Author: trociny
Date: Tue Nov 22 20:40:18 2011
New Revision: 227833
URL: http://svn.freebsd.org/changeset/base/227833
Log:
Add new sysctls, KERN_PROC_ENV and KERN_PROC_AUXV, to return
environment strings and ELF auxiliary vectors from a process stack.
Make sysctl_kern_proc_args to read not cached arguments from the
process stack.
Export proc_getargv() and proc_getenvv() so they can be reused by
procfs and linprocfs.
Suggested by: kib
Reviewed by: kib
Discussed with: kib, rwatson, jilles
Tested by: pho
MFC after: 2 weeks
Modified:
head/sys/kern/kern_proc.c
head/sys/sys/proc.h
head/sys/sys/sysctl.h
Modified: head/sys/kern/kern_proc.c
==============================================================================
--- head/sys/kern/kern_proc.c Tue Nov 22 19:42:17 2011 (r227832)
+++ head/sys/kern/kern_proc.c Tue Nov 22 20:40:18 2011 (r227833)
@@ -41,6 +41,8 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/systm.h>
+#include <sys/elf.h>
+#include <sys/exec.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/lock.h>
@@ -50,6 +52,7 @@ __FBSDID("$FreeBSD$");
#include <sys/mount.h>
#include <sys/mutex.h>
#include <sys/proc.h>
+#include <sys/ptrace.h>
#include <sys/refcount.h>
#include <sys/sbuf.h>
#include <sys/sysent.h>
@@ -1358,6 +1361,289 @@ pargs_drop(struct pargs *pa)
pargs_free(pa);
}
+static int
+proc_read_mem(struct thread *td, struct proc *p, vm_offset_t offset, void* buf,
+ size_t len)
+{
+ struct iovec iov;
+ struct uio uio;
+
+ iov.iov_base = (caddr_t)buf;
+ iov.iov_len = len;
+ uio.uio_iov = &iov;
+ uio.uio_iovcnt = 1;
+ uio.uio_offset = offset;
+ uio.uio_resid = (ssize_t)len;
+ uio.uio_segflg = UIO_SYSSPACE;
+ uio.uio_rw = UIO_READ;
+ uio.uio_td = td;
+
+ return (proc_rwmem(p, &uio));
+}
+
+static int
+proc_read_string(struct thread *td, struct proc *p, const char *sptr, char
*buf,
+ size_t len)
+{
+ size_t i;
+ int error;
+
+ error = proc_read_mem(td, p, (vm_offset_t)sptr, buf, len);
+ /*
+ * Reading the chunk may validly return EFAULT if the string is shorter
+ * than the chunk and is aligned at the end of the page, assuming the
+ * next page is not mapped. So if EFAULT is returned do a fallback to
+ * one byte read loop.
