
*/ */
cap_rights_init(&rights, CAP_MMAP); cap_rights_init(&rights, CAP_MMAP);
if (prot & PROT_READ) if (prot & PROT_READ)
cap_rights_set(&rights, CAP_MMAP_R); cap_rights_set(&rights, CAP_MMAP_R);
if ((flags & MAP_SHARED) != 0) { if ((flags & MAP_SHARED) != 0) {
if (prot & PROT_WRITE) if (prot & PROT_WRITE)
cap_rights_set(&rights, CAP_MMAP_W); cap_rights_set(&rights, CAP_MMAP_W);
} }
if (prot & PROT_EXEC) if (prot & PROT_EXEC)
cap_rights_set(&rights, CAP_MMAP_X); cap_rights_set(&rights, CAP_MMAP_X);
error = fget_mmap(td, fd, &rights, &cap_maxprot, &fp); error = fget_mmap(td, fd, &rights, &cap_maxprot, &fp);
if (error != 0) if (error != 0)
goto done; goto done;
if ((flags & (MAP_SHARED | MAP_PRIVATE)) == 0 && if ((flags & (MAP_SHARED | MAP_PRIVATE)) == 0 &&
markjUnsubmitted
Not Done
Inline Actions

Shouldn't it be (max_prot & cap_maxprot) == max_prot? Otherwise userland can trigger this assertion by requesting a PROT_MAX(PROT_READ) | PROT_READ mapping using a descriptor with read and write rights.

markj: Shouldn't it be `(max_prot & cap_maxprot) == max_prot`? Otherwise userland can trigger this…
brooksAuthorUnsubmitted
Done
Inline Actions

My belief was that this can't happen because of the way fget_mmap is implemented, but rereading, it looks like that's only true when CAPABILITIES is defined (in which case cap_maxprot == prot so this is safe because prot must be a subset of max_prot per the check above). In the non-CAPABILITIES case cap_maxprot is VM_PROT_ALL so this will fail. Dropping the assertion may be the best fix.

brooks: My belief was that this can't happen because of the way fget_mmap is implemented, but rereading…
markjUnsubmitted
Done
Inline Actions

Sorry, I don't see why that assertion worked even with CAPABILITIES defined. fget_mmap() returns the maximum protections permitted by capabilities on the descriptor.

markj: Sorry, I don't see why that assertion worked even with CAPABILITIES defined. fget_mmap()…
brooksAuthorUnsubmitted
Done
Inline Actions

On further reading, you're correct.

brooks: On further reading, you're correct.
td->td_proc->p_osrel >= P_OSREL_MAP_FSTRICT) { td->td_proc->p_osrel >= P_OSREL_MAP_FSTRICT) {
error = EINVAL; error = EINVAL;
goto done; goto done;
} }
/* This relies on VM_PROT_* matching PROT_*. */ /* This relies on VM_PROT_* matching PROT_*. */
error = fo_mmap(fp, &vms->vm_map, &addr, size, prot, error = fo_mmap(fp, &vms->vm_map, &addr, size, prot,
cap_maxprot, flags, pos, td); max_prot & cap_maxprot, flags, pos, td);
kibUnsubmitted
Not Done
Inline Actions

Should we deny the request if (max_prot & cap_maxprot) != max_prot, so that user knows that the call was not really satisfied ?

kib: Should we deny the request if `(max_prot & cap_maxprot) != max_prot`, so that user knows that…
brooksAuthorUnsubmitted
Done
Inline Actions

I'm leaning toward not. I think we'd only want to error when we'd explicitly passed a PROT_MAX(FOO) expression so we'd have to add state for that since we don't want to fail when max_prot defaults to _PROT_ALL or when it's implied. We'd also just add yet another inexplicable EINVAL for a rare case.

brooks: I'm leaning toward not. I think we'd only want to error when we'd explicitly passed a PROT_MAX…
brooksAuthorUnsubmitted
Done
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I've added a KASSERT of this because I'm convinced that with the (prot & max_prot) == prot check above that this will always be safe (cap_maxprot ends up set to something derived directly from prot).

