| Message ID | 20240913140628.77047-1-lorenzo.stoakes@oracle.com (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm/madvise: process_madvise() drop capability check if same mm | expand |
* Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [240913 10:06]: > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > process_madvise") process_madvise() was updated to require the caller to > possess the CAP_SYS_NICE capability to perform the operation, in addition > to a check against PTRACE_MODE_READ performed by mm_access(). > > The mm_access() function explicitly checks to see if the address space of > the process being referenced is the current one, in which case no check is > performed. > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > means that we insist on the caller possessing this capability in order to > perform madvise() operations on its own address space, which seems > nonsensical. > > Simply add a check to allow for an invocation of this function with pidfd > set to the current process without elevation. > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Probably needs a fixes 96cfe2c0fd23 tag? Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > --- > mm/madvise.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 4e64770be16c..ff139e57cca2 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1520,7 +1520,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, > * Require CAP_SYS_NICE for influencing process performance. Note that > * only non-destructive hints are currently supported. > */ > - if (!capable(CAP_SYS_NICE)) { > + if (mm != current->mm && !capable(CAP_SYS_NICE)) { > ret = -EPERM; > goto release_mm; > } > -- > 2.46.0 >
..Add Shakeel's new email address * Liam R. Howlett <Liam.Howlett@oracle.com> [240913 10:31]: > * Lorenzo Stoakes <lorenzo.stoakes@oracle.com> [240913 10:06]: > > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > > process_madvise") process_madvise() was updated to require the caller to > > possess the CAP_SYS_NICE capability to perform the operation, in addition > > to a check against PTRACE_MODE_READ performed by mm_access(). > > > > The mm_access() function explicitly checks to see if the address space of > > the process being referenced is the current one, in which case no check is > > performed. > > > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > > means that we insist on the caller possessing this capability in order to > > perform madvise() operations on its own address space, which seems > > nonsensical. > > > > Simply add a check to allow for an invocation of this function with pidfd > > set to the current process without elevation. > > > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> > > Probably needs a fixes 96cfe2c0fd23 tag? > > Reviewed-by: Liam R. Howlett <Liam.Howlett@Oracle.com> > > > --- > > mm/madvise.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/mm/madvise.c b/mm/madvise.c > > index 4e64770be16c..ff139e57cca2 100644 > > --- a/mm/madvise.c > > +++ b/mm/madvise.c > > @@ -1520,7 +1520,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, > > * Require CAP_SYS_NICE for influencing process performance. Note that > > * only non-destructive hints are currently supported. > > */ > > - if (!capable(CAP_SYS_NICE)) { > > + if (mm != current->mm && !capable(CAP_SYS_NICE)) { > > ret = -EPERM; > > goto release_mm; > > } > > -- > > 2.46.0 > >
On 9/13/24 16:06, Lorenzo Stoakes wrote: > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > process_madvise") process_madvise() was updated to require the caller to > possess the CAP_SYS_NICE capability to perform the operation, in addition > to a check against PTRACE_MODE_READ performed by mm_access(). > > The mm_access() function explicitly checks to see if the address space of > the process being referenced is the current one, in which case no check is > performed. > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > means that we insist on the caller possessing this capability in order to > perform madvise() operations on its own address space, which seems > nonsensical. > > Simply add a check to allow for an invocation of this function with pidfd > set to the current process without elevation. > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > mm/madvise.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/madvise.c b/mm/madvise.c > index 4e64770be16c..ff139e57cca2 100644 > --- a/mm/madvise.c > +++ b/mm/madvise.c > @@ -1520,7 +1520,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, > * Require CAP_SYS_NICE for influencing process performance. Note that > * only non-destructive hints are currently supported. > */ > - if (!capable(CAP_SYS_NICE)) { > + if (mm != current->mm && !capable(CAP_SYS_NICE)) { > ret = -EPERM; > goto release_mm; > }
On Fri, Sep 13, 2024 at 03:06:28PM GMT, Lorenzo Stoakes wrote: > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > process_madvise") process_madvise() was updated to require the caller to > possess the CAP_SYS_NICE capability to perform the operation, in addition > to a check against PTRACE_MODE_READ performed by mm_access(). > > The mm_access() function explicitly checks to see if the address space of > the process being referenced is the current one, in which case no check is > performed. > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > means that we insist on the caller possessing this capability in order to > perform madvise() operations on its own address space, which seems > nonsensical. > > Simply add a check to allow for an invocation of this function with pidfd > set to the current process without elevation. > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: Shakeel Butt <shakeel.butt@linux.dev>
On Fri, 13 Sep 2024, Lorenzo Stoakes wrote: > In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for > process_madvise") process_madvise() was updated to require the caller to > possess the CAP_SYS_NICE capability to perform the operation, in addition > to a check against PTRACE_MODE_READ performed by mm_access(). > > The mm_access() function explicitly checks to see if the address space of > the process being referenced is the current one, in which case no check is > performed. > > We, however, do not do this when checking the CAP_SYS_NICE capability. This > means that we insist on the caller possessing this capability in order to > perform madvise() operations on its own address space, which seems > nonsensical. > > Simply add a check to allow for an invocation of this function with pidfd > set to the current process without elevation. > > Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> Acked-by: David Rientjes <rientjes@google.com>
diff --git a/mm/madvise.c b/mm/madvise.c index 4e64770be16c..ff139e57cca2 100644 --- a/mm/madvise.c +++ b/mm/madvise.c @@ -1520,7 +1520,7 @@ SYSCALL_DEFINE5(process_madvise, int, pidfd, const struct iovec __user *, vec, * Require CAP_SYS_NICE for influencing process performance. Note that * only non-destructive hints are currently supported. */ - if (!capable(CAP_SYS_NICE)) { + if (mm != current->mm && !capable(CAP_SYS_NICE)) { ret = -EPERM; goto release_mm; }
In commit 96cfe2c0fd23 ("mm/madvise: replace ptrace attach requirement for process_madvise") process_madvise() was updated to require the caller to possess the CAP_SYS_NICE capability to perform the operation, in addition to a check against PTRACE_MODE_READ performed by mm_access(). The mm_access() function explicitly checks to see if the address space of the process being referenced is the current one, in which case no check is performed. We, however, do not do this when checking the CAP_SYS_NICE capability. This means that we insist on the caller possessing this capability in order to perform madvise() operations on its own address space, which seems nonsensical. Simply add a check to allow for an invocation of this function with pidfd set to the current process without elevation. Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@oracle.com> --- mm/madvise.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)