+ */
+ if (error == EFAULT) {
+ for (i = 0; i < len; i++, buf++, sptr++) {
+ error = proc_read_mem(td, p, (vm_offset_t)sptr, buf, 1);
+ if (error != 0)
+ return (error);
+ if (*buf == '\0')
+ break;
+ }
+ error = 0;
+ }
+ return (error);
+}
+
+#define PROC_AUXV_MAX 256 /* Safety limit on auxv size. */
+
+enum proc_vector_type {
+ PROC_ARG,
+ PROC_ENV,
+ PROC_AUX,
+};
+
+#ifdef COMPAT_FREEBSD32
+static int
+get_proc_vector32(struct thread *td, struct proc *p, char ***proc_vectorp,
+ size_t *vsizep, enum proc_vector_type type)
+{
+ struct freebsd32_ps_strings pss;
+ Elf32_Auxinfo aux;
+ vm_offset_t vptr, ptr;
+ uint32_t *proc_vector32;
+ char **proc_vector;
+ size_t vsize, size;
+ int i, error;
+
+ error = proc_read_mem(td, p, (vm_offset_t)(p->p_sysent->sv_psstrings),
+ &pss, sizeof(pss));
+ if (error != 0)
+ return (error);
+ switch (type) {
+ case PROC_ARG:
+ vptr = (vm_offset_t)PTRIN(pss.ps_argvstr);
+ vsize = pss.ps_nargvstr;
+ if (vsize > ARG_MAX)
+ return (ENOEXEC);
+ size = vsize * sizeof(int32_t);
+ break;
+ case PROC_ENV:
+ vptr = (vm_offset_t)PTRIN(pss.ps_envstr);
+ vsize = pss.ps_nenvstr;
+ if (vsize > ARG_MAX)
+ return (ENOEXEC);
+ size = vsize * sizeof(int32_t);
+ break;
+ case PROC_AUX:
+ vptr = (vm_offset_t)PTRIN(pss.ps_envstr) +
+ (pss.ps_nenvstr + 1) * sizeof(int32_t);
+ if (vptr % 4 != 0)
+ return (ENOEXEC);
+ for (ptr = vptr, i = 0; i < PROC_AUXV_MAX; i++) {
+ error = proc_read_mem(td, p, ptr, &aux, sizeof(aux));
+ if (error != 0)
+ return (error);
+ if (aux.a_type == AT_NULL)
+ break;
+ ptr += sizeof(aux);
+ }
+ if (aux.a_type != AT_NULL)
+ return (ENOEXEC);
+ vsize = i + 1;
+ size = vsize * sizeof(aux);
+ break;
+ default:
+ KASSERT(0, ("Wrong proc vector type: %d", type));
+ }
+ proc_vector32 = malloc(size, M_TEMP, M_WAITOK);
+ error = proc_read_mem(td, p, vptr, proc_vector32, size);
+ if (error != 0)
+ goto done;
+ if (type == PROC_AUX) {
+ *proc_vectorp = (char **)proc_vector32;
+ *vsizep = vsize;
+ return (0);
+ }
+ proc_vector = malloc(vsize * sizeof(char *), M_TEMP, M_WAITOK);
+ for (i = 0; i < (int)vsize; i++)
+ proc_vector[i] = PTRIN(proc_vector32[i]);
+ *proc_vectorp = proc_vector;
+ *vsizep = vsize;
+done:
+ free(proc_vector32, M_TEMP);
+ return (error);
+}
+#endif
+
+static int
+get_proc_vector(struct thread *td, struct proc *p, char ***proc_vectorp,
+ size_t *vsizep, enum proc_vector_type type)
+{
+ struct ps_strings pss;
+ Elf_Auxinfo aux;
+ vm_offset_t vptr, ptr;
+ char **proc_vector;
+ size_t vsize, size;
+ int error, i;
+
+#ifdef COMPAT_FREEBSD32
+ if (SV_PROC_FLAG(p, SV_ILP32) != 0)
+ return (get_proc_vector32(td, p, proc_vectorp, vsizep, type));
+#endif
+ error = proc_read_mem(td, p, (vm_offset_t)(p->p_sysent->sv_psstrings),
+ &pss, sizeof(pss));
+ if (error != 0)
+ return (error);
+ switch (type) {
+ case PROC_ARG:
+ vptr = (vm_offset_t)pss.ps_argvstr;
+ vsize = pss.ps_nargvstr;
+ if (vsize > ARG_MAX)
+ return (ENOEXEC);
+ size = vsize * sizeof(char *);
+ break;
+ case PROC_ENV:
+ vptr = (vm_offset_t)pss.ps_envstr;
+ vsize = pss.ps_nenvstr;
+ if (vsize > ARG_MAX)
+ return (ENOEXEC);
+ size = vsize * sizeof(char *);
+ break;
+ case PROC_AUX:
+ /*
+ * The aux array is just above env array on the stack. Check
+ * that the address is naturally aligned.