brooks: I've added a KASSERT of this because I'm convinced that with the `(prot & max_prot) == prot`…
} }
if (error == 0) if (error == 0)
td->td_retval[0] = (register_t) (addr + pageoff); td->td_retval[0] = (register_t) (addr + pageoff);
done: done:
if (fp) if (fp)
fdrop(fp, td); fdrop(fp, td);
▲ Show 20 Lines • Show All 214 Lines • ▼ Show 20 Linessys_mprotect(struct thread *td, struct mprotect_args *uap)
return (kern_mprotect(td, (uintptr_t)uap->addr, uap->len, uap->prot)); return (kern_mprotect(td, (uintptr_t)uap->addr, uap->len, uap->prot));
} }
int int
kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot) kern_mprotect(struct thread *td, uintptr_t addr0, size_t size, int prot)
{ {
vm_offset_t addr; vm_offset_t addr;
vm_size_t pageoff; vm_size_t pageoff;
int vm_error, max_prot;
addr = addr0; addr = addr0;
if ((prot & ~(_PROT_ALL | PROT_MAX(_PROT_ALL))) != 0)
return (EINVAL);
brooksAuthorUnsubmitted
Done
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This check is interesting. Linux documents this behavior (EINVAL for invalid protections), but POSIX seems to endorse our silent stripping. I'm inclined to think Linux is more correct here.

brooks: This check is interesting. Linux documents this behavior (EINVAL for invalid protections), but…
markjUnsubmitted
Done
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We should probably document this error in the man page too.

markj: We should probably document this error in the man page too.
max_prot = PROT_MAX_EXTRACT(prot);
prot = (prot & VM_PROT_ALL); prot = (prot & VM_PROT_ALL);
alcUnsubmitted
Done
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While not strictly necessary for correctness, I would advocate changing this to

prot = PROT_EXTRACT(prot);
alc: While not strictly necessary for correctness, I would advocate changing this to ``` prot =…
pageoff = (addr & PAGE_MASK); pageoff = (addr & PAGE_MASK);
addr -= pageoff; addr -= pageoff;
size += pageoff; size += pageoff;
size = (vm_size_t) round_page(size); size = (vm_size_t) round_page(size);
#ifdef COMPAT_FREEBSD32 #ifdef COMPAT_FREEBSD32
if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) { if (SV_PROC_FLAG(td->td_proc, SV_ILP32)) {
if (((addr + size) & 0xffffffff) < addr) if (((addr + size) & 0xffffffff) < addr)
return (EINVAL); return (EINVAL);
} else } else
#endif #endif
if (addr + size < addr) if (addr + size < addr)
return (EINVAL); return (EINVAL);
switch (vm_map_protect(&td->td_proc->p_vmspace->vm_map, addr, if (max_prot != 0) {
addr + size, prot, FALSE)) { if ((max_prot & prot) != prot)
return (EINVAL);
vm_error = vm_map_protect(&td->td_proc->p_vmspace->vm_map,
kibUnsubmitted
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I do not understand this.

Suppose you have a readonly shared mapping of the file, which was created using O_RDONLY file descriptor. Isn't this addition allows to add VM_PROT_WRITE to the corresponding vm_map_entry max_prot ? Then on the next step user can mprotect(2) the mapping to modify the file.

kib: I do not understand this. Suppose you have a readonly shared mapping of the file, which was…
brooksAuthorUnsubmitted
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I think this does the right thing, but I had to read the implementation a couple times to convince myself. In vm_map_protect, when set_max is true, the new max_prot is checked against existing entries max_protection in the first loop over the region:

if ((new_prot & current->max_protection) != new_prot) {
  vm_map_unlock(map);
  return (KERN_PROTECTION_FAILURE);
}

This rejects attempts to upgrade max_prot.

brooks: I think this does the right thing, but I had to read the implementation a couple times to…
addr, addr + size, max_prot, TRUE);
if (vm_error != KERN_SUCCESS)
goto error_out;
markjUnsubmitted
Done
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You can avoid a goto by initializing vm_error to KERN_SUCCESS and skipping the final vm_map_protect() if vm_error != KERN_SUCCESS.

markj: You can avoid a goto by initializing `vm_error` to `KERN_SUCCESS` and skipping the final…
}
vm_error = vm_map_protect(&td->td_proc->p_vmspace->vm_map, addr,
addr + size, prot, FALSE);
error_out:
switch (vm_error) {
case KERN_SUCCESS: case KERN_SUCCESS:
return (0); return (0);
case KERN_PROTECTION_FAILURE: case KERN_PROTECTION_FAILURE:
return (EACCES); return (EACCES);
case KERN_RESOURCE_SHORTAGE: case KERN_RESOURCE_SHORTAGE:
return (ENOMEM); return (ENOMEM);
} }
return (EINVAL); return (EINVAL);
▲ Show 20 Lines • Show All 977 Lines • Show Last 20 Lines