+ */
+ vptr = (vm_offset_t)pss.ps_envstr + (pss.ps_nenvstr + 1)
+ * sizeof(char *);
+#if __ELF_WORD_SIZE == 64
+ if (vptr % sizeof(uint64_t) != 0)
+#else
+ if (vptr % sizeof(uint32_t) != 0)
+#endif
+ return (ENOEXEC);
+ /*
+ * We count the array size reading the aux vectors from the
+ * stack until AT_NULL vector is returned. So (to keep the code
+ * simple) we read the process stack twice: the first time here
+ * to find the size and the second time when copying the vectors
+ * to the allocated proc_vector.
+ */
+ for (ptr = vptr, i = 0; i < PROC_AUXV_MAX; i++) {
+ error = proc_read_mem(td, p, ptr, &aux, sizeof(aux));
+ if (error != 0)
+ return (error);
+ if (aux.a_type == AT_NULL)
+ break;
+ ptr += sizeof(aux);
+ }
+ /*
+ * If the PROC_AUXV_MAX entries are iterated over, and we have
+ * not reached AT_NULL, it is most likely we are reading wrong
+ * data: either the process doesn't have auxv array or data has
+ * been modified. Return the error in this case.
+ */
+ if (aux.a_type != AT_NULL)
+ return (ENOEXEC);
+ vsize = i + 1;
+ size = vsize * sizeof(aux);
+ break;
+ default:
+ KASSERT(0, ("Wrong proc vector type: %d", type));
+ }
+ proc_vector = malloc(size, M_TEMP, M_WAITOK);
+ if (proc_vector == NULL)
+ return (ENOMEM);
+ error = proc_read_mem(td, p, vptr, proc_vector, size);
+ if (error != 0) {
+ free(proc_vector, M_TEMP);
+ return (error);
+ }
+ *proc_vectorp = proc_vector;
+ *vsizep = vsize;
+
+ return (0);
+}
+
+#define GET_PS_STRINGS_CHUNK_SZ 256 /* Chunk size (bytes) for
ps_strings operations. */
+
+static int
+get_ps_strings(struct thread *td, struct proc *p, struct sbuf *sb,
+ enum proc_vector_type type, size_t nchr)
+{
+ size_t done, len, vsize;
+ int error, i;
+ char **proc_vector, *sptr;
+ char pss_string[GET_PS_STRINGS_CHUNK_SZ];
+
+ PROC_ASSERT_HELD(p);
+
+ /*
+ * We are not going to read more than 2 * (PATH_MAX + ARG_MAX) bytes.
+ */
+ if (nchr > 2 * (PATH_MAX + ARG_MAX))
+ nchr = 2 * (PATH_MAX + ARG_MAX);
+
+ error = get_proc_vector(td, p, &proc_vector, &vsize, type);
+ if (error != 0)
+ return (error);
+ for (done = 0, i = 0; i < (int)vsize && done < nchr; i++) {
+ /*
+ * The program may have scribbled into its argv array, e.g. to
+ * remove some arguments. If that has happened, break out
+ * before trying to read from NULL.
+ */
+ if (proc_vector[i] == NULL)
+ break;
+ for (sptr = proc_vector[i]; ; sptr += GET_PS_STRINGS_CHUNK_SZ) {
+ error = proc_read_string(td, p, sptr, pss_string,
+ sizeof(pss_string));
+ if (error != 0)
+ goto done;
+ len = strnlen(pss_string, GET_PS_STRINGS_CHUNK_SZ);
+ if (done + len >= nchr)
+ len = nchr - done - 1;
+ sbuf_bcat(sb, pss_string, len);
+ if (len != GET_PS_STRINGS_CHUNK_SZ)
+ break;
+ done += GET_PS_STRINGS_CHUNK_SZ;
+ }
+ sbuf_bcat(sb, "", 1);
+ done += len + 1;
+ }
+done:
+ free(proc_vector, M_TEMP);
+ return (error);
+}
+
+int
+proc_getargv(struct thread *td, struct proc *p, struct sbuf *sb, size_t nchr)
+{
+
+ return (get_ps_strings(curthread, p, sb, PROC_ARG, nchr));
+}
+
+int
+proc_getenvv(struct thread *td, struct proc *p, struct sbuf *sb, size_t nchr)
+{
+
+ return (get_ps_strings(curthread, p, sb, PROC_ENV, nchr));
+}
+
/*
* This sysctl allows a process to retrieve the argument list or process
* title for another process without groping around in the address space
@@ -1371,7 +1657,8 @@ sysctl_kern_proc_args(SYSCTL_HANDLER_ARG
u_int namelen = arg2;
struct pargs *newpa, *pa;
struct proc *p;
- int error = 0;
+ struct sbuf sb;
+ int error = 0, error2;
if (namelen != 1)
return (EINVAL);
@@ -1391,11 +1678,24 @@ sysctl_kern_proc_args(SYSCTL_HANDLER_ARG
}
pa = p->p_args;
- pargs_hold(pa);
- PROC_UNLOCK(p);
- if (pa != NULL)
+ if (pa != NULL) {
+ pargs_hold(pa);
+ PROC_UNLOCK(p);
error = SYSCTL_OUT(req, pa->ar_args, pa->ar_length);
- pargs_drop(pa);
+ pargs_drop(pa);
+ } else if ((p->p_flag & (P_WEXIT | P_SYSTEM)) == 0) {
+ _PHOLD(p);
+ PROC_UNLOCK(p);
+ sbuf_new_for_sysctl(&sb, NULL, GET_PS_STRINGS_CHUNK_SZ, req);
+ error = proc_getargv(curthread, p, &sb, req->oldlen);
+ error2 = sbuf_finish(&sb);
+ PRELE(p);
+ sbuf_delete(&sb);
+ if (error == 0 && error2 != 0)
+ error = error2;
+ } else {
+ PROC_UNLOCK(p);
+ }
if (error != 0 || req->newptr == NULL)
return (error);
@@ -1416,6 +1716,95 @@ sysctl_kern_proc_args(SYSCTL_HANDLER_ARG
}
/*
+ * This sysctl allows a process to retrieve environment of another process.
+ */
+static int
+sysctl_kern_proc_env(SYSCTL_HANDLER_ARGS)
+{
+ int *name = (int*) arg1;
+ u_int namelen = arg2;
+ struct proc *p;
+ struct sbuf sb;
+ int error, error2;
+
+ if (namelen != 1)
+ return (EINVAL);
+
+ p = pfind((pid_t)name[0]);
+ if (p == NULL)
+ return (ESRCH);
+ if ((p->p_flag & P_WEXIT) != 0) {
+ PROC_UNLOCK(p);
+ return (ESRCH);
+ }
+ if ((error = p_candebug(curthread, p)) != 0) {
+ PROC_UNLOCK(p);
+ return (error);
+ }
+ if ((p->p_flag & P_SYSTEM) != 0) {
+ PROC_UNLOCK(p);
+ return (0);
+ }
+ _PHOLD(p);
+ PROC_UNLOCK(p);
+ sbuf_new_for_sysctl(&sb, NULL, GET_PS_STRINGS_CHUNK_SZ, req);
+ error = proc_getenvv(curthread, p, &sb, req->oldlen);
+ error2 = sbuf_finish(&sb);
+ PRELE(p);
+ sbuf_delete(&sb);
+ return (error != 0 ? error : error2);
+}
+
+/*
+ * This sysctl allows a process to retrieve ELF auxiliary vector of
+ * another process.
+ */
+static int
+sysctl_kern_proc_auxv(SYSCTL_HANDLER_ARGS)
+{
+ int *name = (int*) arg1;
+ u_int namelen = arg2;
+ struct proc *p;
+ size_t vsize;
+ char **auxv;
+ int error;
+
+ if (namelen != 1)
+ return (EINVAL);
+
+ p = pfind((pid_t)name[0]);
+ if (p == NULL)
+ return (ESRCH);
+ if (p->p_flag & P_WEXIT) {
+ PROC_UNLOCK(p);
+ return (ESRCH);
+ }
+ if ((error = p_cansee(curthread, p)) != 0) {
+ PROC_UNLOCK(p);
+ return (error);
+ }
+ if ((p->p_flag & P_SYSTEM) != 0) {
+ PROC_UNLOCK(p);
+ return (0);
+ }
+ _PHOLD(p);
+ PROC_UNLOCK(p);
+ error = get_proc_vector(curthread, p, &auxv, &vsize, PROC_AUX);
+ PRELE(p);
+ if (error == 0) {
+#ifdef COMPAT_FREEBSD32
+ if (SV_PROC_FLAG(p, SV_ILP32) != 0)
+ error = SYSCTL_OUT(req, auxv, vsize *
+ sizeof(Elf32_Auxinfo));
+ else
+#endif
+ error = SYSCTL_OUT(req, auxv, vsize * sizeof(Elf_Auxinfo));
+ free(auxv, M_TEMP);
+ }
+ return (error);
+}
+
+/*
* This sysctl allows a process to retrieve the path of the executable for
* itself or another process.
*/
@@ -2035,6 +2424,14 @@ static SYSCTL_NODE(_kern_proc, KERN_PROC
CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE,
sysctl_kern_proc_args, "Process argument list");
+static SYSCTL_NODE(_kern_proc, KERN_PROC_ENV, env,
+ CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE,
+ sysctl_kern_proc_env, "Process environment");
+
+static SYSCTL_NODE(_kern_proc, KERN_PROC_AUXV, auxv,
+ CTLFLAG_RW | CTLFLAG_ANYBODY | CTLFLAG_MPSAFE,
+ sysctl_kern_proc_auxv, "Process ELF auxiliary vector");
+
static SYSCTL_NODE(_kern_proc, KERN_PROC_PATHNAME, pathname, CTLFLAG_RD |
CTLFLAG_MPSAFE, sysctl_kern_proc_pathname, "Process executable path");
Modified: head/sys/sys/proc.h
==============================================================================
--- head/sys/sys/proc.h Tue Nov 22 19:42:17 2011 (r227832)
+++ head/sys/sys/proc.h Tue Nov 22 20:40:18 2011 (r227833)
@@ -168,6 +168,7 @@ struct p_sched;
struct proc;
struct procdesc;
struct racct;
+struct sbuf;
struct sleepqueue;
struct td_sched;
struct thread;
@@ -844,6 +845,10 @@ int p_canwait(struct thread *td, struct
struct pargs *pargs_alloc(int len);
void pargs_drop(struct pargs *pa);
void pargs_hold(struct pargs *pa);
+int proc_getargv(struct thread *td, struct proc *p, struct sbuf *sb,
+ size_t nchr);
+int proc_getenvv(struct thread *td, struct proc *p, struct sbuf *sb,
+ size_t nchr);
void procinit(void);
void proc_linkup0(struct proc *p, struct thread *td);
void proc_linkup(struct proc *p, struct thread *td);
Modified: head/sys/sys/sysctl.h
==============================================================================
--- head/sys/sys/sysctl.h Tue Nov 22 19:42:17 2011 (r227832)
+++ head/sys/sys/sysctl.h Tue Nov 22 20:40:18 2011 (r227833)
@@ -559,6 +559,8 @@ SYSCTL_ALLOWED_TYPES(UINT64, uint64_t *a
#define KERN_PROC_VMMAP 32 /* VM map entries for process */
#define KERN_PROC_FILEDESC 33 /* File descriptors for process
*/
#define KERN_PROC_GROUPS 34 /* process groups */
+#define KERN_PROC_ENV 35 /* get environment */
+#define KERN_PROC_AUXV 36 /* get ELF auxiliary vector */
/*
* KERN_IPC identifiers
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